WorldWideScience

Sample records for borehole seismic imaging

  1. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P Paulsson

    2002-05-01

    Borehole seismology is the highest resolution geophysical imaging technique available to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This proposal takes direct aim at this shortcoming. P/GSI is developing a 400 level 3C clamped downhole seismic receiver array for borehole seismic 3D imaging. This array will remove the acquisition barrier to record the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. By using 3C surface seismic or borehole seismic sources the 400 level receiver array will furthermore facilitate 9C reservoir imaging. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the fluid types. The data quality and the data volumes from a 400 level 3C array will allow us to develop the data processing technology necessary for high resolution reservoir imaging.

  2. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2002-09-01

    Borehole seismology is the highest resolution geophysical imaging technique available to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This proposal takes direct aim at this shortcoming. P/GSI is developing a 400 level 3C clamped downhole seismic receiver array for borehole seismic 3D imaging. This array will remove the acquisition barrier to record the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore facilitate 9C reservoir imaging. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the fluid types. The data quality and the data volumes from a 400 level 3C array will allow us to develop the data processing technology necessary for high resolution reservoir imaging.

  3. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2004-06-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and

  4. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2003-12-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and

  5. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2004-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative

  6. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2004-05-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and

  7. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P Paulsson

    2003-09-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and

  8. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2002-12-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and

  9. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2005-08-21

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction

  10. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P Paulsson

    2003-07-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and

  11. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2004-05-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and

  12. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P Paulsson

    2006-05-05

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction

  13. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2005-03-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction

  14. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS.

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P Paulsson

    2003-01-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and

  15. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N.P. Paulsson

    2004-12-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative

  16. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N. P. Paulsson

    2005-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction

  17. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N. P. Paulsson

    2006-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to perform high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology has been hampered by the lack of acquisition technology necessary to record large volumes of high frequency, high signal-to-noise-ratio borehole seismic data. This project took aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array has removed the technical acquisition barrier for recording the data volumes necessary to do high resolution 3D VSP and 3D cross-well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that promise to take the gas industry to the next level in their quest for higher resolution images of deep and complex oil and gas reservoirs. Today only a fraction of the oil or gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of detailed compartmentalization of oil and gas reservoirs. In this project, we developed a 400 level 3C borehole seismic receiver array that allows for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. This new array has significantly increased the efficiency of recording large data volumes at sufficiently dense spatial sampling to resolve reservoir complexities. The receiver pods have been fabricated and tested to withstand high temperature (200 C/400 F) and high pressure (25,000 psi), so that they can operate in wells up to 7,620 meters (25,000 feet) deep. The receiver array is deployed on standard production or drill tubing. In combination with 3C surface seismic or 3C borehole seismic sources, the 400

  18. 3D seismic imaging around the 2.5 km deep COSC-1 scientific borehole, central Sweden

    Science.gov (United States)

    Hedin, Peter; Juhlin, Christopher; Buske, Stefan

    2015-04-01

    Following the successful completion of the COSC-1 drilling campaign, a number of geophysical investigations have been performed in and around the 2.5 km deep borehole. Three different seismic experiments were conducted simultaneously in the fall of 2014 to take advantage of the same source points; 1) a Vertical Seismic Profile (VSP) in the borehole, 2) three 2D seismic profiles across the borehole, and 3) a limited 3D seismic survey (presented here). The latter is the first 3D seismic survey on land in Scandinavia to target the Caledonian Nappes and will allow mapping a small part of the Seve Nappe Complex (SNC) in 3D. Furthermore, it will allow extrapolation of results from downhole logging, core analysis and other seismic surveys to structures surrounding the borehole. A total number of 429 receivers (10 Hz single component geophones) were planted with 20 m separation along 7 lines spaced 200 m apart. The total area with receivers covered approximately 1.5 km2 and was centered on the drill site. A combination of a mechanical source (a rock breaking hydraulic hammer, near offsets) and explosive charges (0.5 kg fired at 3.5 - 5 m depth, far offsets) were used. The source points were activated along roads radiating outwards from the COSC-1 drill site in a star pattern. The nominal shot spacing was 20 m (vibrating source) or 80 m (explosives) and maximum horizontal offset was about 5.75 km. The high-grade metamorphic SNC is well known from previous 2D seismic studies to be a highly reflective unit. However, due to the complex 3D geometry and lithological variation within the unit, it has not been clearly imaged. The new 3D data provide a means to image these structures in more detail and to follow the lithological and structural interfaces observed in the core into the surrounding unit. Preliminary results from the 3D processing and correlation with borehole data will be presented.

  19. Seismic imaging in the eastern Scandinavian Caledonides: siting the 2.5 km deep COSC-2 borehole, central Sweden

    Science.gov (United States)

    Juhlin, Christopher; Hedin, Peter; Gee, David G.; Lorenz, Henning; Kalscheuer, Thomas; Yan, Ping

    2016-05-01

    The Collisional Orogeny in the Scandinavian Caledonides (COSC) project, a contribution to the International Continental Scientific Drilling Program (ICDP), aims to provide a deeper understanding of mountain belt dynamics. Scientific investigations include a range of topics, from subduction-related tectonics to the present-day hydrological cycle. COSC investigations and drilling activities are focused in central Scandinavia, where rocks from the middle to lower crust of the orogen are exposed near the Swedish-Norwegian border. Here, rock units of particular interest occur in the Seve Nappe Complex (SNC) of the so-called Middle Allochthon and include granulite facies migmatites (locally with evidence of ultra-high pressures) and amphibolite facies gneisses and mafic rocks. This complex overlies greenschist facies metasedimentary rocks of the dolerite-intruded Sarv Nappes and underlying, lower grade Jamtlandian Nappes (Lower Allochthon). Reflection seismic profiles have been an important component in the activities to image the subsurface structure in the area. Subhorizontal reflections in the upper 1-2 km are underlain and interlayered with strong west- to northwest-dipping reflections, suggesting significant east-vergent thrusting. Two 2.5 km deep fully cored boreholes are a major component of the project, which will improve our understanding of the subsurface structure and tectonic history of the area. Borehole COSC-1 (IGSN: http://hdl.handle.net/10273/ICDP5054EEW1001), drilled in the summer of 2014, targeted the subduction-related Seve Nappe Complex and the contact with the underlying allochthon. The COSC-2 borehole will be located further east and will investigate the lower grade, mainly Cambro-Silurian rocks of the Lower Allochthon, the Jamtlandian decollement, and penetrate into the crystalline basement rocks to identify the source of some of the northwest-dipping reflections. A series of high-resolution seismic profiles have been acquired along a composite ca

  20. Site response assessment using borehole seismic records

    Energy Technology Data Exchange (ETDEWEB)

    Park, Donghee; Chang, Chunjoong; Choi, Weonhack [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    In regions with high seismic activity, such as Japan, the Western United States and Taiwan, borehole seismometers installed deep underground are used to monitor seismic activity during the course of seismic wave propagation at various depths and to study the stress changes due to earthquakes and analyze the connection to fault movements. The Korea Meteorological Administration (KMA) and the Korea Institute of Geology and Mining (KIGAM) have installed and are operating borehole seismometers at a depth of 70∼100 meters for the precise determination of epicenters. Also, Korea Hydro and Nuclear Power Co., Ltd. (KHNP) has installed and is operating 2 borehole seismic stations near Weolseong area to observe at a depth of 140 meters seismic activities connected to fault activity. KHNP plans to operate in the second half of 2014 a borehole seismic station for depths less than 300 and 600 meters in order to study the seismic response characteristics in deep strata. As a basic study for analyzing ground motion response characteristics at depths of about 300 to 600 meters in connection with the deep geological disposal of spent nuclear fuel, the present study examined the background noise response characteristics of the borehole seismic station operated by KHNP. In order to analyze the depth-dependent impact of seismic waves at deeper depths than in Korea, seismic data collected by Japan's KIK-net seismic stations were used and the seismic wave characteristics analyzed by size and depth. In order to analyze the borehole seismic observation data from the seismic station operated by KHNP, this study analyzed the background noise characteristics by using a probability density function.

  1. Seismic investigations for high resolution exploration ahead and around boreholes

    Science.gov (United States)

    Jaksch, Katrin; Giese, Ruediger; Kopf, Matthias

    2013-04-01

    interference the signals of each vibrator must be independently controlled in amplitude and phase. This allows a systematic exploration of areas around the borehole and also in direction ahead of the borehole. Measurements of the developed borehole devices with this seismic method show that structures like nearby galleries of the mine or zones of cracks can be explored depending on the issued direction. Imaging with a three-component Fresnel-Volume-Migration shows clearly the effect of the radiation pattern to the distribution of the seismic wave energy. The migration of the reflected wave field reveals an amplification of the reflected amplitudes at the galleries corresponding to the radiation pattern of the seismic borehole sources. A second borehole device was developed for usage in boreholes up to 2 km depth. After completion first measurements are planned to verify the exploration method for a directional investigation in boreholes. The measurements will take place in different geologies of hard and soft rocks and also depths. This project is funded by the German Federal Environment Ministry.

  2. Borehole prototype for seismic high-resolution exploration

    Science.gov (United States)

    Giese, Rüdiger; Jaksch, Katrin; Krauß, Felix; Krüger, Kay; Groh, Marco; Jurczyk, Andreas

    2014-05-01

    Target reservoirs for the exploitation of hydrocarbons or hot water for geothermal energy supply can comprise small layered structures, for instance thin layers or faults. The resolution of 2D and 3D surface seismic methods is often not sufficient to determine and locate these structures. Borehole seismic methods like vertical seismic profiling (VSP) and seismic while drilling (SWD) use either receivers or sources within the borehole. Thus, the distance to the target horizon is reduced and higher resolution images of the geological structures can be achieved. Even these methods are limited in their resolution capabilities with increasing target depth. To localize structures more accuracy methods with higher resolution in the range of meters are necessary. The project SPWD -- Seismic Prediction While Drilling aims at s the development of a borehole prototype which combines seismic sources and receivers in one device to improve the seismic resolution. Within SPWD such a prototype has been designed, manufactured and tested. The SPWD-wireline prototype is divided into three main parts. The upper section comprises the electronic unit. The middle section includes the upper receiver, the upper clamping unit as well as the source unit and the lower clamping unit. The lower section consists of the lower receiver unit and the hydraulic unit. The total length of the prototype is nearly seven meters and its weight is about 750 kg. For focusing the seismic waves in predefined directions of the borehole axis the method of phased array is used. The source unit is equipped with four magnetostrictive vibrators. Each can be controlled independently to get a common wave front in the desired direction of exploration. Source signal frequencies up to 5000 Hz are used, which allows resolutions up to one meter. In May and September 2013 field tests with the SPWD-wireline prototype have been carried out at the KTB Deep Crustal Lab in Windischeschenbach (Bavaria). The aim was to proof the

  3. Borehole Summary Report for Core Hole C4998 – Waste Treatment Plant Seismic Boreholes Project

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, D. BRENT; Garcia, Benjamin J.

    2006-12-15

    Seismic borehole C4998 was cored through the upper portion of the Columbia River Basalt Group and Ellensburg Formation to provide detailed lithologic information and intact rock samples that represent the geology at the Waste Treatment Plant. This report describes the drilling of borehole C4998 and documents the geologic data collected during the drilling of the cored portion of the borehole.

  4. A combined surface and borehole seismic survey at the COSC-1 borehole

    Science.gov (United States)

    Simon, Helge; Krauß, Felix; Hedin, Peter; Buske, Stefan; Giese, Rüdiger; Juhlin, Christopher

    2015-04-01

    we present first preliminary processing results from the multi-azimuthal walkaway VSP survey and the data that were recorded along the three surface lines. The data quality is generally very good and the shot gathers show many clear and strong reflections up to six seconds two-way-traveltime. In a first step the data set was used to derive a detailed velocity model around the borehole from the inversion of first arrival traveltimes, which is essential for the application of any further imaging approaches. This velocity model was compared to the available logging informations from the COSC-1 borehole and with velocity models derived from older existing high resolution reflection seismic profiles. The further data processing will employ advanced seismic imaging techniques in order to image and characterize the small scale structures around the COSC-1 borehole including the analysis of anisotropic effects caused by aligned fractures and faults and their relation to the stress regime.

  5. Development of the Borehole 2-D Seismic Tomography Software Using MATLAB

    Science.gov (United States)

    Nugraha, A. D.; Syahputra, A.; Fatkhan, F.; Sule, R.; Hendriyana, A.

    2011-12-01

    We developed 2-D borehole seismic tomography software that we called "EARTHMAX-2D TOMOGRAPHY" to image subsurface physical properties including P-wave and S-wave velocities between two boreholes. We used Graphic User Interface (GUI) facilities of MATLAB programming language to create the software. In this software, we used travel time of seismic waves from source to receiver by using pseudo bending ray tracing method as input for tomography inversion. We can also set up a model parameterization, initial velocity model, ray tracing processes, conduct borehole seismic tomography inversion, and finally visualize the inversion results. The LSQR method was applied to solve of tomography inversion solution. We provided the Checkerboard Test Resolution (CTR) to evaluate the model resolution of the tomography inversion. As validation of this developed software, we tested it for geotechnical purposes. We then conducted data acquisition in the "ITB X-field" that is located on ITB campus. We used two boreholes that have a depth of 39 meters. Seismic wave sources were generated by impulse generator and sparker and then they were recorded by borehole hydrophone string type 3. Later on, we analyzed and picked seismic arrival time as input for tomography inversion. As results, we can image the estimated weathering layer, sediment layer, and basement rock in the field depicted by seismic wave structures. More detailed information about the developed software will be presented. Keywords: borehole, tomography, earthmax-2D, inversion

  6. Methods for use in detecting seismic waves in a borehole

    Science.gov (United States)

    West, Phillip B.; Fincke, James R.; Reed, Teddy R.

    2007-02-20

    The invention provides methods and apparatus for detecting seismic waves propagating through a subterranean formation surrounding a borehole. In a first embodiment, a sensor module uses the rotation of bogey wheels to extend and retract a sensor package for selective contact and magnetic coupling to casing lining the borehole. In a second embodiment, a sensor module is magnetically coupled to the casing wall during its travel and dragged therealong while maintaining contact therewith. In a third embodiment, a sensor module is interfaced with the borehole environment to detect seismic waves using coupling through liquid in the borehole. Two or more of the above embodiments may be combined within a single sensor array to provide a resulting seismic survey combining the optimum of the outputs of each embodiment into a single data set.

  7. Borehole-explosion and air-gun data acquired in the 2011 Salton Seismic Imaging Project (SSIP), southern California: description of the survey

    Science.gov (United States)

    Rose, Elizabeth J.; Fuis, Gary S.; Stock, Joann M.; Hole, John A.; Kell, Annie M.; Kent, Graham; Driscoll, Neal W.; Goldman, Mark; Reusch, Angela M.; Han, Liang; Sickler, Robert R.; Catchings, Rufus D.; Rymer, Michael J.; Criley, Coyn J.; Scheirer, Daniel S.; Skinner, Steven M.; Slayday-Criley, Coye J.; Murphy, Janice M.; Jensen, Edward G.; McClearn, Robert; Ferguson, Alex J.; Butcher, Lesley A.; Gardner, Max A.; Emmons, Iain; Loughran, Caleb L.; Svitek, Joseph R.; Bastien, Patrick C.; Cotton, Joseph A.; Croker, David S.; Harding, Alistair J.; Babcock, Jeffrey M.; Harder, Steven H.; Rosa, Carla M.

    2013-01-01

    earthquake energy can travel through the sediments. All of these factors determine how hard the earth will shake during a major earthquake. If we can improve on our understanding of how and where earthquakes will occur, and how strong their resultant shaking will be, then buildings can be designed or retrofitted accordingly in order to resist damage and collapse, and emergency plans can be adequately prepared. In addition, SSIP will investigate the processes of rifting and magmatism in the Salton Trough in order to better understand this important plate-boundary region. The Salton Trough is a unique rift in that subsidence is accompanied by huge influxes of infilling sediment from the Colorado River. Volcanism that accompanies the subsidence here is muted by these influxes of sediment. The Salton Trough, in the central part of the Imperial Valley, is apparently made up of entirely new crust: young sediment in the upper crust and basaltic intrusive rocks in the mid-to-lower crust (Fuis and others, 1984). Similar to the ultrasound and computed tomography (CT) scans performed by the medical industry, seismic imaging is a collection of techniques that enable scientists to obtain a picture of what is underground. The petroleum industry routinely uses these techniques to search for oil and gas at relatively shallow depths; however, the scope of this project demanded that we image as much as 30 km into the Earth’s crust. This project generated and recorded seismic waves, similar to sound waves, which move downward into the Earth and are bent (refracted) or echoed (reflected) back to the surface. SSIP acquired data in a series of intersecting lines that cover key areas of the Salton Trough. The sources of sound waves were detonations (shots) in deep boreholes, designed to create energy equivalent to magnitude 1–2 earthquakes. The study region routinely experiences earthquakes of these magnitudes, but earthquakes are not located in such a way as to permit us to create the

  8. Optical instruments for a combined seismic and geodetic borehole observatory

    Science.gov (United States)

    Zumberge, Mark; Agnew, Duncan; Berger, Jonathan; Hatfield, William; Wyatt, Frank

    2016-04-01

    Optical interferometry offers displacement sensing with the unusual combination of high sensitivity, linearity, and wide dynamic range, and it can be adapted to high temperature environments. We have applied interferometric technology to inertial seismic instruments and to optical fibers for strain measurements. When combining these methods into a single borehole package the result is a system that provides three components of observatory quality seismic recordings, two components of tilt, gravity, and vertical strain. The borehole package is entirely passive with the need for only optical fibers to connect the sensor sonde with surface electronics. One of the sensors in the system is an optical fiber strainmeter, which consists of an optical fiber cable elastically stretched between two borehole anchor points separated by 100 m or more. The fiber's length is recorded optically, enabling sub-nanostrain detection of crustal deformations. A second sensor system uses laser interferometry to record the displacements of inertial mechanical suspensions - spring-mass for the vertical component and pendulums for the horizontal components - housed in a borehole sonde. The combined system is able to measure vertical and horizontal ground velocities, gravity, and tilt with sensitivities that compare favorably with any existing borehole system over time scales from 10 Hz to many days; because the downhole components are entirely passive, the instrument will have a long lifetime and could be made usable at high downhole temperatures. The simplicity and longevity of the metal and glass borehole sonde make it suitable for permanent cementation into a borehole to achieve good coupling and stability. Several versions of the borehole inertial system have been deployed on land with excellent results, and a number of our optical fiber strainmeters have been deployed - both onshore and offshore. The combined system is currently under development.

  9. Geology of the Waste Treatment Plant Seismic Boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, D. BRENT; Bjornstad, Bruce N.; Fecht, Karl R.; Lanigan, David C.; Reidel, Steve; Rust, Colleen F.

    2007-02-28

    In 2006, DOE-ORP initiated the Seismic Boreholes Project (SBP) to emplace boreholes at the Waste Treatment Plant (WTP) site in order to obtain direct Vs measurements and other physical property measurements in Columbia River basalt and interbedded sediments of the Ellensburg Formation. The goal was to reduce the uncertainty in the response spectra and seismic design basis, and potentially recover design margin for the WTP. The characterization effort within the deep boreholes included 1) downhole measurements of the velocity properties of the suprabasalt, basalt, and sedimentary interbed sequences, 2) downhole measurements of the density of the subsurface basalt and sediments, and 3) confirmation of the geometry of the contact between the various basalt and interbedded sediments through examination of retrieved core from the corehole and data collected through geophysical logging of each borehole. This report describes the results of the geologic studies from three mud-rotary boreholes and one cored borehole at the WTP. All four boreholes penetrated the entire Saddle Mountains Basalt and the upper part of the Wanapum Basalt where thick sedimentary interbeds occur between the lava flows. The basalt flows penetrated in Saddle Mountains Basalt included the Umatilla Member, Esquatzel Member, Pomona Member and the Elephant Mountain Member. The underlying Priest Rapids Member of the Wanapum Basalt was also penetrated. The Ellensburg Formation sediments consist of the Mabton Interbed, the Cold Creek Interbed, the Selah Interbed and the Rattlesnake Ridge Interbed; the Byron Interbed occurs between two flows of the Priest Rapids Member. The Mabton Interbed marks the contact between the Wanapum and Saddle Mountains Basalts. The thicknesses of the basalts and interbedded sediments were within expected limits. However, a small reverse fault was found in the Pomona Member flow top. This fault has three periods of movement and less than 15 feet of repeated section. Most of the

  10. High-resolution seismic exploration methods for boreholes and tunnels: experiments, results and test site design

    Science.gov (United States)

    Giese, R.; Harms, U.; Jaksch, K.; Krüger, K.

    2012-12-01

    While surface to ground seismic exploration methods are well known, the utilization of seismic waves for underground surveying is less developed. The major challenge in subsurface seismics is the spatial ambiguity of the recorded wave field due to limited aperture of seismic source and receiver survey geometry. We developed novel imaging techniques and the appropriate measurement systems like phased array borehole sources for directional enhancement of seismic wave energy. Different procedures such as 3-component Kirchhoff-Migration and Fresnel-Volume-Migration were tested and improved to enhance the spatial resolution. The goal of these new approaches is to advance instruments for the detection of small-scale tectonic features or lithological changes in boreholes and tunnels. The key component for the experiments was the setup of our underground lab 150 m below surface (education and research mine Reiche Zeche, TU Freiberg, SE Germany). Surrounded by three galleries, the site comprises a block of homogeneous high-grade gneisses of about 50 m width and 100 m length ensuring constant environmental conditions. Along the galleries thirty 3-component geophones are anchored 1-2 m deep with a distance of 4-9 m from each other. Within this test site, two horizontal 8 ½" boreholes (20 and 30 m long) as well as a vertical hole (70 m depth) allow for 3D nearfield seismic experiments for high-resolution exploration and monitoring of geological structures.

  11. Reversible rigid coupling apparatus and method for borehole seismic transducers

    Science.gov (United States)

    Owen, Thomas E.; Parra, Jorge O.

    1992-01-01

    An apparatus and method of high resolution reverse vertical seismic profile (VSP) measurements is shown. By encapsulating the seismic detector and heaters in a meltable substance (such as wax), the seismic detector can be removably secured in a borehole in a manner capable of measuring high resolution signals in the 100 to 1000 hertz range and higher. The meltable substance is selected to match the overall density of the detector package with the underground formation, yet still have relatively low melting point and rigid enough to transmit vibrations to accelerometers in the seismic detector. To minimize voids in the meltable substance upon solidification, the meltable substance is selected for minimum shrinkage, yet still having the other desirable characteristics. Heaters are arranged in the meltable substance in such a manner to allow the lowermost portion of the meltable substance to cool and solidify first. Solidification continues upwards from bottom-to-top until the top of the meltable substance is solidified and the seismic detector is ready for use. To remove, the heaters melt the meltable substance and the detector package is pulled from the borehole.

  12. System and method for generating 3D images of non-linear properties of rock formation using surface seismic or surface to borehole seismic or both

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Cung Khac; Nihei, Kurt Toshimi; Johnson, Paul A.; Guyer, Robert A.; Ten Cate, James A.; Le Bas, Pierre-Yves; Larmat, Carene S.

    2016-06-07

    A system and method of characterizing properties of a medium from a non-linear interaction are include generating, by first and second acoustic sources disposed on a surface of the medium on a first line, first and second acoustic waves. The first and second acoustic sources are controllable such that trajectories of the first and second acoustic waves intersect in a mixing zone within the medium. The method further includes receiving, by a receiver positioned in a plane containing the first and second acoustic sources, a third acoustic wave generated by a non-linear mixing process from the first and second acoustic waves in the mixing zone; and creating a first two-dimensional image of non-linear properties or a first ratio of compressional velocity and shear velocity, or both, of the medium in a first plane generally perpendicular to the surface and containing the first line, based on the received third acoustic wave.

  13. Crosshole investigations - results from seismic borehole tomography

    International Nuclear Information System (INIS)

    The specially developed system for seismic tomography measurements has proved reliable and versatile in field work. The same equipment can be used for measurements from tens of metres up to a distance of 1000 m. The explosive source has proven reliable, in use although time-consuming. It can be used over the full range of distances. The quality of the tomographic analysis is strongly dependent on the areas under study. In homogeneous rock, and at moderate (i.e. up to 200 m) distances, high-precision tomograms can be obtained. On the other hand, if the rock is heterogeneous, and/or the measuring distance large, the many possible solutions make the interpretation difficult. Information from other types of investigations are then usually needed in order to obtain a satisfactory result. Three-dimensional measurements are possible, although time-consuming. (orig./DG)

  14. Geology of the Waste Treatment Plant Seismic Boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, D. Brent; Fecht, Karl R.; Reidel, Stephen P.; Bjornstad, Bruce N.; Lanigan, David C.; Rust, Colleen F.

    2007-05-11

    In 2006, the U.S. Department of Energy initiated the Seismic Boreholes Project (SBP) to emplace boreholes at the Waste Treatment Plant (WTP) site in order to obtain direct shear wave velocity (Vs) measurements and other physical property measurements in Columbia River basalt and interbedded sediments of the Ellensburg Formation. The goal was to reduce the uncertainty in the response spectra and seismic design basis, and potentially recover design margin for the WTP. The characterization effort within the deep boreholes included 1) downhole measurements of the velocity properties of the suprabasalt, basalt, and sedimentary interbed sequences, 2) downhole measurements of the density of the subsurface basalt and sediments, and 3) geologic studies to confirm the geometry of the contact between the various basalt and interbedded sediments through examination of retrieved core from the core hole and data collected through geophysical logging of each borehole. This report describes the results of the geologic studies from three mud-rotary boreholes and one cored borehole at the WTP. All four boreholes penetrated the entire Saddle Mountains Basalt and the upper part of the Wanapum Basalt where thick sedimentary interbeds occur between the lava flows. The basalt flows penetrated in Saddle Mountains Basalt included the Umatilla Member, Esquatzel Member, Pomona Member, and the Elephant Mountain Member. The underlying Priest Rapids Member of the Wanapum Basalt also was penetrated. The Ellensburg Formation sediments consist of the Mabton Interbed, the Cold Creek Interbed, the Selah Interbed, and the Rattlesnake Ridge Interbed; the Byron Interbed occurs between two flows of the Priest Rapids Member. The Mabton Interbed marks the contact between the Wanapum and Saddle Mountains Basalts. The thicknesses of the basalts and interbedded sediments were within expected limits. However, a small reverse fault was found in the Pomona Member flow top. This fault has three periods of

  15. Sampling and Analysis Plan Waste Treatment Plant Seismic Boreholes Project.

    Energy Technology Data Exchange (ETDEWEB)

    Brouns, Thomas M.

    2007-07-15

    This sampling and analysis plan (SAP) describes planned data collection activities for four entry boreholes through the sediment overlying the Saddle Mountains Basalt, up to three new deep rotary boreholes through the Saddle Mountains Basalt and sedimentary interbeds, and one corehole through the Saddle Mountains Basalt and sedimentary interbeds at the Waste Treatment Plant (WTP) site. The SAP will be used in concert with the quality assurance plan for the project to guide the procedure development and data collection activities needed to support borehole drilling, geophysical measurements, and sampling. This SAP identifies the American Society of Testing Materials standards, Hanford Site procedures, and other guidance to be followed for data collection activities. Revision 3 incorporates all interim change notices (ICN) that were issued to Revision 2 prior to completion of sampling and analysis activities for the WTP Seismic Boreholes Project. This revision also incorporates changes to the exact number of samples submitted for dynamic testing as directed by the U.S. Army Corps of Engineers. Revision 3 represents the final version of the SAP.

  16. A Robust MEMS Based Multi-Component Sensor for 3D Borehole Seismic Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Paulsson Geophysical Services

    2008-03-31

    The objective of this project was to develop, prototype and test a robust multi-component sensor that combines both Fiber Optic and MEMS technology for use in a borehole seismic array. The use such FOMEMS based sensors allows a dramatic increase in the number of sensors that can be deployed simultaneously in a borehole seismic array. Therefore, denser sampling of the seismic wave field can be afforded, which in turn allows us to efficiently and adequately sample P-wave as well as S-wave for high-resolution imaging purposes. Design, packaging and integration of the multi-component sensors and deployment system will target maximum operating temperature of 350-400 F and a maximum pressure of 15000-25000 psi, thus allowing operation under conditions encountered in deep gas reservoirs. This project aimed at using existing pieces of deployment technology as well as MEMS and fiber-optic technology. A sensor design and analysis study has been carried out and a laboratory prototype of an interrogator for a robust borehole seismic array system has been assembled and validated.

  17. Borehole seismic in crystalline environment at the COSC-project in Central Sweden

    Science.gov (United States)

    Krauß, Felix; Hedin, Peter; Almqvist, Bjarne; Simon, Helge; Giese, Rüdiger; Buske, Stefan; Juhlin, Christopher; Lorenz, Henning

    2016-04-01

    As support for the COSC drilling project (Collisional Orogeny in the Scandinavian Caledonides), an extensive seismic survey took place during September and October 2014 in and around the newly drilled 2.5 km deep COSC-1 borehole. The main aim of the COSC project is to better understand orogenic processes in past and recently active mountain belts. For this, the Scandinavian Caledonides provide a well preserved case of Paleozoic collision of the Laurentia and Baltica continental plates. Surface geology and geophysical data provide knowledge about the geometry of the Caledonian structure. The reflectivity geometry of the upper crust was imaged by regional seismic data and the resistivity structure by magnetotelluric methods. The crustal model was refined by seismic pre-site surveys in 2010 and 2011 to define the exact position of the first borehole, COSC-1. The completely cored COSC-1 borehole was drilled in Central Sweden through the Seve Nappe Complex, a part of the Middle Allochthon of the Scandinavian Caledonides that comprises units originating from the outer margin of Baltica. The upper 2350 m consist of alternating layers of highly strained felsic and calc-silicate gneisses and amphibolites. Below 1710 m the mylonite content increases successively and indicates a high strain zone of at least 800 m thickness. At ca. 2350 m, the borehole leaves the Seve Nappe Complex and enters underlying mylonitised lower grade metasedimentary units of unknown tectonostratigraphic position. The seismic survey consisted of three parts: a limited 3D-survey, a high resolution zero-offset VSP (vertical seismic profile) and a multi-azimuthal walkaway VSP (MSP) experiment with sources and receivers along three surface profiles and receivers at seven different depth levels of the borehole. For the zero-offset VSP (ZVSP) a hydraulic hammer source was used and activated over a period of 20 s as a sequence of impacts with increasing hit frequency. The wave field was recorded with 3

  18. Reproducibility in Seismic Imaging

    Directory of Open Access Journals (Sweden)

    González-Verdejo O.

    2012-04-01

    Full Text Available Within the field of exploration seismology, there is interest at national level of integrating reproducibility in applied, educational and research activities related to seismic processing and imaging. This reproducibility implies the description and organization of the elements involved in numerical experiments. Thus, a researcher, teacher or student can study, verify, repeat, and modify them independently. In this work, we document and adapt reproducibility in seismic processing and imaging to spread this concept and its benefits, and to encourage the use of open source software in this area within our academic and professional environment. We present an enhanced seismic imaging example, of interest in both academic and professional environments, using Mexican seismic data. As a result of this research, we prove that it is possible to assimilate, adapt and transfer technology at low cost, using open source software and following a reproducible research scheme.

  19. Characterization of magnetized ore bodies based on three-component borehole magnetic and directional borehole seismic measurements

    Science.gov (United States)

    Virgil, Christopher; Neuhaus, Martin; Hördt, Andreas; Giese, Rüdiger; Krüger, Kay; Jurczyk, Andreas; Juhlin, Christopher; Juhojuntti, Niklas

    2016-04-01

    In the last decades magnetic prospecting using total field data was used with great success for localization and characterization of ferromagnetic ore bodies. Especially borehole magnetic measurements reveal important constraints on the extent and depth of potential mining targets. However, due to the inherent ambiguity of the interpretation of magnetic data, the resulting models of the distribution of magnetized material, such as iron ore bodies, are not entirely reliable. Variations in derived parameters like volume and estimated ore content of the expected body have significant impact on the economic efficiency of a planned mine. An important improvement is the introduction of three-component borehole magnetic sondes. Modern tools comprise orientation modules which allow the continuous determination of the tool's heading regardless of the well inclination and independent of the magnetic field. Using the heading information the recorded three-component magnetic data can be transferred from the internal tool's frame to the geographic reference frame. The vector information yields a more detailed and reliable description of the ore bodies compared to total field or horizontal and vertical field data. Nevertheless complementary information to constrain the model is still advisable. The most important supplementary information for the interpretation of magnetic data is the knowledge of the structural environment of the target regions. By discriminating dissimilar rock units, a geometrical starting model can be derived, constraining the magnetic interpretation and leading to a more robust estimation of the rock magnetizations distribution. The most common approach to reveal the lithological setting rests upon seismic measurements. However, for deep drilling targets surface seismic and VSP lack the required spatial resolution of 10s of meters. A better resolution is achieved by using directed sources and receivers inside the borehole. Here we present the application of

  20. Sampling and Analysis Plan - Waste Treatment Plant Seismic Boreholes Project

    Energy Technology Data Exchange (ETDEWEB)

    Reidel, Steve P.

    2006-05-26

    This sampling and analysis plan (SAP) describes planned data collection activities for four entry boreholes through the sediment overlying the basalt, up to three new deep rotary boreholes through the basalt and sedimentary interbeds, and one corehole through the basalt and sedimentary interbeds at the Waste Treatment Plant (WTP) site. The SAP will be used in concert with the quality assurance plan for the project to guide the procedure development and data collection activities needed to support borehole drilling, geophysical measurements, and sampling. This SAP identifies the American Society of Testing Materials standards, Hanford Site procedures, and other guidance to be followed for data collection activities.

  1. Seismic Readings from the Deepest Borehole in the New Madrid Seismic Zone

    Energy Technology Data Exchange (ETDEWEB)

    Woolery, Edward W [KY Geological Survey, Univ of KY; Wang, Zhenming [KY Geological Survey, Univ of KY; Sturchio, Neil C [Dept of earth and Env. Sciences, Univ of Ill at Chicago

    2006-03-01

    Since the 1980s, the research associated with the UK network has been primarily strong-motion seismology of engineering interest. Currently the University of Kentucky operates a strong-motion network of nine stations in the New Madrid Seismic Zone. A unique feature of the network is the inclusions of vertical strong-motion arrays, each with one or two downhole accelerometers. The deepest borehole array is 260 m below the surfaces at station VASA in Fulton County, Kentucky. A preliminary surface seismic refraction survey was conducted at the site before drilling the hole at VSAS (Woolery and Wang, 2002). The depth to the Paleozoic bedrock at the site was estimated to be approximately 595 m, and the depth to the first very stiff layer (i.e. Porters Creek Clay) was found to be about 260 m. These depths and stratigraphic interpretation correlated well with a proprietary seismic reflection line and the Ken-Ten Oil Exploration No. 1 Sanger hole (Schwalb, 1969), as well as our experience in the area (Street et al., 1995; Woolery et al., 1999).

  2. The detection and characterization of natural fractures using P-wave reflection data, multicomponent VSP, borehole image logs and the in-situ stress field determination

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, P. [Coleman Research Corp., Orlando, FL (United States)

    1995-04-01

    The objectives of this project are to detect and characterize fractures in a naturally fractured tight gas reservoir, using surface seismic methods, borehole imaging logs, and in-situ stress field data. Further, the project aims to evaluate the various seismic methods as to their effectiveness in characterizing the fractures, and to formulate the optimum employment of the seismic methods as regards fracture characterization.

  3. Borehole seismic data processing and interpretation: New free software

    Science.gov (United States)

    Farfour, Mohammed; Yoon, Wang Jung

    2015-12-01

    Vertical Seismic Profile (VSP) surveying is a vital tool in subsurface imaging and reservoir characterization. The technique allows geophysicists to infer critical information that cannot be obtained otherwise. MVSP is a new MATLAB tool with a graphical user interface (GUI) for VSP shot modeling, data processing, and interpretation. The software handles VSP data from the loading and preprocessing stages to the final stage of corridor plotting and integration with well and seismic data. Several seismic and signal processing toolboxes are integrated and modified to suit and enrich the processing and display packages. The main motivation behind the development of the software is to provide new geoscientists and students in the geoscience fields with free software that brings together all VSP modules in one easy-to-use package. The software has several modules that allow the user to test, process, compare, visualize, and produce publication-quality results. The software is developed as a stand-alone MATLAB application that requires only MATLAB Compiler Runtime (MCR) to run with full functionality. We present a detailed description of MVSP and use the software to create synthetic VSP data. The data are then processed using different available tools. Next, real data are loaded and fully processed using the software. The data are then integrated with well data for more detailed analysis and interpretation. In order to evaluate the software processing flow accuracy, the same data are processed using commercial software. Comparison of the processing results shows that MVSP is able to process VSP data as efficiently as commercial software packages currently used in industry, and provides similar high-quality processed data.

  4. Inversion of waveforms from Xiangtang borehole seismic array for soil dynamic property

    Institute of Scientific and Technical Information of China (English)

    CHEN Xue-liang; JIN Xing; TAO Xia-xin; WEI Yong-xiang

    2007-01-01

    In order to understand the site soil response of the Xiangtang borehole seismic array under real strong ground motion, reveal the site response, verify the technique of borehole exploration, and improve the precision of in-situ test and laboratory test, this paper presents a new approach, which is composed of two methods. One is the layered site seismic response method, whose layer transform matrix is always real. The other is a global-local optimization technique, which uses genetic algorithm (GA)-simplex method. An inversion of multi-component waveforms of P, SV and SH wave is carried out simultaneously. By inverting the records of three moderate and small earthquakes obtained from the Xiangtang borehole array (2# ) site, the soil dynamic characteristic parameters, including P velocity, damping ratio and frequency-dependent coefficient b, which has not been given in previous literatures, are calculated. The results show that the soil S wave velocity of the Xiangtang 2# borehole is generally greater than that obtained from the 1994 in-situ test, and is close to the velocity of the 3# borehole, which is more than 200 m away from the 2# borehole. Meanwhile, perceptible soil nonlinear behavior under peak ground motion of about 60×10-2 m/s2 is detected by the inversion analysis. The presented method can be used for studying the soil response of other borehole array sites.

  5. Summary Report of Geophysical Logging For The Seismic Boreholes Project at the Hanford Site Waste Treatment Plant.

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, Martin G.; Price, Randall K.

    2007-02-01

    During the period of June through October 2006, three deep boreholes and one corehole were drilled beneath the site of the Waste Treatment Plant (WTP) at the U.S. Department of Energy (DOE) Hanford Site near Richland, Washington. The boreholes were drilled to provide information on ground-motion attenuation in the basalt and interbedded sediments underlying the WTP site. This report describes the geophysical logging of the deep boreholes that was conducted in support of the Seismic Boreholes Project, defined below. The detailed drilling and geological descriptions of the boreholes and seismic data collected and analysis of that data are reported elsewhere.

  6. An acoustic imaging system of migration technique used in borehole

    Institute of Scientific and Technical Information of China (English)

    LIN Weijun; WU Nan; SUN Jian; ZHANG Hailan

    2008-01-01

    In order to detect the damage of casing boreholes, an acoustic imaging method with a two-dimensional ultrasonic array was presented. Each element of the array independently emits down ultrasonic waves, the echoes received by all elements are sampled and transmitted to a computer on ground surface, where the dynamic migration method is used to form a 2 or 3-dimensional image of the situation in the borehole. The numerical simulation and experiment are conducted that demonstrate a high imaging accuracy with a small number of elements used in array. Since the delay circuits used in the traditional phased array imaging system is not needed in this system, and all data process could be completed in a ground system,the complexity and the volume of system in borehole may be significantly simplified, which is critical to the borehole instrument.

  7. Seismic signatures of partial saturation on acoustic borehole modes

    NARCIS (Netherlands)

    Chao, G.E.; Smeulders, D.M.J.; Van Dongen, M.E.H.

    2007-01-01

    We present an exact theory of attenuation and dispersion of borehole Stoneley waves propagating along porous rocks containing spherical gas bubbles by using the Biot theory. An effective frequency-dependent fluid bulk modulus is introduced to describe the dynamic (oscillatory) behavior of the gas bu

  8. Chemical energy system for a borehole seismic source. [Final report

    Energy Technology Data Exchange (ETDEWEB)

    Engelke, R.; Hedges, R.O.

    1996-03-01

    We describe a detonation system that will be useful in the seismological examination of geological structures. The explosive component of this system is produced by the mixing of two liquids; these liquids are classified as non-explosive materials by the Department of Transportation. This detonation system could be employed in a borehole tool in which many explosions are made to occur at various points in the borehole. The explosive for each explosion would be mixed within the tool immediately prior to its being fired. Such an arrangement ensures that no humans are ever in proximity to explosives. Initiation of the explosive mixture is achieved with an electrical slapper detonator whose specific parameters are described; this electrical initiation system does not contain any explosive. The complete electrical/mechanical/explosive system is shown to be able to perform correctly at temperatures {le}120{degrees}C and at depths in a water-filled borehole of {le} 4600 ft (i.e., at pressures of {le}2000 psig).

  9. Microseismic Monitoring Using Surface and Borehole Seismic Stations in an Oil Field, North Oman

    Science.gov (United States)

    El-Hussain, I.; Al-Hashmi, S.; Al-Shijbi, Y.; Al-Saifi, M.; Al-Toubi, K.; Al-Lazki, A.; Al-Kindy, F.

    2009-05-01

    Five shallow borehole seismic stations were installed to monitor microearthquake activities in a carbonate oil field in northern Oman since 1999. This shallow network of seismic station operated continuously until 2002 after which intermittent seismic recording took place due to lack of maintenance and failure of some stations. The objectives of the study are to determine the microseismic parameters in the oil field and to determine the spatial and temporal distribution of these events to evaluate possible triggering mechanism. Well over 400 microearthquakes per year were recorded in the first three years of operation and after that the level of seismic recording fell to less than 200 microearthquakes per year due to failure of some stations. In March 2008, temporary seismic experiment consisting of five near surface seismic stations were installed in the oil field to augment the shallow network station and to evaluate surface installment of seismic instrument to monitor microseismic activities. It has been recognized that microearthquakes data such as size, spatial, and temporal distribution provide information on the pressure waves initiated by either production of or injection of fluids into reservoirs. A total of 44 local microearthquake events were analyzed and located during the temporary seismic stations deployment using a non-linear location software that allows the use of variable accurate velocity model of the subsurface. The events location is confined to oil field reservoir boundary during the recording period and more events occurring at shallow depth. The correlation coefficient between gas production and number of events is the higher compared with the oil production or water injection. The focal plane solution for the largest event in the sequence indicates normal faulting with extensional stress consistent with the existing mapped normal faults in the oil field. Microseismic signal clearly detected by the collocated sensors of the near surface

  10. Design of technique for foliation measurements from borehole images, borehole OL-KR12

    International Nuclear Information System (INIS)

    Posiva carries out investigations and preparations for spent nuclear fuel disposal in Finnish bedrock in Olkiluoto. The orientation and location of the bedrock foliation, its relation to brokenness and other foliation-related bedrock properties are important factors in planning the facilities for final disposal of the spent nuclear fuel, and in assessing the functionality and safety of the facilities. The borehole optical imaging (BIP, OPTV) has become one of the central data sets of site investigations available from several Olkiluoto deep boreholes. The data was assessed to be suitable for detailed foliation mapping. This work aimed at development of foliation observations and classifications, and verified the observations from core. The report will describe the work and give recommendations for similar later approach. OL- KR12 was selected due to its central location, favourable near- perpendicular orientation with respect to known site-scale foliation (160/45), reasonable length (795.34 m, covering the depth level of the planned depository facilities), and abundant fractures (to compare with orientation of the foliation), as well as because a higher resolution OPTV image was available from it. The type, intensity, location and local orientation of foliation and the rock type containing the foliation were acquired. The concordance between the foliation and rock banding was also collected as a separate parameter. The acquisition of parameters was performed with several parallel methods to find out the best possible working procedure. In the main results of comparison, three different principles were found: 1. the initially 10 meter long borehole TV images were appended to form images of longer depth intervals (30-100 meters) before the foliation measurements. 2. The person performing measurements should be concentrating on one parameter at a time, each phase performed in defined sequence, 3. After measurements, the data must be carefully revised from the drill

  11. Stochastic estimation of aquifer geometry using seismic refraction data with borehole depth constraints

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.; Hubbard, S.S.; Gaines, D.; Korneev, V.; Baker, G.; Watson, D.

    2010-09-01

    We develop a Bayesian model to invert surface seismic refraction data with depth constraints from boreholes for characterization of aquifer geometry and apply it to seismic and borehole datasets collected at the contaminated Oak Ridge National Laboratory site in Tennessee. Rather than the traditional approach of first inverting the seismic arrival times for seismic velocity and then using that information to aid in the spatial interpolation of wellbore data, we jointly invert seismic first arrival time data and wellbore-based information, such as depths of key lithological boundaries. We use a staggered-grid finite-difference algorithm with second order accuracy in time and fourth order accuracy in space to model seismic full waveforms and use an automated method to pick the first arrival times. We use Markov Chain Monte Carlo methods to draw many samples from the joint posterior probability distribution, on which we can estimate the key interfaces and their associated uncertainty as a function of horizontal location and depth. We test the developed method on both synthetic and field case studies. The synthetic studies show that the developed method is effective at rigorous incorporation of multiscale data and the Bayesian inversion reduces uncertainty in estimates of aquifer zonation. Applications of the approach to field data, including two surface seismic profiles located 620 m apart from each other, reveal the presence of a low-velocity subsurface zone that is laterally persistent. This geophysically-defined feature is aligned with the plume axis, suggesting it may serve as an important regional preferential flow pathway.

  12. Borehole seismic monitoring of CO2 storage within a saline aquifer at Ketzin, Germany

    OpenAIRE

    J. Götz

    2014-01-01

    This thesis is about borehole seismic monitoring of CO2 storage within a saline aquifer at Ketzin, Germany. CO2 storage is part of the process ’Carbon dioxide Capture and Storage (CCS)’. As a greenhouse gas, CO2 contributes to the global warming, therefore efforts are made to slow down the increase of CO2 concentration in the atmosphere. CCS is considered because ”fossil fuels are the dominant form of energy utilised in the world (86 %) and account for 75% of current anthropoge...

  13. Geological interpretation of borehole image and sonic logs. A case study from the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Vahle, C. [Eriksfiord GmbH, Walldorf (Germany)

    2013-08-01

    Borehole imagers and dipole sonic tools form the ideal pair of instruments for observation and evaluation of structural tilt, faulting and fracturing as well as sediment transport direction and depositional architecture. In addition, the stress field can be inverted in combination with rock mechanical data. The structural tilt and its variation along the well are evaluated in stereograms and projections along the well trace. Changes in structural tilt are attributed to fault block rotation as well as angular unconformities. Fault zones are usually easily recognised in borehole images by e.g. juxtaposition of different strata/facies and deformation of adjacent layering. Integration with micro-scale core data as well as macro-scale seismics, if available, is of vital importance. Furthermore, calibration against core observations is helpful for e.g. fracture characterisation. The stress field orientation is interpreted from breakout and drilling-induced fractures, which are usually easy to detect in borehole images. However, in case of slanted and highly deviated wells the full stress tensor including the stress magnitudes is necessary to evaluate the stress field orientation. The full stress tensor is inverted by utilising rock mechanical data from core measurement and/or from empirical relations with elastic properties such as Poission's ratio and Young's modulus with respect to breakout and drilling-induced fractures. In addition, the stress field can be simulated using numerical methods to match the current observations. Sedimentary features such as cross-beds or slumps may indicate sediment transport directions after the data set was corrected for structural tilt. Image facies and their stacking patterns in combination with standard petrophysical curves are interpreted with respect to the depositional environment and included in a sequence stratigraphic framework. A correlation with core observations provides important calibration of the image facies

  14. Seismic Observation in Deep Boreholes and Its Applications - Workshop Proceedings, Niigata Institute of Technology, Kashiwazaki, Japan

    International Nuclear Information System (INIS)

    4 was only 70% that of Unit 2 at the same site. Given these circumstances, JNES initiated the 'Observation and Evaluation Study of Ground Motion Amplification' project by drilling a three-kilometer deep borehole on the premises of the Niigata Institute of Technology, which is located near the Kashiwazaki site, and proposed a series of workshops related to deep underground seismic observation and ground motion evaluation to the Seismic Subgroup of the OECD/NEA/IAGE Group at the April 2010 meeting. The first was held from 24-26 November 2010 as part of the first Kashiwazaki International Symposium on seismic safety, and the second was held on 7 to 9 November 2012. In the second WS, 36 papers were presented by the participants from eight countries including two international organizations, and discussed in three sessions (i.e. observation technology, evaluation of the observed seismic motion and the multipurpose use). Regarding the observation technology session, useful lessons-learned in probe development, setup and maintenance under the challenging conditions posed by great depth were described. This information from SAFORD and Kashiwazaki was thought to be particularly valuable for the planning and operation of similar facilities. As for the seismic observations from a deep borehole, it was identified that such observations are very effective for investigation of the earthquake generating process and are important for detailed understanding of the three-dimensional underground structure. There is not yet much experience with observation and application of a deep borehole, and therefore future developments and achievements are expected. The importance of simple ground motion evaluation technology combined with geophysical exploration was also acknowledged. Examples of multipurpose utilization and the advantage of seismic observations in deep boreholes were discussed. Multipurpose use was discussed not only for seismic design and evaluation of nuclear installations

  15. An Effective Method for Borehole Imaging of Buried Tunnels

    Directory of Open Access Journals (Sweden)

    Loreto Di Donato

    2012-01-01

    Full Text Available Detection and imaging of buried tunnels is a challenging problem which is relevant to both geophysical surveys and security monitoring. To comply with the need of exploring large portions of the underground, electromagnetic measurements carried out under a borehole configuration are usually exploited. Since this requires to drill holes in the soil wherein the transmitting and receiving antennas have to be positioned, low complexity of the involved apparatus is important. On the other hand, to effectively image the surveyed area, there is the need for adopting efficient and reliable imaging methods. To address these issues, in this paper we investigate the feasibility of the linear sampling method (LSM, as this inverse scattering method is capable to provide almost real-time results even when 3D images of very large domains are built, while not requiring approximations of the underlying physics. In particular, the results of the reported numerical analysis show that the LSM is capable of performing the required imaging task while using a quite simple measurement configuration consisting of two boreholes and a few number of multiview-multistatic acquisitions.

  16. Using stochastic borehole seismic velocity tomography and Bayesian simulation to estimate Ni, Cu and Co grades.

    Science.gov (United States)

    Perozzi, Lorenzo; Gloaguen, Erwan; Rondenay, Stephane; Leite, André; McDowell, Glenn; Wheeler, Robert

    2010-05-01

    In the mining industry, classic methods to build a grade model for ore deposits are based on kriging or cokriging of grades for targeted minerals measured in drill core in fertile geological units. As the complexity of the geological geometry increases, so does the complexity of grade estimations. For example, in layered mafic or ultramafic intrusions, it is necessary to know the layering geometry in order to perform kriging of grades in the most fertile zones. Without additional information on geological framwork, the definition of fertile zones is a low-precision exercise that requires extensive experience and good ability from the geologist. Recently, thanks to computer and geophysical tool improvements, seismic tomography became very attractive for many application fields. Indeed, this non-intrusive technique allows inferring the mechanical properties of the ground using travel times and amplitude analysis of the transmitted wavelet between two boreholes, hence provide additional information on the nature of the deposit. Commonly used crosshole seismic velocity tomography algorithms estimate 2D slowness models (inverse of velocity) in the plane between the boreholes using the measured direct wave travel times from the transmitter (located in one of the hole) to the receivers (located in the other hole). Furthermore, geophysical borehole logging can be used to constrain seismic tomography between drill holes. Finally, this project aims to estimate grade of economically worth mineral by integrating seismic tomography data with respectively drill core measured grades acquired by Vale Inco for one of their mine sites in operation. In this study, a new type algorithm that combines geostatistical simulation and tomography in the same process (namely stochastic tomography) has been used. The principle of the stochastic tomography is based on the straight ray approximation and use the linear relationship between travel time and slowness to estimate the slowness

  17. Microearthquake Observations in a 7-level Vertical Seismic Array in the TCDP Borehole, Taiwan

    Science.gov (United States)

    Lin, Y.; Wu, H.; Ma, K.; Oye, V.; Tanaka, H.

    2007-12-01

    In order to obtain in-situ information on slip zones of the 1999 Chi-Chi earthquake, the Taiwan Chelungpu-fault drilling project (TCDP) drilled two vertical boreholes (A, B) and a branch hole (C) through the fault where a displacement of 12 m had occurred. The TCDP hole A is 2 km deep, and a slip zone was identified at a depth of 1111 m. Hole B (with side track, hole C) is 1.3 km deep with an identified slip zone at 1138 m. In July 2006, a 7- level vertical borehole seismic array (TCDP BHS) was installed in hole A covering a depth from 946 m to 1274 m with 50- 60 m depth intervals. For this layout, three seismometers were placed in the hanging wall and footwall, respectively. The forth one is located at the depth of 1110.28 m, close to the identified slip zone. Microearthquakes with magnitude down to -0.5 were detected by the TCDP BHS. A temporary seismic array with 10 short period seismometers around the TCDP drill site was also installed to incorporate with the TCDP BHS for the precise locations of the microearthquakes. A real-time location software (MIMO) (Oye and Roth, 2003) was used to automatically determine P- and S-wave onset times, incidence and azimuth angles and locations of the microearthquakes. Regardless of the large co-seismic slip of 12 m at the drill site during the 1999 Chi-Chi earthquake, our preliminary studies do not show any close-by seismicity near the drill site after almost 8 years since the large earthquake happened. The microearthquakes clustered at a depth of 8-10 km, where the 30 degree dipping of the Chelungpu thrust fault becomes flat to a decollement of the Taiwan fold-and-thrust tectonic structure. As a continuous GPS survey did not observe post-slip at the large slip region, and as no seismicity was observed near the drill site, we suggest that the thrust belt above the decollement during the interseismic period seems to be locked. A Fluid Injection Test (FIT), pumping high pressure fluid into hole B and C with hole A as

  18. Change in Seismic Attenuation of the Nojima Fault Zone Measured Using Spectral Ratios from Borehole Seismometers

    Science.gov (United States)

    Kano, Y.; Tadokoro, K.; Nishigami, K.; Mori, J.

    2006-12-01

    We measured the seismic attenuation of the rock mass surrounding the Nojima fault, Japan, by estimating the P-wave quality factor, Qp, using spectral ratios derived from a multi-depth (800 m and 1800 m) seismometer array. We detected an increase of Qp in 2003-2006 compared to 1999-2000. Following the 1995 Kobe earthquake, the project "Fault Zone Probe" drilled three boreholes to depths of 500 m, 800 m, 1800 m, in Toshima, along the southern part of the Nojima fault. The 1800-m borehole was reported to reach the fault surface. One seismometer (TOS1) was installed at the bottom of the 800-m borehole in 1996 and another (TOS2) at the bottom of 1800-m borehole in 1997. The sampling rate of the seismometers is 100 Hz. The slope of the spectral ratios for the two stations plotted on a linear-log plot is -π t^{*}, where t^{*} is the travel time divided by the Qp for the path difference between the stations. For the estimation of Qp, we used events recorded by both TOS1 and TOS2 for periods of 1999-2000 and 2003-2006. To improve the signal-to-noise ratio of the spectral ratios, we first calculated spectra ratios between TOS1 and TOS2 for each event and averaged the values over the earthquakes for each period. We used the events that occurred within 10 km from TOS2, and the numbers of events are 74 for 1999-2000 and 105 for 2003-2006. Magnitudes of the events range from M0.5 to M3.1. The average value of Qp for 1999-2000 increased significantly compared to 2003-2006. The attenuation of rock mass surrounding the fault in 2003-2006 is smaller than that in 1999-2000, which suggests that the fault zone became stiffer after the earthquake. At the Nojima fault, permeability measured by repeated pumping tests decreased with time from the Kobe earthquake, infering the closure of cracks and a fault healing process occurred The increase of Qp is another piece of evidence for the healing process of the Nojima fault zone. u.ac.jp/~kano/

  19. Surface and borehole electromagnetic imaging of conducting contaminant plumes. 1997 annual progress report

    International Nuclear Information System (INIS)

    'Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The EM source field is produced by induction coil (magnetic dipole) transmitters deployed at the surface or in boreholes. Vertical and horizontal component magnetic field detectors are deployed in other boreholes or on the surface. Sources and receivers are typically deployed in a configuration surrounding the region of interest. The goal of this procedure is to image electrical conductivity variations in the earth, much as x-ray tomography is used to image density variations through cross-sections of the body. Although such EM field techniques have been developed and applied, the algorithms for inverting the magnetic data to produce the desired images of electrical conductivity have not kept pace. One of the main reasons for the lag in the algorithm development has been the fact that the magnetic induction problem is inherently three dimensional: other imaging methods such as x-ray and seismic can make use of two-dimensional approximations that are not too far from reality, but the author does not have this luxury in EM induction tomography. In addition, previous field experiments were conducted at controlled test sites that typically do not have much external noise or extensive surface clutter problems often associated with environmental sites. To use the same field techniques in environments more typical of cleanup sites requires a new set of data processing tools to remove the effects of both noise and clutter. The goal of this project is to join theory and experiment to produce enhanced images of electrically conducting fluids underground, allowing better localization of contaminants and improved planning strategies for the subsequent remediation efforts. After explaining the physical context in more detail, this report will summarize the progress made in the first year of this project: (1) on code development and (2) on field tests of

  20. Quantitative elastic migration. Applications to 3D borehole seismic surveys; Migration elastique quantitative. Applications a la sismique de puits 3D

    Energy Technology Data Exchange (ETDEWEB)

    Clochard, V.

    1998-12-02

    3D VSP imaging is nowadays a strategic requirement by petroleum companies. It is used to precise in details the geology close to the well. Because of the lack of redundancy and limited coverage in the data. this kind of technology is more restrictive than surface seismic which allows an investigation at a higher scale. Our contribution was to develop an elastic quantitative imagine (GRT migration) which can be applied to 3 components borehole dataset. The method is similar to the Kirchhoff migration using sophistical weighting of the seismic amplitudes. In reality. GRT migration uses pre-calculated Green functions (travel time. amplitude. polarization). The maps are obtained by 3D ray tracing (wavefront construction) in the velocity model. The migration algorithm works with elementary and independent tasks. which is useful to process different kind of dataset (fixed or moving geophone antenna). The study has been followed with validations using asymptotic analytical solution. The ability of reconstruction in 3D borehole survey has been tested in the Overthrust synthetic model. The application to a real circular 3D VSP shows various problems like velocity model building, anisotropy factor and the preprocessing (deconvolution. wave mode separation) which can destroy seismic amplitudes. An isotropic 3 components preprocessing of the whole dataset allows a better lateral reconstruction. The choice of a big migration aperture can help the reconstruction of strong geological dip in spite of migration smiles. Finally, the methodology can be applied to PS converted waves. (author)

  1. New UK in-situ stress orientation for northern England and controls on borehole wall deformation identified using borehole imaging

    Science.gov (United States)

    Kingdon, Andrew; Fellgett, Mark W.; Waters, Colin N.

    2016-04-01

    The nascent development of a UK shale gas industry has highlighted the inadequacies of previous in-situ stress mapping which is fundamental to the efficacy and safety of potential fracturing operations. The limited number of stress inversions from earthquake focal plane mechanisms and overcoring measurements of in-situ stress in prospective areas increases the need for an up-to-date stress map. Borehole breakout results from 36 wells with newly interpreted borehole imaging data are presented. Across northern England these demonstrate a consistent maximum horizontal stress orientation (SHmax) orientation of 150.9° and circular standard deviation of 13.1°. These form a new and quality assured evidence base for both industry and its regulators. Widespread use of high-resolution borehole imaging tools has facilitated investigation of micro-scale relationships between stress and lithology, facilitating identification of breakouts as short as 25 cm. This is significantly shorter than those identified by older dual-caliper logging (typically 1-10+ m). Higher wall coverage (90%+ using the highest resolution tools) and decreasing pixel size (down to 4mm vertically by 2° of circumference) also facilitates identification of otherwise undetectable sub-centimetre width Drilling Induced Tensile Fractures (DIFs). Examination of borehole imaging from wells in North Yorkshire within the Carboniferous Pennine Coal Measures Group has showed that even though the stress field is uniform, complex micro-stress relationships exist. Different stress field indicators (SFI) are significantly affected by geology with differing failure responses from adjacent lithologies, highlighted by borehole imaging on sub-metre scales. Core-log-borehole imaging integration over intervals where both breakouts and DIFs have been identified allows accurate depth matching and thus allows a synthesis of failure for differing lithology and micro-structures under common in-situ conditions. Understanding these

  2. Geophysical borehole logging, dummy-sonding and optical imaging of the borehole OL-KR24 at Olkiluoto 2005

    International Nuclear Information System (INIS)

    Suomen Malmi Oy conducted geophysical borehole logging, dummy-sonding and optical imaging surveys of the borehole OL-KR24 at the Olkiluoto site in Eurajoki during 1.10.2005 - 4.10.2005. The survey is a part of Posiva Oy's detailed investigation program for the final disposal of spent nuclear fuel. The methods applied are caliper survey and optical imaging. The assignment included the field work of surveys, interpretation and processing of the data. The report describes the field operation, equipment as well as processing procedures and shows the obtained results and their quality in the appendices. The raw and processed data are delivered digitally in WellCAD and Excel format. (orig.)

  3. Development and Test of a 1,000 Level 3C Fiber Optic Borehole Seismic Receiver Array Applied to Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Paulsson, Bjorn N.P. [Paulsson, Inc., Van Nuys, CA (United States)

    2015-02-28

    To address the critical site characterization and monitoring needs for CCS programs, US Department of Energy (DOE) awarded Paulsson, Inc. in 2010 a contract to design, build and test a fiber optic based ultra-large bandwidth clamped borehole seismic vector array capable of deploying up to one thousand 3C sensor pods suitable for deployment into high temperature and high pressure boreholes. Paulsson, Inc. has completed a design or a unique borehole seismic system consisting of a novel drill pipe based deployment system that includes a hydraulic clamping mechanism for the sensor pods, a new sensor pod design and most important – a unique fiber optic seismic vector sensor with technical specifications and capabilities that far exceed the state of the art seismic sensor technologies. These novel technologies were all applied to the new borehole seismic system. In combination these technologies will allow for the deployment of up to 1,000 3C sensor pods in vertical, deviated or horizontal wells. Laboratory tests of the fiber optic seismic vector sensors developed during this project have shown that the new borehole seismic sensor technology is capable of generating outstanding high vector fidelity data with extremely large bandwidth: 0.01 – 6,000 Hz. Field tests have shown that the system can record events at magnitudes much smaller than M-2.3 at frequencies up to 2,000 Hz. The sensors have also proved to be about 100 times more sensitive than the regular coil geophones that are used in borehole seismic systems today. The fiber optic seismic sensors have furthermore been qualified to operate at temperatures over 300°C (572°F). The fibers used for the seismic sensors in the system are used to record Distributed Temperature Sensor (DTS) data allowing additional value added data to be recorded simultaneously with the seismic vector sensor data.

  4. Challenges and opportunities for fractured rock imaging using 3D cross-borehole electrical resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Judith; Johnson, Timothy C.; Slater, Lee D.

    2015-02-02

    There is an increasing need to characterize discrete fractures away from boreholes to better define fracture distributions and monitor solute transport. We performed a 3D evaluation of static and time-lapse cross-borehole electrical resistivity tomography (ERT) data sets from a limestone quarry in which flow and transport are controlled by a bedding-plane feature. Ten boreholes were discretized using an unstructured tetrahedral mesh, and 2D panel measurements were inverted for a 3D distribution of conductivity. We evaluated the benefits of 3D versus 2.5D inversion of ERT data in fractured rock while including the use of borehole regularization disconnects (BRDs) and borehole conductivity constraints. High-conductivity halos (inversion artifacts) surrounding boreholes were removed in static images when BRDs and borehole conductivity constraints were implemented. Furthermore, applying these constraints focused transient changes in conductivity resulting from solute transport on the bedding plane, providing a more physically reasonable model for conductivity changes associated with solute transport at this fractured rock site. Assuming bedding-plane continuity between fractures identified in borehole televiewer data, we discretized a planar region between six boreholes and applied a fracture regularization disconnect (FRD). Although the FRD appropriately focused conductivity changes on the bedding plane, the conductivity distribution within the discretized fracture was nonunique and dependent on the starting homogeneous model conductivity. Synthetic studies performed to better explain field observations showed that inaccurate electrode locations in boreholes resulted in low-conductivity halos surrounding borehole locations. These synthetic studies also showed that the recovery of the true conductivity within an FRD depended on the conductivity contrast between the host rock and fractures. Our findings revealed that the potential exists to improve imaging of fractured

  5. Investigation on the real-time prediction of ground motions using seismic records observed in deep boreholes

    Science.gov (United States)

    Miyakoshi, H.; Tsuno, S.

    2013-12-01

    The present method of the EEW system installed in the railway field of Japan predicts seismic ground motions based on the estimated earthquake information about epicentral distances and magnitudes using initial P-waves observed on the surface. In the case of local earthquakes beneath the Tokyo Metropolitan Area, however, a method to directly predict seismic ground motions using P-waves observed in deep boreholes could issue EEWs more simply and surely. Besides, a method to predict seismic ground motions, using S-waves observed in deep boreholes and S-wave velocity structures beneath seismic stations, could show planar distributions of ground motions for train operation control areas in the aftermath of earthquakes. This information is available to decide areas in which the emergency inspection of railway structures should be performed. To develop those two methods, we investigated relationships between peak amplitudes on the surface and those in deep boreholes, using seismic records of KiK-net stations in the Kanto Basin. In this study, we used earthquake accelerograms observed in boreholes whose depths are deeper than the top face of Pre-Neogene basement and those on the surface at 12 seismic stations of KiK-net. We selected 243 local earthquakes whose epicenters are located around the Kanto Region. Those JMA magnitudes are in the range from 4.5 to 7.0. We picked the on-set of P-waves and S-waves using a vertical component and two horizontal components, respectively. Peak amplitudes of P-waves and S-waves were obtained using vertical components and vector sums of two horizontal components, respectively. We estimated parameters which represent site amplification factors beneath seismic stations, using peak amplitudes of S-waves observed in the deep borehole and those on the surface, to minimize the residuals between calculations by the theoretical equation and observations. Correlation coefficients between calculations and observations are high values in the range

  6. Seismic time-lapse monitoring of potential gas hydrate dissociation around boreholes : could it be feasible? A conceptual 2D study linking geomechanical and seismic FD models

    Energy Technology Data Exchange (ETDEWEB)

    Pecher, I.; Yang, J.; Anderson, R.; Tohidi, B.; MacBeth, C. [Heriot-Watt Univ., Edinburgh (United Kingdom). Inst. of Petroleum Engineering; Freij-Ayoub, R.; Clennell, B. [CSIRO Petroleum, Bentley, WA (Australia)

    2008-07-01

    Dissociation of gas hydrate to water and potentially overpressured gas around boreholes may pose a hazard for deep-water hydrocarbon production. Strategies to mitigate this risk include monitoring for early detection of dissociation. Seismic methods are especially promising, primarily because of a high sensitivity of P-wave velocity to gas in the pore space of unconsolidated sediments. This paper presented a study that applied commonly used rock physics modeling to predict the seismic response to gas hydrate dissociation with a focus on P-impedance and performed sensitivity tests. The geomechanical model was translated into seismic models. In order to determine which parameters needed to be particularly well calibrated in experimental and modeling studies, the sensitivity of seismic properties to a variation of input parameters was estimated. The seismic response was predicted from dissociating gas hydrates using two-dimensional finite-difference wave-propagation modeling to demonstrate that despite the small predicted lateral extent of hydrate dissociation, its pronounced effect on seismic properties should allow detection with a seismic source on a drilling platform and receivers on the seafloor. The paper described the methods, models, and results of the study. It was concluded that the key factors for predicting the seismic response of sediments to hydrate dissociation were the mode of gas hydrate distribution, gas distribution in the sediments, gas saturation, and pore pressure. 33 refs., 3 tabs., 8 figs.

  7. Seismically Initiated Carbon Dioxide Gas Bubble Growth in Groundwater: A Mechanism for Co-seismic Borehole Water Level Rise and Remotely Triggered Secondary Seismicity

    Science.gov (United States)

    Crews, Jackson B.

    of freshwater. Co-seismic borehole water level increases of the same magnitude were observed in Parkfield, California, and Long Valley caldera, California, in response to the propagation of a Rayleigh wave in the same amplitude and frequency range produced by the June 28, 1992 MW 7.3 Landers, California, earthquake. Co-seismic borehole water level rise is well documented in the literature, but the mechanism is not well understood, and the results of core-scale experiments indicate that seismically initiated CO2 gas bubble nucleation and growth in groundwater is a reasonable mechanism. Remotely triggered secondary seismicity is also well documented, and the reduction of effective stress due to CO2 bubble nucleation and growth in critically loaded faults may potentially explain how, for example, the June 28, 1992 MW 7.3 Landers, California, earthquake triggered seismicity as far away as Yellowstone, Wyoming, 1250 km from the hypocenter. A numerical simulation was conducted using Euler's method and a first-order kinetic model to compute the pore fluid pressure response to confining stress excursions on a Berea sandstone core flooded with initially under-saturated aqueous CO2. The model was calibrated on the pore pressure response to a rapid drop and later recovery of the confining stress. The model predicted decreasing overpressure as the confining stress oscillation frequency increased from 0.05 Hz to 0.30 Hz, in contradiction with the experimental results and field observations, which exhibit larger excess pore fluid pressure in response to higher frequency oscillations. The limitations of the numerical model point to the important influence of non-ideal behavior arising from a discontinuous gas phase and complex dynamics at the gas-liquid interface.

  8. Elastic-Wavefield Seismic Stratigraphy: A New Seismic Imaging Technology

    Energy Technology Data Exchange (ETDEWEB)

    Bob A. Hardage; Milo M. Backus; Michael V. DeAngelo; Sergey Fomel; Khaled Fouad; Robert J. Graebner; Paul E. Murray; Randy Remington; Diana Sava

    2006-07-31

    The purpose of our research has been to develop and demonstrate a seismic technology that will provide the oil and gas industry a better methodology for understanding reservoir and seal architectures and for improving interpretations of hydrocarbon systems. Our research goal was to expand the valuable science of seismic stratigraphy beyond the constraints of compressional (P-P) seismic data by using all modes (P-P, P-SV, SH-SH, SV-SV, SV-P) of a seismic elastic wavefield to define depositional sequences and facies. Our objective was to demonstrate that one or more modes of an elastic wavefield may image stratal surfaces across some stratigraphic intervals that are not seen by companion wave modes and thus provide different, but equally valid, information regarding depositional sequences and sedimentary facies within that interval. We use the term elastic wavefield stratigraphy to describe the methodology we use to integrate seismic sequences and seismic facies from all modes of an elastic wavefield into a seismic interpretation. We interpreted both onshore and marine multicomponent seismic surveys to select the data examples that we use to document the principles of elastic wavefield stratigraphy. We have also used examples from published papers that illustrate some concepts better than did the multicomponent seismic data that were available for our analysis. In each interpretation study, we used rock physics modeling to explain how and why certain geological conditions caused differences in P and S reflectivities that resulted in P-wave seismic sequences and facies being different from depth-equivalent S-wave sequences and facies across the targets we studied.

  9. Scientific results from the deepened Lopra-1 borehole, Faroe Islands: Borehole seismic studies of a volcanic succession from the Lopra-1/1A borehole in the Faroe Islands, northern North Atlantic

    Directory of Open Access Journals (Sweden)

    Cowper, David

    2006-07-01

    Full Text Available Extruded basalt flows overlying sedimentary sequences present a challenge to hydrocarbon exploration using reflection seismic techniques. The Lopra-1/1A re-entry well on the Faroese island of Suðuroy allowed us to study the seismic characteristics of a thick sequence of basalt flows from well logs and borehole seismic recordings. Data acquired during the deepening operation in 1996 are presented here.The re-entry well found that the seismic event at 2340 m, prognosed from the pre-drill Vertical Seismic Profile (VSP as a decrease in impedance, was not base basalt and the deepened well remainedwithin the lower series basalts. Nonetheless, compressional and shear sonic logs and a density log were recorded over the full open hole interval. These allowed a firm tie to be made with the reflectedwavefield from a new VSP. The sonic logs show a compressional to shear wavespeed ratio of 1.84 which is almost constant with depth. Sonic compressional wavespeeds are 3% higher than seismicvelocities, suggesting dispersion in the basalt flows. Azimuthal anisotropy was weakly indicated by the shear sonic log but its orientation is consistent with the directions of mapped master joints in the vicinity of the well.The VSP downgoing compressional wavelet shows good persistence, retaining a dominant period of 28 ms at 3510 m depth. Average vertical velocity is 5248 m/s, higher than previously reported.Attenuation can largely be modelled by geometrical spreading and scattering loss, consistent with other studies. Within the piled flows, the effective Q from scattering is about 35. Elastic layeredmedium modelling shows some hope that a mode-converted shear wave may be observed at moderate offsets. Like its predecessor, the 1996 VSP indicates a decrease in impedance below the final depth ofthe well. However, it is unlikely to be basement or sediment and is probably an event within the volcanic sequence.

  10. Site study plan for EDBH (Engineering Design Boreholes) seismic surveys, Deaf Smith County site, Texas: Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Hume, H.

    1987-12-01

    This site study plan describes seismic reflection surveys to run north-south and east-west across the Deaf Smith County site, and intersecting near the Engineering Design Boreholes (EDBH). Both conventional and shallow high-resolution surveys will be run. The field program has been designed to acquire subsurface geologic and stratigraphic data to address information/data needs resulting from Federal and State regulations and Repository program requirements. The data acquired by the conventional surveys will be common-depth- point, seismic reflection data optimized for reflection events that indicate geologic structure near the repository horizon. The data will also resolve the basement structure and shallow reflection events up to about the top of the evaporite sequence. Field acquisition includes a testing phase to check/select parameters and a production phase. The field data will be subjected immediately to conventional data processing and interpretation to determine if there are any anamolous structural for stratigraphic conditions that could affect the choice of the EDBH sites. After the EDBH's have been drilled and logged, including vertical seismic profiling, the data will be reprocessed and reinterpreted for detailed structural and stratigraphic information to guide shaft development. The shallow high-resulition seismic reflection lines will be run along the same alignments, but the lines will be shorter and limited to immediate vicinity of the EDBH sites. These lines are planned to detect faults or thick channel sands that may be present at the EDBH sites. 23 refs. , 7 figs., 5 tabs.

  11. null Seismic Creep, null Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seismic creep is the constant or periodic movement on a fault as contrasted with the sudden rupture associated with an earthquake. It is a usually slow deformation...

  12. Salvo: Seismic imaging software for complex geologies

    Energy Technology Data Exchange (ETDEWEB)

    OBER,CURTIS C.; GJERTSEN,ROB; WOMBLE,DAVID E.

    2000-03-01

    This report describes Salvo, a three-dimensional seismic-imaging software for complex geologies. Regions of complex geology, such as overthrusts and salt structures, can cause difficulties for many seismic-imaging algorithms used in production today. The paraxial wave equation and finite-difference methods used within Salvo can produce high-quality seismic images in these difficult regions. However this approach comes with higher computational costs which have been too expensive for standard production. Salvo uses improved numerical algorithms and methods, along with parallel computing, to produce high-quality images and to reduce the computational and the data input/output (I/O) costs. This report documents the numerical algorithms implemented for the paraxial wave equation, including absorbing boundary conditions, phase corrections, imaging conditions, phase encoding, and reduced-source migration. This report also describes I/O algorithms for large seismic data sets and images and parallelization methods used to obtain high efficiencies for both the computations and the I/O of seismic data sets. Finally, this report describes the required steps to compile, port and optimize the Salvo software, and describes the validation data sets used to help verify a working copy of Salvo.

  13. Geostatistical Borehole Image-Based Mapping of Karst-Carbonate Aquifer Pores.

    Science.gov (United States)

    Sukop, Michael C; Cunningham, Kevin J

    2016-03-01

    Quantification of the character and spatial distribution of porosity in carbonate aquifers is important as input into computer models used in the calculation of intrinsic permeability and for next-generation, high-resolution groundwater flow simulations. Digital, optical, borehole-wall image data from three closely spaced boreholes in the karst-carbonate Biscayne aquifer in southeastern Florida are used in geostatistical experiments to assess the capabilities of various methods to create realistic two-dimensional models of vuggy megaporosity and matrix-porosity distribution in the limestone that composes the aquifer. When the borehole image data alone were used as the model training image, multiple-point geostatistics failed to detect the known spatial autocorrelation of vuggy megaporosity and matrix porosity among the three boreholes, which were only 10 m apart. Variogram analysis and subsequent Gaussian simulation produced results that showed a realistic conceptualization of horizontal continuity of strata dominated by vuggy megaporosity and matrix porosity among the three boreholes. PMID:26174850

  14. Geostatistical borehole image-based mapping of karst-carbonate aquifer pores

    Science.gov (United States)

    Michael Sukop,; Cunningham, Kevin J.

    2016-01-01

    Quantification of the character and spatial distribution of porosity in carbonate aquifers is important as input into computer models used in the calculation of intrinsic permeability and for next-generation, high-resolution groundwater flow simulations. Digital, optical, borehole-wall image data from three closely spaced boreholes in the karst-carbonate Biscayne aquifer in southeastern Florida are used in geostatistical experiments to assess the capabilities of various methods to create realistic two-dimensional models of vuggy megaporosity and matrix-porosity distribution in the limestone that composes the aquifer. When the borehole image data alone were used as the model training image, multiple-point geostatistics failed to detect the known spatial autocorrelation of vuggy megaporosity and matrix porosity among the three boreholes, which were only 10 m apart. Variogram analysis and subsequent Gaussian simulation produced results that showed a realistic conceptualization of horizontal continuity of strata dominated by vuggy megaporosity and matrix porosity among the three boreholes.

  15. Experimental evidence for seismically initiated gas bubble nucleation and growth in groundwater as a mechanism for coseismic borehole water level rise and remotely triggered seismicity

    Science.gov (United States)

    Crews, Jackson B.; Cooper, Clay A.

    2014-09-01

    Changes in borehole water levels and remotely triggered seismicity occur in response to near and distant earthquakes at locations around the globe, but the mechanisms for these phenomena are not well understood. Experiments were conducted to show that seismically initiated gas bubble growth in groundwater can trigger a sustained increase in pore fluid pressure consistent in magnitude with observed coseismic borehole water level rise, constituting a physically plausible mechanism for remote triggering of secondary earthquakes through the reduction of effective stress in critically loaded geologic faults. A portion of the CO2 degassing from the Earth's crust dissolves in groundwater where seismic Rayleigh and P waves cause dilational strain, which can reduce pore fluid pressure to or below the bubble pressure, triggering CO2 gas bubble growth in the saturated zone, indicated by a spontaneous buildup of pore fluid pressure. Excess pore fluid pressure was measured in response to the application of 0.1-1.0 MPa, 0.01-0.30 Hz confining stress oscillations to a Berea sandstone core flooded with initially subsaturated aqueous CO2, under conditions representative of a confined aquifer. Confining stress oscillations equivalent to the dynamic stress of the 28 June 1992 Mw 7.3 Landers, California, earthquake Rayleigh wave as it traveled through the Long Valley caldera, and Parkfield, California, increased the pore fluid pressure in the Berea core by an average of 36 ± 15 cm and 23 ± 15 cm of equivalent freshwater head, respectively, in agreement with 41.8 cm and 34 cm rises recorded in wells at those locations.

  16. OGS improvements in 2012 in running the North-eastern Italy Seismic Network: the Ferrara VBB borehole seismic station

    OpenAIRE

    Pesaresi, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Romanelli, M.; OGS; Barnaba, C.; OGS, Trieste; Bragato, P. L.; OGS; Durì, G.; OGS

    2014-01-01

    The Centro di Ricerche Sismologiche (CRS, Seismological Research Centre) of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italian National Institute for Oceanography and Experimental Geophysics) in Udine (Italy) after the strong earthquake of magnitude M=6.4 occurred in 1976 in the Italian Friuli-Venezia Giulia region, started to operate the North-eastern Italy Seismic Network: it currently consists of 17 very sensitive broad band and 18 simpler short period seismic...

  17. The multi-parameter borehole system and high resolution seismic studies in the western part of the main Marmara Fault in the frame of MARSITE Project.

    Science.gov (United States)

    Ozel, Oguz; Guralp, Cansun; Tunc, Suleyman; Yalcinkaya, Esref

    2016-04-01

    The main objective of this study is to install a multi-parameter borehole system and surface array as close to the main Marmara Fault (MMF) in the western Marmara Sea as possible, and measure continuously the evolution of the state of the fault zone surrounding the MMF and to detect any anomaly or change, which may occur before earthquakes by making use of the data from the arrays already running in the eastern part of the Marmara Sea. The multi-parameter borehole system is composed of very wide dynamic range and stable borehole (VBB) broad band seismic sensor, and incorporate strain meter, tilt meter, and temperature and local hydrostatic pressure measuring devices. The borehole seismic station uses the latest update technologies and design ideas to record "Earth tides" signals to the smallest magnitude -3 events. Additionally, a surface microearthquake observation array, consisting of 8-10 seismometers around the borehole is established to obtain continuous high resolution locations of micro-seismicity and to better understand the existing seismically active structures and their roles in local tectonic settings.Bringing face to face the seismograms of microearthquakes recorded by borehole and surface instruments portrays quite different contents. The shorter recording duration and nearly flat frequency spectrum up to the Nyquist frequencies of borehole records are faced with longer recording duration and rapid decay of spectral amplitudes at higher frequencies of a surface seismogram. The main causative of the observed differences are near surface geology effects that mask most of the source related information the seismograms include, and that give rise to scattering, generating longer duration seismograms. In view of these circumstances, studies on microearthquakes employing surface seismograms may bring on misleading results. Particularly, the works on earthquake physics and nucleation process of earthquakes requires elaborate analysis of tiny events. It is

  18. Distributed computing of Seismic Imaging Algorithms

    CERN Document Server

    Emami, Masnida; Jaberi, Nasrin

    2012-01-01

    The primary use of technical computing in the oil and gas industries is for seismic imaging of the earth's subsurface, driven by the business need for making well-informed drilling decisions during petroleum exploration and production. Since each oil/gas well in exploration areas costs several tens of millions of dollars, producing high-quality seismic images in a reasonable time can significantly reduce the risk of drilling a "dry hole". Similarly, these images are important as they can improve the position of wells in a billion-dollar producing oil field. However seismic imaging is very data- and compute-intensive which needs to process terabytes of data and require Gflop-years of computation (using "flop" to mean floating point operation per second). Due to the data/computing intensive nature of seismic imaging, parallel computing are used to process data to reduce the time compilation. With introducing of Cloud computing, MapReduce programming model has been attracted a lot of attention in parallel and di...

  19. Advanced seismic imaging for geothermal development

    Energy Technology Data Exchange (ETDEWEB)

    Louie, John [UNR; Pullammanappallil, Satish [Optim; Honjas, Bill [Optim

    2016-08-01

    J. N. Louie, Pullammanappallil, S., and Honjas, W., 2011, Advanced seismic imaging for geothermal development: Proceedings of the New Zealand Geothermal Workshop 2011, Nov. 21-23, Auckland, paper 32, 7 pp. Preprint available at http://crack.seismo.unr.edu/geothermal/Louie-NZGW11.pdf

  20. OGS improvements in 2012 in running the North-eastern Italy Seismic Network: the Ferrara VBB borehole seismic station

    OpenAIRE

    D. Pesaresi; Romanelli, M.; BARNABA, C; Bragato, P. L.; Durì, G.

    2014-01-01

    The Centro di Ricerche Sismologiche (CRS, Seismological Research Centre) of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italian National Institute for Oceanography and Experimental Geophysics) in Udine (Italy) after the strong earthquake of magnitude M=6.4 occurred in 1976 in the Italian Friuli-Venezia Giulia region, started to operate the North-eastern Italy Seismic Network: it currently consists of 17 very sensitive broad band and 18 simpler sh...

  1. High-Resolution Imaging of San Andreas Fault at Parkfield, California, Using Seismic Velocity and Anisotropy Tomography and Seismic Interferometry

    Science.gov (United States)

    Zhang, H.; Thurber, C.; Liu, Y.; Roecker, S.; Lu, R.; Toksoz, N.

    2007-12-01

    We characterized the detailed structure of the San Andreas fault zone at multiple scales using an extensive dataset collected around the SAFOD site from our long-term deployments of PASSCAL and USArray seismic instruments, and the USGS Northern California and UC Berkeley HRSN networks, SAFOD borehole logs, borehole seismometers, and several active-source projects. A suite of techniques are employed to better constrain the internal structure of the fault zone, including seismic travel-time tomography, shear-wave splitting tomography and seismic interferometry. Adaptive-mesh double-difference tomography is used to derive high-resolution Vp and Vs models around the fault zone with the waveform cross-correlation derived differential times. Knowing three-dimensional (3-D) Vp/Vs variations is helpful to have a more complete characterization of the mechanical properties and geological identity of fault zone materials. Vp/Vs variations are reliably determined by the inversion of S-P time differences constructed only from similar P and S ray paths. Our velocity models show the high-velocity granitic rocks on the southwest side of the fault, a complex low-velocity zone beneath and southwest of the surface fault trace, and an extensive low-velocity zone overlying deeper bedrock on the northeast side. We systematically analyzed shear wave splitting for seismic data observed at PASO and UC Berkeley HRSN networks. Although polarization direction of the fast shear wave and the delay time show substantial scatter for different events observed at a common station, there are spatially consistent patterns when projecting them to various depths along corresponding ray paths, derived from a 3-D shear velocity model. We developed a 3-D shear-wave splitting tomography method to image the spatial anisotropy distribution by back projecting shear wave splitting delay times along ray paths. The anisotropy percentage model shows strong heterogeneities, consistent with the strong spatial

  2. Combined Borehole Seismic and Electromagnetic Inversion For High-Resolution Petrophysical Assessment Of Hydocarbon Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Carlos Torres-Verdin; G. Michael Hoversten; Ki Ha Lee; Gregory Newman; Kurt Nihei

    2008-12-31

    This report summarizes the work performed between January 2005 and December 2007, under DOE research contract DE-FC26-04NT15507. The project is was performed by the Center for Petroleum and Geosystems Engineering of The University of Texas at Austin and Lawrence Berkeley National Laboratory under the auspices of the National Energy Technology Office (NETL) and the Strategic Center for Natural Gas and Oil (SCNGO). During the three-year project, we developed new methods to combine borehole sonic and electromagnetic (EM) measurements for the improved assessment of elastic and petrophysical properties of rock formations penetrated by a well. Sonic measurements consisted of full waveform acoustic amplitudes acquired with monopole and dipole sources, whereas EM measurements consisted of frequency-domain voltages acquired with multi-coil induction systems. The combination of sonic and EM measurements permitted the joint estimation of elastic and petrophysical properties in the presence of mud-filtrate invasion. It was conclusively shown that the combined interpretation of sonic and EM measurements reduced non-uniqueness in the estimation of elastic and petrophysical properties and improved the spatial resolution of the estimations compared to estimations yielded separately from the two types of measurements. Moreover, this approach enabled the assessment of dynamic petrophysical properties such as permeability, as it incorporated the physics of mud-filtrate invasion in the interpretation of the measurements. The first part of the project considered the development of fast and reliable numerical algorithms to simulate borehole sonic waveforms in 2D, 3D, and radial 1D media. Such algorithms were subsequently used in the quantitative estimation of elastic properties jointly from borehole sonic and EM measurements. In the second part of the project we developed a new algorithm to estimate water saturation, porosity, and dry-rock elastic moduli jointly from borehole sonic and

  3. Integration of borehole geophysical properties into surface multichannel seismic data sets: First results from the SCOPSCO ICDP project

    Science.gov (United States)

    Lindhorst, Katja; Krastel, Sebastian; Baumgarten, Henrike; Wonik, Thomas; Francke, Alexander; Wagner, Bernd

    2015-04-01

    Lake Ohrid (Macedonia/Albania), located on the Balkan Peninsula within the Dinaride-Hellenide-Albanide mountain belt is probably the oldest, continuously existing lake in Europe (2-5 Ma). Multidisciplinary studies at Lake Ohrid prove that it is an important archive to study the sedimentary and tectonic evolution of a graben system over a long time period. Within the frame of the International Continental Drilling Program (ICDP) a successful deep drilling campaign was carried out in spring 2013 with more than 2000 m of sediment cores at four sites. Downhole logging was realized at each site after coring, enabling us to integrate geophysical and sedimentological data into seismic cross sections in order to get a profound knowledge of climatic and environmental changes in the catchment area. The longest record (~569 m, site DEEP), recovered in the central part of lake Ohrid likely covers the entire lacustrine succession within Lake Ohrid Basin including several Interglacial and Glacial cycles. Sedimentological analyses are still ongoing; however, the upper 260 m of the DEEP reflecting the time period between Mid-Pleistocene Transition to present. An integration of borehole geophysical data into surface seismic lines shows that sediments, within the central part of Lake Ohrid, were deposited in a deep water environment over the last 600 ka. For the uppermost sediment cover, about 50 m of penetration, a very high resolution sediment echosounder data set allows us to identify major tephra layers and track them through the entire deep basin. Furthermore, a vertical seismic profile was carried out at site DEEP resulting in a conversion from two-way-travel-time into sediment depth. One major outcome is a corridor stack of the upgoing wave that clearly shows several reflectors linked to changes of sediment properties of cores and hence environmental and climate changes in the surrounding area of Lake Ohrid Basin. Several changes from Glacial to Interglacial, and vice versa

  4. Optical imaging of the boreholes KR37, KR37B and KR38 at Olkiluoto 2005

    International Nuclear Information System (INIS)

    Suomen Malmi Oy conducted optical imaging surveys of the boreholes KR37, KR37B and KR38 at the Olkiluoto site in Eurajoki during September 2005. The survey is a part of Posiva Oy's detailed investigation program for the final disposal of spent nuclear fuel. The assignment included the field work and preliminary processing of the images. The report describes the field operation, equipment as well as processing procedures and shows the obtained results and their quality through example images. The raw and processed data are delivered digitally in WellCAD format. The images are also attached to the appendix CD of this report in Adobe Acrobat PDF-format. (orig.)

  5. Seismic structure of oceanic crust at ODP borehole 504B: Investigating anisotropy and layer 2 characteristics

    Science.gov (United States)

    Gregory, E. P. M.; Hobbs, R. W.; Peirce, C.; Wilson, D. J.

    2015-12-01

    Fracture and fault networks in the upper oceanic crust influence the circulation of hydrothermal fluids and heat transfer between crust and ocean. These fractures form by extensional stresses, with a predominant orientation parallel to the ridge axis, creating porosity- and permeability-derived anisotropy that can be measured in terms of seismic velocity. These properties change as the crust ages and evolves through cooling, alteration and sedimentation. The rate at which these changes occur and their effects on oceanic crustal structure and hydrothermal flow patterns are currently not well constrained. The NERC-funded OSCAR project aims to understand the development of upper oceanic crust, the extent and influence of hydrothermal circulation on the crust, and the behavior of fluids flowing in fractured rock. We show P-wave velocity models centered on DSDP/ODP Hole 504B, located ~200 km south of the Costa Rica Rift, derived from data acquired during a recent integrated geophysics and oceanography survey of the Panama Basin. The data were recorded by 25 four-component OBSs deployed in a grid, that recorded ~10,000 full azimuthal coverage shots fired by a combined high- and low-frequency seismic source. Both reflection and refraction data are integrated to reveal the seismic velocity structure of the crust within the 25 km by 25 km grid. The down-hole geological structure of 6 Ma crust at 504B comprises 571.5 m of extrusive basalts overlying a 209 m transition zone of mixed pillows and dikes containing a clear alteration boundary, which grades to >1050 m of sheeted dikes. Our model results are compared with this lithological structure and other previously published results to better understand the nature of velocity changes within seismic layer 2. The data provide a 3D framework, which together with analysis of the S-wave arrivals and particle motion studies, constrain estimates of the seismic anisotropy and permeability structure of the upper oceanic crust as it

  6. Late-stage stretching and subsidence rates in the Danakil Depression, evidenced from borehole records and seismic reflection data

    Science.gov (United States)

    Booth, Adam; Bastow, Ian; Magee, Craig; Keir, Derek; Corti, Giacomo; Jackson, Chris; Wilkinson, Jason

    2016-04-01

    The Ethiopian and Afar Rift systems provide a globally unique opportunity to study the incipient transition from continental rifting to sea-floor spreading. A consensus has emerged that a considerable proportion of plate extension in Ethiopia is accommodated by dyke intrusion, with smaller contributions from crustal thinning. However, observations of thinned crust and a pulse in Quaternary-Recent basaltic volcanism within Ethiopia's Danakil Depression have been cited (Bastow and Keir, 2011) as evidence that localised plate stretching may mark the final stages of continent-ocean transition. We explore this hypothesis using an archive of five 2-D seismic reflection profiles, each between 7-10 km in length, and ˜120 borehole records distributed over an area of 225 km2. From depth and age relationships of key marker horizons, we also suggest local subsidence and extension rates. The borehole archive reveals extensive evaporite sequences deposited in and around an asymmetric basin, bounded to the west by a network of east-dipping normal faults. West of the basin, the maximum observed thickness of evaporites is 150 m, beneath which are deposits of clastic sediment, but a sequence of evaporites at least 900 m thick is observed at the basin centre. The sedimentary architecture of these sequences suggests deposition in a shallow salt-pan environment, with seasonal - potentially diurnal - freshening of the brine supply (Warren, 2012). Isotopic analysis of reef carbonates in the basin flank dates the last marine incursion into the Danakil Depression at 24-230ka (Lalou et al., 1970; Bonatti et al., 1971; Bannert et al., 1971), therefore the evaporite sequence must be younger than this. A key marker horizon within the evaporites is the potash-bearing Houston Formation, also distinct in borehole records given its high porosity (25-40%) and radioactivity (50-250 API units). The elevation of the Houston Formation is ˜500 m deeper in the centre of the basin than on the flank

  7. High Resolution Seismic Imaging of the Brawley Seismic Fault Zone

    Science.gov (United States)

    Goldman, M.; Catchings, R. D.; Rymer, M. J.; Lohman, R. B.; McGuire, J. J.; Sickler, R. R.; Criley, C.; Rosa, C.

    2011-12-01

    In March 2010, we acquired a series of high-resolution P-wave seismic reflection and refraction data sets across faults in the Brawley seismic zone (BSZ) within the Salton Sea Geothermal Field (SSGF). Our objectives were to determine the dip, possible structural complexities, and seismic velocities within the BSZ. One dataset was 3.4 km long trending east-west, and consisted of 334 shots recorded by a 2.4 km spread of 40 hz geophones placed every 10 meters. The spread was initially laid out from the first station at the eastern end of the profile to roughly 2/3 into the profile. After about half the shots, the spread was shifted from roughly 1/3 into the profile to the last station at the western end of the profile. P-waves were generated by Betsy-Seisgun 'shots' spaced every 10 meters. Initial analysis of first breaks indicate near-surface velocities of ~500-600 meters/sec, and deeper velocities of around 2000 meters/sec. Preliminary investigation of shot gathers indicate a prominent fault that extends to the ground surface. This fault is on a projection of the Kalin fault from about 40 m to the south, and broke the surface down to the west with an approximately north-south strike during a local swarm of earthquakes in 2005 and also slipped at the surface in association with the 2010 El Mayor-Cucapah earthquake in Baja California. The dataset is part of the combined Obsidian Creep data set, and provides the most detailed, publicly available subsurface images of fault structures in the BSZ and SSGF.

  8. Towards Exascale Seismic Imaging and Inversion

    Science.gov (United States)

    Tromp, J.; Bozdag, E.; Lefebvre, M. P.; Smith, J. A.; Lei, W.; Ruan, Y.

    2015-12-01

    Post-petascale supercomputers are now available to solve complex scientific problems that were thought unreachable a few decades ago. They also bring a cohort of concerns tied to obtaining optimum performance. Several issues are currently being investigated by the HPC community. These include energy consumption, fault resilience, scalability of the current parallel paradigms, workflow management, I/O performance and feature extraction with large datasets. In this presentation, we focus on the last three issues. In the context of seismic imaging and inversion, in particular for simulations based on adjoint methods, workflows are well defined.They consist of a few collective steps (e.g., mesh generation or model updates) and of a large number of independent steps (e.g., forward and adjoint simulations of each seismic event, pre- and postprocessing of seismic traces). The greater goal is to reduce the time to solution, that is, obtaining a more precise representation of the subsurface as fast as possible. This brings us to consider both the workflow in its entirety and the parts comprising it. The usual approach is to speedup the purely computational parts based on code optimization in order to reach higher FLOPS and better memory management. This still remains an important concern, but larger scale experiments show that the imaging workflow suffers from severe I/O bottlenecks. Such limitations occur both for purely computational data and seismic time series. The latter are dealt with by the introduction of a new Adaptable Seismic Data Format (ASDF). Parallel I/O libraries, namely HDF5 and ADIOS, are used to drastically reduce the cost of disk access. Parallel visualization tools, such as VisIt, are able to take advantage of ADIOS metadata to extract features and display massive datasets. Because large parts of the workflow are embarrassingly parallel, we are investigating the possibility of automating the imaging process with the integration of scientific workflow

  9. Full 3-D numerical modeling of borehole electric image logging and the evaluation model of fracture

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A full 3-D finite element method numerical modeling program is written based on the principle and technical specification of borehole electric image well logging tool. The response of well logging is computed in the formation media model with a single fracture. The effect of changing fracture aperture and resistivity ratio to the logging response is discussed. The identification ability for two parallel fractures is also present. A quantitative evaluation formula of fracture aperture from borehole electric image logging data is set up. A case study of the model well is done to verify the accuracy of the for-mula. The result indicates that the formula is more accurate than the foreign one.

  10. Imaging fault zones using 3D seismic image processing techniques

    Science.gov (United States)

    Iacopini, David; Butler, Rob; Purves, Steve

    2013-04-01

    Significant advances in structural analysis of deep water structure, salt tectonic and extensional rift basin come from the descriptions of fault system geometries imaged in 3D seismic data. However, even where seismic data are excellent, in most cases the trajectory of thrust faults is highly conjectural and still significant uncertainty exists as to the patterns of deformation that develop between the main faults segments, and even of the fault architectures themselves. Moreover structural interpretations that conventionally define faults by breaks and apparent offsets of seismic reflectors are commonly conditioned by a narrow range of theoretical models of fault behavior. For example, almost all interpretations of thrust geometries on seismic data rely on theoretical "end-member" behaviors where concepts as strain localization or multilayer mechanics are simply avoided. Yet analogue outcrop studies confirm that such descriptions are commonly unsatisfactory and incomplete. In order to fill these gaps and improve the 3D visualization of deformation in the subsurface, seismic attribute methods are developed here in conjunction with conventional mapping of reflector amplitudes (Marfurt & Chopra, 2007)). These signal processing techniques recently developed and applied especially by the oil industry use variations in the amplitude and phase of the seismic wavelet. These seismic attributes improve the signal interpretation and are calculated and applied to the entire 3D seismic dataset. In this contribution we will show 3D seismic examples of fault structures from gravity-driven deep-water thrust structures and extensional basin systems to indicate how 3D seismic image processing methods can not only build better the geometrical interpretations of the faults but also begin to map both strain and damage through amplitude/phase properties of the seismic signal. This is done by quantifying and delineating the short-range anomalies on the intensity of reflector amplitudes

  11. Anatomy of the Chesapeake Bay impact structure revealed by seismic imaging, Delmarva Peninsula, Virginia, USA

    Science.gov (United States)

    Catchings, R.D.; Powars, D.S.; Gohn, G.S.; Horton, J.W.; Goldman, M.R.; Hole, J.A.

    2008-01-01

    A 30-km-long, radial seismic reflection and refraction survey completed across the northern part of the late Eocene Chesapeake Bay impact structure (CBIS) on the Delmarva Peninsula, Virginia, USA, confirms that the CBIS is a complex central-peak crater. We used a tomographic P wave velocity model and low-fold reflection images, constrained by data from two deep boreholes located on the profile, to interpret the structure and composition of the upper 5 km of crust. The seismic images exhibit well-defined structural features, including (with increasing radial distance) a collapsed central uplift, a breccia-filled moat, and a collapsed transient-crater margin (which collectively constitute a ???40-km-wide collapsed transient crater), and a shallowly deformed annular trough. These seismic images are the first to resolve the deep structure of the crater (>1 km) and the boundaries between the central uplift, moat, and annular trough. Several distinct seismic signatures distinguish breccia units from each other and from more coherent crystalline rocks below the central uplift, moat, and annular trough. Within the moat, breccia extends to a minimum depth of 1.5 km or a maximum of 3.5 km, depending upon the interpretation of the deepest layered materials. The images show ???350 to 500 m of postimpact sediments above the impactites. The imaged structure of the CBIS indicates a complex sequence of event during the cratering process that will provide new constraints for numerical modeling. Copyright 2008 by the American Geophysical Union.

  12. Variations in geoacoustic emissions in a deep borehole and its correlation with seismicity

    Directory of Open Access Journals (Sweden)

    A. Storcheus

    2008-06-01

    Full Text Available Continuous geoacoustic emission (GAE measurements were acquired using a three-component geophone placed in a borehole at a depth of near 1000 m at Petropavlovsk-Kamchatsky starting in August 2000. Using geophones consisting of magneto-elastic crystal ferromagnetic sensors, and installed at such a depth allows measurement of natural geoacoustic background with signal amplitude less than 1×10-4 m/s3 in frequency band from 3 to 1500 Hz. According to the data from a 4-year survey period the characteristics of diurnal geoacoustic variations change before every earthquake with MLH? 5.0 that occurs at a distance of less than 300 km from the observation point or before each earthquake with MLH?5.5 occurring at distance R?550 km from the observation point. The changes in GAE regime correlate with the strongest earthquakes that occurred during survey period. Measurements of the natural electromagnetic field of the Earth were carried out simultaneously with the help of an underground electric antenna. The behavior of GAE in aseismic periods appears to be related to the effect of diurnal variations of the natural electromagnetic field.

  13. New developments in high resolution borehole seismology and their applications to reservoir development and management

    Energy Technology Data Exchange (ETDEWEB)

    Paulsson, B.N.P. [Chevron Petroleum Technology Company, La Habra, CA (United States)

    1997-08-01

    Single-well seismology, Reverse Vertical Seismic Profiles (VSP`s) and Crosswell seismology are three new seismic techniques that we jointly refer to as borehole seismology. Borehole seismic techniques are of great interest because they can obtain much higher resolution images of oil and gas reservoirs than what is obtainable with currently used seismic techniques. The quality of oil and gas reservoir management decisions depend on the knowledge of both the large and the fine scale features in the reservoirs. Borehole seismology is capable of mapping reservoirs with an order of magnitude improvement in resolution compared with currently used technology. In borehole seismology we use a high frequency seismic source in an oil or gas well and record the signal in the same well, in other wells, or on the surface of the earth.

  14. a Borehole Seismic System for Active and Passive Seimsic Studies to 3 KM at Ptrc's Aquistore Project

    Science.gov (United States)

    Schmitt, D. R.; Nixon, C.; Kofman, R.; White, D. J.; Worth, K.

    2015-12-01

    We have constructed a downhole seismic recording system for application to depths of nearly 3 km and temperatures up to 135 °C at Aquistore, an independent research and monitoring project in which liquid CO2 is being stored in a brine and sandstone water formation. The key component to this system is a set of commercially available slim-hole 3-C sondes carrying 15 Hz geophones deployable in open and cased boreholes with diameters as small as 57 mm. The system is currently hosted on a 4-conductor wireline with digital information streamed to the surface recording unit. We have further incorporated these sondes into a mobile passive monitoring unit that includes a number of redundancies such as a multiple Tbyte network accessible RAID hard-drive system (NAS) and a self-designed uninterruptible power supply. The system can be remotely controlled via the internet. The system is currently deployed covering a range of depths from 2850 m to 2910 m. Ambient temperatures at this depth are approximately 110 °C with onboard tool temperatures running at 115 °C. Data is continuously streamed to the NAS for archiving, approximately 11 GBytes of data is recorded per day at the sampling period of 0.5 ms. The lack of noise at this depth allows short data snippets to be flagged with a simple amplitude threshold criteria. The greatly reduced data volume of the snippets allows for ready access via the internet to the system for ongoing quality control. Spurious events, mostly small amplitude tube waves originating at or near the surface, are readily discounted. Active seismic measurements are carried out simultaneously but these require that an appropriately accurate independent GPS based time synchronization be used. Various experiences with event detection, orientation of sondes using both explosives and seismic vibrator, potential overheating of the surface electronics, and issues related to loss of shore power provide for a detailed case study. Aquistore, managed by the

  15. Borehole images while drilling : real-time dip picking in the foothills

    Energy Technology Data Exchange (ETDEWEB)

    Dexter, D. [Schlumberger Canada Ltd., Calgary, AB (Canada); Brezsnyak, F. [Talisman Energy Inc., Calgary, AB (Canada); Roth, J. [Talisman Energy Inc., Calgary, AB (Canada)

    2008-07-01

    The Alberta Foothills drilling environment is a structurally complex thrust belt with slow costly drilling and frequent plan changes after logging. The cross sections are not always accurate due to poor resolution. Therefore, the placement of the wellbore is crucial to success. This presentation showed borehole images from drilling in the Foothills. Topics that were addressed included the Foothills drilling environment; target selection; current well placement methods; and current well performance. Borehole images included resistivity images and density images. The presentation addressed why real-time images should be run. These reasons include the ability to pick dips in real-time; structural information in real time allows for better well placement; it is easier to find and stay in producing areas; reduced non-productive time and probability of sidetracks; and elimination of pipe conveys logs. Applications in the Alberta Foothills such as the commercial run for GVR4 were also offered. Among the operational issues and lessons learned, it was determined that the reservoir thickness to measurement point distance ratio is too great to avoid exiting the sweet spot and that the survey calculation error cause image offset. It was concluded that GVR is a drillers tool for well placement. figs.

  16. Improving Seismic Image with Advanced Processing Techniques

    Directory of Open Access Journals (Sweden)

    Mericy Lastra Cunill

    2012-07-01

    Full Text Available Taking Taking into account the need to improve the seismic image in the central area of Cuba, specifically in the area of the Venegas sector, located in the Cuban Folded Belt, the seismic data acquired by Cuba Petróleo (CUPET in the year 2007 was reprocessed according to the experience accumulated during the previous processing carried out in the same year, and the new geologic knowledge on the area. This was done with the objective of improving the results. The processing applied previously was analyzed by reprocessing the primary data with new focuses and procedures, among them are the following: the attenuation of the superficial wave with a filter in the Radon domain in its lineal variant, the change of the primary statics corrections of elevation by those of refraction, the study of velocity with the selection automatic biespectral of high density, the study of the anisotropy, the attenuation of the random noise, and the pre stack time and depth migration. As a result of this reprocessing, a structure that was not identified in the seismic sections of the previous processing was located at the top of a Continental Margin sediment located to the north of the sector that increased the potentialities of finding hydrocarbons in quantities of economic importance thus diminishing the risk of drilling in the sector Venegas.

  17. Investigations on alluvial deposits through borehole stratigraphy, radiocarbon dating and passive seismic technique (Carnic Alps, NE Italy)

    Science.gov (United States)

    Viero, Alessia; Marchi, Lorenzo; Cavalli, Marco; Crema, Stefano; Fontana, Alessandro; Mozzi, Paolo; Venturini, Corrado

    2016-04-01

    their extent and the maximum depths. Two passive seismic campaigns were carried out near the borehole site and along the But valley at different elevations. The aim was to investigate the depth of the buried bedrock and therefore to indirectly characterize the thickness of alluvial deposits. We calibrated the fundamental frequency of each site by constraining average shear velocity of the alluvial sediments close to the borehole site with known stratigraphy. Eight HVSR (Horizontal to Vertical Spectral Ratio, Nakamura, 1989) were carried out, and thus a first sketch of the buried valley floor along a longitudinal profile of about 5 km was depicted. The values of the derived bedrock depth allow to quantify the differences in thickness between the alluvial deposits and the Moscardo Torrent fan deposits. This information helps to address the contribution of the debris-flow processes in damming the upper But River during the last five centuries. The results confirm the role of debris-flow deposits from the Moscardo Torrent in shaping the morphology of the valley floor of But River and show suitability of an integrated approach, encompassing log stratigraphy, geophysical surveys and analysis of historical documents, for gaining insights on the evolution of alpine valleys. Reference Nakamura, Y., 1989. A method for dynamic characteristic estimation of subsurface using microtremor on the ground surface. Quarterly Report of Railway Technical Research Institute, 30(1): 25-33.

  18. EVOLUTION OF SOUTHERN AFRICAN CRATONS BASED ON SEISMIC IMAGING

    DEFF Research Database (Denmark)

    Thybo, Hans; Soliman, Mohammad Youssof Ahmad; Artemieva, Irina

    2014-01-01

    present a new seismic model for the structure of the crust and lithospheric mantle of the Kalahari Craton, constrained by seismic receiver functions and finite-frequency tomography based on the seismological data from the South Africa Seismic Experiment (SASE). The combination of these two methods...... since formation of the craton, and (3) seismically fast lithospheric keels are imaged in the Kaapvaal and Zimabwe cratons to depths of 300-350 km. Relatively low velocity anomalies are imaged beneath both the paleo-orogenic Limpopo Belt and the Bushveld Complex down to depths of ~250 km and ~150 km...

  19. Near-surface seismic imaging. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Scheffers, B.C.

    1993-01-01

    Processing of seismic data requires more and more sophisticated techniques as hydrocarbon plays get smaller and smaller. Depth migration, for example, depends on accurate velocity models of the subsurface to obtain correctly imaged depth sections or depth cubes of small hydrocarbon reservoirs. Much research is carried out on new techniques for the estimation of such macro velocity models. Currently, research is concentrated in two directions: techniques for estimating the velocity of the weather layer (the ultra shallow zone), and techniques for estimating the macro model of the total overburden (of the deep zone). The objective of this thesis is to present an improved and cost-effective data acquistion and inversion technique that provides a velocity macro model of ultra shallow and the shallow zone, using an algorithm that incorporates all available information.

  20. On Boreholes and PBO Borehole Strain

    Science.gov (United States)

    Gladwin, M. T.; Mee, M. W.

    2003-12-01

    Borehole tensor strainmeters (GTSM) installed in Australia and California have established a baseline of data spanning more than twenty years. The current baseline of data allows characterisation of a moderate number of instruments in a range of very different environments in a way which defines reasonable performance expectations for the upcoming PBO deployments. A generic understanding of effects which result from the process of installation of the instrument in a stressed rock mass emerges. This indicates that, provided due allowance is made for experimentally determined borehole recovery effects, the contribution of borehole strain meters more than adequately fills the observational gap between high stability/long term geodetic measurements of strain and strain rates and high resolution/high frequency seismic observations of earth deformation processes. The various strain relief processes associated with the installation procedures and borehole recovery effects associated with pre-existing stress fields will be documented. Procedures for calibration of the total borehole inclusion and for progressive removal of effects due to rock anisotropy and visco-elastic creep of the grout and rock close to the borehole from far field tectonic effects will be defined and illustrated with examples. Observed deviations from these processes will be shown to be small and consistent with otherwise observed or implied fault motions. Full details of these borehole induced processes are, however, difficult to determine in the early years following installation, particularly if there is significant tectonic activity at the time. Once quantified for each site, the effects can be robustly removed from data streams.

  1. Conductive fracture mapping. A study on the correlation between borehole TV- and radar images and difference flow logging results in borehole KLX02

    Energy Technology Data Exchange (ETDEWEB)

    Carlsten, S.; Straahle, A.; Ludvigson, Jan-Erik [GEOSIGMA AB, Uppsala (Sweden)

    2001-10-01

    This study presents an attempt to correlate images from borehole-TV (BIPS) and borehole radar with interpreted flow anomalies from Difference Flow Meter logging (DIFF). The measurements were performed in the interval 200-400 m in borehole KLX02 at Laxemar. In total, 59 flow anomalies were interpreted by the DIFF-log in this borehole interval. However, 14 flow anomalies were below the rigorous measurement limit for the actual flow meter and are thus regarded as uncertain. In total, 261 features were primarily interpreted by the BIPS-characterization in the borehole interval 200-400 m but only 12 radar reflectors. The low number of interpreted radar reflectors most likely depends on the low frequency of the antenna used in this case which gave a poor depth resolution. The total number of fractures recorded by the core mapping in this interval was 374 (279 in the rock together with 95 fractures in interpreted crush zones). Prior to the correlation analysis it was necessary to adjust the length scales of the BIPS-measurements relative to the length scale of the Difference Flow logging due to non-linear stretching of logging cables etc to achieve the necessary resolution of the depth scale.This adjustment was done by comparing the distances between clearly identified single features in the BIPS-images with the corresponding distances between clearly identified flow anomalies. The BIPS-measurements consist of 5 independent logging sequences in the studied borehole interval, which resulted in 'jumps' when comparing the non-conform length scales of the different sequences. All of the 59 flow anomalies could be correlated (matched) with BIPS-features with varying degree of certainty. A majority of the correlated BIPS-features was classified as open fractures or fractures with cavities. Most of the flow anomalies below the measurement limit were correlated to veins in the rock. In the correlation between borehole radar reflectors and BIPS-features, the calculated

  2. Test-bench system for a borehole azimuthal acoustic reflection imaging logging tool

    Science.gov (United States)

    Liu, Xianping; Ju, Xiaodong; Qiao, Wenxiao; Lu, Junqiang; Men, Baiyong; Liu, Dong

    2016-06-01

    The borehole azimuthal acoustic reflection imaging logging tool (BAAR) is a new generation of imaging logging tool, which is able to investigate stratums in a relatively larger range of space around the borehole. The BAAR is designed based on the idea of modularization with a very complex structure, so it has become urgent for us to develop a dedicated test-bench system to debug each module of the BAAR. With the help of a test-bench system introduced in this paper, test and calibration of BAAR can be easily achieved. The test-bench system is designed based on the client/server model. The hardware system mainly consists of a host computer, an embedded controlling board, a bus interface board, a data acquisition board and a telemetry communication board. The host computer serves as the human machine interface and processes the uploaded data. The software running on the host computer is designed based on VC++. The embedded controlling board uses Advanced Reduced Instruction Set Machines 7 (ARM7) as the micro controller and communicates with the host computer via Ethernet. The software for the embedded controlling board is developed based on the operating system uClinux. The bus interface board, data acquisition board and telemetry communication board are designed based on a field programmable gate array (FPGA) and provide test interfaces for the logging tool. To examine the feasibility of the test-bench system, it was set up to perform a test on BAAR. By analyzing the test results, an unqualified channel of the electronic receiving cabin was discovered. It is suggested that the test-bench system can be used to quickly determine the working condition of sub modules of BAAR and it is of great significance in improving production efficiency and accelerating industrial production of the logging tool.

  3. Seismic imaging of a fractured gas hydrate system in the Krishna-Godavari Basin offshore India

    Science.gov (United States)

    Riedel, M.; Collett, T.S.; Kumar, P.; Sathe, A.V.; Cook, A.

    2010-01-01

    Gas hydrate was discovered in the Krishna-Godavari (KG) Basin during the India National Gas Hydrate Program (NGHP) Expedition 1 at Site NGHP-01-10 within a fractured clay-dominated sedimentary system. Logging-while-drilling (LWD), coring, and wire-line logging confirmed gas hydrate dominantly in fractures at four borehole sites spanning a 500m transect. Three-dimensional (3D) seismic data were subsequently used to image the fractured system and explain the occurrence of gas hydrate associated with the fractures. A system of two fault-sets was identified, part of a typical passive margin tectonic setting. The LWD-derived fracture network at Hole NGHP-01-10A is to some extent seen in the seismic data and was mapped using seismic coherency attributes. The fractured system around Site NGHP-01-10 extends over a triangular-shaped area of ~2.5 km2 defined using seismic attributes of the seafloor reflection, as well as " seismic sweetness" at the base of the gas hydrate occurrence zone. The triangular shaped area is also showing a polygonal (nearly hexagonal) fault pattern, distinct from other more rectangular fault patterns observed in the study area. The occurrence of gas hydrate at Site NGHP-01-10 is the result of a specific combination of tectonic fault orientations and the abundance of free gas migration from a deeper gas source. The triangular-shaped area of enriched gas hydrate occurrence is bound by two faults acting as migration conduits. Additionally, the fault-associated sediment deformation provides a possible migration pathway for the free gas from the deeper gas source into the gas hydrate stability zone. It is proposed that there are additional locations in the KG Basin with possible gas hydrate accumulation of similar tectonic conditions, and one such location was identified from the 3D seismic data ~6 km NW of Site NGHP-01-10. ?? 2010.

  4. Testing & Validating: 3D Seismic Travel Time Tomography (Detailed Shallow Subsurface Imaging)

    Science.gov (United States)

    Marti, David; Marzan, Ignacio; Alvarez-Marron, Joaquina; Carbonell, Ramon

    2016-04-01

    A detailed full 3 dimensional P wave seismic velocity model was constrained by a high-resolution seismic tomography experiment. A regular and dense grid of shots and receivers was use to image a 500x500x200 m volume of the shallow subsurface. 10 GEODE's resulting in a 240 channels recording system and a 250 kg weight drop were used for the acquisition. The recording geometry consisted in 10x20m geophone grid spacing, and a 20x20 m stagered source spacing. A total of 1200 receivers and 676 source points. The study area is located within the Iberian Meseta, in Villar de Cañas (Cuenca, Spain). The lithological/geological target consisted in a Neogen sedimentary sequence formed from bottom to top by a transition from gyspum to silstones. The main objectives consisted in resolving the underground structure: contacts/discontinuities; constrain the 3D geometry of the lithology (possible cavities, faults/fractures). These targets were achieved by mapping the 3D distribution of the physical properties (P-wave velocity). The regularly space dense acquisition grid forced to acquire the survey in different stages and with a variety of weather conditions. Therefore, a careful quality control was required. More than a half million first arrivals were inverted to provide a 3D Vp velocity model that reached depths of 120 m in the areas with the highest ray coverage. An extended borehole campaign, that included borehole geophysical measurements in some wells provided unique tight constraints on the lithology an a validation scheme for the tomographic results. The final image reveals a laterally variable structure consisting of four different lithological units. In this methodological validation test travel-time tomography features a high capacity of imaging in detail the lithological contrasts for complex structures located at very shallow depths.

  5. Imaging the West Bohemia Seismic Zone

    Science.gov (United States)

    Alexandrakis, C.; Calo, M.; Bouchaala, F.; Vavrycuk, V.

    2013-12-01

    West Bohemia is located at the suture of three mantle lithosphere plates, the Eger Rift, the Cheb basin and is the site of Quaternary volcanism. This complex tectonic setting results in localized, periodic earthquake swarms throughout the region and many CO2 springs and gas exhalation sites. Nový Kostel, the most active swarm area, experiences frequent swarms of several hundreds to thousands of earthquakes over a period of weeks to several months. It is a unique study area, since the swarm region is surrounded by the West Bohemia Seismic Network (WEBNET), providing observations in all directions. Larger swarms, such as those in 1985/1986, 1997, 2000, 2007 and 2008, have been studied in terms of source mechanisms and swarm characteristics (Fischer and Michálek, 2003; Fischer et al., 2010; Vavryčuk, 2011). The seismicity is always located in the same area and depth range (6-15 km), however the active fault planes differ. This indicates changes to the local stress field, and may relate to the complicated tectonic situation and/or migrating fluids. Many studies have examined individual swarms and compared the earthquake episodes, however the mechanisms behind the phenomenon are still not understood. This has motivated many studies, including recent proposals for a reflection seismic profile directly over the swarm area and multidisciplinary monitoring through ICDP. In this study, we image the velocity structure within and around the swarm area using double-difference tomography (Zhang and Thurber, 2003) and Weighted Average Model (WAM) post-processing analysis (Calò et al., 2011). The WAM analysis averages together velocity models calculated with a variety of reasonable starting parameters. The velocities are weighted by the raypath proximity and density at an inversion node. This reduces starting model bias and artifacts, and yields a weighted standard deviation at each grid point. Earthquake locations and WEBNET P and S arrival times for the two most recent large

  6. Lamont Doherty Seismic Reflection Scanned Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains single channel seismic reflection profiles as provided to NGDC by Lamont Doherty Earh Observatory (LDEO). The profiles were originally...

  7. Imaging Fracture Networks Using Angled Crosshole Seismic Logging and Change Detection Techniques

    Science.gov (United States)

    Knox, H. A.; Grubelich, M. C.; Preston, L. A.; Knox, J. M.; King, D. K.

    2015-12-01

    We present results from a SubTER funded series of cross borehole geophysical imaging efforts designed to characterize fracture zones generated with an alternative stimulation method, which is being developed for Enhanced Geothermal Systems (EGS). One important characteristic of this stimulation method is that each detonation will produce multiple fractures without damaging the wellbore. To date, we have collected six full data sets with ~30k source-receiver pairs each for the purposes of high-resolution cross borehole seismic tomographic imaging. The first set of data serves as the baseline measurement (i.e. un-stimulated), three sets evaluate material changes after fracture emplacement and/or enhancement, and two sets are used for evaluation of pick error and seismic velocity changes attributable to changing environmental factors (i.e. saturation due to rain/snowfall in the shallow subsurface). Each of the six datasets has been evaluated for data quality and first arrivals have been picked on nearly 200k waveforms in the target area. Each set of data is then inverted using a Vidale-Hole finite-difference 3-D eikonal solver in two ways: 1) allowing for iterative ray tracing and 2) with fixed ray paths determined from the test performed before the fracture stimulation of interest. Utilizing these two methods allows us to compare and contrast the results from two commonly used change detection techniques. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  8. System and method to create three-dimensional images of non-linear acoustic properties in a region remote from a borehole

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Cung; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher; Johnson, Paul A.; Guyer, Robert; TenCate, James A.; Le Bas, Pierre-Yves

    2013-01-01

    In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed. In some aspects, the method includes arranging a first source in the borehole and generating a steered beam of elastic energy at a first frequency; arranging a second source in the borehole and generating a steerable beam of elastic energy at a second frequency, such that the steerable beam at the first frequency and the steerable beam at the second frequency intercept at a location away from the borehole; receiving at the borehole by a sensor a third elastic wave, created by a three wave mixing process, with a frequency equal to a difference between the first and second frequencies and a direction of propagation towards the borehole; determining a location of a three wave mixing region based on the arrangement of the first and second sources and on properties of the third wave signal; and creating three-dimensional images of the non-linear properties using data recorded by repeating the generating, receiving and determining at a plurality of azimuths, inclinations and longitudinal locations within the borehole. The method is additionally used to generate three dimensional images of the ratio of compressional to shear acoustic velocity of the same volume surrounding the borehole.

  9. Time-lapse seismic imaging of the Reykjanes geothermal reservoir

    Science.gov (United States)

    Weemstra, Cornelis; Obermann, Anne; Blanck, Hanna; Verdel, Arie; Paap, Bob; Árni Guðnason, Egill; Páll Hersir, Gylfi; Jousset, Philippe; Sigurðsson, Ómar

    2016-04-01

    We report on the results obtained from a dense seismic deployment over a geothermal reservoir. The reservoir has been producing continuously for almost a decade and is located on the tip of the Reykjanes peninsula, SW Iceland. The seismic stations on top of the reservoir have continuously recorded the ambient seismic wavefield between April 2014 and September 2015. The density of the seismic network makes the data well suited for time-lapse seismic imaging of the reservoir. To that end we compute time-lapse responses through the application of seismic interferometry. These interferometric lapse responses are obtained by simple crosscorrelation of the seismic noise recorded by the different seismic stations. We subsequently evaluate the temporal variation of the coda of these crosscorrelations. The term coda refers to the later arriving, multiple scattered waves. The multiple scattering implies that these waves have sampled the subsurface very densely and hence become highly sensitive to tiny mechanical and structural changes in that subsurface. This sensitivity allows one, in principle at least, to monitor the geothermal reservoir. Preliminary results indeed suggest a relation between the temporal variation of the coda waves and the reservoir. Ultimately, this method may lead to a means to monitor a geothermal reservoir in both space and time.

  10. A Coulomb stress model for induced seismicity distribution due to fluid injection and withdrawal in deep boreholes

    Science.gov (United States)

    Troiano, Antonio; Di Giuseppe, Maria Giulia; Troise, Claudia; Tramelli, Anna; De Natale, Giuseppe

    2013-10-01

    Fluid injection in and withdrawal from wells are basic procedures in mining activities and deep resources exploitation, such as oil and gas extraction, permeability enhancement for geothermal exploitation and waste fluid disposal. All of these activities have the potential to induce seismicity, as exemplified by the 2006 Basel earthquake (ML 3.4). Despite several decades of experience, the mechanisms of induced seismicity are not known in detail, which prevents effective risk assessment and/or mitigation. In this study, we provide an interpretation of induced seismicity based on computation of Coulomb stress changes that result from fluid injection/withdrawal at depth, mainly focused on the interpretation of induced seismicity due to stimulation of a geothermal reservoir. Seismicity is, theoretically, more likely where Coulomb stress changes are larger. For modeling purposes, we simulate the thermodynamic evolution of a system after fluid injection/withdrawal. The associated changes in pressure and temperature are subsequently considered as sources of incremental stress changes, which are then converted to Coulomb stress changes on favourably oriented faults, taking into account the background regional stress. Numerical results are applied to the water injection that was performed to create the fractured reservoir at the enhanced-geothermal-system site, Soultz-sous-Forets (France). Our approach describes well the observed seismicity, and provides an explanation for the different behaviors of a system when fluids are injected or withdrawn.

  11. Impact and mitigation of borehole related effects in permanent crosshole resistivity imaging: An example from the Ketzin CO2 storage site

    Science.gov (United States)

    Wagner, Florian M.; Bergmann, Peter; Rücker, Carsten; Wiese, Bernd; Labitzke, Tim; Schmidt-Hattenberger, Cornelia; Maurer, Hansruedi

    2015-12-01

    Geoelectrical methods are particularly suited for CO2 injection monitoring due to their high sensitivity to fluid displacement processes in porous rock formations. The use of borehole electrodes is favorable for deep storage horizons. Yet data acquisition based on permanently installed borehole electrodes can be challenged by the finite extent of the electrodes, unintended borehole deviation and complex borehole completion. Such conditions can lead to systematic errors in the electrical data sets, distortions of tomograms, and ultimately misinterpretations. We systematically analyze the effects of different borehole related error sources on tomographic inversion results and present respective methods for mitigation. Specifically, we incorporate the finite extent of the ring electrodes and the borehole completion into the electrical finite-element models and discuss the opportunity to infer borehole deviations solely based on geoelectrical data by means of a coupled inversion. While the finite extent of ring electrodes can be neglected if the electrode spacing is sufficiently large (> 5 m), different borehole completion materials used to fill the well annulus can cause potentially strong resistivity contrasts between the borehole completion and the rock formation, i.e., close to the electrodes. Resulting inversion artifacts are generally less severe when the borehole completion is more resistive compared to the surrounding rock. It is also shown that 2.5D inversion approaches are not adequate for imaging injection experiments in the presence of borehole completion. Unintended borehole deviation can result in geometric errors. Especially, vertical electrode shifts cause strong and localized inversion artifacts. Coupled inverse schemes potentially provide the opportunity to infer electrode shifts solely based on geoelectrical data provided the availability of high quality measurements (saturation from time-lapse geoelectrical measurements.

  12. Sparse seismic imaging using variable projection

    NARCIS (Netherlands)

    Aravkin, Aleksandr Y.; Tu, Ning; van Leeuwen, Tristan

    2013-01-01

    We consider an important class of signal processing problems where the signal of interest is known to be sparse, and can be recovered from data given auxiliary information about how the data was generated. For example, a sparse Green's function may be recovered from seismic experimental data using s

  13. The Obsidian Creep Project: Seismic Imaging in the Brawley Seismic Zone and Salton Sea Geothermal Field, Imperial County, California

    Science.gov (United States)

    Catchings, R. D.; Rymer, M. J.; Goldman, M.; Lohman, R. B.; McGuire, J. J.

    2010-12-01

    the south, which broke the surface during a local swarm of earthquakes in 2005 and which also slipped at the surface in association with the 2010 El Mayor-Cucapah earthquake in Baja California. The faults imaged in our profiles will be compared to high-precision earthquake relocations for the 2005 earthquake swarm and more recent events recorded by the Cal Energy borehole seismic network, and will be used as input into a reanalysis of geodetic observations spanning the 2005 earthquake swarm. The combined Obsidian Creep data set provides the most detailed, publicly available subsurface images of fault structures in the BSZ and SSGF.

  14. The application of vertical seismic profiling and cross-hole tomographic imaging for fracture characterization at Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    Majer, E.L.; Peterson, J.E.; Tura, M.A.; McEvilly, T.V.

    1990-01-01

    In order to obtain the necessary characterization for the storage of nuclear waste, much higher resolution of the features likely to affect the transport of radionuclides will be required than is normally achieved in conventional surface seismic reflection used in the exploration and characterization of petroleum and geothermal resources. Because fractures represent a significant mechanical anomaly seismic methods using are being investigated as a means to image and characterize the subsurface. Because of inherent limitations in applying the seismic methods solely from the surface, state-of-the-art borehole methods are being investigated to provide high resolution definition within the repository block. Therefore, Vertical Seismic Profiling (VSP) and cross-hole methods are being developed to obtain maximum resolution of the features that will possible affect the transport of fluids. Presented here will be the methods being developed, the strategy being pursued, and the rational for using VSP and crosshole methods at Yucca Mountain. The approach is intended to be an integrated method involving improvements in data acquisition, processing, and interpretation as well as improvements in the fundamental understanding of seismic wave propagation in fractured rock. 33 refs., 4 figs.

  15. The application of vertical seismic profiling and cross-hole tomographic imaging for fracture characterization at Yucca Mountain

    International Nuclear Information System (INIS)

    In order to obtain the necessary characterization for the storage of nuclear waste, much higher resolution of the features likely to affect the transport of radionuclides will be required than is normally achieved in conventional surface seismic reflection used in the exploration and characterization of petroleum and geothermal resources. Because fractures represent a significant mechanical anomaly seismic methods using are being investigated as a means to image and characterize the subsurface. Because of inherent limitations in applying the seismic methods solely from the surface, state-of-the-art borehole methods are being investigated to provide high resolution definition within the repository block. Therefore, Vertical Seismic Profiling (VSP) and cross-hole methods are being developed to obtain maximum resolution of the features that will possible affect the transport of fluids. Presented here will be the methods being developed, the strategy being pursued, and the rational for using VSP and crosshole methods at Yucca Mountain. The approach is intended to be an integrated method involving improvements in data acquisition, processing, and interpretation as well as improvements in the fundamental understanding of seismic wave propagation in fractured rock. 33 refs., 4 figs

  16. Imaging of seismic scatterers beneath the Gauribidanur (GBA) array

    International Nuclear Information System (INIS)

    A study has been conducted to image seismic scatterers beneath the Gauribidanur (GBA) array in the Precambrian shield of south India. Short period digital data from teleseisms and regional events recorded over the 20 station L shaped array was used to image seismic scatterers beneath the array employing semblance technique. The results indicate a zone of dominant scattering encompassing the crust in a region west of GBA. The inferred zone of scattering coincides with a large N-S elongated granitic intrusion believed to be Precambrian suture zone between the East and West Dharwar craton. (author). 16 refs, 7 figs, 1 tab

  17. Seismic Imaging of Complex Structures in the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    Ning Guo; Chao Wu; Stuart Fagin

    2015-01-01

    Conventional time imaging techniques are not capable of producing accurate seismic imaging of the subsurface in the mountain front of the Tarim Basin, China. Their imaged structures have led to some major drilling failures before, bearing a disrepute that “their structural closures have wheels and their structural highs have springs”. This article first lists the imaging challenges, and explains in a schematic why the time imaging techniques fail in this area. Then through a series of real data examples, it demonstrates that when there exist lateral velocity variations, depth imaging is the only solution to tackle the imaging challenges in this area. Depth imaging accounts for the com-plexity of the wavefield, therefore produces superior and geological plausible images. The core task in properly performing depth imaging is building the velocity model. This article stresses some the main aspects in this regard.

  18. Seismic reflection imaging of mixing processes in Fram Strait

    Science.gov (United States)

    Sarkar, Sudipta; Sheen, Katy L.; Klaeschen, Dirk; Brearley, J. Alexander; Minshull, Timothy A.; Berndt, Christian; Hobbs, Richard W.; Naveira Garabato, Alberto C.

    2015-10-01

    The West Spitsbergen Current, which flows northward along the western Svalbard continental slope, transports warm and saline Atlantic water (AW) into the Arctic Ocean. A combined analysis of high-resolution seismic images and hydrographic sections across this current has uncovered the oceanographic processes involved in horizontal and vertical mixing of AW. At the shelf break, where a strong horizontal temperature gradient exists east of the warmest AW, isopycnal interleaving of warm AW and surrounding colder waters is observed. Strong seismic reflections characterize these interleaving features, with a negative polarity reflection arising from an interface of warm water overlying colder water. A seismic-derived sound speed image reveals the extent and lateral continuity of such interleaving layers. There is evidence of obliquely aligned internal waves emanating from the slope at 450-500 m. They follow the predicted trajectory of internal S2 tidal waves and can promote vertical mixing between Atlantic and Arctic-origin waters.

  19. Reflection seismic imaging of a hydraulically conductive fracture zone in a high noise area, Forsmark, Sweden

    Science.gov (United States)

    Juhlin, C.; Stephens, M. B.; Cosma, C.

    2007-05-01

    High resolution reflection seismic methods have proven to be useful tools for locating fracture zones in crystalline rock. Siting of potential high-level nuclear waste repositories is a particularly important application of these methods. By using small explosive sources (15-75 grams), high resolution images of the sub-surface have been obtained in the depth range 100 m to 2 km in Sweden, Canada and elsewhere. Although ambient noise conditions in areas such as the Fennoscandian and Canadian shields are generally low, industrial noise can be high in some areas, particularly at potential sites suitable for repositories, since these are often close to existing infrastructure. In addition, the presence of this infrastructure limits the choice of sources available to the geophysicist. Forsmark, located about 140 km north of Stockholm, is one such potential site where reflection seismics have been carried out. Existing infrastructure includes nuclear reactors for power generation and a low- level waste repository. In the vicinity of the reactors, it was not possible to use an explosive source due to permitting restrictions. Instead, a VIBSIST system consisting of a tractor mounted hydraulic hammer was used in the vicinity of the reactors. By repeatedly hitting the pavement, without breaking it, at predefined sweeps and then stacking the signals, shot records comparable to explosive data could be generated. These shot records were then processed using standard methods to produce stacked sections along 3 profiles within the reactor area. Clear reflections are seen in the uppermost 600 m along 3 of these profiles. Correlation of crossing profiles shows that the strongest reflection (B8) is generated by a gently east-southeast dipping interface. Prior to construction of the reactors, several boreholes were drilled to investigate the bedrock in the area. One of these boreholes was located close to where two of the profiles cross. Projection of the B8 reflection into the

  20. Seismic imaging of sandbox experiments - laboratory hardware setup and first reflection seismic sections

    Science.gov (United States)

    Krawczyk, C. M.; Buddensiek, M.-L.; Oncken, O.; Kukowski, N.

    2012-10-01

    With the study and technical development introduced here, we combine analogue sandbox simulation techniques with seismic physical modelling of sandbox models. For that purpose, we designed and developed a new mini-seismic facility for laboratory use, comprising a seismic tank, a PC-driven control unit, a positioning system, and piezo-electric transducers used here the first time in an array mode. To assess the possibilities and limits of seismic imaging of small-scale structures in sandbox models, different geometry setups were tested in the first experiments that also tested the proper functioning of the device and studied the seismo-elastic properties of the granular media used. Simple two-layer models of different materials and layer thicknesses as well as a more complex model comprising channels and shear zones were tested using different acquisition geometries and signal properties. We suggest using well sorted and well rounded grains with little surface roughness (glass beads). Source receiver-offsets less than 14 cm for imaging structures as small as 2.0-1.5 mm size have proven feasible. This is the best compromise between wide beam and high energy output, and being applicable with a consistent waveform. Resolution of the interfaces of layers of granular materials depends on the interface preparation rather than on the material itself. Flat grading of interfaces and powder coverage yields the clearest interface reflections. Finally, sandbox seismic sections provide images of very good quality showing constant thickness layers as well as predefined channel structures and fault traces from shear zones. Since these can be regarded in sandbox models as zones of decompaction, they behave as reflectors and can be imaged. The multiple-offset surveying introduced here improves the quality with respect to S/N-ratio and source signature even more; the maximum depth penetration in glass bead layers thereby amounts to 5 cm. Thus, the presented mini-seismic device is

  1. Seismic imaging of sandbox experiments – laboratory hardware setup and first reflection seismic sections

    Directory of Open Access Journals (Sweden)

    N. Kukowski

    2012-10-01

    Full Text Available With the study and technical development introduced here, we combine analogue sandbox simulation techniques with seismic physical modelling of sandbox models. For that purpose, we designed and developed a new mini-seismic facility for laboratory use, comprising a seismic tank, a PC-driven control unit, a positioning system, and piezo-electric transducers used here the first time in an array mode. To assess the possibilities and limits of seismic imaging of small-scale structures in sandbox models, different geometry setups were tested in the first experiments that also tested the proper functioning of the device and studied the seismo-elastic properties of the granular media used. Simple two-layer models of different materials and layer thicknesses as well as a more complex model comprising channels and shear zones were tested using different acquisition geometries and signal properties. We suggest using well sorted and well rounded grains with little surface roughness (glass beads. Source receiver-offsets less than 14 cm for imaging structures as small as 2.0–1.5 mm size have proven feasible. This is the best compromise between wide beam and high energy output, and being applicable with a consistent waveform. Resolution of the interfaces of layers of granular materials depends on the interface preparation rather than on the material itself. Flat grading of interfaces and powder coverage yields the clearest interface reflections. Finally, sandbox seismic sections provide images of very good quality showing constant thickness layers as well as predefined channel structures and fault traces from shear zones. Since these can be regarded in sandbox models as zones of decompaction, they behave as reflectors and can be imaged. The multiple-offset surveying introduced here improves the quality with respect to S/N-ratio and source signature even more; the maximum depth penetration in glass bead layers thereby amounts to 5 cm. Thus, the presented mini-seismic

  2. Fabry-Perot MEMS Accelerometers for Advanced Seismic Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chisum, Brad [Lumedyne Technologies Incorporated, San Diego, CA (United States)

    2015-05-31

    This report summarizes the technical achievements that occurred over the duration of the project. On November 14th, 2014, Lumedyne Technologies Incorporated was acquired. As a result of the acquisition, the work toward seismic imaging applications was suspended indefinitely. This report captures the progress achieved up to that time.

  3. Seismic imaging of sandbox experiments – laboratory hardware setup and first reflection seismic sections

    Directory of Open Access Journals (Sweden)

    C. M. Krawczyk

    2013-02-01

    Full Text Available With the study and technical development introduced here, we combine analogue sandbox simulation techniques with seismic physical modelling of sandbox models. For that purpose, we designed and developed a new mini-seismic facility for laboratory use, comprising a seismic tank, a PC-driven control unit, a positioning system, and piezoelectric transducers used here for the first time in an array mode. To assess the possibilities and limits of seismic imaging of small-scale structures in sandbox models, different geometry setups were tested in the first 2-D experiments that also tested the proper functioning of the device and studied the seismo-elastic properties of the granular media used. Simple two-layer models of different materials and layer thicknesses as well as a more complex model comprising channels and shear zones were tested using different acquisition geometries and signal properties. We suggest using well sorted and well rounded grains with little surface roughness (glass beads. Source receiver-offsets less than 14 cm for imaging structures as small as 2.0–1.5 mm size have proven feasible. This is the best compromise between wide beam and high energy output, and is applicable with a consistent waveform. Resolution of the interfaces of layers of granular materials depends on the interface preparation rather than on the material itself. Flat grading of interfaces and powder coverage yields the clearest interface reflections. Finally, sandbox seismic sections provide images of high quality showing constant thickness layers as well as predefined channel structures and indications of the fault traces from shear zones. Since these were artificially introduced in our test models, they can be regarded as zones of disturbance rather than tectonic shear zones characterized by decompaction. The multiple-offset surveying introduced here, improves the quality with respect to S / N ratio and source signature even more; the maximum depth

  4. Stratigraphy of a proposed wind farm site southeast of Block Island: Utilization of borehole samples, downhole logging, and seismic profiles

    Science.gov (United States)

    Sheldon, Dane P. H.

    Seismic stratigraphy, sedimentology, lithostratigraphy, downhole geophysical logging, mineralogy, and palynology were used to study and interpret the upper 70 meters of the inner continental shelf sediments within a proposed wind farm site located approximately two to three nautical miles to the southeast of Block Island, Rhode Island. Core samples and downhole logging collected from borings drilled for geotechnical purposes at proposed wind turbine sites along with seismic surveys in the surrounding area provide the data for this study. Cretaceous coastal plain sediments that consist of non-marine to marine sand, silt, and clay are found overlying bedrock at a contact depth beyond the sampling depth of this study. The upper Cretaceous sediments sampled in borings are correlated with the Magothy/Matawan formations described regionally from New Jersey to Nantucket. An unconformity formed through sub-aerial, fluvial, marine, and glacial erosion marks the upper strata of the Cretaceous sediments separating them from the overlying deposits. The majority of Quaternary deposits overlying the unconformity represent the advance, pulsing, and retreat of the Laurentide ice sheet that reached its southern terminus in the area of Block Island approximately 25,000 to 21,000 years before present. The sequence consists of a basal glacial till overlain by sediments deposited by meltwater environments ranging from deltaic to proglacial lakefloor. A late Pleistocene to early Holocene unconformity marks the top of the glacial sequence and was formed after glacial retreat through fluvial and subaerial erosion/deposition. Overlying the glacial sequence are sediments deposited during the late Pleistocene and Holocene consisting of interbedded gravel, sand, silt, and clay. Sampling of these sediments was limited and surficial reflectors in seismic profiles were masked due to a hard bottom return. However, two depositional periods are interpreted as representing fluvial and estuarine

  5. Fractured bedrock investigation by using high-resolution borehole images and the Distributed Temperature Sensing technique

    OpenAIRE

    Radioti, Georgia; Delvoie, Simon; Radu, Jean-Pol; Nguyen, Frédéric; Charlier, Robert

    2015-01-01

    In order to investigate the fracturing of the bedrock and its possible heterogeneous distribution in situ, four boreholes equipped with double-U geothermal pipes of 100 m long were installed on the campus of the University of Liege (Liege, Belgium) over a surface area of 32 m². The bedrock, which starts at a depth approximately of 8 m, is quite fractured and consists mainly of siltstone and shale interbedded with sandstone. Different geophysical methods are applied at two different phas...

  6. Use of seismic interferometry to improve the imaging of a heterogeneous landfill

    NARCIS (Netherlands)

    Konstantaki, L.A.; Draganov, D.S.; Ghose, R.; Heimovaara, T.J.

    2015-01-01

    In this study we investigate the application of seismic interferometry (SI) to seismic reflection data recorded over a landfill. Landfills represent strongly heterogeneous subsurfaces making the seismic reflection imaging challenging. We show that SI improves the imaging of high-density areas, which

  7. Seismic reflection imaging, accounting for primary and multiple reflections

    Science.gov (United States)

    Wapenaar, Kees; van der Neut, Joost; Thorbecke, Jan; Broggini, Filippo; Slob, Evert; Snieder, Roel

    2015-04-01

    Imaging of seismic reflection data is usually based on the assumption that the seismic response consists of primary reflections only. Multiple reflections, i.e. waves that have reflected more than once, are treated as primaries and are imaged at wrong positions. There are two classes of multiple reflections, which we will call surface-related multiples and internal multiples. Surface-related multiples are those multiples that contain at least one reflection at the earth's surface, whereas internal multiples consist of waves that have reflected only at subsurface interfaces. Surface-related multiples are the strongest, but also relatively easy to deal with because the reflecting boundary (the earth's surface) is known. Internal multiples constitute a much more difficult problem for seismic imaging, because the positions and properties of the reflecting interfaces are not known. We are developing reflection imaging methodology which deals with internal multiples. Starting with the Marchenko equation for 1D inverse scattering problems, we derived 3D Marchenko-type equations, which relate reflection data at the surface to Green's functions between virtual sources anywhere in the subsurface and receivers at the surface. Based on these equations, we derived an iterative scheme by which these Green's functions can be retrieved from the reflection data at the surface. This iterative scheme requires an estimate of the direct wave of the Green's functions in a background medium. Note that this is precisely the same information that is also required by standard reflection imaging schemes. However, unlike in standard imaging, our iterative Marchenko scheme retrieves the multiple reflections of the Green's functions from the reflection data at the surface. For this, no knowledge of the positions and properties of the reflecting interfaces is required. Once the full Green's functions are retrieved, reflection imaging can be carried out by which the primaries and multiples are

  8. Passive Seismic Reflectivity Imaging with Ocean-Bottom Cable Data

    Science.gov (United States)

    Hohl, D.; Mateeva, A.

    2005-12-01

    The idea of imaging the subsurface reflectivity distribution by correlating long traces of seismic ``noise'' (i.e. seismic data recorded without active sources) goes back more than 30 years [1]. To this day, passive seismic reflectivity imaging has not been exploited for business use in the E&P industry. The conditions for successful passive seismic reflection imaging have greatly improved over the past few years, and the prize of cheap continuous sourceless seismic imaging and possibly monitoring is still large. Nearly unlimited quantities of very high quality passive noise data are now available from permanent 4C ocean bottom cable (OBC) installations. In the present contribution, we report our initial results for single-line (2D) OBC data collected in the North Sea and GOM. The OBCs used for the experiment are of length 6-10 km with 4C receivers spaced 50 m apart. They are deployed in both shallow and deep water over large hydrocarbon reservoirs. Passive noise data were recorded for 8-24 h periods, sometimes several times, and months apart. In the analysis presented here only the hydrophone records are used, and the data from all recording periods are used together to produce a single 2D migrated reflectivity section. We observe that environmental noise (e.g. boat and rig activity) play an important role for imaging and usually requires pre-migration seismic processing steps to filter out unwanted signals. At the core of our image generation and processing sequence is the crosscorrelation of noise trace pairs and subsequent prestack time migration [1] with a velocity model established for the active-source OBC data processing. We compute 4 sec of lag time to either side of t=0. After removing unwanted signals (e.g. seafloor interface waves) from these ``virtual shot gathers'' one can clearly detect the linear-moveout direct water wave with velocity 1500 m/s, and a linear interface wave with velocity 2000 m/s. Other ``events'' with moveout are visible, but the

  9. The Salton Seismic Imaging Project (SSIP): Active Rift Processes in the Brawley Seismic Zone

    Science.gov (United States)

    Han, L.; Hole, J. A.; Stock, J. M.; Fuis, G. S.; Rymer, M. J.; Driscoll, N. W.; Kent, G.; Harding, A. J.; Gonzalez-Fernandez, A.; Lazaro-Mancilla, O.

    2011-12-01

    The Salton Seismic Imaging Project (SSIP), funded by NSF and USGS, acquired seismic data in and across the Salton Trough in southern California and northern Mexico in March 2011. The project addresses both rifting processes at the northern end of the Gulf of California extensional province and earthquake hazards at the southern end of the San Andreas Fault system. Seven lines of onshore refraction and low-fold reflection data were acquired in the Coachella, Imperial, and Mexicali Valleys, two lines and a grid of airgun and OBS data were acquired in the Salton Sea, and onshore-offshore data were recorded. Almost 2800 land seismometers and 50 OBS's were used in almost 5000 deployments at almost 4300 sites, in spacing as dense as 100 m. These instruments received seismic signals from 126 explosive shots up to 1400 kg and over 2300 airgun shots. In the central Salton Trough, North American lithosphere appears to have been rifted completely apart. Based primarily on a 1979 seismic refraction project, the 20-22 km thick crust is apparently composed entirely of new crust added by magmatism from below and sedimentation from above. Active rifting of this new crust is manifested by shallow (geothermal energy production. This presentation is focused on an onshore-offshore line of densely sampled refraction and low-fold reflection data that crosses the Brawley Seismic Zone and Salton Buttes in the direction of plate motion. At the time of abstract submission, data analysis was very preliminary, consisting of first-arrival tomography of the onshore half of the line for upper crustal seismic velocity. Crystalline basement (>5 km/s), comprised of late-Pliocene to Quaternary sediment metamorphosed by the high heat flow, occurs at ~2 km depth beneath the Salton Buttes and geothermal field and ~4 km depth south of the BSZ. Preliminary result suggests that the velocity of basement is lower in the BSZ than to the south, which may result from fracturing. Basement velocity appears to be

  10. Borehole Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature derived from boreholes drilled into the Earth crust. Parameter keywords describe what was measured in this data set. Additional summary...

  11. Seismic Images of the Crust across D-E Seismic Profile (TS04-Tsujal Project): Results of Reflection and Wide-Angle Seismic Study

    Science.gov (United States)

    Nunez, D.; Lopez Ortiz, J. Y.; Bartolome, R.; Barba, D. C., Sr.; Nunez-Cornu, F. J.; Danobeitia, J.; Zamora-Camacho, A.; Escudero, C. R.

    2014-12-01

    As a part of TSUJAL Project (Crustal characterization of the Rivera Plate-Jalisco Block boundary and its implications for seismic and tsunami hazard assessment), a geophysical study has been carried out during February and March 2014 in western continental margin of Jalisco where seismic reflection, wide-angle seismic, bathymetry and potential fields (gravity and magnetism) data have been obtained. Eight land seismic stations vertical component and 4.5 Hz model TEXAN 125A (REFTEK), were deployed along an offshore-onshore seismic profile of 140 km length in SW-NE orientation. These stations registered, in continuous model, the airgun shots provided by RRS James Cook used for Multichannel Seismic Reflection data acquisition every 50 m of distance interval and total capacity of 5800 ci along seismic profile D-E (TS04). In the onshore region, these stations were deployed every 20 km from Pérula to Nacastillo (Jalisco, Mexico). The study region corresponds to onshore-offshore line limited by (18o 54'N, 105o 59'W) (19o 26'N, 105o7'W) coordinates. In this work, seismic images of the crust along a deep seismic profile of 140 km length are presented. These images provide new cortical information about the southern part of Rivera Plate, continental accretionary wedge and first kilometers of Jalisco Block continental zone.

  12. Seismic Imaging at Whataroa Valley (New Zealand) for the Deep-Fault-Drilling-Project Alpine Fault

    Science.gov (United States)

    Lay, V.; Buske, S.; Kovacs, A.; Gorman, A. R.

    2013-12-01

    gathers were further processed, including basic trace editing, bandpass filtering, trace equalization, FK-filtering and automatic gain control. The high-quality data show various indicators of the Alpine Fault such as strong reflections and distorted first-arrival wavefields which are clearly visible already in single shot gathers. Generally, we expect a sediment layer with a thickness of a few hundred meters above Schist rocks. A corresponding change in physical parameters is confirmed by the velocity model, that has been obtained by first-arrival tomography. On the basis of this velocity model 3D pre-stack depth migration has been applied to the data set. With the help of these high resolution seismic images we can study the shallow structures of the subsurface thus gaining information about the location and dip of reflectors. Further detailed processing and intensive interpretative work will enable a seismic site characterization providing important information for the selection of the borehole location. Additionally the high resolution seismic images themselves allow a better understanding of the tectonic and geodynamic settings.

  13. Imaging Near-Surface Controls on Hot Spring Expression Using Shallow Seismic Refraction in Yellowstone National Park

    Science.gov (United States)

    Price, A. N.; Lindsey, C.; Fairley, J. P., Jr.; Larson, P. B.

    2015-12-01

    We used shallow seismic refraction to image near-surface materials in the vicinity of a small group of hot springs, located in the Morning Mist Springs area of Lower Geyser Basin, Yellowstone National Park, Wyoming. Seismic velocities in the area surveyed range from a low of 0.3 km/s to a high of approximately 2.5 km/s. The survey results indicate an irregular surface topography overlain by silty sediments. The observed seismic velocities are consistent with a subsurface model in which sorted sands and gravels, probably outwash materials from the Pinedale glaciation, are overlain by silts and fine sands deposited in the flat-lying areas of the Morning Springs area. These findings are supported by published geologic maps of the area and well logs from a nearby borehole. The near-surface materials appear to be saturated with discharging hydrothermal fluids of varying temperature, and interbedded with semi-lithified geothermal deposits (sinter). We hypothesize that the relatively low-conductivity deposits of fines at the surface may serve to confine a shallow, relatively low-temperature (sub-boiling) hydrothermal aquifer, and that the distribution of sinter in the shallow subsurface plays an important role in determining the geometry of hydrothermal discharge (hot springs) at the land surface. Few studies of the shallow controls on hot spring expression exist for the Yellowstone caldera, and the present study therefore offers a unique glimpse into near-subsurface fluid flow controls.

  14. Detecting a fluid-filled borehole using elastic waves from a remote borehole.

    Science.gov (United States)

    Tang, Xiaoming; Cao, Jingji; Li, Zhen; Su, Yuanda

    2016-08-01

    The interaction of a fluid-filled borehole with incident elastic waves is an important topic for downhole acoustic measurements. By analyzing the wave phenomena of this problem, one can simulate the detection of a borehole target using a source-receiver system in a remote borehole. The analysis result shows that the wave signals from the target borehole are of sufficient amplitude even though the borehole size is small compared to wavelength. Consequently, the target borehole can be detected when the two boreholes are far away from each other. The result can be utilized to provide a method for testing downhole acoustic imaging tools. PMID:27586782

  15. Toward seismic source imaging using seismo-ionospheric data

    Science.gov (United States)

    Rolland, L.; Larmat, C. S.; Mikesell, D.; Sladen, A.; Khelfi, K.; Astafyeva, E.; Lognonne, P. H.

    2014-12-01

    The worldwide coverage offered by global navigation space systems (GNSS) such as GPS, GLONASS or Galileo allows seismological measurements of a new kind. GNSS-derived total electron content (TEC) measurements can be especially useful to image seismically active zones that are not covered by conventional instruments. For instance, it has been shown that the Japanese dense GPS network GEONET was able to record images of the ionosphere response to the initial coseismic sea-surface motion induced by the great Mw 9.0 2011 Tohoku-Oki earthquake less than 10 minutes after the rupture initiation (Astafyeva et al., 2013). But earthquakes of lower magnitude, down to about 6.5 would also induce measurable ionospheric perturbations, when GNSS stations are located less than 250 km away from the epicenter. In order to make use of these new data, ionospheric seismology needs to develop accurate forward models so that we can invert for quantitative seismic sources parameters. We will present our current understanding of the coupling mechanisms between the solid Earth, the ocean, the atmosphere and the ionosphere. We will also present the state-of-the-art in the modeling of coseismic ionospheric disturbances using acoustic ray theory and a new 3D modeling method based on the Spectral Element Method (SEM). This latter numerical tool will allow us to incorporate lateral variations in the solid Earth properties, the bathymetry and the atmosphere as well as realistic seismic source parameters. Furthermore, seismo-acoustic waves propagate in the atmosphere at a much slower speed (from 0.3 to ~1 km/s) than seismic waves propagate in the solid Earth. We are exploring the application of back-projection and time-reversal methods to TEC observations in order to retrieve the time and space characteristics of the acoustic emission in the seismic source area. We will first show modeling and inversion results with synthetic data. Finally, we will illustrate the imaging capability of our approach

  16. LAND STREAMER SEISMIC DATA FROM NORTHERN DELAWARE: A VIABLE ALTERNATIVE FOR IMAGING AQUIFERS IN SUBURBAN AREAS

    Science.gov (United States)

    Velez, C. C.; McLaughlin, P. P.; McGeary, S. E.; Sargent, S. L.

    2009-12-01

    The Potomac Formation includes the most important confined aquifers in the Coastal Plain of northern Delaware. Development and a growing suburban population are increasing demand for groundwater in the area, making accurate assessment of groundwater water supply increasingly important. Previous studies of subsurface geology indicate that the Potomac Formation is characterized by laterally discontinuous fluvial sand bodies, making it difficult to precisely delineate the distribution and geometry of the aquifer facies based on well correlations alone. A 20-km high-resolution seismic reflection dataset was collected using a land-streamer system in 2008 to constrain subsurface stratigraphy between disparate well locations. The data were collected along roadways in an area of mixed development that includes suburban housing tracts, farmlands, and large industry. A 152-m-deep continuous-cored test hole was drilled in the summer of 2009 adjacent to one of the lines and a full suite of borehole geophysical logs obtained. The land-streamer data are compared to a 3-km dataset collected also in 2008 using conventional methods on farmland in the northern part of the study area. The land streamer system proved to be more effective than conventional seismic reflection methods in this area. Several advantages are evident for the land streamer: 1) overall, the conventional dataset has a higher S/N, 2) on average, collecting data with the land streamer system is four times faster, and 3) the land streamer lines can be longer and therefore more continuous than the conventional lines in a developed area. The land-streamer system has minor disadvantages: traffic control, traffic noise, and in some cases a need for larger crews. Regardless, the land streamer dataset is easier to process, of higher quality, and more cost effective. The final depth images from the land streamer data indicate that the minimum and maximum depths imaged are ~18 m and ~ 268m, with a resolution of ~4 m. This

  17. Mesoscopics of ultrasound and seismic waves: application to passive imaging

    Science.gov (United States)

    Larose, É.

    2006-05-01

    This manuscript deals with different aspects of the propagation of acoustic and seismic waves in heterogeneous media, both simply and multiply scattering ones. After a short introduction on conventional imaging techniques, we describe two observations that demonstrate the presence of multiple scattering in seismic records: the equipartition principle, and the coherent backscattering effect (Chap. 2). Multiple scattering is related to the mesoscopic nature of seismic and acoustic waves, and is a strong limitation for conventional techniques like medical or seismic imaging. In the following part of the manuscript (Chaps. 3 5), we present an application of mesoscopic physics to acoustic and seismic waves: the principle of passive imaging. By correlating records of ambient noise or diffuse waves obtained at two passive sensors, it is possible to reconstruct the impulse response of the medium as if a source was placed at one sensor. This provides the opportunity of doing acoustics and seismology without a source. Several aspects of this technique are presented here, starting with theoretical considerations and numerical simulations (Chaps. 3, 4). Then we present experimental applications (Chap. 5) to ultrasound (passive tomography of a layered medium) and to seismic waves (passive imaging of California, and the Moon, with micro-seismic noise). Physique mésoscopique des ultrasons et des ondes sismiques : application à l'imagerie passive. Cet article de revue rassemble plusieurs aspects fondamentaux et appliqués de la propagation des ondes acoustiques et élastiques dans les milieux hétérogènes, en régime de diffusion simple ou multiple. Après une introduction sur les techniques conventionelles d'imagerie sismique et ultrasonore, nous présentons deux expériences qui mettent en évidence la présence de diffusion multiple dans les enregistrements sismologiques : l'équipartition des ondes, et la rétrodiffusion cohérente (Chap. 2). La diffusion multiple des

  18. Seismic imaging in laboratory trough laser Doppler vibrometry

    Science.gov (United States)

    Brito, Daniel; Poydenot, Valier; Garambois, Stéphane; Diaz, Julien; Bordes, Clarisse; Rolando, Jean-Paul

    2016-04-01

    Mimic near-surface seismic field measurements at a small scale, in the laboratory, under a well-controlled environment, may lead to a better understanding of wave propagation in complex media such as in geological materials. Laboratory experiments can help in particular to constrain and refine theoretical and numerical modelling of physical phenomena occurring during seismic propagation, in order to make a better use of the complete set of measurements recorded in the field. We have developed a laser Doppler vibrometer (laser interferometry) platform designed to measure non-contact seismic displacements (or velocities) of a surface. This technology enables to measure displacements as small as a tenth of a nanometer on a wide range of frequencies, from a few tenths to a few megahertz. Our experimental set-up is particularly suited to provide high-density spatial and temporal records of displacements on the edge of any vibrating material. We will show in particular a study of MHz wave propagation (excited by piezoelectric transducers) in cylindrical cores of typical diameter size around 10 cm. The laser vibrometer measurements will be first validated in homogeneous materials cylinders by comparing the measurements to a direct numerical simulation. Special attention will be given to the comparison of experimental versus numerical amplitudes of displacements. In a second step, we will conduct the same type of study through heterogeneous carbonate cores, possibly fractured. Tomographic images of velocity in 2D slices of the carbonate core will be derived based upon on the time of first arrival. Preliminary attempts of tomographic attenuation maps will also be presented based on the amplitudes of first arrivals. Experimental records will be confronted to direct numerical simulations and tomographic images will be compared to x-ray scanner imaging of the cylindrical cores.

  19. Advanced Reservoir Imaging Using Frequency-Dependent Seismic Attributes

    Energy Technology Data Exchange (ETDEWEB)

    Fred Hilterman; Tad Patzek; Gennady Goloshubin; Dmitriy Silin; Charlotte Sullivan; Valeri Korneev

    2007-12-31

    Our report concerning advanced imaging and interpretation technology includes the development of theory, the implementation of laboratory experiments and the verification of results using field data. We investigated a reflectivity model for porous fluid-saturated reservoirs and demonstrated that the frequency-dependent component of the reflection coefficient is asymptotically proportional to the reservoir fluid mobility. We also analyzed seismic data using different azimuths and offsets over physical models of fractures filled with air and water. By comparing our physical model synthetics to numerical data we have identified several diagnostic indicators for quantifying the fractures. Finally, we developed reflectivity transforms for predicting pore fluid and lithology using rock-property statistics from 500 reservoirs in both the shelf and deep-water Gulf of Mexico. With these transforms and seismic AVO gathers across the prospect and its down-dip water-equivalent reservoir, fluid saturation can be estimated without a calibration well that ties the seismic. Our research provides the important additional mechanisms to recognize, delineate, and validate new hydrocarbon reserves and assist in the development of producing fields.

  20. Triple seismic source, double research ship, single ambitious goal: integrated imaging of young oceanic crust in the Panama Basin

    Science.gov (United States)

    Wilson, Dean; Peirce, Christine; Hobbs, Richard; Gregory, Emma

    2016-04-01

    Understanding geothermal heat and mass fluxes through the seafloor is fundamental to the study of the Earth's energy budget. Using geophysical, geological and physical oceanography data we are exploring the interaction between the young oceanic crust and the ocean in the Panama Basin. We acquired a unique geophysical dataset that will allow us to build a comprehensive model of young oceanic crust from the Costa Rica Ridge axis to ODP borehole 504B. Data were collected over two 35 x 35 km2 3D grid areas, one each at the ridge axis and the borehole, and along three 330 km long 2D profiles orientated in the spreading direction, connecting the two grids. In addition to the 4.5 km long multichannel streamer and 75 ocean-bottom seismographs (OBS), we also deployed 12 magnetotelluric (MT) stations and collected underway swath bathymetry, gravity and magnetic data. For the long 2D profiles we used two research vessels operating synchronously. The RRS James Cook towed a high frequency GI-gun array (120 Hz) to image the sediments, and a medium frequency Bolt-gun array (50 Hz) for shallow-to-mid-crustal imaging. The R/V Sonne followed the Cook, 9 km astern and towed a third seismic source; a low frequency, large volume G-gun array (30 Hz) for whole crustal and upper mantle imaging at large offsets. Two bespoke vertical hydrophone arrays recorded real far field signatures that have enabled us to develop inverse source filters and match filters. Here we present the seismic reflection image, forward and inverse velocity-depth models and a density model along the primary 330 km north-south profile, from ridge axis to 6 Ma crust. By incorporating wide-angle streamer data from our two-ship, synthetic aperture acquisition together with traditional wide-angle OBS data we are able to constrain the structure of the upper oceanic crust. The results show a long-wavelength trend of increasing seismic velocity and density with age, and a correlation between velocity structure and basement

  1. Lattice Boltzmann methods applied to large-scale three-dimensional virtual cores constructed from digital optical borehole images of the karst carbonate Biscayne aquifer in southeastern Florida

    Science.gov (United States)

    Michael Sukop,; Cunningham, Kevin J.

    2014-01-01

    Digital optical borehole images at approximately 2 mm vertical resolution and borehole caliper data were used to create three-dimensional renderings of the distribution of (1) matrix porosity and (2) vuggy megaporosity for the karst carbonate Biscayne aquifer in southeastern Florida. The renderings based on the borehole data were used as input into Lattice Boltzmann methods to obtain intrinsic permeability estimates for this extremely transmissive aquifer, where traditional aquifer test methods may fail due to very small drawdowns and non-Darcian flow that can reduce apparent hydraulic conductivity. Variogram analysis of the borehole data suggests a nearly isotropic rock structure at lag lengths up to the nominal borehole diameter. A strong correlation between the diameter of the borehole and the presence of vuggy megaporosity in the data set led to a bias in the variogram where the computed horizontal spatial autocorrelation is strong at lag distances greater than the nominal borehole size. Lattice Boltzmann simulation of flow across a 0.4 × 0.4 × 17 m (2.72 m3 volume) parallel-walled column of rendered matrix and vuggy megaporosity indicates a high hydraulic conductivity of 53 m s−1. This value is similar to previous Lattice Boltzmann calculations of hydraulic conductivity in smaller limestone samples of the Biscayne aquifer. The development of simulation methods that reproduce dual-porosity systems with higher resolution and fidelity and that consider flow through horizontally longer renderings could provide improved estimates of the hydraulic conductivity and help to address questions about the importance of scale.

  2. The ICDP Snake River Geothermal Drilling Project: preliminary overview of borehole geophysics

    Science.gov (United States)

    Schmitt, Douglas R.; Liberty, Lee M.; Kessler, James E.; Kuck, Jochem; Kofman, Randolph; Bishop, Ross; Shervais, John W.; Evans, James P.; Champion, Duane E.

    2012-01-01

    Hotspot: The Snake River Geothermal Drilling Project was undertaken to better understand the geothermal systems in three locations across the Snake River Plain with varying geological and hydrological structure. An extensive series of standard and specialized geophysical logs were obtained in each of the wells. Hydrogen-index neutron and γ-γ density logs employing active sources were deployed through the drill string, and although not fully calibrated for such a situation do provide semi-quantitative information related to the ‘stratigraphy’ of the basalt flows and on the existence of alteration minerals. Electrical resistivity logs highlight the existence of some fracture and mineralized zones. Magnetic susceptibility together with the vector magnetic field measurements display substantial variations that, in combination with laboratory measurements, may provide a tool for tracking magnetic field reversals along the borehole. Full waveform sonic logs highlight the variations in compressional and shear velocity along the borehole. These, together with the high resolution borehole seismic measurements display changes with depth that are not yet understood. The borehole seismic measurements indicate that seismic arrivals are obtained at depth in the formations and that strong seismic reflections are produced at lithological contacts seen in the corresponding core logging. Finally, oriented ultrasonic borehole televiewer images were obtained over most of the wells and these correlate well with the nearly 6 km of core obtained. This good image log to core correlations, particularly with regards to drilling induced breakouts and tensile borehole and core fractures will allow for confident estimates of stress directions and or placing constraints on stress magnitudes. Such correlations will be used to orient in core orientation giving information useful in hydrological assessments, paleomagnetic dating, and structural volcanology.

  3. Enhanced imaging of CO2 at the Ketzin storage site: Inversion of 3D time-lapse seismic data

    Science.gov (United States)

    Gil, M.; Götz, J.; Ivanova, A.; Juhlin, C.; Krawczyk, C. M.; Lüth, S.; Yang, C.

    2012-04-01

    The Ketzin test site, located near Berlin, is Europe's longest-operating on-shore CO2 storage site. As of December 2011, more than 56,000 tons of food grade CO2 has been injected since June 2008 in an anticlinal structure of the Northeast German Basin. The target reservoir consists of porous, brine bearing sandstone units of the Upper Triassic Stuttgart Formation at approximately 630 to 650 m depth. In order to enhance the understanding of the structural geometry of the site and to investigate the extension of the CO2-plume, several geophysical monitoring methods are being applied at Ketzin, among these are active seismic measurements, geoelectrics and borehole measurements. Among the various seismic techniques (e.g. 2D reflection surveys, crosshole tomography, Vertical Seismic Profiling, 2D- and 3D-Moving Source Profiling) employed at this pilot site, 3D time-lapse reflection surveys are an important component. The baseline 3D survey was acquired in 2005 and the first repeat measurements were performed in 2009 after injection of about 22,000 tons of CO2. The second repeat survey is planned to be carried out in fall 2012. These measurements allow the time-lapse signature of the injected CO2 to be imaged. The time-lapse amplitude variation attributed to the injected CO2 in the reservoir matches, considering detection limits of seismic surface measurements, the expected distribution of the CO2 plume derived from reservoir simulations. Previous attempts towards a quantitative interpretation were based on integrative considerations of different types of geophysical measurements using strict assumptions and characterized by large error bars. In order to increase the resolution and reliability of the data and to improve estimation of rock properties and especially to enhance the imaging resolution of the CO2-plume, the time-lapse 3D seismic data have now been inverted for seismic impedances with different methods, which is the focus of this presentation. One difficulty

  4. Seismic imaging using finite-differences and parallel computers

    Energy Technology Data Exchange (ETDEWEB)

    Ober, C.C. [Sandia National Labs., Albuquerque, NM (United States)

    1997-12-31

    A key to reducing the risks and costs of associated with oil and gas exploration is the fast, accurate imaging of complex geologies, such as salt domes in the Gulf of Mexico and overthrust regions in US onshore regions. Prestack depth migration generally yields the most accurate images, and one approach to this is to solve the scalar wave equation using finite differences. As part of an ongoing ACTI project funded by the US Department of Energy, a finite difference, 3-D prestack, depth migration code has been developed. The goal of this work is to demonstrate that massively parallel computers can be used efficiently for seismic imaging, and that sufficient computing power exists (or soon will exist) to make finite difference, prestack, depth migration practical for oil and gas exploration. Several problems had to be addressed to get an efficient code for the Intel Paragon. These include efficient I/O, efficient parallel tridiagonal solves, and high single-node performance. Furthermore, to provide portable code the author has been restricted to the use of high-level programming languages (C and Fortran) and interprocessor communications using MPI. He has been using the SUNMOS operating system, which has affected many of his programming decisions. He will present images created from two verification datasets (the Marmousi Model and the SEG/EAEG 3D Salt Model). Also, he will show recent images from real datasets, and point out locations of improved imaging. Finally, he will discuss areas of current research which will hopefully improve the image quality and reduce computational costs.

  5. Automatic performance tuning of parallel and accelerated seismic imaging kernels

    KAUST Repository

    Haberdar, Hakan

    2014-01-01

    With the increased complexity and diversity of mainstream high performance computing systems, significant effort is required to tune parallel applications in order to achieve the best possible performance for each particular platform. This task becomes more and more challenging and requiring a larger set of skills. Automatic performance tuning is becoming a must for optimizing applications such as Reverse Time Migration (RTM) widely used in seismic imaging for oil and gas exploration. An empirical search based auto-tuning approach is applied to the MPI communication operations of the parallel isotropic and tilted transverse isotropic kernels. The application of auto-tuning using the Abstract Data and Communication Library improved the performance of the MPI communications as well as developer productivity by providing a higher level of abstraction. Keeping productivity in mind, we opted toward pragma based programming for accelerated computation on latest accelerated architectures such as GPUs using the fairly new OpenACC standard. The same auto-tuning approach is also applied to the OpenACC accelerated seismic code for optimizing the compute intensive kernel of the Reverse Time Migration application. The application of such technique resulted in an improved performance of the original code and its ability to adapt to different execution environments.

  6. Review on improved seismic imaging with closure phase

    KAUST Repository

    Schuster, Gerard T.

    2014-08-13

    The timing and amplitudes of arrivals recorded in seismic traces are influenced by velocity variations all along the associated raypaths. Consequently, velocity errors far from the target can lead to blurred imaging of the target body. To partly remedy this problem, we comprehensively reviewed inverting differential traveltimes that satisfied the closure-phase condition. The result is that the source and receiver statics are completely eliminated in the data and velocities far from the target do not need to be known. We successfully used the phase closure equation for traveltime tomography, refraction statics, migration, refraction tomography, and earthquake location, all of which demonstrated the higher resolution achievable by processing data with differential traveltimes rather than absolute traveltimes. More generally, the stationary version of the closure-phase equation is equivalent to Fermat’s principle and can be derived from the equations of seismic interferometry. In summary, the general closure-phase equation is the mathematical foundation for approximately redatuming sources and/or receivers to the target of interest without the need to accurately know the statics or the velocity model away from the target.

  7. Model experiments on imaging subsurface fracture permeability by pulsed Doppler borehole televiewer; Pulse doppler borehole televiewer ni yoru kiretsu tosuisei hyoka ni kansuru model jikken

    Energy Technology Data Exchange (ETDEWEB)

    Inagaki, Y.; Niitsuma, H. [Tohoku University, Sendai (Japan). Faculty of Engineering

    1996-05-01

    This paper reports model experiments to evaluate flow rates of fluids passing through a fracture by using a Doppler borehole televiewer (DBHTV). A supersonic transducer disposed on a well axis transmits transmission pulses, and a transducer receives scattered waves generated by particulates in water and waves reflected on a well wall. This signal is applied with time gating to extract only the scattered waves from particulates in the vicinity of the well wall. Deriving spectra in the recorded Doppler signal obtains flow velocity components in the direction of the well radius. A model was made with a polyvinylchloride pipe with a diameter of 14.6 cm to simulate a well, to which an aluminum pipe with an inner diameter of 2 mm is connected to be used as a simulated fracture, and mud water is circulated in the pipe. The result of deriving a passed flow volume in this model by integrating flow rate distribution derived by using the above method to a predetermined range in the vicinity of the fracture showed a good proportional relationship with actual flow rate in the simulated fracture. 1 ref., 7 figs.

  8. Novel approach for improving signal to noise ratio of seismic images

    Institute of Scientific and Technical Information of China (English)

    陈凤; 李金宗; 李冬冬

    2004-01-01

    A novel approach of digital image processing technology is applied to improve SNR of seismic images. At first,we analyze the characters of line-like texture in seismic images, and then a preprocessing method named 2 D tracing horizon filtering is designed. After that, the technology of optical flow analysis is adopted to calculate the displacement vectors of adjacent pixels between neighboring seismic images. At last, the novel image accumulation algorithms are proposed, which are applied to greatly improve SNR and definition of seismic images. The experimental results show that SNR of seismic section images with SNR of about 20 dB and 17 dB are increased 8 dB~9 dB under keeping signal energy 67%~80% by processing section images and 3dB~4dB under keeping signalenergy 80~90% by processing horizontal slice images. Thereby, the proposed novel approaches are very helpful to the correct seismic interpretation and have very important significance for seismic exploring.

  9. Improvement of seismic imaging of complex geologic structures

    Energy Technology Data Exchange (ETDEWEB)

    Duquet, B.

    1996-04-11

    Successful imaging of complex geologic structures by pre-stack depth migration requires a correct velocity model of the subsurface. In recent years, it has been proposed to use pre-stack depth migration of the cube of pre-stack depth migrated images and the subsequent use of the interpretation for velocity model update. However, in complex geologic structures, pre-stack depth migration does not yield results of sufficient quality for interpretation. We therefore propose a new wave-field imaging technique based on linearized inversion using the paraxial approximation of the wave equation. Using this technique we can remove the artifacts contaminating the individual depth images by integrating a priori information in the inverse problem. The application of the method to synthetic and real data shows that it allows us to largely improve the quality of the depth images at reasonable cost.We thus obtain an interpretable cube of depth images that makes migration velocity analysis feasible in complex structures. In 3D, due to the size of the problem there is still a large interest in using post stack techniques for velocity model determination. The quality of the results of such techniques relies on the quality of the stacking process. Classical data stacking techniques rely on simplifications that are not valid anymore in case of complex geologic structures. We propose a data stacking technique based on depth domain stacking after pre-stack depth migration, followed by explosive reflector modeling, to obtain the stacked seismic data. This method which is totally automatic yield 3 D stacked data that are suitable for 3D post stack velocity determination techniques.

  10. Structure and Stratigraphy of the Rift Basins in the Northern Gulf of California: Results from Analysis of Seismic Reflection and Borehole Data.

    Science.gov (United States)

    Martín, A.; González, M.; Helenes, J.; García, J.; Aragón, M.; Carreño, A.

    2008-12-01

    The northern Gulf of California contains two parallel, north-south trending rift basin systems separated by a basement-high. The interpretation of several exploration wells, and ~4500 km of seismic reflection data from PEMEX (Mexican national oil company) indicate that the tectonically active basins to the west (Wagner- Consag and Upper Delfin basins) may have initiated synchronously with the now abandoned Tiburón- Tepoca-Altar basins to the east in the Sonora margin. In both basin systems the lower sequence (A) is marine mudstone-siltstone, has parallel reflectors and a largely uniform thickness that reaches up to1.5 km, and gradually pinches out toward the lateral margins. This suggests that the unit was deposited prior to their segmentation by transtensional faulting. Marine microfossils from borehole samples from sequence A in the Tiburón and Consag basins indicates middle Miocene (>11.2 Ma) proto-Gulf conditions. Sequence B conformably overlies sequence A, and is characterized by up to 2 km growth strata with a fanning geometry that show a clear genetic relationship to the major transtensional faults that control the segmentation of the two basin systems. Sequence C in the Tiburón and Tepoca basins is comparatively thin (<800 m) and includes several unconformities, but is much less affected by faulting. In contrast, sequence C in the active Wagner, Consag and Upper Delfin basin is a much thicker (up to 2 km) growth sequence with abundant volcanic intrusions. Marked variations in sequence C in the different basin systems clearly demonstrate a major westward shift of deformation and subsidence at this time. The modern depocenter in Wagner-Consag basins is controlled by the Consag and Wagner faults, which trend parallel to the north ~20 km apart, and show opposite normal offset. These two faults merge at an oblique angle (70°-50°, respectively) into the Cerro Prieto transform fault to the north and likely accommodate an important amount of dextral shear. To

  11. Passive Seismic Imaging of the Ruby Mountains Core Complex, Nevada

    Science.gov (United States)

    Litherland, M.; Klemperer, S. L.

    2015-12-01

    We investigate the deep crustal structure of the Ruby Mountains Core Complex (RMCC) using data collected from the Ruby Mountains Seismic Experiment. This project, part of the Earthscope Flexible Array program, deployed 50 passive broadband stations across the RMCC from 2010 to 2012. Previous investigations of the area have included extensive surface mapping and active seismic profiles across the surrounding basins, but better imaging beneath the mountain range is needed to understand the tectonic processes that formed the RMCC. The RMCC exhibits typical core-complex structure of deep crustal rocks exhumed to the surface beneath a gently dipping detachment, with a thick mylonitic shear zone directly underlying the detachment. In the RMCC, the westward dip of the detachment, the ~1km-thick mylonite zone formed in the Paleogene, and a south-to-north increase in metamorphic grade provide targets for imaging. We used common conversion point stacking of receiver functions to produce 3 profiles of structural discontinuities beneath the RMCC: one along the axis of the RMCC, and two crossing lines, one in the northern RMCC, and one in the southern part of the range. Due to the deep sedimentary basins surrounding the RMCC, various de-multiple processes were required to reduce the effects of basin reverberations. To better constrain the velocity structure of the area, we used ambient-noise tomography, and finally, we produced a joint inversion of our receiver functions and ambient-noise data. We observe a mostly flat Moho at about 30 km depth beneath the RMCC that dips slightly to the south, with faint mid-crustal converters that also dip south at ~30°. In the southern RMCC, the Moho dips ~20° westward, but this is not observed in the northern RMCC. This suggests that much of the exhumation involved in the RMCC formation likely involved ductile flow that left a mostly flat Moho, but more recent processes also may have left observable changes in lower-crustal structure.

  12. 3D Seismic Imaging over a Potential Collapse Structure

    Science.gov (United States)

    Gritto, Roland; O'Connell, Daniel; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

    2016-04-01

    The Middle-East has seen a recent boom in construction including the planning and development of complete new sub-sections of metropolitan areas. Before planning and construction can commence, however, the development areas need to be investigated to determine their suitability for the planned project. Subsurface parameters such as the type of material (soil/rock), thickness of top soil or rock layers, depth and elastic parameters of basement, for example, comprise important information needed before a decision concerning the suitability of the site for construction can be made. A similar problem arises in environmental impact studies, when subsurface parameters are needed to assess the geological heterogeneity of the subsurface. Environmental impact studies are typically required for each construction project, particularly for the scale of the aforementioned building boom in the Middle East. The current study was conducted in Qatar at the location of a future highway interchange to evaluate a suite of 3D seismic techniques in their effectiveness to interrogate the subsurface for the presence of karst-like collapse structures. The survey comprised an area of approximately 10,000 m2 and consisted of 550 source- and 192 receiver locations. The seismic source was an accelerated weight drop while the geophones consisted of 3-component 10 Hz velocity sensors. At present, we analyzed over 100,000 P-wave phase arrivals and performed high-resolution 3-D tomographic imaging of the shallow subsurface. Furthermore, dispersion analysis of recorded surface waves will be performed to obtain S-wave velocity profiles of the subsurface. Both results, in conjunction with density estimates, will be utilized to determine the elastic moduli of the subsurface rock layers.

  13. Tomographic image of a seismically active volcano: Mammoth Mountain, California

    Science.gov (United States)

    Dawson, Phillip B.; Chouet, Bernard A.; Pitt, Andrew M.

    2016-01-01

    High-resolution tomographic P wave, S wave, and VP/VS velocity structure models are derived for Mammoth Mountain, California, using phase data from the Northern California Seismic Network and a temporary deployment of broadband seismometers. An anomalous volume (5.1 × 109 to 5.9 × 1010m3) of low P and low S wave velocities is imaged beneath Mammoth Mountain, extending from near the surface to a depth of ∼2 km below sea level. We infer that the reduction in seismic wave velocities is due to the presence of CO2 distributed in oblate spheroid pores with mean aspect ratio α = 1.6 × 10−3 to 7.9 × 10−3 (crack-like pores) and mean gas volume fraction ϕ = 8.1 × 10−4 to 3.4 × 10−3. The pore density parameter κ = 3ϕ/(4πα) = na3=0.11, where n is the number of pores per cubic meter and a is the mean pore equatorial radius. The total mass of CO2 is estimated to be 4.6 × 109 to 1.9 × 1011 kg. The local geological structure indicates that the CO2 contained in the pores is delivered to the surface through fractures controlled by faults and remnant foliation of the bedrock beneath Mammoth Mountain. The total volume of CO2 contained in the reservoir suggests that given an emission rate of 500 tons day−1, the reservoir could supply the emission of CO2 for ∼25–1040 years before depletion. Continued supply of CO2 from an underlying magmatic system would significantly prolong the existence of the reservoir.

  14. Shear wave seismic interferometry for lithospheric imaging: Application to southern Mexico

    NARCIS (Netherlands)

    Frank, J.G.; Ruigrok, E.N.; Wapenaar, C.P.A.

    2014-01-01

    Seismic interferometry allows for the creation of new seismic traces by cross correlating existing ones. With sufficient sampling of remote-source positions, it is possible to create a virtual source record by transforming a receiver location into a virtual source. The imaging technique developed he

  15. Method of high-density seismic imaging exploration and application samples

    Institute of Scientific and Technical Information of China (English)

    熊章强; 张学强; 李修忠; 谢尚平; 张大洲

    2004-01-01

    The paper introduces the method of high-density seismic imaging exploration, discusses its features different fromconventional shallow seismic reflection wave technique, and illustrates the application effect of the method usingthree samples of engineering geological explorations on land and in water - exploration of underground cavity,location survey of sunk ship and investigation of channel silt depth.

  16. Shear wave seismic interferometry for lithospheric imaging : Application to southern Mexico

    NARCIS (Netherlands)

    Frank, J. G.; Ruigrok, E. N.; Wapenaar, K.

    2014-01-01

    Seismic interferometry allows for the creation of new seismic traces by cross correlating existing ones. With sufficient sampling of remote-source positions, it is possible to create a virtual source record by transforming a receiver location into a virtual source. The imaging technique developed he

  17. Multichannel analysis of surface-waves and integration of downhole acoustic televiewer imaging, ultrasonic Vs and Vp, and vertical seismic profiling in an NEHRP-standard classification, South of Concordia, Kansas, USA

    Science.gov (United States)

    Raef, Abdelmoneam; Gad, Sabreen; Tucker-Kulesza, Stacey

    2015-10-01

    Seismic site characteristics, as pertaining to earthquake hazard reduction, are a function of the subsurface elastic moduli and the geologic structures. This study explores how multiscale (surface, downhole, and laboratory) datasets can be utilized to improve "constrained" average Vs30 (shear-wave velocity to a 30-meter depth). We integrate borehole, surface and laboratory measurements for a seismic site classification based on the standards of the National Earthquake Hazard Reduction Program (NEHRP). The seismic shear-wave velocity (Vs30) was derived from a geophysical inversion workflow that utilized multichannel analysis of surface-waves (MASW) and downhole acoustic televiewer imaging (DATI). P-wave and S-wave velocities, based on laboratory measurements of arrival times of ultrasonic-frequency signals, supported the workflow by enabling us to calculate Poisson's ratio, which was incorporated in building an initial model for the geophysical inversion of MASW. Extraction of core samples from two boreholes provided lithology and thickness calibration of the amplitudes of the acoustic televiewer imaging for each layer. The MASW inversion, for calculating Vs sections, was constrained with both ultrasonic laboratory measurements (from first arrivals of Vs and Vp waveforms at simulated in situ overburden stress conditions) and the downhole acoustic televiewer (DATV) amplitude logs. The Vs30 calculations enabled categorizing the studied site as NEHRP-class "C" - very dense soil and soft rock. Unlike shallow fractured carbonates in the studied area, S-wave and P-wave velocities at ultrasonic frequency for the deeper intact shale core-samples from two boreholes were in better agreement with the corresponding velocities from both a zero-offset vertical seismic profiling (VSP) and inversion of Rayleigh-wave velocity dispersion curves.

  18. Chronicle of Bukit Bunuh for possible complex impact crater by 2-D resistivity imaging (2-DERI) with geotechnical borehole records

    Science.gov (United States)

    Jinmin, M.; Saad, R.; Saidin, M.; Ismail, N. A.

    2015-03-01

    A 2-D resistivity imaging (2-DERI) study was conducted at Bukit Bunuh, Lenggong, Perak. Archaeological Global Research Centre, Universiti Sains Malaysia shows the field evidence of shock metamorphisms (suevite breccia) and crater morphology at Bukit Bunuh. A regional 2-DERI study focusing at Bukit Bunuh to identify the features of subsurface and detail study was then executed to verify boundary of the crater with the rebound effects at Bukit Bunuh which covered approximately 132.25 km2. 2-DERI survey used resistivity equipment by ABEM SAS4000 Terrameter and ES10-64C electrode slector with pole-dipole array. The survey lines were carried out using `roll-along' technique. The data were processed and analysed using RES2DINV, Excel and Surfer software to obtain resistivity results for qualitative interpretations. Bedrock depths were digitized from section by sections obtained. 2-DERI results gives both regional and detail study shows that the study area was divided into two main zones, overburden consists of alluvium mix with boulders embedded with resistivity value of 10-800 Ωm and granitic bedrock with resistivity value of >1500 Ωm and depth 5-50 m. The low level bedrock was circulated by high level bedrock (crater rim) was formed at the same area with few spots of high level bedrock which appeared at the centre of the rim which suspected as rebound zones (R). Assimilations of 2-DERI with boreholes are successful give valid and reliable results. The results of the study indicates geophysical method are capable to retrieve evidence of meteorite impact subsurface of the studied area.

  19. Seismic Calibration Shots Conducted in 2009 in the Imperial Valley, Southern California, for the Salton Seismic Imaging Project (SSIP)

    OpenAIRE

    Murphy, Janice; Goldman, Mark; Fuis, Gary; Rymer, Michael; Sickler, Robert; Miller, Summer; Butcher, Lesley; Ricketts, Jason; Criley, Coyn; Stock, Joann; Hole, John; Chavez, Greg

    2011-01-01

    The Salton Seismic Imaging Project (SSIP) is a large-scale collaborative project with the goal of developing a detailed 3-D structural image of the Salton Trough (including both the Coachella and Imperial Valleys). The image will be used for earthquake hazard analysis, geothermal studies, and studies of plate-boundary transition from an ocean-ocean to a continent-continent plate-boundary. As part of SSIP, a series of calibration shots were detonated in June 2009 in the southern Imperial Va...

  20. Seismic Imaging and Inversion: Application of Linear Theory (2012), Cambridge University Press, co-authored with Bob Stolt

    Energy Technology Data Exchange (ETDEWEB)

    Weglein, Arthur B.; Stolt, Bob H.

    2012-03-01

    Extracting information from seismic data requires knowledge of seismic wave propagation and reflection. The commonly used method involves solving linearly for a reflectivity at every point within the Earth, but this book follows an alternative approach which invokes inverse scattering theory. By developing the theory of seismic imaging from basic principles, the authors relate the different models of seismic propagation, reflection and imaging - thus providing links to reflectivity-based imaging on the one hand and to nonlinear seismic inversion on the other. The comprehensive and physically complete linear imaging foundation developed presents new results at the leading edge of seismic processing for target location and identification. This book serves as a fundamental guide to seismic imaging principles and algorithms and their foundation in inverse scattering theory and is a valuable resource for working geoscientists, scientific programmers and theoretical physicists.

  1. Determination of porosity and facies trends in a complex carbonate reservoir, by using 3-D seismic, borehole tools, and outcrop geology

    Energy Technology Data Exchange (ETDEWEB)

    Zacharakis, T.G. Jr.; Comet, J.N.; Murillo, A.A. [Respol Exploracion, S.A., Madrid (Spain)] [and others

    1996-08-01

    Mesozoic carbonate reservoirs are found in the Mediterranean Sea, off the east coast of Spain. A wide variation of porosities are found in the core samples and logs: vuggy, breccia, fractures, and cavern porosity. In addition, complex Tertiary carbonate geometries include olistostromes, breccia bodies, and reef buildups, which are found on top of Mesozoic carbonates. Predicting the porosity trends within these oil productive reservoirs requires an understanding of how primary porosity was further enhanced by secondary processes, including fractures, karstification, and dolomitization in burial conditions. Through an extensive investigation of field histories, outcrop geology, and seismic data, a series of basic reservoir styles have been identified and characterized by well log signature and seismic response. The distribution pattern of the different reservoirs styles is highly heterogeneous, but by integrating subsurface data and outcrop analogs, it is possible to distinguish field-scale and local patterns of both vertical and local variations in reservoir properties. Finally, it is important to quantify these reservoir properties through the study of seismic attributes, such as amplitude variations, and log responses at the reservoir interval. By incorporating 3-D seismic data, through the use of seismic inversion, it is possible to predict porosity trends. Further, the use of geostatistics can lead to the prediction of reservoir development within the carbonate facies.

  2. Characterization and interpretation of a fractured rocky massif from borehole data. Boreholes of geothermal project at Soultz-sous-Forets and other examples of unidirectional sampling; Caracterisation et interpretation d`un volume rocheux fracture a partir de donnees de forages. Les forages geothermiques de Soultz-sous-Forets et autres exemples d`echantillonnages unidirectionnels

    Energy Technology Data Exchange (ETDEWEB)

    Dezayes, CH.

    1995-12-18

    In this thesis, we study fractures from borehole data on two sites: in one, located at Soultz-sous-Forets (Alsace) in the Rhine graben, boreholes reach a delta Jurassic series forming a petroleum reservoir. At Soultz, fractures have been studied on cores and borehole images. Striated faults present on cores permit to determine the tectonic history of the granite, completed by field study in Vosges Massif. This history corresponds to the Rhine graben history knowing by different authors. The analysis of vertical induced fractures observed on borehole images indicates a present-day NW-SE to NNW-SSE compression. These variations of stress direction are confirmed by others in situ measurements, as hydraulic injection, micro-seismicity, etc... On cores and borehole images, numerous fractures have been observed. Most of them are linked to the E-W distension, which permits the Rhine graben opening at Oligocene. At greatest scale, in quartz minerals, the micro-fractures are constitute by fluid inclusion trails. Several sets are related to the E-W distension, but others sets are linked to compressive stages. These sets are not observed on cores. This is a under-sampling of some fractures by the boreholes, but theses fractures exit into to rock massif. On borehole images, fracture density is weakest than the cores, however the set organisation is the same. At Ravenscar, the distribution of fracture spacing along different unidirectional sampling shows a exponential negative law. However, the fracture density varies with sampling. (author) 199 refs.

  3. Automatic detection of karstic sinkholes in seismic 3D images using circular Hough transform

    Science.gov (United States)

    Heydari Parchkoohi, Mostafa; Keshavarz Farajkhah, Nasser; Salimi Delshad, Meysam

    2015-10-01

    More than 30% of hydrocarbon reservoirs are reported in carbonates that mostly include evidence of fractures and karstification. Generally, the detection of karstic sinkholes prognosticate good quality hydrocarbon reservoirs where looser sediments fill the holes penetrating hard limestone and the overburden pressure on infill sediments is mostly tolerated by their sturdier surrounding structure. They are also useful for the detection of erosional surfaces in seismic stratigraphic studies and imply possible relative sea level fall at the time of establishment. Karstic sinkholes are identified straightforwardly by using seismic geometric attributes (e.g. coherency, curvature) in which lateral variations are much more emphasized with respect to the original 3D seismic image. Then, seismic interpreters rely on their visual skills and experience in detecting roughly round objects in seismic attribute maps. In this paper, we introduce an image processing workflow to enhance selective edges in seismic attribute volumes stemming from karstic sinkholes and finally locate them in a high quality 3D seismic image by using circular Hough transform. Afterwards, we present a case study from an on-shore oilfield in southwest Iran, in which the proposed algorithm is applied and karstic sinkholes are traced.

  4. Reflection seismic imaging of the upper crystalline crust for characterization of potential repository sites: Fine tuning the seismic source

    International Nuclear Information System (INIS)

    SKB is currently carrying out studies to determine which seismic techniques, and how, they will be used for investigations prior to and during the building of a high-level nuclear waste repository. Active seismic methods included in these studies are refraction seismics, reflection seismics, and vertical seismic profiling (VSP). The main goal of the active seismic methods is to locate fracture zones in the crystalline bedrock. Plans are to use longer reflection seismic profiles (3.4 km) in the initial stages of the site investigations. The target depth for these seismic profiles is 100-1500 m. Prior to carrying out the seismic surveys over actual candidate waste repository sites it has been necessary to carry out a number of tests to determine the optimum acquisition parameters. This report constitutes a summary of the tests carried out by Uppsala University. In addition, recommended acquisition and processing parameters are presented at the end of the report. A major goal in the testing has been to develop a methodology for acquiring high-resolution reflection seismic data over crystalline rock in as a cost effective manner as possible. Since the seismic source is generally a major cost in any survey, significant attention has been given to reducing the cost of the source. It was agreed upon early in the study that explosives were the best source from a data quality perspective and, therefore, only explosive source methods have been considered in this study. The charge size and shot hole dimension required to image the upper 1-1.5 km of bedrock is dependent upon the conditions at the surface. In this study two types of shot hole drilling methods have been employed depending upon whether the thickness of the loose sediments at the surface is greater or less than 0.5 m. The charge sizes and shot hole dimensions required are: Loose sediment thickness less than 0.5 m: 15 g in 90 cm deep 12 mm wide uncased shot holes. Loose sediment thickness greater than 0.5 m: 75 g

  5. Multiscale Seismic Inversion in the Data and Image Domains

    KAUST Repository

    Zhang, Sanzong

    2015-12-01

    I present a general methodology for inverting seismic data in either the data or image domains. It partially overcomes one of the most serious problems with current waveform inversion methods, which is the tendency to converge to models far from the actual one. The key idea is to develop a multiscale misfit function that is composed of both a simplified version of the data and one associated with the complex part of the data. Misfit functions based on simple data are characterized by many fewer local minima so that a gradient optimization method can make quick progress in getting to the general vicinity of the actual model. Once we are near the actual model, we then use the gradient based on the more complex data. Below, we describe two implementations of this multiscale strategy: wave equation traveltime inversion in the data domain and generalized differential semblance optimization in the image domain. • Wave Equation Traveltime Inversion in the Data Domain (WT): The main difficulty with iterative waveform inversion is that it tends to get stuck in local minima associated with the waveform misfit function. To mitigate this problem and avoid the need to fit amplitudes in the data, we present a waveequation method that inverts the traveltimes of reflection events, and so is less prone to the local minima problem. Instead of a waveform misfit function, the penalty function is a crosscorrelation of the downgoing direct wave and the upgoing reflection wave at the trial image point. The time lag which maximizes the crosscorrelation amplitude represents the reflection-traveltime residual that is back-projected along the reflection wavepath to update the velocity. Shot- and angle-domain crosscorrelation functions are introduced to estimate the reflection-traveltime residual by semblance analysis and scanning. In theory, only the traveltime information is inverted and there is no need to precisely fit the amplitudes or assume a high-frequency approximation. Results

  6. The Utility of the Extended Images in Ambient Seismic Wavefield Migration

    Science.gov (United States)

    Girard, A. J.; Shragge, J. C.

    2015-12-01

    Active-source 3D seismic migration and migration velocity analysis (MVA) are robust and highly used methods for imaging Earth structure. One class of migration methods uses extended images constructed by incorporating spatial and/or temporal wavefield correlation lags to the imaging conditions. These extended images allow users to directly assess whether images focus better with different parameters, which leads to MVA techniques that are based on the tenets of adjoint-state theory. Under certain conditions (e.g., geographical, cultural or financial), however, active-source methods can prove impractical. Utilizing ambient seismic energy that naturally propagates through the Earth is an alternate method currently used in the scientific community. Thus, an open question is whether extended images are similarly useful for ambient seismic migration processing and verifying subsurface velocity models, and whether one can similarly apply adjoint-state methods to perform ambient migration velocity analysis (AMVA). Herein, we conduct a number of numerical experiments that construct extended images from ambient seismic recordings. We demonstrate that, similar to active-source methods, there is a sensitivity to velocity in ambient seismic recordings in the migrated extended image domain. In synthetic ambient imaging tests with varying degrees of error introduced to the velocity model, the extended images are sensitive to velocity model errors. To determine the extent of this sensitivity, we utilize acoustic wave-equation propagation and cross-correlation-based migration methods to image weak body-wave signals present in the recordings. Importantly, we have also observed scenarios where non-zero correlation lags show signal while zero-lags show none. This may be a valuable missing piece for ambient migration techniques that have yielded largely inconclusive results, and might be an important piece of information for performing AMVA from ambient seismic recordings.

  7. New seismic images of the crust across the Rivera Plate and Jalisco Block (Mexico)

    Science.gov (United States)

    Cordoba, Diego; Núñez-Cornú, Francisco Javier; Bartolomé, Rafael; José Dañobeitia, Juan; Bandy, William Lee; Núñez, Diana; Prada, Manel; Escudero-Ayala, Christian; Espíndola, Juan Manuel; Zamora, Araceli; Gómez, Adán; Ortiz, Modesto; Tsujal Working Group

    2015-04-01

    (Jalisco coast).These instruments registered 3 borehole explosions of 1000 kg specially made for this project, in the northern, central and southern parts of this profile. These new data provide a dense sampling of tectonic plates, W Mexico, and give new seismic constraints on the deformation along and across the subduction zone, accretionary wedge size, at contact between Rivera and North American Plates and, in the transition zone between oceanic and continental crust.

  8. Seismic wave attenuation from borehole and surface records in the top 2.5 km beneath the city of Basel, Switzerland

    KAUST Repository

    Bethmann, Falko

    2012-08-01

    We investigate attenuation (Q−1) of sediments of 2.5–3.5km thickness underneath the city of Basel, Switzerland. We use recordings of 195 induced events that were obtained during and after the stimulation of a reservoir for a Deep Heat Mining Project in 2006 and 2007. The data set is ideally suited to estimate Q as all events are confined to a small source volume and were recorded by a dense surface network as well as six borehole sensors at various depths. The deepest borehole sensor is positioned at a depth of 2.7km inside the crystalline basement at a mean hypocentral distance of 1.8km. This allows us to measure Q for frequencies between 10 and 130 Hz. We apply two different methods to estimate Q. First, we use a standard spectral ratio technique to obtain Q, and as a second measure we estimate Q in the time domain, by convolving signals recorded by the deepest sensor with a Q operator and then comparing the convolved signals to recordings at the shallower stations. Both methods deliver comparable values for Q. We also observe similar attenuation for P- and S- waves (QP∼QS). As expected, Q increases with depth, but with values around 30–50, it is low even for the consolidated Permian and Mesozoic sediments between 500 and 2700 m.

  9. Optical imaging of the boreholes KR29, KR29B, KR30, KR31, KR31B, KR32, KR33 and KR33B, at Olkiluoto 2005

    International Nuclear Information System (INIS)

    Suomen Malmi Oy conducted optical imaging surveys of the boreholes KR29, KR29B, KR30, KR31, KR31B, KR32, KR33 and KR33B at the Olkiluoto site in Eurajoki during June 2005. The survey is a part of Posiva Oy's detailed investigation program for the final disposal of spent nuclear fuel. The assignment included the field work and preliminary processing of the images. The report describes the field operation, equipment as well as processing procedures and shows the obtained results and their quality through example images. The raw and processed data are delivered digitally in WellCAD format. The images are also attached to the appendix CD of this report in Adobe Acrobat PDF-format. (orig.)

  10. Imaging the Jakarta Basin with Seismic Ambient Noise

    Science.gov (United States)

    Saygin, Erdinc; Cummins, Phil; Pandhu, Rakhindro; Murjaya, Jaya; Irsyam, Masyhur; Pranata, Bayu

    2014-05-01

    Jakarta, the capital of Indonesia, is one of the most populous cities in the world with a population over 28 million including the metro area. In July 2012, 8 short period and broadband seismic stations were deployed progressively to record seismic noise at 36 different locations in Jakarta for a duration of 31 days. The recorded seismic noise is then cross-correlated between the simultaneously operated stations for retrieving the inter-station Green's functions. The traveltimes of Rayleigh wave Green's functions measured at different periods are later inverted with nonlinear tomography. The results mark the presence of a very low velocity body due to the alluvial deposits, which cover most of the Jakarta area. In October 2013, we deployed 52 broadband stations across Jakarta with a typical station spacing of 2 km for a duration of 4 months. We divide the city to 3 sectors, which each area was covered by a dense deployment each subsequent month. The recorded noise is used in high-resolution 2D Bayesian tomography to map the 2D seismic velocity model of the city. The resulting models will be used in estimating the seismic amplification and other seismic hazards of the city.

  11. Rock mass structure analysis based on seismic velocity and attenuation images

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Seismic traveltime, amplitude and pulse-width can be used to reconstruct seismic velocity and attenuation coefficient images for a rock mass. This study discusses the appearance differences of velocity and attenuation coefficient in the ore vein and rock mass in the images. The location of the rock vein and the characteristic of the rock mass are discussed according to the difference responses of velocity and attenuation from the ore vein and mixed rock vein, fracture and rock body. The effect and limitation of the seismic tomography method for investigating ore body and rock mass is suggested on the basis of a field test result. The special observation method in this study gives a good reference for obtaining full position and directional observation in seismic tomography.

  12. Using Seismic Tomography and Holography Ground Imaging to Investigate Ground Conditions

    Institute of Scientific and Technical Information of China (English)

    Ed Kase; Tim Ross

    2004-01-01

    Unforeseen, variable subsurface ground conditions present the greatest challenge to the heavy construction and civil engineering industry in the design, construction, and maintenance of large projects. A detailed, accurate site investigation will reduce project risk, improve construction performance and safety, prolong the life of the tunnel or structure,and prevent waste in over - design. Presently, site characterization and geotechnical engineering are limited by the inability to adequately describe these subsurface ground conditions.NSA Geotechnical Services has successfully applied seismic tomography and holography ground imaging technologies on tunneling and heavy civil excavations worldwide. Seismic signal waveforms traveling through a complex medium consist of various arrivals from refractions, reflections, scattering, and dispersion. Tomography and holography are proven inversion technologies for estimating location and extent of material property variations causing changes in signal waveforms.ent attenuation rates and velocities. Seismic waves will travel faster through competent material and be generally less attenuated than through broken/fractured ground or voids.encounters an interface between ground zones possessing different seismic properties. Most geologic structures, anomalies,and changes in lithology provide detectable seismic reflections if they are within a reasonable distance of the seismic source.This paper will present various applications of these technologies, illustrating how seismic imaging can provide accurate information regarding ground conditions associated with tunneling projects. With this information, engineers can complete projects safely, within time and budget constraints.

  13. Seismic calibration shots conducted in 2009 in the Imperial Valley, southern California, for the Salton Seismic Imaging Project (SSIP)

    Science.gov (United States)

    Murphy, Janice; Goldman, Mark; Fuis, Gary; Rymer, Michael; Sickler, Robert; Miller, Summer; Butcher, Lesley; Ricketts, Jason; Criley, Coyn; Stock, Joann; Hole, John; Chavez, Greg

    2011-01-01

    Rupture of the southern section of the San Andreas Fault, from the Coachella Valley to the Mojave Desert, is believed to be the greatest natural hazard facing California in the near future. With an estimated magnitude between 7.2 and 8.1, such an event would result in violent shaking, loss of life, and disruption of lifelines (freeways, aqueducts, power, petroleum, and communication lines) that would bring much of southern California to a standstill. As part of the Nation's efforts to prevent a catastrophe of this magnitude, a number of projects are underway to increase our knowledge of Earth processes in the area and to mitigate the effects of such an event. One such project is the Salton Seismic Imaging Project (SSIP), which is a collaborative venture between the United States Geological Survey (USGS), California Institute of Technology (Caltech), and Virginia Polytechnic Institute and State University (Virginia Tech). This project will generate and record seismic waves that travel through the crust and upper mantle of the Salton Trough. With these data, we will construct seismic images of the subsurface, both reflection and tomographic images. These images will contribute to the earthquake-hazard assessment in southern California by helping to constrain fault locations, sedimentary basin thickness and geometry, and sedimentary seismic velocity distributions. Data acquisition is currently scheduled for winter and spring of 2011. The design and goals of SSIP resemble those of the Los Angeles Region Seismic Experiment (LARSE) of the 1990's. LARSE focused on examining the San Andreas Fault system and associated thrust-fault systems of the Transverse Ranges. LARSE was successful in constraining the geometry of the San Andreas Fault at depth and in relating this geometry to mid-crustal, flower-structure-like decollements in the Transverse Ranges that splay upward into the network of hazardous thrust faults that caused the 1971 M 6.7 San Fernando and 1987 M 5

  14. Seismic and magneto-telluric imaging for geothermal exploration at Jemez pueblo in New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lianjie [Los Alamos National Laboratory; Albrecht, Michael [LOS ALAMOS GEOTHERMAL

    2011-01-25

    A shallow geothermal reservoir in the Pueblo of Jemez in New Mexico may indicate a commercial-scale geothermal energy potential in the area. To explore the geothermal resource at Jemez Pueblo, seismic surveys are conducted along three lines for the purpose of imaging complex subsurface structures near the Indian Springs fault zone. A 3-D magneto-telluric (MT) survey is also carried out in the same area. Seismic and MT imaging can provide complementary information to reveal detailed geologic formation properties around the fault zones. The high-resolution seismic images will be used together with MT images, geologic mapping, and hydrogeochemistry, to explore the geothermal resource at Jemez Pueblo, and to determine whether a conunercial-scale geothermal resource exists for power generation or direct use applications after drilling and well testing.

  15. Shear wave seismic interferometry for lithospheric imaging: Application to southern Mexico

    OpenAIRE

    Frank, J.G.; Ruigrok, E.N.; Wapenaar, K.

    2014-01-01

    Seismic interferometry allows for the creation of new seismic traces by cross correlating existing ones. With sufficient sampling of remote-source positions, it is possible to create a virtual source record by transforming a receiver location into a virtual source. The imaging technique developed here directly retrieves reflectivity information from the subsurface. Other techniques, namely receiver-function and tomography, rely on mode-converted energy and perturbations in a velocity field, r...

  16. Seismic wave imaging in visco-acoustic media

    Institute of Scientific and Technical Information of China (English)

    WANG Huazhong; ZHANG Libin; MA Zaitian

    2004-01-01

    Realistic representation of the earth may be achieved by combining the mechanical properties of elastic solids and viscousliquids. That is to say, the amplitude will be attenuated withdifferent frequency and the phase will be changed in the seismicdata acquisition. In the seismic data processing, this effect mustbe compensated. In this paper, we put forward a visco-acoustic wavepropagator which is of better calculating stability and tolerablecalculating cost (little more than an acoustic wave propagator).The quite good compensation effect is demonstrated by thenumerical test results with synthetic seismic data and real data.

  17. Seismic Imaging of Sub-Glacial Sediments at Jakobshavn Isbræ and NEEM Greenland

    Science.gov (United States)

    Tsoflias, G. P.; Velez-Gonzalez, J. A.; Black, R. A.; van der Veen, C. J.

    2015-12-01

    Sub-glacial sediment conditions can have a major control on glacier flow yet these are difficult to measure directly. We present active source seismic reflection experiments that imaged sub-glacial sections at Jakobshavn Isbræ, West Greenland and at the North Greenland Eemian Ice Drilling (NEEM) location. At Jakobshavn Isbræ we re-processed an existing 9.8 km-long high-resolution seismic line using an iterative approach to determine seismic velocities for enhancing sub-glacial imaging. The seismic profile imaged sediments ranging in thickness between 35 and 200 meters, and the underlying bedrock. Based on the geometry of the reflections we interpret three distinct seismic facies: a basal till layer, accreted sediments and re-worked till. The basal till and accreted sediments vary in thickness from less than 5 m to nearly 100 m thick and are interpreted as the zone of most recent deposition. A reflection polarity reversal observed at a low topographic region along the ice-sediment interface suggests the presence of liquid water spanning approximately 200 m along the profile. At NEEM we acquired a 5.8 km long-offset shot gather. Seismic imaging revealed two prominent reflections at the base of the ice. The upper reflection is interpreted at the base of ice - top of till interface whereas the lower reflection is interpreted as the base of till - top of bedrock. The thickness of the subglacial sediment section at NEEM is estimated to approximately 50 m using seismic imaging. The NEEM ice core drilled through the upper part of this section and ceased drilling before reaching bedrock.

  18. Numerical study on scanning radiation acoustic field in formations generated from a borehole

    Institute of Scientific and Technical Information of China (English)

    CHE Xiaohua; ZHANG Hailan; QIAO Wenxiao; JU Xiaodong

    2005-01-01

    Numerical study on scanning radiation acoustic field in formations generated by linear phased array transmitters in a fluid-filled borehole is carried out using a real axis integration (RAI) method. The main lobe width of the acoustic beams and the incident angle on the borehole wall can be controlled by means of adjusting parameters, such as the element number and the delay time between the neighboring array elements of linear phased array transmitter. The steered angle of longitudinal waves generated in the formation satisfies the Snell's law for plane waves when the incident angle on the borehole wall is less than the first critical angle. When the lobe width of the acoustic beams is narrow and the steered angle is less than the first critical angle, the acoustic field in the formation can be approximately calculated given that the linear phased array is put in the formation without borehole. The technique of scanning radiation acoustic field can be applied to enhancing investigation resolution and signal-to-noise ratio in crosswell seismic survey and borehole acoustic reflection imaging.

  19. Developing Advanced Seismic Imaging Methods For Characterizing the Fault Zone Structure

    Science.gov (United States)

    Zhang, Haijiang

    2015-04-01

    Here I present a series of recent developments on seismic imaging of fault zone structure. The goals of these advanced methods are to better determine the physical properties (including seismic velocity, attenuation, and anisotropy) around the fault zone and its boundaries. In order to accurately determine the seismic velocity structure of the fault zone, we have recently developed a wavelet-based double-difference seismic tomography method, in which the wavelet coefficients of the velocity model, rather than the model itself, are solved using both the absolute and differential arrival times. This method takes advantage of the multiscale nature of the velocity model and the multiscale wavelet representation property. Because of the velocity model is sparse in the wavelet domain, a sparsity constraint is applied to tomographic inversion. Compared to conventional tomography methods, the new method is both data- and model-adaptive, and thus can better resolve the fault zone structure. In addition to seismic velocity property of the fault zone, seismic anisotropy and attenuation properties are also important to characterize the fault zone structure. For this reason, we developed the seismic anisotropy tomography method to image the three-dimensional anisotropy strength model of the fault zone using shear wave splitting delay times between fast and slow shear waves. The applications to the San Andreas fault around Parkfield, California and north Anatolian fault in Turkey will be shown. To better constrain the seismic attenuation structure, we developed a new seismic attenuation tomography method using measured t* values for first arrival body waves, in which the structures of attenuation and velocity models are similar through the cross-gradient constraint. Seismic tomography can, however, only resolve the smooth variations in elastic properties in Earth's interior. To image structure at length scales smaller than what can be resolved tomographically, including

  20. Joint inversion of 3-D seismic, gravimetric and magnetotelluric data for sub-basalt imaging in the Faroe-Shetland Basin

    Science.gov (United States)

    Heincke, B.; Moorkamp, M.; Jegen, M.; Hobbs, R. W.

    2012-12-01

    collected along parallel lines by a shipborne gradiometer and the marine MT data set is composed of 41 stations that are distributed over the whole investigation area. Logging results from a borehole located in the central part of the investigation area enable us to derive parameter relationships between seismic velocities, resistivities and densities that are adequately describe the rock property behaviors of both the basaltic lava flows and sedimentary layers in this region. In addition, a 3-D reflection seismic survey covering the central part allows us to incorporate the top of basalt and other features as constraints in the joint inversions and to evaluate the quality of the final results. Literature: D. Colombo, M. Mantovani, S. Hallinan, M. Virgilio, 2008. Sub-basalt depth imaging using simultaneous joint inversion of seismic and electromagnetic (MT) data: a CRB field study. SEG Expanded Abstract, Las Vegas, USA, 2674-2678. M. Jordan, J. Ebbing, M. Brönner, J. Kamm , Z. Du, P. Eliasson, 2012. Joint Inversion for Improved Sub-salt and Sub-basalt Imaging with Application to the More Margin. EAGE Expanded Abstracts, Copenhagen, DK. M. Moorkamp, B. Heincke, M. Jegen, A.W.Roberts, R.W. Hobbs, 2011. A framework for 3-D joint inversion of MT, gravity and seismic refraction data. Geophysical Journal International, 184, 477-493.

  1. Reflection seismic imaging in the volcanic area of the geothermal field Wayang Windu, Indonesia

    Science.gov (United States)

    Polom, Ulrich; Wiyono, Wiyono; Pramono, Bambang; Krawczyk, CharLotte M.

    2014-05-01

    Reflection seismic exploration in volcanic areas is still a scientific challenge and requires major efforts to develop imaging workflows capable of an economic utilization, e.g., for geothermal exploration. The SESaR (Seismic Exploration and Safety Risk study for decentral geothermal plants in Indonesia) project therefore tackles still not well resolved issues concerning wave propagation or energy absorption in areas covered by pyroclastic sediments using both active P-wave and S-wave seismics. Site-specific exploration procedures were tested in different tectonic and lithological regimes to compare imaging conditions. Based on the results of a small-scale, active seismic pre-site survey in the area of the Wayang Windu geothermal field in November 2012, an additional medium-scale active seismic experiment using P-waves was carried out in August 2013. The latter experiment was designed to investigate local changes of seismic subsurface response, to expand the knowledge about capabilities of the vibroseis method for seismic surveying in regions covered by pyroclastic material, and to achieve higher depth penetration. Thus, for the first time in the Wayang Windu geothermal area, a powerful, hydraulically driven seismic mini-vibrator device of 27 kN peak force (LIAG's mini-vibrator MHV2.7) was used as seismic source instead of the weaker hammer blow applied in former field surveys. Aiming at acquiring parameter test and production data southeast of the Wayang Windu geothermal power plant, a 48-channel GEODE recording instrument of the Badan Geologi was used in a high-resolution configuration, with receiver group intervals of 5 m and source intervals of 10 m. Thereby, the LIAG field crew, Star Energy, GFZ Potsdam, and ITB Bandung acquired a nearly 600 m long profile. In general, we observe the successful applicability of the vibroseis method for such a difficult seismic acquisition environment. Taking into account the local conditions at Wayang Windu, the method is

  2. 3D VSP imaging in the Deepwater GOM

    Science.gov (United States)

    Hornby, B. E.

    2005-05-01

    Seismic imaging challenges in the Deepwater GOM include surface and sediment related multiples and issues arising from complicated salt bodies. Frequently, wells encounter geologic complexity not resolved on conventional surface seismic section. To help address these challenges BP has been acquiring 3D VSP (Vertical Seismic Profile) surveys in the Deepwater GOM. The procedure involves placing an array of seismic sensors in the borehole and acquiring a 3D seismic dataset with a surface seismic gunboat that fires airguns in a spiral pattern around the wellbore. Placing the seismic geophones in the borehole provides a higher resolution and more accurate image near the borehole, as well as other advantages relating to the unique position of the sensors relative to complex structures. Technical objectives are to complement surface seismic with improved resolution (~2X seismic), better high dip structure definition (e.g. salt flanks) and to fill in "imaging holes" in complex sub-salt plays where surface seismic is blind. Business drivers for this effort are to reduce risk in well placement, improved reserve calculation and understanding compartmentalization and stratigraphic variation. To date, BP has acquired 3D VSP surveys in ten wells in the DW GOM. The initial results are encouraging and show both improved resolution and structural images in complex sub-salt plays where the surface seismic is blind. In conjunction with this effort BP has influenced both contractor borehole seismic tool design and developed methods to enable the 3D VSP surveys to be conducted offline thereby avoiding the high daily rig costs associated with a Deepwater drilling rig.

  3. Seismic imaging of the shallow subsurface with high frequency seismic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kaelin, B [Univ. of California, Berkeley, CA (United States). Dept. of Geology and Geophysics

    1998-07-01

    Elastic wave propagation in highly heterogeneous media is investigated and theoretical calculations and field measurements are presented. In the first part the dynamic composite elastic medium (DYCEM) theory is derived for one-dimensional stratified media. A self-consistent method using the scattering functions of the individual layers is formulated, which allows the calculation of phase velocity, attenuation and waveform. In the second part the DYCEM theory has been generalized for three-dimensional inclusions. The specific case of spherical inclusions is calculated with the exact scattering functions and compared with several low frequency approximations. In the third part log and VSP data of partially water saturated tuffs in the Yucca Mountain region of Nevada are analyzed. The anomalous slow seismic velocities can be explained by combining self-consistent theories for pores and cracks. The fourth part analyzes an air injection experiment in a shallow fractured limestone, which has shown large effects on the amplitude, but small effects on the travel time of the transmitted seismic waves. The large amplitude decrease during the experiment is mainly due to the impedance contrast between the small velocities of gas-water mixtures inside the fracture and the formation. The slow velocities inside the fracture allow an estimation of aperture and gas concentration profiles.

  4. Seismic remote sensing image segmentation based on spectral histogram and dynamic region merging

    Science.gov (United States)

    Wang, Peng; Sun, Genyun; Wang, Zhenjie

    2015-12-01

    Image segmentation is the foundation of seismic information extraction from high-resolution remote sensing images. While the complexity of the seismic image brings great challenges to its segmentation. Compared with the traditional pixel-level approaches, the region-level approaches are found prevailing in dealing with the complexity. This paper addresses the seismic image segmentation problem in a region-merging style. Starting from many over-segmented regions, the image segmentation is performed by iteratively merging the neighboring regions. In the proposed algorithm, the merging criterion and merging order are two essential issues to be emphatically considered. An effective merging criterion is largely depends on the region feature and neighbor homogeneity measure. The region's spectral histogram represents the global feature of each region and enhances the discriminability of neighboring regions. Therefore, we utilize it to solve the merging criterion. Under a certain the merging criterion, a better performance could be obtained if the most similar regions are always ensured to be merged first, which can be transformed into a least-cost problem. Rather than predefine an order queue, we solve the order problem with a dynamic scheme. The proposed approach mainly contains three parts. Firstly, starting from the over-segmented regions, the spectral histograms are constructed to represent each region. Then, we use the homogeneity that combines the distance and shape measure to conduct the merge criterion. Finally, neighbor regions are dynamically merged following the dynamic program (DP) theory and breadth-first strategy. Experiments are conducted using the earthquake images, including collapsed buildings and seismic secondary geological disaster. The experimental results show that, the proposed method segments the seismic image more correctly.

  5. Seismic reflection data imaging and interpretation from Braniewo2014 experiment using additional wide-angle refraction and reflection and well-logs data

    Science.gov (United States)

    Trzeciak, Maciej; Majdański, Mariusz; Białas, Sebastian; Gaczyński, Edward; Maksym, Andrzej

    2015-04-01

    Braniewo2014 reflection and refraction experiment was realized in cooperation between Polish Oil and Gas Company (PGNiG) and the Institute of Geophysics (IGF), Polish Academy of Sciences, near the locality of Braniewo in northern Poland. PGNiG realized a 20-km-long reflection profile, using vibroseis and dynamite shooting; the aim of the reflection survey was to characterise Silurian shale gas reservoir. IGF deployed 59 seismic stations along this profile and registered additional full-spread wide-angle refraction and reflection data, with offsets up to 12 km; maximum offsets from the seismic reflection survey was 3 km. To improve the velocity information two velocity logs from near deep boreholes were used. The main goal of the joint reflection-refraction interpretation was to find relations between velocity field from reflection velocity analysis and refraction tomography, and to build a velocity model which would be consistent for both, reflection and refraction, datasets. In this paper we present imaging results and velocity models from Braniewo2014 experiment and the methodology we used.

  6. On the focusing conditions in time-reversed acoustics, seismic interferometry, and Marchenko imaging

    NARCIS (Netherlands)

    Wapenaar, C.P.A.; Van der Neut, J.R.; Thorbecke, J.W.; Vasconcelos, I.; Van Manen, D.J.; Ravasi, M.

    2014-01-01

    Despite the close links between the fields of time-reversed acoustics, seismic interferometry and Marchenko imaging, a number of subtle differences exist. This paper reviews the various focusing conditions of these methods, the causality/acausality aspects of the corresponding focusing wavefields, a

  7. Reflection imaging of the Moon's interior using deep-moonquake seismic interferometry

    Science.gov (United States)

    Nishitsuji, Yohei; Rowe, C. A.; Wapenaar, Kees; Draganov, Deyan

    2016-04-01

    The internal structure of the Moon has been investigated over many years using a variety of seismic methods, such as travel time analysis, receiver functions, and tomography. Here we propose to apply body-wave seismic interferometry to deep moonquakes in order to retrieve zero-offset reflection responses (and thus images) beneath the Apollo stations on the nearside of the Moon from virtual sources colocated with the stations. This method is called deep-moonquake seismic interferometry (DMSI). Our results show a laterally coherent acoustic boundary around 50 km depth beneath all four Apollo stations. We interpret this boundary as the lunar seismic Moho. This depth agrees with Japan Aerospace Exploration Agency's (JAXA) SELenological and Engineering Explorer (SELENE) result and previous travel time analysis at the Apollo 12/14 sites. The deeper part of the image we obtain from DMSI shows laterally incoherent structures. Such lateral inhomogeneity we interpret as representing a zone characterized by strong scattering and constant apparent seismic velocity at our resolution scale (0.2-2.0 Hz).

  8. Exploratory borehole Weiach. Working programme

    International Nuclear Information System (INIS)

    An extensive geophysical borehole logging programme will serve to verify the results of the core analysis and comlement the core data. Numerous borehole logs are to be registered with different types of tools. These allow one to determine various parameters essential for the full description of the rock sequences penetrated. A first category of logs enables the petrographical identification of the different rock types and indicates porous zones that are either water- or hydrocarbon bearing. A second category provides data e.g. on the degree of pore and fracture fill, rock density and rock temperature, natural gamma radiation and rock-mechanical properties. Other logs measure strike and dip of the sedimentary layers and the position of rock fractures. A fourth category provides information on the diameter and the deviation of the borehole, the quality of casing cementations and the position of casing joints. In addition, well shooting surveys will supply exact values of seismic velocities for the various rock units; data that are needed for the depth correction of the reflection profiles from Nagra's regional seismic network. With numerous hydrological tests ranging from an open-hole production test of the Muschelkalk aquifer to labelled slug tests in low-permeability crystalline sections, the hydraulic conditions of deep groundwater flow will be investigated. The recovered water samples will undergo full physical and geochemical analysis. Furthermore, their isotope content is to be measured in order to estimate the age of the various formation waters. To round off the scientific investigations, a series of rock-mechanical and geotechnical laboratory tests will provide characteristic values to be applied eventually in the design and construction of shafts and caverns for an underground repository

  9. Exploratory borehole Riniken. Working programme

    International Nuclear Information System (INIS)

    An extensive geophysical borehole logging programme will serve to verify the results of the core analysis and comlement the core data. Numerous borehole logs are to be registered with different types of tools. These allow one to determine various parameters essential for the full description of the rock sequences penetrated. A first category of logs enables the petrographical identification of the different rock types and indicates porous zones that are either water- or hydrocarbon-bearing. A second category provides data e.g. on the degree of pore and fracture fill, rock density and rock temperature, natural gamma radiation and rock-mechanical properties. Other logs measure strike and dip of the sedimentary layers and the position of rock fractures. A forth category provides information on the diameter and the deviation of the borehole, the quality of casing cementations and the position of casing joints. In addition, well shooting surveys will supply exact values of seismic velocities for the various rock units; data that are needed for the depth correction of the reflection profiles from Nagra's regional seismic network. With numerous hydrological tests ranging from a production test of the Muschelkalk aquifer to labelled slug tests in low-permeability crystalline sections, the hydraulic conditions of deep groundwater flow will be investigated. The recovered water samples will undergo full physical and geochemical analysis. Furthermore, their isotope content is to be measured in order to estimate the age of the various formation waters and their time of residence in the subsurface. To round off the scientific investigations, a series of rock-mechanical and geotechnical laboratory tests will provide characteristic values to be applied eventually in the design and construction of shafts and caverns for an underground repository

  10. Exploratory borehole Leuggern. Working program

    International Nuclear Information System (INIS)

    An extensive geophysical borehole logging programme will serve to verify the results of the core analysis and complement the core data. Numerous borehole logs are to be registered with different types of tools. These allow one to determine various parameters essential for the full description of the rock sequences penetrated. A first category of logs enables the petrographical identification of the different rock types and indicates porous zones that are either water- or hydrocarbon-bearing. A second category provides data e.g. on the degree of pore and fracture fill, rock density and rock temperature, natural gamma radiation and rock-mechanical properties. Other logs measure strike and dip of the sedimentary layers and the position of rock fractures. A fourth category provides information on the diameter and the deviation of the borehole, the quality of casing cementations and the position of casing joints. In addition, well shooting surveys will supply exact values of seismic velocities for the various rock units; data that are needed for the depth correction of the reflection profiles from Nagra's regional seismic network. With numerous hydrological tests ranging from a production tests of the Muschelkalk and Buntsandstein aquifers to labelled slug-tests in low-permeability crystalline sections, the hydraulic conditions of deep groundwater flow will be investigated. The recovered water samples will undergo full physical and geochemical analysis. Furthermore, their isotope content is to be measured in order to estimate the age of the various formation waters and their time of residence in the subsurface. To round off the scientific investigations, a series of rock-mechanical and geotechnical laboratory tests will provide characteristic values to be applied eventually in the design and construction of shafts and caverns for an underground repository

  11. Exploratory borehole Kaisten. Working program

    International Nuclear Information System (INIS)

    The next well on the Nagra drilling programme, Kaisten, lies at the southern border of the Rhine valley. An extensive geophysical borehole logging programme will serve to verify the results of the core analysis and complement the core data. Numerous borehole logs are to be registered with different types of tools. These allow one to determine various parameters essential for the full description of the rock sequences penetrated. A first category of logs enables the petrographical identification of the different rock types and indicates porous zones that are either water- or hydrocarbon-bearing. A second category provides data e.g. on the degree of pore and fracture fill, rock density and rock temperature, natural gamma radiation and rock-mechanical properties. Other logs measure strike and dip of the sedimentary layers and the position of rock fractures. A fourth category provides information on the diameter and the deviation of the borehole, the quality of casing cementations and the position of casing joints. In addition, well shooting surveys will supply exact values of seismic velocities for the various rock units; data that are needed for the depth correction of the reflection profiles from Nagra's regional seismic network. With numerous hydrological tests ranging from production tests of the Buntsandstein aquifer to labelled slug-tests in low-permeability crystalline sections, the hydraulic conditions of deep groundwater flow will be investigated. The recovered water samples will undergo full physical and geochemical analysis. Furthermore, their isotope content is to be measured in order to estimate the age of the various formation waters and their time of residence in the subsurface

  12. Seismic imaging of deformation zones associated with normal fault-related folding

    Science.gov (United States)

    Lapadat, Alexandru; Imber, Jonathan; Iacopini, David; Hobbs, Richard

    2016-04-01

    Folds associated with normal faulting, which are mainly the result of fault propagation and linkage of normal fault segments, can exhibit complex deformation patterns, with multiple synthetic splay faults, reverse faults and small antithetic Riedel structures accommodating flexure of the beds. Their identification is critical in evaluating connectivity of potential hydrocarbon reservoirs and sealing capacity of faults. Previous research showed that seismic attributes can be successfully used to image complex structures and deformation distribution in submarine thrust folds. We use seismic trace and coherency attributes, a combination of instantaneous phase, tensor discontinuity and semblance attributes to identify deformation structures at the limit of seismic resolution, which accommodate seismic scale folding associated with normal faulting from Inner Moray Firth Basin, offshore Scotland. We identify synthetic splay faults and reverse faults adjacent to the master normal faults, which are localized in areas with highest fold amplitudes. This zone of small scale faulting is the widest in areas with highest fault throw / fold amplitude, or where a bend is present in the main fault surface. We also explore the possibility that changes in elastic properties of the rocks due to deformation can contribute to amplitude reductions in the fault damage zones. We analyse a pre-stack time-migrated 3D seismic data-set, where seismic reflections corresponding to a regionally-continuous and homogeneous carbonate layer display a positive correlation between strain distribution and amplitude variations adjacent to the faults. Seismic amplitude values are homogeneously distributed within the undeformed area of the footwall, with a minimum deviation from a mean amplitude value calculated for each seismic line. Meanwhile, the amplitude dimming zone is more pronounced (negative deviation increases) and widens within the relay zone, where sub-seismic scale faults, which accommodate

  13. First images and orientation of internal waves from a 3-D seismic oceanography data set

    Directory of Open Access Journals (Sweden)

    T. M. Blacic

    2009-10-01

    Full Text Available We present 3-D images of ocean finestructure from a unique industry-collected 3-D multichannel seismic dataset from the Gulf of Mexico that includes expendable bathythermograpgh casts for both swaths. 2-D processing reveals strong laterally continuous reflectors throughout the upper ~800 m as well as a few weaker but still distinct reflectors as deep as ~1100 m. Two bright reflections are traced across the 225-m-wide swath to produce reflector surface images that show the 3-D structure of internal waves. We show that the orientation of internal wave crests can be obtained by calculating the orientations of contours of reflector relief. Preliminary 3-D processing further illustrates the potential of 3-D seismic data in interpreting images of oceanic features such as internal wave strains. This work demonstrates the viability of imaging oceanic finestructure in 3-D and shows that, beyond simply providing a way to see what oceanic finestructure looks like, quantitative information such as the spatial orientation of features like internal waves and solitons can be obtained from 3-D seismic images. We expect complete, optimized 3-D processing to improve both the signal to noise ratio and spatial resolution of our images resulting in increased options for analysis and interpretation.

  14. Anatomy of the western Java plate interface from depth-migrated seismic images

    Science.gov (United States)

    Kopp, H.; Hindle, D.; Klaeschen, D.; Oncken, O.; Reichert, C.; Scholl, D.

    2009-01-01

    Newly pre-stack depth-migrated seismic images resolve the structural details of the western Java forearc and plate interface. The structural segmentation of the forearc into discrete mechanical domains correlates with distinct deformation styles. Approximately 2/3 of the trench sediment fill is detached and incorporated into frontal prism imbricates, while the floor sequence is underthrust beneath the d??collement. Western Java, however, differs markedly from margins such as Nankai or Barbados, where a uniform, continuous d??collement reflector has been imaged. In our study area, the plate interface reveals a spatially irregular, nonlinear pattern characterized by the morphological relief of subducted seamounts and thicker than average patches of underthrust sediment. The underthrust sediment is associated with a low velocity zone as determined from wide-angle data. Active underplating is not resolved, but likely contributes to the uplift of the large bivergent wedge that constitutes the forearc high. Our profile is located 100 km west of the 2006 Java tsunami earthquake. The heterogeneous d??collement zone regulates the friction behavior of the shallow subduction environment where the earthquake occurred. The alternating pattern of enhanced frictional contact zones associated with oceanic basement relief and weak material patches of underthrust sediment influences seismic coupling and possibly contributed to the heterogeneous slip distribution. Our seismic images resolve a steeply dipping splay fault, which originates at the d??collement and terminates at the sea floor and which potentially contributes to tsunami generation during co-seismic activity. ?? 2009 Elsevier B.V.

  15. Applying the seismic interferometry method to vertical seismic profile data using tunnel excavation noise as source

    Science.gov (United States)

    Jurado, Maria Jose; Teixido, Teresa; Martin, Elena; Segarra, Miguel; Segura, Carlos

    2013-04-01

    In the frame of the research conducted to develop efficient strategies for investigation of rock properties and fluids ahead of tunnel excavations the seismic interferometry method was applied to analyze the data acquired in boreholes instrumented with geophone strings. The results obtained confirmed that seismic interferometry provided an improved resolution of petrophysical properties to identify heterogeneities and geological structures ahead of the excavation. These features are beyond the resolution of other conventional geophysical methods but can be the cause severe problems in the excavation of tunnels. Geophone strings were used to record different types of seismic noise generated at the tunnel head during excavation with a tunnelling machine and also during the placement of the rings covering the tunnel excavation. In this study we show how tunnel construction activities have been characterized as source of seismic signal and used in our research as the seismic source signal for generating a 3D reflection seismic survey. The data was recorded in vertical water filled borehole with a borehole seismic string at a distance of 60 m from the tunnel trace. A reference pilot signal was obtained from seismograms acquired close the tunnel face excavation in order to obtain best signal-to-noise ratio to be used in the interferometry processing (Poletto et al., 2010). The seismic interferometry method (Claerbout 1968) was successfully applied to image the subsurface geological structure using the seismic wave field generated by tunneling (tunnelling machine and construction activities) recorded with geophone strings. This technique was applied simulating virtual shot records related to the number of receivers in the borehole with the seismic transmitted events, and processing the data as a reflection seismic survey. The pseudo reflective wave field was obtained by cross-correlation of the transmitted wave data. We applied the relationship between the transmission

  16. Detailed Seismic Reflection Images of the Central American Volcanic Arc

    Science.gov (United States)

    McIntosh, K. D.; Fulthorpe, C. S.

    2005-12-01

    New high-resolution seismic reflection profiles across the Central American volcanic arc (CAVA) reveal an asymmetric deformation pattern with large-scale folding and uplift of basinal strata in the forearc contrasted by intrusive bodies, normal faults, and possible strikes-slip faults in the backarc. Since Miocene times the CAVA has migrated seaward, apparently impinging on the Sandino forearc basin and creating or modifying the low-lying Nicaragua depression, which contains the backarc and much of the arc. However the structural nature of the depression and its possible relationship to forearc sliver movement is poorly known. In November-December 2004 we recorded a large, high-resolution, seismic reflection dataset largely on the Pacific shelf (forearc) area of Central America, extending from NW Costa Rica to the SE edge of El Salvador's territorial waters. We seized an opportunity to study the nature of the CAVA by recording data into the Gulf of Fonseca, a large embayment at the intersection of Nicaragua, Honduras, and El Salvador. With 3 GI airguns and a 2100 m streamer we recorded data with typical penetration of 2-3 seconds in the Sandino basin and frequency content of ~10-250 Hz (at shallow levels). Penetration was limited over the arc summit with high velocity volcanic rocks encountered at depths as shallow as a few hundred meters. To the NE the edge of the Nicaragua depression occurs abruptly; our data show a well-developed sedimentary basin 1.5-3 km thick separated by numerous steeply-dipping faults. The broadband signal and good penetration of this dataset will help us determine the chronology of arc development in this position and the styles of deformation in the forearc, arc, and backarc areas. In turn, this will help us understand the regional tectonic and stratigraphic development of this margin due to the profound affects of the arc.

  17. Frequency-dependent traveltime tomography using fat rays: application to near-surface seismic imaging

    Science.gov (United States)

    Jordi, Claudio; Schmelzbach, Cedric; Greenhalgh, Stewart

    2016-08-01

    Frequency-dependent traveltime tomography does not rely on the high frequency assumption made in classical ray-based tomography. By incorporating the effects of velocity structures in the first Fresnel volume around the central ray, it offers a more realistic and accurate representation of the actual physics of seismic wave propagation and thus, enhanced imaging of near-surface structures is expected. The objective of this work was to apply frequency-dependent first arrival traveltime tomography to surface seismic data that were acquired for exploration scale and near-surface seismic imaging. We adapted a fat ray tomography algorithm from global-earth seismology that calculates the Fresnel volumes based on source and receiver (adjoint source) traveltime fields. The fat ray tomography algorithm was tested on synthetic model data that mimics the dimensions of two field data sets. The field data sets are presented as two case studies where fat ray tomography was applied for near-surface seismic imaging. The data set of the first case study was recorded for high-resolution near-surface imaging of a Quaternary valley (profile length 10 km). All results of fat ray tomography are compared against the results of classical ray-based tomography. We show that fat ray tomography can provide enhanced tomograms and that it is possible to recover more information on the subsurface when compared to ray tomography. However, model assessment based on the column sum of the Jacobian matrix revealed that especially the deep parts of the structure in the fat ray tomograms might not be adequately covered by fat rays. Furthermore, the performance of the fat ray tomography depends on the chosen input frequency in relation to the scale of the seismic survey. Synthetic data testing revealed that the best results were obtained when the frequency was chosen to correspond to an approximate wavelength-to-target depth ratio of 0.1.

  18. Developments of borehole strain observation outside China

    Institute of Scientific and Technical Information of China (English)

    邱泽华; 石耀霖

    2004-01-01

    Borehole strain observation is playing an increasingly important role in the study on the crustal movements. It hasbeen used by many countries such as China, USA, Japan, Peru, Australia, South Africa, Iceland and Italy, in research fields of plate tectonics, earthquake, volcanic eruption, dam safety, oil field subsidence, mining collapse andso on. Borehole strainmeter has been improved rapidly and tends to get more and more components included inone probe. Based on observations by this kind of instruments, studies on seismic strain step, slow earthquake,earthquake precursor and volcanic eruption forecasting have made remarkable achievements. In the coming years,borehole strain observation is going to become one major geodetic means, together with GPS and InSAR.

  19. Source estimation with surface-related multiples—fast ambiguity-resolved seismic imaging

    Science.gov (United States)

    Tu, Ning; Aravkin, Aleksandr; van Leeuwen, Tristan; Lin, Tim; Herrmann, Felix J.

    2016-06-01

    We address the problem of obtaining a reliable seismic image without prior knowledge of the source wavelet, especially from data that contain strong surface-related multiples. Conventional reverse-time migration requires prior knowledge of the source wavelet, which is either technically or computationally challenging to accurately determine; inaccurate estimates of the source wavelet can result in seriously degraded reverse-time migrated images, and therefore wrong geological interpretations. To solve this problem, we present a `wavelet-free' imaging procedure that simultaneously inverts for the source wavelet and the seismic image, by tightly integrating source estimation into a fast least-squares imaging framework, namely compressive imaging, given a reasonably accurate background velocity model. However, this joint inversion problem is difficult to solve as it is plagued with local minima and the ambiguity with respect to amplitude scalings because of the multiplicative, and therefore nonlinear, appearance of the source wavelet in the otherwise linear formalism. We have found a way to solve this nonlinear joint-inversion problem using a technique called variable projection, and a way to overcome the scaling ambiguity by including surface-related multiples in our imaging procedure following recent developments in surface-related multiple prediction by sparse inversion. As a result, we obtain without prior knowledge of the source wavelet high-resolution seismic images, comparable in quality to images obtained assuming the true source wavelet is known. By leveraging the computationally efficient compressive-imaging methodology, these results are obtained at affordable computational costs compared with conventional processing work flows that include surface-related multiple removal and reverse-time migration.

  20. High-resolution seismic imaging of the gas and gas hydrate system at Green Canyon 955 in the Gulf of Mexico

    Science.gov (United States)

    Haines, S. S.; Hart, P. E.; Collett, T. S.; Shedd, W. W.; Frye, M.

    2015-12-01

    High-resolution 2D seismic data acquired by the USGS in 2013 enable detailed characterization of the gas and gas hydrate system at lease block Green Canyon 955 (GC955) in the Gulf of Mexico, USA. Earlier studies, based on conventional industry 3D seismic data and logging-while-drilling (LWD) borehole data acquired in 2009, identified general aspects of the regional and local depositional setting along with two gas hydrate-bearing sand reservoirs and one layer containing fracture-filling gas hydrate within fine-grained sediments. These studies also highlighted a number of critical remaining questions. The 2013 high-resolution 2D data fill a significant gap in our previous understanding of the site by enabling interpretation of the complex system of faults and gas chimneys that provide conduits for gas flow and thus control the gas hydrate distribution observed in the LWD data. In addition, we have improved our understanding of the main channel/levee sand reservoir body, mapping in fine detail the levee sequences and the fault system that segments them into individual reservoirs. The 2013 data provide a rarely available high-resolution view of a levee reservoir package, with sequential levee deposits clearly imaged. Further, we can calculate the total gas hydrate resource present in the main reservoir body, refining earlier estimates. Based on the 2013 seismic data and assumptions derived from the LWD data, we estimate an in-place volume of 840 million cubic meters or 29 billion cubic feet of gas in the form of gas hydrate. Together, these interpretations provide a significantly improved understanding of the gas hydrate reservoirs and the gas migration system at GC955.

  1. Low Noise Borehole Triaxial Seismometer Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, James D; McClung, David W

    2006-11-06

    This report describes the preliminary design and the effort to date of Phase II of a Low Noise Borehole Triaxial Seismometer for use in networks of seismic stations for monitoring underground nuclear explosions. The design uses the latest technology of broadband seismic instrumentation. Each parameter of the seismometer is defined in terms of the known physical limits of the parameter. These limits are defined by the commercially available components, and the physical size constraints. A theoretical design is proposed, and a preliminary prototype model of the proposed instrument has been built. This prototype used the sensor module of the KS2000. The installation equipment (hole locks, etc.) has been designed and one unit has been installed in a borehole. The final design of the sensors and electronics and leveling mechanism is in process. Noise testing is scheduled for the last quarter of 2006.

  2. 24-CHANNEL GEOPHONE ARRAY FOR HORIZONTAL OR VERTICAL BOREHOLES

    Energy Technology Data Exchange (ETDEWEB)

    Erik C. Westman

    2003-10-24

    Improved ground-imaging capabilities have enormous potential to increase energy, environmental, and economic benefits by improving exploration accuracy and reducing energy consumption during the mining cycle. Seismic tomography has been used successfully to monitor and evaluate geologic conditions ahead of a mining face. A primary limitation to existing seismic tomography, however, is the placement of sensors. The goal of this project is to develop an array of 24 seismic sensors capable of being mounted in either a vertical or horizontal borehole. Development of this technology reduces energy usage in excavation, transportation, ventilation, and processing phases of the mining operation because less waste is mined and the mining cycle suffers fewer interruptions. This new technology benefits all types of mines, including metal/nonmetal, coal, and quarrying. The primary research tasks focused on sensor placement method, sensor housing and clamping design, and cabling and connector selection. An initial design is described in the report. Following assembly, a prototype was tested in the laboratory as well as at a surface stone quarry. Data analysis and tool performance were used for subsequent design modifications. A final design is described, of which several components are available for patent application. Industry partners have shown clear support for this research and demonstrated an interest in commercialization following project completion.

  3. Geoelectrical Resistivity Imaging and Refraction Seismic Investigations at Sg.Udang, Melaka

    OpenAIRE

    Zeinab Asry; Abdul Rahim Samsudin; Wan Zuhairi Yaacob; Jasni Yaakub

    2012-01-01

    Problem statement: A Reconnaissance geophysical survey of an area near Sg.Udang, Melaka was conducted using geoelectrical resistivity and seismic refraction methods. The main objective of this study is to determine the depth of bedrock in the study area. The resistivity imaging measurement employing Wenner electrode configuration was carried out using an ABEM SAS 1000 terrameter and electrode selector system ES464. Electrodes were arranged in a straight line with constant spacing and connecte...

  4. Vertical seismic profiling and integration with reflection seismic studies at Laxemar, 2000

    International Nuclear Information System (INIS)

    Vertical seismic profile (VSP) data were acquired in October 2000 in the 1700 m deep KLX02 borehole, near Laxemar in southeastern Sweden. The objectives of the VSP were to image reflectors in the borehole for correlation with surface seismic and borehole data, study the signal penetration of explosive versus mechanical sources and determine the seismic velocity as a function of depth. Five principal source points were used, one located close to the KLX02 wellhead and 4 others that were offset by about 200 m to 400 m. An explosive source was only used at the wellhead and consisted of 15 grams of dynamite in 90 cm deep shot holes in bedrock. A swept impact seismic source (SIST) was also used at the wellhead, as well as at the other four offset source points. The primary SIST source consisted of a computer controlled mechanical hammer mounted on a tractor. By activating the hammer over a 15 second sweep length, the total energy transferred to the ground is on the same order as that produced by the dynamite. The recorded data are then processed to generate seismic records that are equivalent to a single impact source. A smaller hand held SIST source was also tested at the wellhead. Tests of both the tractor mounted source and dynamite were made at a location offset somewhat from the wellhead at a site containing loose sediments at the surface. Full waveform sonic, resistivity and gamma logs were also acquired in conjunction the VSP survey. A comparison between the explosive and large SIST source shows that comparable energy levels are produced by the two methods. The SIST source appears to be more stable in terms of the energy level, although the frequency content of data are somewhat lower. However, its most significant advantage is the low cost of preparation of the source points and the speed of the acquisition. Numerous reflections are observed on the VSP, as is the case on the surface seismic, implying a complex structure in the vicinity of the KLX02 borehole

  5. Imaging Reservoir Quality: Seismic Signatures of Geologic Processes

    Energy Technology Data Exchange (ETDEWEB)

    Department of Geophysics

    2008-06-30

    }20 % to 23%). This trend is explained by a sequence stratigraphic model which predicts progressive increase in sorting by turbidity current along the flow, as well as, quantified by a rock model that heuristically accounts for sorting. The results can be applied to improve quantitative predication of sediment parameters from seismic impedance, away from well locations.

  6. Coherent features of the Alpine mantle slabs imaged by recent seismic tomography studies

    Science.gov (United States)

    Brueckl, E.; Brueckl, J.; Keller, G. R.; Dando, B.

    2012-04-01

    The bifurcation of the East Alpine mountain range into branches extending northeastward to the Carpathians and southeastward to the Dinarides represents a triple junction between the European platform (EU), the Adriatic micro-plate (AD), and the Pannonian fragment (PA). During the last decade, controlled source and passive source seismic data have provided a variety of detailed images of the lithosphere and upper mantle in this area. However, the geodynamic interpretation of lithospheric slabs under the Alpine - Adriatic collision zone is still under debate. So far, arguments have been based mainly on images provided by individual seismic tomography studies. In order to enhance robust features of the upper mantle structure, we have averaged four tomographic models, weighted according to their coverage by seismic stations and boundaries of high resolution. We achieved an image of the Alpine slab of unprecedented clarity. It extends coherently from the border between the Western Alps and the Apennines to the EU-AD-PA triple junction, dipping southeastward in the west and nearly vertically in the east. The whole slab can be connected to European mantle lithosphere and a flip of subduction polarity must not be induced. The geometry of the slab infers also additional constraints on the development of the triple junction during the post-collision phase of the Eastern Alps.

  7. A seismic reflection image for the base of a tectonic plate.

    Science.gov (United States)

    Stern, T A; Henrys, S A; Okaya, D; Louie, J N; Savage, M K; Lamb, S; Sato, H; Sutherland, R; Iwasaki, T

    2015-02-01

    Plate tectonics successfully describes the surface of Earth as a mosaic of moving lithospheric plates. But it is not clear what happens at the base of the plates, the lithosphere-asthenosphere boundary (LAB). The LAB has been well imaged with converted teleseismic waves, whose 10-40-kilometre wavelength controls the structural resolution. Here we use explosion-generated seismic waves (of about 0.5-kilometre wavelength) to form a high-resolution image for the base of an oceanic plate that is subducting beneath North Island, New Zealand. Our 80-kilometre-wide image is based on P-wave reflections and shows an approximately 15° dipping, abrupt, seismic wave-speed transition (less than 1 kilometre thick) at a depth of about 100 kilometres. The boundary is parallel to the top of the plate and seismic attributes indicate a P-wave speed decrease of at least 8 ± 3 per cent across it. A parallel reflection event approximately 10 kilometres deeper shows that the decrease in P-wave speed is confined to a channel at the base of the plate, which we interpret as a sheared zone of ponded partial melts or volatiles. This is independent, high-resolution evidence for a low-viscosity channel at the LAB that decouples plates from mantle flow beneath, and allows plate tectonics to work.

  8. A seismic reflection image for the base of a tectonic plate.

    Science.gov (United States)

    Stern, T A; Henrys, S A; Okaya, D; Louie, J N; Savage, M K; Lamb, S; Sato, H; Sutherland, R; Iwasaki, T

    2015-02-01

    Plate tectonics successfully describes the surface of Earth as a mosaic of moving lithospheric plates. But it is not clear what happens at the base of the plates, the lithosphere-asthenosphere boundary (LAB). The LAB has been well imaged with converted teleseismic waves, whose 10-40-kilometre wavelength controls the structural resolution. Here we use explosion-generated seismic waves (of about 0.5-kilometre wavelength) to form a high-resolution image for the base of an oceanic plate that is subducting beneath North Island, New Zealand. Our 80-kilometre-wide image is based on P-wave reflections and shows an approximately 15° dipping, abrupt, seismic wave-speed transition (less than 1 kilometre thick) at a depth of about 100 kilometres. The boundary is parallel to the top of the plate and seismic attributes indicate a P-wave speed decrease of at least 8 ± 3 per cent across it. A parallel reflection event approximately 10 kilometres deeper shows that the decrease in P-wave speed is confined to a channel at the base of the plate, which we interpret as a sheared zone of ponded partial melts or volatiles. This is independent, high-resolution evidence for a low-viscosity channel at the LAB that decouples plates from mantle flow beneath, and allows plate tectonics to work. PMID:25653000

  9. Shear wave seismic interferometry for lithospheric imaging: Application to southern Mexico

    Science.gov (United States)

    Frank, J. G.; Ruigrok, E. N.; Wapenaar, K.

    2014-07-01

    Seismic interferometry allows for the creation of new seismic traces by cross correlating existing ones. With sufficient sampling of remote-source positions, it is possible to create a virtual source record by transforming a receiver location into a virtual source. The imaging technique developed here directly retrieves reflectivity information from the subsurface. Other techniques, namely receiver-function and tomography, rely on mode-converted energy and perturbations in a velocity field, respectively, to make inferences regarding structure. We select shear phases as an imaging source because of their lower propagation velocity, sensitivity to melt, and ability to treat vertical shear and horizontal shear wavefields independently. Teleseismic shear phases approximate a plane wave due to the extent of wavefront spread compared to a finite receiver array located on the free surface. The teleseismic shear phase transmission responses are used as input to the seismic interferometry technique. We create virtual shear source records by converting each receiver in the array into a virtual source. By cross correlating the received signals, the complex source character of distant earthquakes is imprinted on the virtual source records as the average autocorrelation of individual source-time functions. We demonstrate a technique that largely removes this imprint by filtering in the common-offset domain. A field data set was selected from the Meso-America Subduction Experiment. Despite the suboptimal remote-source sampling, an image of the lithosphere was produced that confirms features of the subduction zone that were previously found with the receiver-function technique.

  10. High Resolution/High Fidelity Seismic Imaging and Parameter Estimation for Geological Structure and Material Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Ru-Shan Wu, Xiao-Bi Xie, Thorne Lay

    2005-06-06

    In this project, we develop new theories and methods for multi-domain one-way wave-equation based propagators, and apply these techniques to seismic modeling, seismic imaging, seismic illumination and model parameter estimation in 3D complex environments. The major progress of this project includes: (1) The development of the dual-domain wave propagators. We continue to improve the one-way wave-equation based propagators. Our target is making propagators capable of handling more realistic velocity models. A wide-angle propagator for transversely isotropic media with vertically symmetric axis (VTI) has been developed for P-wave modeling and imaging. The resulting propagator is accurate for large velocity perturbations and wide propagation angles. The thin-slab propagator for one-way elastic-wave propagation is further improved. With the introduction of complex velocities, the quality factors Qp and Qs have been incorporated into the thin-slab propagator. The resulting viscoelastic thin-slab propagator can handle elastic-wave propagation in models with intrinsic attenuations. We apply this method to complex models for AVO modeling, random media characterization and frequency-dependent reflectivity simulation. (2) Exploring the Information in the Local Angle Domain. Traditionally, the local angle information can only be extracted using the ray-based method. We develop a wave-equation based technique to process the local angle domain information. The approach can avoid the singularity problem usually linked to the high-frequency asymptotic method. We successfully apply this technique to seismic illumination and the resulting method provides a practical tool for three-dimensional full-volume illumination analysis in complex structures. The directional illumination also provides information for angle-domain imaging corrections. (3) Elastic-Wave Imaging. We develop a multicomponent elastic migration method. The application of the multicomponent one-way elastic propagator

  11. Receiver function analysis - Seismic imaging of the crust beneath TROLL seismic station in Queen Maud Land, Antarctica

    OpenAIRE

    Torsvik, Andreas

    2015-01-01

    In this this study, receiver function analysis of the crust underneath TROLL seismic station in Queen Maud Land, Antarctica was performed. An analysis of the neighboring seismic station SNAA was carried out as well to provide ground of comparison. Receiver function analysis is a seismic method utilizing that fact that teleseismic P-waves encountering a subsurface boundary at particular angels of incidence will result in refracted and reflected P and S-waves. The generated waves of interest ar...

  12. Imaging architecture of the Jakarta Basin, Indonesia with transdimensional inversion of seismic noise

    Science.gov (United States)

    Saygin, E.; Cummins, P. R.; Cipta, A.; Hawkins, R.; Pandhu, R.; Murjaya, J.; Masturyono, Irsyam, M.; Widiyantoro, S.; Kennett, B. L. N.

    2016-02-01

    In order to characterize the subsurface structure of the Jakarta Basin, Indonesia, a dense portable seismic broad-band network was operated by The Australian National University (ANU) and the Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) between October 2013 and February 2014. Overall 96 locations were sampled through successive deployments of 52 seismic broad-band sensors at different parts of the city. Oceanic and anthropogenic noises were recorded as well as regional and teleseismic earthquakes. We apply regularized deconvolution to the recorded ambient noise of the vertical components of available station pairs, and over 3000 Green's functions were retrieved in total. Waveforms from interstation deconvolutions show clear arrivals of Rayleigh fundamental and higher order modes. The traveltimes that were extracted from group velocity filtering of fundamental mode Rayleigh wave arrivals, are used in a 2-stage Transdimensional Bayesian method to map shear wave structure of subsurface. The images of S wave speed show very low velocities and a thick basin covering most of the city with depths up to 1.5 km. These low seismic velocities and the thick basin beneath the city potentially cause seismic amplification during a subduction megathrust or other large earthquake close to the city of Jakarta.

  13. Demasking Multiple Artifact in Crustal Seismic Images from Marine Reflection Data in the Southern California Borderland

    Institute of Scientific and Technical Information of China (English)

    Christopher Gantela; Aifei Bian; Hua-Wei Zhou; Tom Bjorklund

    2015-01-01

    Marine seismic reflection surveys are often masked by strong water-bottom multiples that limit the use of data beyond the first multiple waves. In this study, we have successfully suppressed much of the multiple artifacts in the depth images of two of the marine seismic reflection profiles from the Los Angeles regional seismic experiment (LARSE) by applying reverse time migration (RTM). In contrast to most seismic reflection methods that use only primary reflections and diffractions, the two-way RTM migrates both primaries and multiple reflections to their places of origination:seabed multiples to the sea bottom and primaries to the reflecting interfaces. Based on the RTM depth sections of LARSE lines 1 and 2, we recognize five stratigraphic units from the sea bottom to a depth of 6 km. These units are Pliocene and younger strata, probably Miocene syntectonic strata, two deeper sequences of unknown age and lithology as well as Miocene volcanic layers on Catalina ridge. Several inferred igneous intrusions in the upper crust comprise a sixth unit. The existence of a thick sedimentary section in the Catalina Basin, which might include Paleogene and Cretaceous fore-arc strata, has important geologic significance. If borne out by further studies, significant revisions of current structural and stratigraphic interpretations of the California borderland would be warranted.

  14. Theory of reflectivity blurring in seismic depth imaging

    Science.gov (United States)

    Thomson, C. J.; Kitchenside, P. W.; Fletcher, R. P.

    2016-05-01

    A subsurface extended image gather obtained during controlled-source depth imaging yields a blurred kernel of an interface reflection operator. This reflectivity kernel or reflection function is comprised of the interface plane-wave reflection coefficients and so, in principle, the gather contains amplitude versus offset or angle information. We present a modelling theory for extended image gathers that accounts for variable illumination and blurring, under the assumption of a good migration-velocity model. The method involves forward modelling as well as migration or back propagation so as to define a receiver-side blurring function, which contains the effects of the detector array for a given shot. Composition with the modelled incident wave and summation over shots then yields an overall blurring function that relates the reflectivity to the extended image gather obtained from field data. The spatial evolution or instability of blurring functions is a key concept and there is generally not just spatial blurring in the apparent reflectivity, but also slowness or angle blurring. Gridded blurring functions can be estimated with, for example, a reverse-time migration modelling engine. A calibration step is required to account for ad hoc band limitedness in the modelling and the method also exploits blurring-function reciprocity. To demonstrate the concepts, we show numerical examples of various quantities using the well-known SIGSBEE test model and a simple salt-body overburden model, both for 2-D. The moderately strong slowness/angle blurring in the latter model suggests that the effect on amplitude versus offset or angle analysis should be considered in more realistic structures. Although the description and examples are for 2-D, the extension to 3-D is conceptually straightforward. The computational cost of overall blurring functions implies their targeted use for the foreseeable future, for example, in reservoir characterization. The description is for scalar

  15. Seismic imaging of the downwelling Indian lithosphere beneath central Tibet.

    Science.gov (United States)

    Tilmann, Frederik; Ni, James

    2003-05-30

    A tomographic image of the upper mantle beneath central Tibet from INDEPTH data has revealed a subvertical high-velocity zone from approximately 100- to approximately 400-kilometers depth, located approximately south of the Bangong-Nujiang Suture. We interpret this zone to be downwelling Indian mantle lithosphere. This additional lithosphere would account for the total amount of shortening in the Himalayas and Tibet. A consequence of this downwelling would be a deficit of asthenosphere, which should be balanced by an upwelling counterflow, and thus could explain the presence of warm mantle beneath north-central Tibet.

  16. Seismic signatures of the Lodgepole fractured reservoir in Utah-Wyoming overthrust belt

    Energy Technology Data Exchange (ETDEWEB)

    Parra, J.; Collier, H.; Angstman, B.

    1997-08-01

    In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based upon the effects of such conditions on the propagation of acoustic and seismic waves in the rock. We present the feasibility of using seismic measurement techniques to map the fracture zones between wells spaced 2400 ft at depths of about 1000 ft. For this purpose we constructed computer models (which include azimuthal anisotropy) using Lodgepole reservoir parameters to predict seismic signatures recorded at the borehole scale, crosswell scale, and 3 D seismic scale. We have integrated well logs with existing 2D surfaces seismic to produce petrophysical and geological cross sections to determine the reservoir parameters and geometry for the computer models. In particular, the model responses are used to evaluate if surface seismic and crosswell seismic measurements can capture the anisotropy due to vertical fractures. Preliminary results suggested that seismic waves transmitted between two wells will propagate in carbonate fracture reservoirs, and the signal can be received above the noise level at the distance of 2400 ft. In addition, the large velocities contrast between the main fracture zone and the underlying unfractured Boundary Ridge Member, suggested that borehole reflection imaging may be appropriate to map and fracture zone thickness variation and fracture distributions in the reservoir.

  17. Point spread functions for earthquake source imaging: An interpretation based on seismic interferometry

    Science.gov (United States)

    Nakahara, Hisashi; Haney, Matt

    2015-01-01

    Recently, various methods have been proposed and applied for earthquake source imaging, and theoretical relationships among the methods have been studied. In this study, we make a follow-up theoretical study to better understand the meanings of earthquake source imaging. For imaging problems, the point spread function (PSF) is used to describe the degree of blurring and degradation in an obtained image of a target object as a response of an imaging system. In this study, we formulate PSFs for earthquake source imaging. By calculating the PSFs, we find that waveform source inversion methods remove the effect of the PSF and are free from artifacts. However, the other source imaging methods are affected by the PSF and suffer from the effect of blurring and degradation due to the restricted distribution of receivers. Consequently, careful treatment of the effect is necessary when using the source imaging methods other than waveform inversions. Moreover, the PSF for source imaging is found to have a link with seismic interferometry with the help of the source-receiver reciprocity of Green’s functions. In particular, the PSF can be related to Green’s function for cases in which receivers are distributed so as to completely surround the sources. Furthermore, the PSF acts as a low-pass filter. Given these considerations, the PSF is quite useful for understanding the physical meaning of earthquake source imaging.

  18. The Eifel Plume-imaged with converted seismic waves

    Science.gov (United States)

    Budweg, Martin; Bock, Günter; Weber, Michael

    2006-08-01

    Receiver functions (RF) are used to investigate the upper mantle structure beneath the Eifel, the youngest volcanic area of Central Europe. Data from 96 teleseismic events recorded by 242 seismological stations from permanent and a temporary network has been analysed. The temporary network operated from 1997 November to 1998 June and covered an area of approximately 400 × 250 km2 centred on the Eifel volcanic fields. The average Moho depth in the Eifel is approximately 30 km, thinning to ca. 28 km under the Eifel volcanic fields. RF images suggest the existence of a low velocity zone at about 60-90 km depth under the West Eifel. This observation is supported by P- and S-wave tomographic results and absorption (but the array aperture limits the resolution of the tomographic methods to the upper 400 km). There are also indications for a zone of elevated velocities at around 200 km depth, again in agreement with S-wave and absorption tomographic results. This anomaly is not visible in P-wave tomography and could be due to S-wave anisotropy. The RF anomalies at the Moho, at 60-90 km, and near 200 km depth have a lateral extent of about 100 km. The 410 km discontinuity under the Eifel is depressed by 15-25 km, which could be explained by a maximum temperature increase of +200°C to +300°C. In the 3-D RF image of the Eifel Plume we also notice two additional currently unexplained conversions between 410 and 550 km depth. They could represent remnants of previous subduction or anomalies due to delayed phase changes. The lateral extent of these conversions and the depression of the 410 km discontinuity is about 200 km. The 660 km discontinuity does not show any depth deviation from its expected value. Our observations are consistent with interpretation in terms of an upper mantle plume but they do not rule out connections to processes at larger depth.

  19. Active-source seismic imaging below Lake Malawi (Nyasa) from the SEGMeNT project

    Science.gov (United States)

    Shillington, D. J.; Scholz, C. A.; Gaherty, J. B.; Accardo, N. J.; McCartney, T.; Chindandali, P. R. N.; Kamihanda, G.; Trinhammer, P.; Wood, D. A.; Khalfan, M.; Ebinger, C. J.; Nyblade, A.; Mbogoni, G. J.; Mruma, A. H.; Salima, J.; Ferdinand-Wambura, R.

    2015-12-01

    Little is known about the controls on the initiation and development of magmatism and segmentation in young rift systems. The northern Lake Malawi (Nyasa) rift in the East African Rift System is an early stage rift exhibiting pronounced tectonic segmentation, which is defined in the upper crust by ~100-km-long border faults. Very little volcanism is associated with rifting; the only surface expression of magmatism occurs in an accommodation zone between segments to the north of the lake in the Rungwe Volcanic Province. The SEGMeNT (Study of Extension and maGmatism in Malawi aNd Tanzania) project is a multidisciplinary, multinational study that is acquiring a suite of geophysical, geological and geochemical data to characterize deformation and magmatism in the crust and mantle lithosphere along 2-3 segments of this rift. As a part of the SEGMeNT project, we acquired seismic reflection and refraction data in Lake Malawi (Nyasa) in March-April 2015. Over 2000 km of seismic reflection data were acquired with a 500 to 2580 cu in air gun array from GEUS/Aarhus and a 500- to 1500-m-long seismic streamer from Syracuse University over a grid of lines across and along the northern and central basins. Air gun shots from MCS profiles and 1000 km of additional shooting with large shot intervals were also recorded on 27 short-period and 6 broadband lake bottom seismometers from Scripps Oceanographic Institute as a part of the Ocean Bottom Seismic Instrument Pool (OBSIP) as well as the 55-station onshore seismic array. The OBS were deployed along one long strike line and two dip lines. We will present preliminary data and results from seismic reflection and refraction data acquired in the lake and their implications for crustal deformation within and between rift segments. Seismic reflection data image structures up to ~5-6 km below the lake bottom, including syntectonic sediments, intrabasinal faults and other complex horsts. Some intrabasinal faults in both the northern and

  20. Seismic imaging of reservoir flow properties: Time-lapse amplitude changes

    Energy Technology Data Exchange (ETDEWEB)

    Vasco, D.W.; Datta-Gupta, Akhil; Behrens, Ron; Condon, Pat; Rickett, Jame s

    2003-03-13

    Asymptotic methods provide an efficient means by which to infer reservoir flow properties, such as permeability, from time-lapse seismic data. A trajectory-based methodology, much like ray-based methods for medical and seismic imaging, is the basis for an iterative inversion of time-lapse amplitude changes. In this approach a single reservoir simulation is required for each iteration of the algorithm. A comparison between purely numerical and the trajectory-based sensitivities demonstrates their accuracy. An application to a set of synthetic amplitude changes indicates that they can recover large-scale reservoir permeability variations from time-lapse data. In an application of actual time-lapse amplitude changes from the Bay Marchand field in the Gulf of Mexico we are able to reduce the misfit by 81% in twelve iterations. The time-lapse observations indicate lower permeabilities are required in the central portion of the reservoir.

  1. Enhancement in Seismic Imaging using Diffraction Studies and Hybrid Traveltime Technique for PSDM

    Science.gov (United States)

    Bashir, Y.; Ghosh, D. P.; Moussavi Alashloo, S. Y.; Sum, C. W.

    2016-07-01

    The accurate migration of seismic data is conditional on the parameters which are nominated. The effective velocity used in residual processing for migration is small compared to the original migration velocity. Considering traveltime computation is a significant part of seismic imaging algorithms. Conventional implementation of Kirchhoff migration is essential for precomputing a traveltime table from the categories involving traditional ray-tracing methods and finite difference eikonal solvers. In this paper, we examine the accuracy using, the eikonal solver and paraxial ray tracing traveltime computation in pre-stack Kirchhoff depth migration. This hybrid traveltime technique can be applied to a variety of problems related to faults, fractures, and complex region. To evaluate the relevance of this identical traveltime technique, we applied on a Marmousi data set.

  2. Next Generation Seismic Imaging; High Fidelity Algorithms and High-End Computing

    Science.gov (United States)

    Bevc, D.; Ortigosa, F.; Guitton, A.; Kaelin, B.

    2007-05-01

    The rich oil reserves of the Gulf of Mexico are buried in deep and ultra-deep waters up to 30,000 feet from the surface. Minerals Management Service (MMS), the federal agency in the U.S. Department of the Interior that manages the nation's oil, natural gas and other mineral resources on the outer continental shelf in federal offshore waters, estimates that the Gulf of Mexico holds 37 billion barrels of "undiscovered, conventionally recoverable" oil, which, at 50/barrel, would be worth approximately 1.85 trillion. These reserves are very difficult to find and reach due to the extreme depths. Technological advances in seismic imaging represent an opportunity to overcome this obstacle by providing more accurate models of the subsurface. Among these technological advances, Reverse Time Migration (RTM) yields the best possible images. RTM is based on the solution of the two-way acoustic wave-equation. This technique relies on the velocity model to image turning waves. These turning waves are particularly important to unravel subsalt reservoirs and delineate salt-flanks, a natural trap for oil and gas. Because it relies on an accurate velocity model, RTM opens new frontier in designing better velocity estimation algorithms. RTM has been widely recognized as the next chapter in seismic exploration, as it can overcome the limitations of current migration methods in imaging complex geologic structures that exist in the Gulf of Mexico. The chief impediment to the large-scale, routine deployment of RTM has been a lack of sufficient computer power. RTM needs thirty times the computing power used in exploration today to be commercially viable and widely usable. Therefore, advancing seismic imaging to the next level of precision poses a multi-disciplinary challenge. To overcome these challenges, the Kaleidoscope project, a partnership between Repsol YPF, Barcelona Supercomputing Center, 3DGeo Inc., and IBM brings together the necessary components of modeling, algorithms and the

  3. Using boreholes as windows into groundwater ecosystems.

    Directory of Open Access Journals (Sweden)

    James P R Sorensen

    Full Text Available Groundwater ecosystems remain poorly understood yet may provide ecosystem services, make a unique contribution to biodiversity and contain useful bio-indicators of water quality. Little is known about ecosystem variability, the distribution of invertebrates within aquifers, or how representative boreholes are of aquifers. We addressed these issues using borehole imaging and single borehole dilution tests to identify three potential aquifer habitats (fractures, fissures or conduits intercepted by two Chalk boreholes at different depths beneath the surface (34 to 98 m. These habitats were characterised by sampling the invertebrates, microbiology and hydrochemistry using a packer system to isolate them. Samples were taken with progressively increasing pumped volume to assess differences between borehole and aquifer communities. The study provides a new conceptual framework to infer the origin of water, invertebrates and microbes sampled from boreholes. It demonstrates that pumping 5 m(3 at 0.4-1.8 l/sec was sufficient to entrain invertebrates from five to tens of metres into the aquifer during these packer tests. Invertebrates and bacteria were more abundant in the boreholes than in the aquifer, with associated water chemistry variations indicating that boreholes act as sites of enhanced biogeochemical cycling. There was some variability in invertebrate abundance and bacterial community structure between habitats, indicating ecological heterogeneity within the aquifer. However, invertebrates were captured in all aquifer samples, and bacterial abundance, major ion chemistry and dissolved oxygen remained similar. Therefore the study demonstrates that in the Chalk, ecosystems comprising bacteria and invertebrates extend from around the water table to 70 m below it. Hydrogeological techniques provide excellent scope for tackling outstanding questions in groundwater ecology, provided an appropriate conceptual hydrogeological understanding is applied.

  4. Micro-seismic Imaging Using a Source Independent Waveform Inversion Method

    KAUST Repository

    Wang, Hanchen

    2016-04-18

    Micro-seismology is attracting more and more attention in the exploration seismology community. The main goal in micro-seismic imaging is to find the source location and the ignition time in order to track the fracture expansion, which will help engineers monitor the reservoirs. Conventional imaging methods work fine in this field but there are many limitations such as manual picking, incorrect migration velocity and low signal to noise ratio (S/N). In traditional surface survey imaging, full waveform inversion (FWI) is widely used. The FWI method updates the velocity model by minimizing the misfit between the observed data and the predicted data. Using FWI to locate and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. Use the FWI technique, and overcomes the difficulties of manual pickings and incorrect velocity model for migration. However, the technique of waveform inversion of micro-seismic events faces its own problems. There is significant nonlinearity due to the unknown source location (space) and function (time). We have developed a source independent FWI of micro-seismic events to simultaneously invert for the source image, source function and velocity model. It is based on convolving reference traces with the observed and modeled data to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. To examine the accuracy of the inverted source image and velocity model the extended image for source wavelet in z-axis is extracted. Also the angle gather is calculated to check the applicability of the migration velocity. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity in the synthetic experiments with both parts of the Marmousi and the SEG

  5. Faults dominant structure? -Seismic images of the subsurface structure for the Ilan geothermal field in Taiwan.

    Science.gov (United States)

    Chang, Yu-Chun; Shih, Ruey-Chyuan; Wang, Chien-Ying; Kuo, Hsuan-Yu; Chen, Wen-Shan

    2016-04-01

    A prototype deep geothermal power plant is to be constructed at the Ilan plain in northeastern Taiwan. The site will be chosen from one of the two potential areas, one in the west and the other in the eastern side of the plain. The triangle-shaped Ilan plane is bounded by two mountain ranges at the northwest and the south, with argillite and slate outcrops exposed, respectively. The Ilan plane is believed situating in a structure extending area at the southwestern end of the Okinawa Trough. Many studies about subsurface structure of the plain have been conducted for years. The results showed that the thickest sediments, around 900 m, is located at the eastern coast of the plain, at north of the largest river in the plain, the Lanyang river, and then became shallower to the edges of the plain. Since the plane is covered by thick sediments, formations and structures beneath the sediments are barely known. However, the observed high geothermal gradient and the abundant hot spring in the Ilan area indicate that this area is having a high potential of geothermal energy. In order to build up a conceptual model for tracing the possible paths of geothermal water and search for a suitable site for the geothermal well, we used the seismic reflection method to delineate the subsurface structure. The seismic profiles showed a clear unconformity separating the sediments and the metamorphic bedrock, and some events dipping to the east in the bedrock. Seismic images above the unconformity are clear; however, seismic signals in the metamorphic bedrock are sort of ambiguous. There were two models interpreted by using around 10 seismic images that collected by us in the past 3 years by using two mini-vibrators (EnviroVibe) and a 360-channel seismic data acquisition system. In the first model, seismic signals in the bedrock were interpreted as layer boundaries, and a fractured metamorphic layer down the depth of 1200m was thought as the source of geothermal water reservoir. In the

  6. Retrieving Drill Bit Seismic Signals Using Surface Seismometers

    Institute of Scientific and Technical Information of China (English)

    Linfei Wang; Huaishan Liu; Siyou Tong; Yanxin Yin; Lei Xing; Zhihui Zou; Xiugang Xu

    2015-01-01

    Seismic while drilling (SWD) is an emerging borehole seismic imaging technique that uses the downhole drill-bit vibrations as seismic source. Without interrupting drilling, SWD technique can make near-real-time images of the rock formations ahead of the bit and optimize drilling operation, with reduction of costs and the risk of drilling. However, the signal to noise ratio (SNR) of surface SWD-data is severely low for the surface acquisition of SWD data. Here, we propose a new method to retrieve the drill-bit signal from the surface data recorded by an array of broadband seismometers. Taking advantages of wavefield analysis, different types of noises are identified and removed from the surface SWD-data, resulting in the significant improvement of SNR. We also optimally synthesize seis-mic response of the bit source, using a statistical cross-coherence analysis to further improve the SNR and retrieve both the drill-bit direct arrivals and reflections which are then used to establish a reverse vertical seismic profile (RVSP) data set for the continuous drilling depth. The subsurface images de-rived from these data compare well with the corresponding images of the three-dimension surface seis-mic survey cross the well.

  7. Imaging using cross-hole seismoelectric tomography

    Science.gov (United States)

    Araji, A.H.; Revil, A.; Jardani, A.; Minsley, B.

    2011-01-01

    We propose a new cross-hole imaging approach based on seismoelectric conversions associated with the transmission of seismic waves from seismic sources located in a borehole to receivers electrodes located in a second borehole. The seismoelectric seismic-to-electric problem is solved using Biot theory coupled with a generalized Ohm's law with an electrokinetic coupling term. The components of the displacement of the solid phase, the fluid pressure, and the electrical potential are solved using a finite element approach with PML boundary conditions for the seismic waves and boundary conditions mimicking an infinite material for the electrostatic problem. We have developed an inversion algorithm using the electrical disturbances recorded in the second borehole to localize the position of the heterogeneities responsible for the seismoelectric conversions. Because of the ill-posed nature of the inverse problem, regularization is used to constrain the solution at each time in the seismoelectric time window comprised between the time of the seismic shot and the time of the first arrival of the seismic waves in the second borehole. All the inverted volumetric current source densities are stacked to produce an image of the position of the heterogeneities between the two boreholes. Two simple synthetic case studies are presented to test this concept. The first case study corresponds to a vertical discontinuity between two homogeneous sub-domains. The second case study corresponds to a poroelastic inclusion embedded into an homogenous poroelastic formation. In both cases, the position of the heterogeneity is fairly well-recovered using only the electrical disturbances associated with the seismoelectric conversions. ?? 2011 Society of Exploration Geophysicists.

  8. Seismic Imaging of Rifted Margins in the Southern Gulf of California

    Science.gov (United States)

    Paramo, P.; Holbrook, S. W.; Brown, H. E.; Lizarralde, D.; Umhoefer, P.; Kent, G.; Harding, A.; Fletcher, J.; Gonzalez, A.; Axen, G.

    2004-12-01

    We present preliminary velocity models from two wide-angle seismic transects located in the southern Gulf of California along with coincident seismic reflection images. Continental rupture in the Gulf of California occurred recently and the conjugate margins can be studied with little uncertainty in plate reconstruction. Therefore it is considered an ideal place to analyze patterns of crustal extension and rift magmatism. The seismic reflection data were acquired with a 6-km-long streamer, 480-channel, aboard R/V Maurice Ewing, and ocean-bottom seismographs (OBSs) were deployed from R/V New Horizon. Onshore seismographs were also deployed along onshore extensions of the transects. Transect 5W runs northwest-southeast from the Los Cabos block, at the southern tip of the Baja California Peninsula, to the East Pacific Rise in the mouth of the Gulf. Transect 0E runs northeast-southwest from the hills of Sierra Madre in mainland Mexico near Mazatlán to approximately 115 km into the Gulf of California. Preliminary velocity models from Transect 5W margin show an abrupt transition from a 25-km-thick continental crust to an oceanic crust of normal thickness. Transect 0E crosses what is believed to be extended continental crust and lies in the initial direction of extension characteristic of the protogulf.

  9. New imaging method for seismic reflection wave and its theoretical basis

    Institute of Scientific and Technical Information of China (English)

    HUANG; Guangyuan

    2001-01-01

    [1]Huang Guangyuan, Principle of "3-Basic Colors" for imaging from reflected seismic wave, Acta Geophysica Sinica (in Chinese), 2000, 43(1): 138.[2]Huang Guangyuan, Revisions of convolution model of reflected seismic wave, Chinese Physics Letters, 1998, 15(11): 851.[3]Charles, K. C., An Introduction to Wavelets, San Diego: Academic Press, Inc., 1992.[4]Huang Guangyuan, Liu Weiqian, Revision wave expression and wave equation, Abstracts of Chinese Sci. & Tech. (Letters) (in Chinese), 1999, 5(3): 335.[5]Silvia, M. T., Deconvolution of geophysical time series in the exploration for oil and natural gas, Amsterdam-Oxford-New York: Elsevier Scientific Publishing Company, 1973.[6]Huang Guangyuan, Liu Xiaojun, Inverse Problems in Mathematical Physics (in Chinese), Jinan: Shandong Sci. & Tech. Press, 1993.[7]Huang Guangyuan, Liu Xiaojun, Discussion of several mathematical inverse models in seismic prospecting, CT Theory and Application (in Chinese), 1992, 1(2): 8.[8]Huang Guangyuan, The second discussion on acoustic velocity inversion from wave equation, CT Theory and Application (in Chinese), 1993, 2(3): 14[9]Huang Guangyuan, Dynamic revision of classical laws in physics from the viewpoint of system science, Systems Science and Systems Engineering, 1993, 2(1): 15[10]Brekhovskikh, L. M., Wave in Layered Media, San Diego: Academic Press, 1980.

  10. Drilling, logging, and testing information from borehole UE-25 UZ number-sign 16, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Borehole UE-25 UZ number-sign 16 is the first of two boreholes that may be used to determine the subsurface structure at Yucca Mountain by using vertical seismic profiling. This report contains information collected while this borehole was being drilled, logged, and tested from May 27, 1992, to April 22, 1994. It does not contain the vertical seismic profiling data. This report is intended to be used as: (1) a reference for drilling similar boreholes in the same area, (2) a data source on this borehole, and (3) a reference for other information that is available from this borehole. The reference information includes drilling chronology, equipment, parameters, coring methods, penetration rates, completion information, drilling problems, and corrective actions. The data sources include lithology, fracture logs, a list of available borehole logs, and depths at which water was recorded. Other information is listed in an appendix that includes studies done after April 22, 1994

  11. Drilling, logging, and testing information from borehole UE-25 UZ{number_sign}16, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Thamir, F.; Thordarson, W.; Kume, J.; Rousseau, J. [Geological Survey, Denver, CO (United States). Yucca Mountain Project Branch; Long, R. [Dept. of Energy, Las Vegas, NV (United States); Cunningham, D.M. Jr. [Science Applications International Corp., Las Vegas, NV (United States)

    1998-09-01

    Borehole UE-25 UZ{number_sign}16 is the first of two boreholes that may be used to determine the subsurface structure at Yucca Mountain by using vertical seismic profiling. This report contains information collected while this borehole was being drilled, logged, and tested from May 27, 1992, to April 22, 1994. It does not contain the vertical seismic profiling data. This report is intended to be used as: (1) a reference for drilling similar boreholes in the same area, (2) a data source on this borehole, and (3) a reference for other information that is available from this borehole. The reference information includes drilling chronology, equipment, parameters, coring methods, penetration rates, completion information, drilling problems, and corrective actions. The data sources include lithology, fracture logs, a list of available borehole logs, and depths at which water was recorded. Other information is listed in an appendix that includes studies done after April 22, 1994.

  12. Calibration Shots Recorded for the Salton Seismic Imaging Project, Salton Trough, California

    Science.gov (United States)

    Murphy, J. M.; Rymer, M. J.; Fuis, G. S.; Stock, J. M.; Goldman, M.; Sickler, R. R.; Miller, S. A.; Criley, C. J.; Ricketts, J. W.; Hole, J. A.

    2009-12-01

    The Salton Seismic Imaging Project (SSIP) is a collaborative venture between the U.S. Geological Survey, California Institute of Technology, and Virginia Polytechnic Institute and State University, to acquire seismic reflection/wide angle refraction data, and currently is scheduled for data acquisition in 2010. The purpose of the project is to get a detailed subsurface 3-D image of the structure of the Salton Trough (including both the Coachella and Imperial Valleys) that can be used for earthquake hazards analysis, geothermal studies, and studies of the transition from ocean-ocean to continent-continent plate-boundary. In June 2009, a series of calibration shots were detonated in the southern Imperial Valley with specific goals in mind. First, these shots were used to measure peak particle velocity and acceleration at various distances from the shots. Second, the shots were used to calibrate the propagation of energy through sediments of the Imperial Valley. Third, the shots were used to test the effects of seismic energy on buried clay drainage pipes, which are abundant throughout the irrigated parts of the Salton Trough. Fourth, we tested the ODEX drilling technique, which uses a down-hole casing hammer for a tight casing fit. Information obtained from the calibration shots will be used for final planning of the main project. The shots were located in an unused field adjacent to Hwy 7, about 6 km north of the U.S. /Mexican border (about 18 km southeast of El Centro). Three closely spaced shot points (16 meters apart) were aligned N-S and drilled to 21-m, 23.5-m, and 27-m depth. The holes were filled with 23-kg, 68-kg, and 123-kg of ammonium-nitrate explosive, respectively. Four instrument types were used to record the seismic energy - six RefTek RT130 6-channel recorders with a 3-component accelerometer and a 3-component 2-Hz velocity sensor, seven RefTek RT130 3-channel recorders with a 3-component 4.5-Hz velocity sensor, 35 Texans with a vertical component 4

  13. Installation of borehole seismometer for earthquake characteristics in deep geological environment

    International Nuclear Information System (INIS)

    Deep geological disposal is currently accepted as the most appropriate method for permanently removing spent nuclear fuel from the living sphere of humans. For implementation of deep geological disposal, we need to understand the geological changes that have taken place over the past 100,000 years, encompassing active faults, volcanic activity, elevation, ubsidence, which as yet have not been considered in assessing the site characteristics for general facilities, as well as to investigate and analyze the geological structures, fracture systems and seismic responses regarding deep geological environment about 500 meters or more underground. In regions with high seismic activity, such as Japan, the Western United States and Taiwan, borehole seismometers installed deep underground are used to monitor seismic activity during the course of seismic wave propagation at various depths and to study the stress changes due to earthquakes and analyze the connection to fault movements. Korea Hydro and Nuclear Power Co., Ltd. (KHNP) have installed the deep borehole earthquake observatory at depths of about 300 to 600 meters in order to study the seismic response characteristics in deep geological environment on June, 2014 in Andong area. This paper will show the status of deep borehole earthquake observatory and the results of background noise response characteristics of these deep borehole seismic data as a basic data analysis. We present here the status of deep borehole seismometer installation by KHNP. In order to basic data analysis for the borehole seismic observation data, this study shows the results of the orientation of seismometer and background noise characteristics by using a probability density function. Together with the ground motion data recorded by the borehole seismometers can be utilized as basic data for seismic response characteristics studies with regard to spent nuclear fuel disposal depth and as the input data for seismic hazard assessment that

  14. Installation of borehole seismometer for earthquake characteristics in deep geological environment

    Energy Technology Data Exchange (ETDEWEB)

    Park, Dong Hee; Choi, Weon Hack; Cho, Sung Il; Chang, Chun Joong [KHNP CRI, Seoul (Korea, Republic of)

    2014-10-15

    Deep geological disposal is currently accepted as the most appropriate method for permanently removing spent nuclear fuel from the living sphere of humans. For implementation of deep geological disposal, we need to understand the geological changes that have taken place over the past 100,000 years, encompassing active faults, volcanic activity, elevation, ubsidence, which as yet have not been considered in assessing the site characteristics for general facilities, as well as to investigate and analyze the geological structures, fracture systems and seismic responses regarding deep geological environment about 500 meters or more underground. In regions with high seismic activity, such as Japan, the Western United States and Taiwan, borehole seismometers installed deep underground are used to monitor seismic activity during the course of seismic wave propagation at various depths and to study the stress changes due to earthquakes and analyze the connection to fault movements. Korea Hydro and Nuclear Power Co., Ltd. (KHNP) have installed the deep borehole earthquake observatory at depths of about 300 to 600 meters in order to study the seismic response characteristics in deep geological environment on June, 2014 in Andong area. This paper will show the status of deep borehole earthquake observatory and the results of background noise response characteristics of these deep borehole seismic data as a basic data analysis. We present here the status of deep borehole seismometer installation by KHNP. In order to basic data analysis for the borehole seismic observation data, this study shows the results of the orientation of seismometer and background noise characteristics by using a probability density function. Together with the ground motion data recorded by the borehole seismometers can be utilized as basic data for seismic response characteristics studies with regard to spent nuclear fuel disposal depth and as the input data for seismic hazard assessment that

  15. Imaging the Jalisco Block and Rivera Plate from Seismicity and Wide Angle Seismic Data from TsuJal Project

    Science.gov (United States)

    Núñez-Cornú, Francisco J.; Cordoba, Diego; Núñez, Diana; Gutierrez Peña, Quiriart; Escudero, Christian; Zamora Camacho, Araceli; José Dañobeitia, Juan; Bartolomé, Rafael

    2015-04-01

    A crustal model for the northern coast of Jalisco have been obtained from wide angle seismic data from Tsujal experiment using data collected by portable stations and the Jalisco Seismic and Accelerometric Network (RESAJ) permanent seismic stations. This model has been compare with data from the local seismicity recorded in the frame of the project "Mapping the Riviera Subduction Zone" (MARS); a temporary seismic network that was installed in the states of Jalisco, Colima and Michoacán between January 2006 and June 2007, and the data collected from RESAJ. A relocation of all MARS events using Hypo71 and the P-wave velocity model used by the RESAJ. The dataset comprise more than 2,000 earthquakes with local magnitude between 1.4 and 5.9 and depths between 1.0 and 109 km. Some crustal seismicity alignments are observed on the Jalisco Block. The geometry of the slabs is different; both are clearly separated beneath the Colima Graben. The northerly Rivera plate exhibits a curvature or bend, possibly the result of an oblique suduction process, dipping from the trench with an angle of about 10° just south of Bahía Banderas to a dip angle of 25° at the Eastern contact with the Colima Graben. We have produced profiles parallel to the trench, in a profile along the shore line and a second one 50 km inland. A subduction dip angle of 12° towards the SE direction is observed in the Rivera plate in profiles inland from Bahia de Banderas to the Colima Graben, but the seismicity ceases to define the plate for more westerly profiles which enounter the graben.

  16. Seismic Imaging of the San Jacinto Fault Zone Area From Seismogenic Depth to the Surface

    Science.gov (United States)

    Ben-Zion, Y.

    2015-12-01

    I review multi-scale multi-signal seismological results on structural properties within and around the San Jacinto Fault Zone (SJFZ). The results are based on data of the regional southern California and ANZA networks, additional near-fault seismometers and linear arrays with instrument spacing 25-50 m that cross the SJFZ at several locations, and a spatially-dense rectangular array with 1108 vertical-component sensors separated by 10-30 m centered on the fault. The studies utilize earthquake data to derive Vp and Vs velocity models with horizontal resolution of 1-2 km over the depth section 2-15 km, ambient noise with frequencies up to 1 Hz to image with similar horizontal resolution the depth section 0.5-7 km, and high-frequency seismic noise from the linear and rectangular arrays for high-resolution imaging of the top 0.5 km. Pronounced damage regions with low seismic velocities and anomalous Vp/Vs ratios are observed around the SJFZ, as well as the San Andreas and Elsinore faults. The damage zones follow generally a flower-shape with depth. The section of the SJFZ from Cajon pass to the San Jacinto basin has a faster SW side, while the section farther to the SE has an opposite velocity contrast with faster NE side. The damage zones and velocity contrasts produce at various locations fault zone trapped and head waves that are utilized to obtain high-resolution information on inner fault zone components (bimaterial interfaces, trapping structures). Analyses of high-frequency noise recorded by the fault zone arrays reveal complex shallow material with very low seismic velocities and strong lateral and vertical variations.

  17. Final Report (O1-ERD-051) Dynamic InSAR: Imaging Seismic Waves Remotely from Space

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, P; Rodgers, A; Dodge, D; Zucca, J; Schultz, C; Walter, B; Portnoff, M

    2003-02-07

    The purpose of this LDRD project was to determine the feasibility of using InSAR (interferometric synthetic aperture radar) to image seismic waves remotely from space. If shown to be feasible, the long-term goal of this project would be to influence future SAR satellite missions and airborne SAR platforms to include a this new capability. This final report summarizes the accomplishments of the originally-planned 2-year project that was cut short to 1 year plus 2 months due to a funding priority change that occurred in the aftermath of the September 11th tragedy. The LDRD-ER project ''Dynamic InSAR: Imaging Seismic Waves from Space'' (01-ERD-051) began in October, (FY01) and ended in December (FY02). Consequently, most of the results and conclusions for this project are represented in the FY0l Annual Report. Nonetheless, additional conclusions and insights regarding the progress of this work are included in this report. In should be noted that this work was restarted and received additional funding under the NA-22 DOE Nonproliferation Program in FY03.

  18. Tomographic Imaging of Jakarta Area from Cross-correlation of Seismic Ambient Noise

    Science.gov (United States)

    Pranata, B.; Saygin, E.; Cummins, P. R.; Widiyantoro, S.; Nugraha, A. D.; Harjadi, P.; Suhardjono, S.

    2012-12-01

    Seismic imaging of sediment thickness of Jakarta is crucial where Jakarta city is currently being rapidly developed with major installations and high-rise structures being constructed at a fast pace. Therefore, information of surface geology and surface sediment thickness for Jakarta city is urgently required in order to mitigate the effects of earthquake hazards in the future. Because of this need, we deployed 36 broadband and shortperiod stations across Jakarta to record seismic ambient noise. We apply cross-correlation method to the simultaneously recorded data to retrieve interstation Green's functions. We measure group velocity dispersion of the retrieved Green's functions by applying narrowband filters. Dispersion measurements are then inverted with a nonlinear tomographic technique to image the shallow structure of Jakarta and its surrounding regions. Preliminary results from tomographic maps show low velocities dominantly located in central, west and north Jakarta. While the highest rate obtained is between stations in South Jakarta. This conforms with the known geological conditions in which the structure of sedimentary cover in northern Jakarta is thicker than the southern part.

  19. Imaging the Seattle Fault Zone with high-resolution seismic tomography

    Science.gov (United States)

    Calvert, A.J.; Fisher, M.A.

    2001-01-01

    The Seattle fault, which trends east-west through the greater Seattle metropolitan area, is a thrust fault that, around 1100 years ago, produced a major earthquake believed to have had a magnitude greater than 7. We present the first high resolution image of the shallow P wave velocity variation across the fault zone obtained by tomographic inversion of first arrivals recorded on a seismic reflection profile shot through Puget Sound adjacent to Seattle. The velocity image shows that above 500 m depth the fault zone extending beneath Seattle comprises three distinct fault splays, the northernmost of which dips to the south at around 60??. The degree of uplift of Tertiary rocks within the fault zone suggests that the slip-rate along the northernmost splay during the Quaternary is 0.5 mm a-1, which is twice the average slip-rate of the Seattle fault over the last 40 Ma.

  20. New imaging method for seismic reflection wave and its theoretical basis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Some new imaging formulas for seismic reflection wave and theirtheoretical basis are given. Phenomena of wave propagation should be characterized by instantaneous spectrum and expressed by complex function of three variables (time, space and frequency) in mathematics. Various physical parameters of medium are also complex functions of two variables (space and frequency). The relationship between reflection coefficient of medium and spectrum of reflected wave is given. Multi-reflection and filter of formations are considered in inversion formulas. Prob-lems in classical convolution model and wave equation are illustrated. All these inversion formulas can be used to image underground medium by wavelet transform and method of "3-basic colors". Different colors mean different media.

  1. Critical zone weathering in the southern Sierra Nevada and Laramie Mountains imaged by seismic tomography

    Science.gov (United States)

    Hayes, J. L.; Holbrook, W. S.; Riebe, C. S.

    2011-12-01

    Near-surface variations in seismic velocity reflect differences in physical properties such as density and porosity, which in turn reflect differences in alteration of parent material by exposure to water and biologic activity. Here we present tomographic analysis of the extent of weathering from seismic refraction experiments at two areas underlain by granite: the Southern Sierra Critical Zone Observatory (SSCZO) in the fall of 2010 & 2011 and the Laramie Mountains in the spring of 2010. A 48-channel geophone array and hammer source was deployed in both surveys. In both areas seismic velocities suggest that weathering has progressed to depths of 10 m or more. When coupled with geochemical measurements of the degree of regolith weathering, these depths imply that the potential for subsurface water storage in regolith may be a larger component of the water budget than previously thought at the SSCZO. The velocity of granite bedrock was determined independently in both studies to be ~4 km/s by seismic experiments directly on outcropping granite. Two other ranges of seismic velocities seem consistent between the studies: a saprolite layer of chemically altered but still intact rock (2-4 km/s) and a regolith layer more altered than the underlying saprolite layer (<2 km/s). Using these parameters we tested hypotheses in two different granite-weathering environments. In the SSCZO a velocity-depth profile that crosses a water-saturated meadow and an adjoining forest reveal relatively low gradients in the first ten meters beneath the forest (0.75 km/s per 10 m) and higher gradients beneath the meadow (3 km/s per 10 m). From these observations, we hypothesize that the saturated meadow may provide a reducing environment that inhibits chemical weathering relative to better-drained, more oxidizing conditions in the forest. In the 1.4 Ga Sherman batholith of the Laramie Mountains we observe isolated outcrops of Lincoln Granite within the Sherman Granite. Two 0.5 km profiles

  2. Imaging 3D seismic velocity along the seismogenic zone of Algarve region (southern Portugal)

    Science.gov (United States)

    Rocha, João.; Bezzeghoud, Mourad; Caldeira, Bento; Dias, Nuno; Borges, José; Matias, Luís.; Dorbath, Catherine; Carrilho, Fernando

    2010-05-01

    The present seismic tomographic study is focused around Algarve region, in South of Portugal. To locate the seismic events and find the local velocity structure of epicentral area, the P and S arrival times at 38 stations are used. The data used in this study were obtained during the Algarve campaign which worked from January/2006 to July/2007. The preliminary estimate of origin times and hypocentral coordinates are determined by the Hypoinverse program. Linearized inversion procedure was applied to comprise the following two steps: 1) finding the minimum 1D velocity model using Velest and 2) simultaneous relocation of hypocenters and determination of local velocity structure. The velocity model we have reached is a 10 layer model which gave the lowest RMS, after several runnings of eight different velocity models that we used "a priori". The model parameterization assumes a continuous velocity field between 4.5 km/s and 7.0 km/s until 30 km depth. The earth structure is represented in 3D by velocity at discrete points, and velocity at any intervening point is determined by linear interpolation among the surrounding eight grid points. A preliminary analysis of the resolution capabilities of the dataset, based on the Derivative Weight Sum (DWS) distribution, shows that the velocity structure is better resolved in the West part of the region between the surface to15 km. The resulting tomographic image has a prominent low-velocity anomaly that shows a maximum decrease in P-wave velocity in the first 12 kms in the studied region. We also identified the occurrence of local seismic events of reduced magnitude not catalogued, in the neighbourhood of Almodôvar (low Alentejo). The spatial distribution of epicentres defines a NE-SW direction that coincides with the strike of the mapped geological faults of the region and issued from photo-interpretation. Is still expectable to refine the seismicity of the region of Almodôvar and establish more rigorously its role in the

  3. Improved structural characterization of the Earth's crust at the German Continental Deep Drilling Site using advanced seismic imaging techniques

    Science.gov (United States)

    Hloušek, F.; Hellwig, O.; Buske, S.

    2015-10-01

    This paper describes the principles of three novel seismic imaging techniques and their application to two deep seismic reflection data sets from the vicinity of the German Continental Deep Drilling Site (KTB). These imaging techniques are based on Kirchhoff prestack depth migration and use an inherent restriction of the migration operator to focus the wavefield to its actual reflection point. For Fresnel volume migration, the emergent angle at the receivers is estimated and then used to propagate the wavefield back into the subsurface along which the Fresnel volume is determined. The migration operator is restricted to this volume, thereby focusing the image to the part of the isochrone which physically contributes to the reflection. For coherency migration, the coherency of the wavefield at neighboring traces is calculated and used as a weighting factor within the migration integral, leading to a comparable focusing to the reflection point. For coherency-based Fresnel volume migration, both approaches are combined, resulting in an even more focused seismic image with significantly increased image quality. We applied these methods to two seismic data sets from the area around the KTB: a survey with standard split-spread geometry (KTB8502) and a sparse data set with a small number of source points in combination with short receiver lines (INSTRUCT93). The focusing approaches yield major improvements in the final images for both data sets. Incoherent noise and migration artifacts are reduced and the visibility of crustal structures is strongly enhanced, allowing for an improved geologic and tectonic characterization.

  4. Pressure and fluid saturation prediction in a multicomponent reservoir, using combined seismic and electromagnetic imaging

    International Nuclear Information System (INIS)

    This paper presents a method for combining seismic and electromagnetic measurements to predict changes in water saturation, pressure, and CO2 gas/oil ratio in a reservoir undergoing CO2 flood. Crosswell seismic and electromagnetic data sets taken before and during CO2 flooding of an oil reservoir are inverted to produce crosswell images of the change in compressional velocity, shear velocity, and electrical conductivity during a CO2 injection pilot study. A rock properties model is developed using measured log porosity, fluid saturations, pressure, temperature, bulk density, sonic velocity, and electrical conductivity. The parameters of the rock properties model are found by an L1-norm simplex minimization of predicted and observed differences in compressional velocity and density. A separate minimization, using Archie's law, provides parameters for modeling the relations between water saturation, porosity, and the electrical conductivity. The rock-properties model is used to generate relationships between changes in geophysical parameters and changes in reservoir parameters. Electrical conductivity changes are directly mapped to changes in water saturation; estimated changes in water saturation are used along with the observed changes in shear wave velocity to predict changes in reservoir pressure. The estimation of the spatial extent and amount of CO2 relies on first removing the effects of the water saturation and pressure changes from the observed compressional velocity changes, producing a residual compressional velocity change. This velocity change is then interpreted in terms of increases in the CO2/oil ratio. Resulting images of the CO2/oil ratio show CO2-rich zones that are well correlated to the location of injection perforations, with the size of these zones also correlating to the amount of injected CO2. The images produced by this process are better correlated to the location and amount of injected CO2 than are any of the individual images of change in

  5. Imaging of demultipled data: a new approach based on seismic interferometry and Marchenko autofocusing

    Science.gov (United States)

    Meles, Giovanni Angelo; Löer, Katrin; Ravasi, Matteo; Curtis, Andrew; da Costa Filho, Carlos

    2015-04-01

    Standard seismic processing steps such as velocity analysis and reverse time migration are based on the single-scattering Born approximation, and assume that all reflections are primaries; multiples represent a source of coherent noise and must be suppressed to avoid artefacts. Surface related multiples particularly impact on seismic images resulting from marine data, and much effort has been devoted to their removal. Internal multiples strongly affect land data, and relatively fewer techniques exist to predict and remove them from reflection data. We present a novel internal-multiples prediction method based on the combined use of seismic interferometry and Marchenko autofocusing. Seismic interferometry techniques synthesise Green's functions between real source or receiver locations by integrating cross-correlations or convolutions of wavefields recorded by receivers or emanating from sources located elsewhere. Marchenko autofocusing estimates up- and down-going components of Green's functions between virtual source locations inside a medium and real receivers at the surface. In contrast to interferometry, autofocusing requires an estimate of the direct wave from the virtual source, illumination only from one side of the medium, and no physical receivers inside the medium. We first illustrate how primary and internal multiple reflections are reconstructed in convolutional interferometry by combining up- and down- going Green's functions from virtual sources in the subsurface. These Green's functions can usually be neither directly measured nor modelled accurately. However, autofocusing estimates all such Green's functions and their up- and down-going components. We then discuss how primaries and internal multiples intrinsically differ in terms of the constitutive components involved in the interferometric process. Specifically, we show that primary reflections reconstructed through convolutional interferometry necessarily involve direct and reflected Green

  6. Subduction Zone Science - Examples of Seismic Images of the Central Andes and Subducting Nazca Slab

    Science.gov (United States)

    Beck, S. L.; Zandt, G.; Scire, A. C.; Ward, K. M.; Portner, D. E.; Bishop, B.; Ryan, J. C.; Wagner, L. S.; Long, M. D.

    2015-12-01

    Subduction has shaped large regions of the Earth and constitute over 55,000 km of convergent plate margin today. The subducting slabs descend from the surface into the lower mantle and impacts earthquake occurrence, surface uplift, arc volcanism and mantle convection as well as many other processes. The subduction of the Nazca plate beneath the South America plate is one example and constitutes the largest present day ocean-continent convergent margin system and has built the Andes, one of the largest actively growing mountain ranges on Earth. This active margin is characterized by along-strike variations in arc magmatism, upper crustal shortening, crustal thickness, and slab geometry that make it an ideal region to study the relationship between the subducting slab, the mantle wedge, and the overriding plate. After 20 years of portable seismic deployments in the Central Andes seismologists have combined data sets and used multiple techniques to generate seismic images spanning ~3000 km of the South American subduction zone to ~800 km depth with unprecedented resolution. For example, using teleseismic P- waves we have imaged the Nazca slab penetrating through the mantle transition zone (MTZ) and into the uppermost lower mantle. Our tomographic images show that there is significant along-strike variation in the morphology of the Nazca slab in the upper mantle, MTZ, and the lower mantle, including possible tears, folding, and internal deformation. Receiver function studies and surface wave tomography have revealed major changes in lithospheric properties in the Andes. Improved seismic images allow us to more completely evaluate tectonic processes in the formation and uplift of the Andes including: (1) overthickened continental crust driven by crustal shortening, (2) changes in slab dip and coupling with the overlying plate (3) localized lithospheric foundering, and (4) large-scale mantle and crustal melting leading to magmatic addition and/or crustal flow. Although

  7. Feasibility of CDP seismic reflection to image structures in a 200-m deep, 3-m thick coal zone near Palau, Coahuila, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.D.; Saenz, V.; Huggins, R.J. (Kansas University, Lawrence, KS (USA). Kansas Geological Survey)

    1992-10-01

    The common-depth-point (CDP) seismic-reflection method was used to delineate subsurface structure in a 3-m thick, 220-m deep coal zone in the Palau area of Coahuila, Mexico. An extensive series of walkaway-noise tests was performed to optimize recording parameters and equipment. Reflection events can be interpreted from depths of approximately 100 to 300 m on CDP stacked seismic sections. The seismic data allow accurate identification of the horizontal location of the structure responsible for a drill-discovered 3-m difference in coal-zone depth between boreholes 150m apart. The reflection method can discriminate folding with wavelengths in excess of 20 m and faulting with offset greater than 2 m at this site.

  8. Geophysical borehole logging

    International Nuclear Information System (INIS)

    Most of the available literature on geophysical borehole logging refers to studies carried out in sedimentary rocks. It is only in recent years that any great interest has been shown in geophysical logging in boreholes in metamorphic and igneous rocks following the development of research programmes associated with geothermal energy and nuclear waste disposal. This report is concerned with the programme of geophysical logging carried out on the three deep boreholes at Altnabreac, Caithness, to examine the effectiveness of these methods in crystalline rock. Of particular importance is the assessment of the performance of the various geophysical sondes run in the boreholes in relation to the rock mass properties. The geophysical data can be used to provide additional in-situ information on the geological, hydrogeological and engineering properties of the rock mass. Fracturing and weathering in the rock mass have a considerable effect on both the design parameters for an engineering structure and the flow of water through the rock mass; hence, the relation between the geophysical properties and the degree of fracturing and weathering is examined in some detail. (author)

  9. A Low Velocity Zone along the Chaochou Fault in Southern Taiwan: Seismic Image Revealed by a Linear Seismic Array

    Directory of Open Access Journals (Sweden)

    Hsin-Chieh Pu

    2010-01-01

    Full Text Available The Chaochou fault is one of the major boundary faults in southern Taiwan where strong convergence has taken place between the Eurasian and Philippine Sea plates. The surface fault trace between the Pingtung plain and the Central Range follows a nearly N-S direction and stretches to 80 km in length. In order to examine the subsurface structures along the Chaochou fault, a linear seismic array with 14 short-period stations was deployed across the fault to record seismic data between August and December 2001. Detailed examination of seismic data generated by 10 local earthquakes and recorded by the linear array has shown that the incidence angles of the first P-waves recorded by several seismic stations at the fault zone were significantly larger than those located farther away from the fault zone. This difference might reflect the lateral variation of velocity structures across the Chaochou fault. Further examination of ray-paths of seismic wave propagation indicates that a low-velocity zone along the Chaochou fault is needed to explain the significant change in incidence angles across the fault zone. Although we do not have adequate information to calculate the exact geometry of the fault zone well, the variation in incidence angles across the fault can be explained by the existence of a low-velocity zone that is about 3 km in width on the surface and extends downward to a depth of 5 km. The low-velocity zone along the Chaochou fault might imply that the fault system consists of several splay faults on the hanging wall in the Central Range.

  10. Joint Geophysical Imaging of the Utah Area Using Seismic Body Waves, Surface Waves and Gravity Data

    Science.gov (United States)

    Zhang, H.; Maceira, M.; Toksoz, M. N.; Burlacu, R.; Yang, Y.

    2009-12-01

    We present a joint geophysical imaging method that makes use of seismic body wave arrival times, surface wave dispersion measurements, and gravity data to determine three-dimensional (3D) Vp and Vs models. An empirical relationship mapping densities to Vp and Vs for earth materials is used to link them together. The joint inversion method takes advantage of strengths of individual data sets and is able to better constrain the velocity models from shallower to greater depths. Combining three different data sets to jointly invert for the velocity structure is equivalent to a multiple-objective optimization problem. Because it is unlikely that the different “objectives” (data types) would be optimized by the same parameter choices, some trade-off between the objectives is needed. The optimum weighting scheme for different data types is based on relative uncertainties of individual observations and their sensitivities to model parameters. We will apply this joint inversion method to determine 3D Vp and Vs models of the Utah area. The seismic body wave arrival times are assembled from waveform data recorded by the University of Utah Seismograph Stations (UUSS) regional network for the past 7 years. The surface wave dispersion measurements are obtained from the ambient noise tomography study by the University of Colorado group using EarthScope/USArray stations. The gravity data for the Utah area is extracted from the North American Gravity Database managed by the University of Texas at El Paso. The preliminary study using the seismic body wave arrival times indicates strong low velocity anomalies in middle crust beneath some known geothermal sites in Utah. The joint inversion is expected to produce a reasonably well-constrained velocity structure of the Utah area, which is helpful for characterizing and exploring existing and potential geothermal reservoirs.

  11. High Resolution/High Fidelity Seismic Imaging and Parameter Estimation for Geological Structure and Material Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Ru-Shan Wu; Xiao-Bi Xie

    2008-06-08

    Our proposed work on high resolution/high fidelity seismic imaging focused on three general areas: (1) development of new, more efficient, wave-equation-based propagators and imaging conditions, (2) developments towards amplitude-preserving imaging in the local angle domain, in particular, imaging methods that allow us to estimate the reflection as a function of angle at a layer boundary, and (3) studies of wave inversion for local parameter estimation. In this report we summarize the results and progress we made during the project period. The report is divided into three parts, totaling 10 chapters. The first part is on resolution analysis and its relation to directional illumination analysis. The second part, which is composed of 6 chapters, is on the main theme of our work, the true-reflection imaging. True-reflection imaging is an advanced imaging technology which aims at keeping the image amplitude proportional to the reflection strength of the local reflectors or to obtain the reflection coefficient as function of reflection-angle. There are many factors which may influence the image amplitude, such as geometrical spreading, transmission loss, path absorption, acquisition aperture effect, etc. However, we can group these into two categories: one is the propagator effect (geometric spreading, path losses); the other is the acquisition-aperture effect. We have made significant progress in both categories. We studied the effects of different terms in the true-amplitude one-way propagators, especially the terms including lateral velocity variation of the medium. We also demonstrate the improvements by optimizing the expansion coefficients in different terms. Our research also includes directional illumination analysis for both the one-way propagators and full-wave propagators. We developed the fast acquisition-aperture correction method in the local angle-domain, which is an important element in the true-reflection imaging. Other developments include the super

  12. Seismic interferometry of railroad induced ground motions: body and surface wave imaging

    Science.gov (United States)

    Quiros, Diego A.; Brown, Larry D.; Kim, Doyeon

    2016-04-01

    Seismic interferometry applied to 120 hr of railroad traffic recorded by an array of vertical component seismographs along a railway within the Rio Grande rift has recovered surface and body waves characteristic of the geology beneath the railway. Linear and hyperbolic arrivals are retrieved that agree with surface (Rayleigh), direct and reflected P waves observed by nearby conventional seismic surveys. Train-generated Rayleigh waves span a range of frequencies significantly higher than those recovered from typical ambient noise interferometry studies. Direct P-wave arrivals have apparent velocities appropriate for the shallow geology of the survey area. Significant reflected P-wave energy is also present at relatively large offsets. A common midpoint stack produces a reflection image consistent with nearby conventional reflection data. We suggest that for sources at the free surface (e.g. trains) increasing the aperture of the array to record wide angle reflections, in addition to longer recording intervals, might allow the recovery of deeper geological structure from railroad traffic. Frequency-wavenumber analyses of these recordings indicate that the train source is symmetrical (i.e. approaching and receding) and that deeper refracted energy is present although not evident in the time-offset domain. These results confirm that train-generated vibrations represent a practical source of high-resolution subsurface information, with particular relevance to geotechnical and environmental applications.

  13. Imaging blended vertical seismic profiling data using full-wavefield migration in the common-receiver domain

    NARCIS (Netherlands)

    Soni, A.K.; Verschuur, D.J.

    2015-01-01

    For vertical-seismic-profiling (VSP) measurements, the use of blended acquisition, with time-overlapping shot records, can greatly reduce the downtime and, thereby, provide large cost savings. For directly imaging blended VSP measurements, we have used full-wavefield migration (FWM). FWM is an inver

  14. Seismic imaging of North China: insight into intraplate volcanism and seismotectonics

    Science.gov (United States)

    Zhao, D.

    2004-12-01

    and middle crust and thus contribute to the initiation of the large crustal earthquakes. Similar features are also found in the source areas of the 1995 Kobe earthquake (M 7.2) in Japan (Zhao et al., 1996) and the 2001 Bhuj earthquake (M 7.8) in India (Mishra and Zhao, 2003). Zhao, D. (2004) Global tomographic images of mantle plumes and subducting slabs: insight into deep Earth dynamics. Phys. Earth Planet. Inter. 146, 3-34. Zhao, D., J. Lei, R. Tang (2004) Origin of the intraplate Changbai volcano in Northeast China: Evidence from seismic tomography. Chinese Science Bulletin 49(13), 1401-1408. Huang, J., D. Zhao (2004) Crustal heterogeneity and seismotectonics of the region around Beijing, China. Tectonophysics 385, 159-180.

  15. Shallow seismic imaging of flank collapse structures in oceanic island volcanoes: Application to the Western Canary Islands

    Science.gov (United States)

    Sanchez, L.; González, P.; Tiampo, K. F.

    2013-12-01

    Volcanic flank collapse counts among the many hazards associated with volcanic activity. This type of event involves the mobilization of large volumes, producing debris avalanches. It affects mostly oceanic island volcanoes, involving the potential for tsunami occurrence. Geophysical imaging can illuminate subvolcanic features such as volcano-tectonic structures, magmatic plumbing systems or differences in rock type. The most commonly used geophysical methods are gravity, electromagnetics and seismics. In particular, seismic measurements quantify anomalies in seismic waves propagation velocities and can be used to obtain information on the subsurface arrangement of different materials. In the Western Canary Islands, the Cumbre Vieja volcano in La Palma (Canary Islands) has been proposed to be near the collapse stage. Previous geophysical studies that have been carried out on the flank of the volcano comprise gravity and electromagnetic methods. These types of surveys gather information on the deep structures of the volcano (1-2 km). In this project, we complement previous studies by using seismic methods to investigate the near-surface seismic structure of the Cumbre Vieja fault system (La Palma Island) and the structure of the well-developed San Andres fault system (El Hierro Island). We aim to compare the Cumbre Vieja and San Andres fault systems to infer the degree of maturity of collapse structures. We carried out reflection and refraction seismic surveys in order to image approximately the first 10 meters of the subsurface. We used 24 low frequency (4,5 Hz) geophones as receivers and a sledge hammer as the seismic source. The survey lines were located across visible parts of the fault systems at the Cumbre Vieja volcano and the San Andres fault in El Hierro. Here, we present the survey setup and results from the preliminary analysis of the data.

  16. Deep critical zone weathering at the southern Sierra Nevada Critical Zone Observatory imaged by seismic waveform tomography

    Science.gov (United States)

    Hayes, J. L.; Holbrook, W.; Riebe, C. S.

    2012-12-01

    We present seismic velocity profiles that constrain the extent of weathering and frequency of velocity heterogeneities at depths less than 40 m in the southern Sierra Nevada Critical Zone Observatory (SSCZO) from waveform tomography modeling of a seismic refraction experiment. Near-surface variations in seismic velocity reflect differences in alteration of parent material by chemical, hydrological and biological processes. Previous traveltime tomography models from these data suggest that the depth to bedrock in the SSCZO is typically ~25 m; thus the potential for subsurface water storage in regolith may be a larger component of water storage than previously thought. Traveltime tomography is unable to resolve heterogeneities with horizontal wavelengths less than 10 m, such as those observed along a surveyed road cut beneath our seismic profile. For a higher resolution seismic image, we apply waveform tomography, which is more robust than traveltime tomography at approximating the wave equation and thus should provide images of subsurface heterogeneities such as corestones and fracture networks. This technique uses a weak scattering approximation to account for the amplitude and phase of the recorded waveforms, rather than just the traveltimes. A 48-channel vertical geophone array and hammer source was deployed over a 7 m high road cut with receiver and shot spacing of 2 m and 4 m respectively. The road cut displays lateral variation in weathering from a friable saprolite to coherent granodiorite which are compared to velocity variations modeled using waveform tomography.

  17. Drill bit seismic, vertical seismic profiling, and seismic depth imaging to aid drilling decisions in the Tho Tinh structure, Nam Con Son basin, Vietnam

    Energy Technology Data Exchange (ETDEWEB)

    Borland, W.; Hayashida, N.; Kusaka, H.; Leaney, W.; Nakanishi, S.

    1996-10-01

    This paper reviews the problem of overpressure, a common reason for acquiring look-ahead VSPs, and the seismic trace inversion problem, a fundamental issue in look-ahead prediction. The essential components of intermediate VSPs were examined from acquisition through processing to inversion, and recently acquired real data were provided, which were indicative of the advances being made toward developing an exclusive high resolution VSP service. A simple interpretation method and an end product of predicted mud weight versus depth were also presented, which were obtained from the inverted acoustic impedance and empirical relations. Of paramount importance in predicting the depth to a target was the velocity function used below the intermediate TD. The use of empirical or assumed density functions was an obvious weak link in the procedure. The advent of real-time time-depth measurements from drill bit seismic allowed a continuously updated predicted target depth below the present bit depth. 8 refs., 7 figs.

  18. JPEG image of Seismic-Reflection Profiles Collected in the Pulley Ridge Study Area

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These seismic data were collected to infer the paleodepositional environment of Pulley Ridge through seismic facies analysis. Without actual rock cores, remote...

  19. San Francisco Bay Area Velocity Structure From Controlled-Source Seismic Refraction Imaging

    Science.gov (United States)

    Goldman, M. R.; Catchings, R. D.; Steedman, C. E.; Gandhok, G.; Boatwright, J.; Rymer, M. J.

    2004-12-01

    To better understand the velocities and structures of the crust and upper mantle in the San Francisco Bay area, we developed 2-D tomographic velocity models along four seismic refraction profiles acquired along and across the bay area in the early 1990's. The four profiles extended from (1) Hollister to Inverness along the San Francisco and Marin Peninsulas (~200 km long), (2) Hollister to Santa Rosa along the East Bay (~220 km long), (3) the Pacific Ocean to Livermore crossing the bay (~100 km long), and (4) the Pacific Ocean to the western Santa Clara Valley (~25 km long), centered on the epicenter of the1989 M. 6.9 Loma Prieta earthquake. Velocity models were not previously developed for three of the seismic profiles, and the previously developed model for the fourth profile (Catchings and Kohler, 1996) did not include some of the currently available seismic data. The profiles along the bay image structures from the near surface to about 25 km depth, and they show velocity anomalies associated with the major faults (San Andreas, Hayward, Rodgers Creek, Calaveras) and basins along the profile. Velocities range from about 2 km/s in the basins to about 7 km/s at the Moho, which dips southward along both sides of the bay. The cross bay profile shows velocity anomalies associated with six fault zones between the Pacific Ocean and the Livermore Valley and higher upper-crustal velocities (~6.2 km/s) between the San Andreas and Hayward faults than to the southwest (~5 km/s) or northeast (~4 km/s) of those faults. The Loma Prieta profile shows velocities ranging from 2 km/s to 6 km/s in the upper 5 km, with the highest velocities in the epicentral region of the 1989 Loma Prieta earthquake. A pronounced, northeast-dipping, low-velocity zone is located beneath the surface expression of the San Andreas fault zone, but other fault zones along the profile show high-velocity anomalies beneath their surface expressions. Collectively, the velocity images show the complexity of

  20. Advances in directional borehole radar data analysis and visualization

    Science.gov (United States)

    Smith, D.V.G.; Brown, P.J.

    2002-01-01

    The U.S. Geological Survey is developing a directional borehole radar (DBOR) tool for mapping fractures, lithologic changes, and underground utility and void detection. An important part of the development of the DBOR tool is data analysis and visualization, with the aim of making the software graphical user interface (GUI) intuitive and easy to use. The DBOR software system consists of a suite of signal and image processing routines written in Research Systems' Interactive Data Language (IDL). The software also serves as a front-end to many widely accepted Colorado School of Mines Center for Wave Phenomena (CWP) Seismic UNIX (SU) algorithms (Cohen and Stockwell, 2001). Although the SU collection runs natively in a UNIX environment, our system seamlessly emulates a UNIX session within a widely used PC operating system (MicroSoft Windows) using GNU tools (Noer, 1998). Examples are presented of laboratory data acquired with the prototype tool from two different experimental settings. The first experiment imaged plastic pipes in a macro-scale sand tank. The second experiment monitored the progress of an invasion front resulting from oil injection. Finally, challenges to further development and planned future work are discussed.

  1. Identifying borehole geology projects

    OpenAIRE

    Brearley, S.D.

    2004-01-01

    Over the years, the British Geological Survey (BGS) has amassed a large collection of paper borehole logs from a variety of sources in the UK. This has partly occurred in response to various legal statutes requiring companies to lodge copies of this information with the BGS, as well as resulting from commercial storage contracts and voluntary donations. These hardcopy records, together with other geological and contextual documents, comprise BGS’ National Geological Records Cen...

  2. Directional borehole antenna - Theory

    International Nuclear Information System (INIS)

    A directional antenna has been developed for the borehole radar constructed during phase 2 of the Stripa project. The new antenna can determine the azimuth of a strong reflector with an accuracy of about 3 degrees as confirmed during experiments in Stripa, although the ratio of borehole diameter to wavelength is small, about 0.03. The antenna synthesizes the effect of a loop antenna rotating in the borehole from four signals measured in turn by a stationary antenna. These signals are also used to calculate an electric dipole signal and a check sum which is used to examine the function of the system. The theory of directional antennas is reviewed and used to design an antenna consisting of four parallel wires. The radiation pattern of this antenna is calculated using transmission line theory with due regard to polarization, which is of fundamental importance for the analysis of directional data. In particular the multipole expansion of the field is calculated to describe the antenna radiation pattern. Various sources of error, e.g. the effect of the borehole, are discussed and the methods of calibrating the antenna are reviewed. The ambiguity inherent in a loop antenna can be removed by taking the phase of the signal into account. Typical reflectors in rock, e.g. fracture zones an tunnels, may be modelled as simple geometrical structures. The corresponding analysis is described and exemplified on measurements from Stripa. Radar data is nowadays usually analyzed directly on the computer screen using the program RADINTER developed within the Stripa project. An algorithm for automatic estimation of the parameters of a reflector have been tested with some success. The relation between measured radar data and external coordinates as determined by rotational indicators is finally expressed in terms of Euler angles. (au)

  3. Subducting slab structure below the eastern Sunda arc inferred from non-linear seismic tomographic imaging

    Science.gov (United States)

    Widiyantoro, S.; Pesicek, J. D.; Thurber, C. H.

    2011-12-01

    Detailed P-wave speed velocity structure beneath the Sunda arc has been successfully imaged by applying a non-linear approach to seismic tomography. Nearly one million compressional phases from events within the Indonesian region have been used. These include the surface-reflected depth phases pP and pwP in order to improve the sampling of the uppermantle structure, particularly below the back-arc regions. We have combined a high-resolution regional inversion with a low-resolution global inversion to minimize the mapping of distant aspherical mantle structure into the study region. In this paper, we focus our discussion on the upper mantle structure beneath the eastern part of the Sunda arc. The tomographic images confirm previous observations of a hole in the subducted slab in the upper mantle beneath eastern Java. The images also suggest that a tear in the slab exists below the easternmost part of the Sunda arc, where the down-going slab is deflected in the mantle transition zone. In good agreement with previous studies, the properties of the deflected slab show a strong bulk-sound signature.

  4. Seismic imaging of a mid-lithospheric discontinuity beneath Ontong Java Plateau

    Science.gov (United States)

    Tharimena, Saikiran; Rychert, Catherine A.; Harmon, Nicholas

    2016-09-01

    Ontong Java Plateau (OJP) is a huge, completely submerged volcanic edifice that is hypothesized to have formed during large plume melting events ∼90 and 120 My ago. It is currently resisting subduction into the North Solomon trench. The size and buoyancy of the plateau along with its history of plume melting and current interaction with a subduction zone are all similar to the characteristics and hypothesized mechanisms of continent formation. However, the plateau is remote, and enigmatic, and its proto-continent potential is debated. We use SS precursors to image seismic discontinuity structure beneath Ontong Java Plateau. We image a velocity increase with depth at 28 ± 4 km consistent with the Moho. In addition, we image velocity decreases at 80 ± 5 km and 282 ± 7 km depth. Discontinuities at 60-100 km depth are frequently observed both beneath the oceans and the continents. However, the discontinuity at 282 km is anomalous in comparison to surrounding oceanic regions; in the context of previous results it may suggest a thick viscous root beneath OJP. If such a root exists, then the discontinuity at 80 km bears some similarity to the mid-lithospheric discontinuities (MLDs) observed beneath continents. One possibility is that plume melting events, similar to that which formed OJP, may cause discontinuities in the MLD depth range. Plume-plate interaction could be a mechanism for MLD formation in some continents in the Archean prior to the onset of subduction.

  5. Macroscopic Fault Structure of the 1911 Mw8.1 Chon Kemin Earthquake (Tien Shan, Kyrgyzstan) from Combined Seismic Imaging, Palaeo-Seismological Investigations and Historial Seismicity

    Science.gov (United States)

    Haberland, C. A.; Sonnemann, T.; Landgraf, A.; Ryberg, T.; Kulikova, G.; Krueger, F.; Dzhumabaeva, A.; Abdrakhmatov, K.; Abdybachaev, U.; Orunbaev, S.; Rosenwinkel, S.; Sharshebaev, A.

    2014-12-01

    Earthquakes in low-strain regions and their driving forces are still sparsely studied and understood, and constitute serious first-order research questions. Data acquisition concerning paleo-earthquakes, related hazards, and tectonic activity beyond historical records plays an important role. Such information can be obtained with tools from tectonic geomorphology, geophysics, historic seismicity, and paleo-seismology that should span a variety of time and length scales. The Chon-Kemin Valley in the northern Tien Shan (Kyrgyzstan) is a small, intermontane basin of unknown origin framed by a network of active faults. In the year 1911, the Chon-Kemin earthquake (Mw=8.1) activated fault structures of about 200 km length which also ruptured the surface along the Chon-Kemin Valley and caused numerous landslides and rock avalanches of up to several tens of millions of cubic meters in volume. The Chon-Kemin earthquake was one of a series of strong seismic events that affected the northern Tien Shan between 1885 and 1938. A seismic survey across the Chon-Kemin Valley was conducted to investigate the subsurface velocity structure of the valley and its surrounding faults. Tomographic inversion techniques were applied to first-arrival traveltimes of refracted P waves, and the seismic data were screened for reflection signatures. Additionally, the region was analyzed through paleo-seismological trenching. Tomographic and reflection images identified a shallow basin structure bounded by a set of thrust faults in the south only which - in part - correlate with the surface trace of the rupture. The deformation seems to be distributed in time and space across several sub-parallel fault strands. Synthesis of historical (analog) recordings of this earthquake provide new insights into the source mechanisms and processes.

  6. Exploratory borehole Schafisheim. Programme of work

    International Nuclear Information System (INIS)

    An extensive geophysical borehole logging programme will serve to verify the results of the core analysis and complement the core data. Numerous borehole logs are to be registered with different types of tools. These allow one to determine various parameters essential for the full description of the rock sequences penetrated. A first category of logs enables the petrographical identification of the different rock types and indicates porous zones that are either water- or hydrocarbon-bearing. A second category provides data e.g. on the degree of pore and fracture fill, rock density and rock temperature, natural gamma radiation and rock-mechanical properties. Other logs measure strike and dip of the sedimentary layers and the position of rock fractures. A fourth category provides information on the diameter and the deviation of the borehole, the quality of casing cementations and the position of casing joints. In addition, well shooting surveys will supply exact values of seismic velocities for the various rock units; data that are needed for the depth correction of the reflection profiles from Nagra's regional seismic network. With numerous hydrological tests ranging from a production tests of the triassic Muschelkalk aquifer to labelled slug tests in low-permeability crystalline sections, the hydraulic conditions of deep groundwater flow will be investigated. The recovered water samples will undergo full physical and geochemical analysis. Furthermore, their isotope content is to be measured in order to estimate the age of the various formation waters and their time of residence in the various aquifers. To round off the scientific investigations, a series of rock-mechanical and geotechnical laboratory tests will provide characteristic values to be applied eventually in the design and construction of shafts and caverns for an underground repository

  7. Imaging the seismic structure beneath oceanic spreading centers using ocean bottom geophysical techniques

    Science.gov (United States)

    Zha, Yang

    This dissertation focuses on imaging the crustal and upper mantle seismic velocity structure beneath oceanic spreading centers. The goals are to provide a better understanding of the crustal magmatic system and the relationship between mantle melting processes, crustal architecture and ridge characteristics. To address these questions I have analyzed ocean bottom geophysical data collected from the fast-spreading East Pacific Rise and the back-arc Eastern Lau Spreading Center using a combination of ambient noise tomography and seafloor compliance analysis. To characterize the crustal melt distribution at fast spreading ridges, I analyze seafloor compliance - the deformation under long period ocean wave forcing - measured during multiple expeditions between 1994 and 2007 at the East Pacific Rise 9º - 10ºN segment. A 3D numerical modeling technique is developed and used to estimate the effects of low shear velocity zones on compliance measurements. The forward modeling suggests strong variations of lower crustal shear velocity along the ridge axis, with zones of possible high melt fractions beneath certain segments. Analysis of repeated compliance measurements at 9º48'N indicates a decrease of crustal melt fraction following the 2005 - 2006 eruption. This temporal variability provides direct evidence for short-term variations of the magmatic system at a fast spreading ridge. To understand the relationship between mantle melting processes and crustal properties, I apply ambient noise tomography of ocean bottom seismograph (OBS) data to image the upper mantle seismic structure beneath the Eastern Lau Spreading Center (ELSC). The seismic images reveal an asymmetric upper mantle low velocity zone (LVZ) beneath the ELSC, representing a zone of partial melt. As the ridge migrates away from the volcanic arc, the LVZ becomes increasingly offset and separated from the sub-arc low velocity zone. The separation of the ridge and arc low velocity zones is spatially coincident

  8. Accurate location of nuclear explosions at Azgir, Kazakhstan, from satellite images and seismic data: Implications for monitoring decoupled explosions

    Energy Technology Data Exchange (ETDEWEB)

    Sykes, L.R.; Deng, J. (Lamont-Doherty Earth Observatory, Palisades, NY (United States) Columbia Univ., New York, NY (United States)); Lyubomirskiy, P. (Lamont-Doherty Earth Observatory, Palisades, NY (United States))

    1993-09-15

    This paper reports on the accurate location of ten large tamped nuclear explosions near Azgir, Kazakhstan, conducted by the former Soviet Union in salt domes. The events are located from shot points on a SPOT satellite image, and from reconstructed seismic events recorded on seismographs scattered around the world, including recently released data from the Soviet Union. A concern behind the location of these events, is the possibility that the caverns created by these shots might be used for seismically decoupled testing of nuclear explosions in the future.

  9. Research borehole drilling activity for boreholes DH-18, DH-19, DC-12, DC-13, DC-14, DC-15, and deepening of existing borehole DC-7

    Energy Technology Data Exchange (ETDEWEB)

    1979-09-01

    This report is an environmental evaluation of the impacts of proposed borehole drilling activities at the Hanford Site, northwest of Richland, Washington. The proposed action is to drill six research boreholes ranging in depth from 137 to 1372 meters (m) (250 to 4500 +- feet (ft)). In addition, an existing borehole (DC-7) will be extended from 1249 to 1524 m (4099 to 5000 +- ft). The purpose of the US Department of Energy's (DOE) borehole drilling activities is to collect data on in situ rock formations that are considered potentialy suitable for nuclear waste repositories. The technical program efforts necessary to identify and qualify specific underground waste facility sites in candidate rock formations include geologic and hydrologic studies (seismicity and tectonics, rock structure and stratigraphy, lithology, etc.). Borehole drilling is an integral part of the geological studies and is essential to a thorough understanding of potentially suitable geologic formations. The purpose of the proposed drilling activities is to obtain data for evaluating Columbia River basalts that are being evaluated by the National Waste Terminal Storage (NWTS) Program to determine their suitability potential for nuclear waste repositories. Unavoidable impact to the environment is limited primarily to the clearing of land needed for access and drilling operations. Considerations exercised during site preparation, drilling, and subsequent site restoration will limit modification of the natural environment to the minimum required for accomplishment of test objectives.

  10. Seismic and bathymetric imaging of gas seepage in the St. Lawrence estuary : a window to the St. Lawrence Platform

    Energy Technology Data Exchange (ETDEWEB)

    Duchesne, M.J. [Natural Resources Canada, Quebec, PQ (Canada). Geological Survey of Canada, Quebec Division

    2006-07-01

    The Geological Survey of Canada has gathered multichannel and single channel high-resolution seismic data in the St. Lawrence Estuary since 2003 in order to acquire more information about the nature and geology of the St. Lawrence Platform beneath the St. Lawrence Estuary. Seismic data gathered from Tadoussac to Pointe-des-Monts provided images of 42 different sedimentary sequences within the Grenville basement, the St. Lawrence Platform and the Appalachians tectonic wedge. A very-high-resolution bathymetric picture of the seafloor was generated using multibeam data. The study revealed that, in contrast to surrounding geological domains, the topography of the upper part of the St. Lawrence platform is smooth. The topographic expression of the platform appears to be derived from glacial episodes, and from the structural and lithological characteristics of the platform rocks. Differential glacial erosion scoured softer rocks leaving a positive relief over harder rocks. The datasets revealed seismic and bathymetric anomalies related to gas or fluid seepage such as chimneys, bright spots, amplitude blanking, and morphological evidences of pockmarks. Seismic anomalies are typically found along the northern side of the studied area while pockmarks are found downstream of the Bic Islands, on both northern and southern parts of the surveyed area. Pockmarks on the seafloor occur as linearly distributed, isolated or nested circles in areas where the sedimentary column is less than 200 metres thick. Seismic anomalies are not related to the thickness of the sedimentary column. Relationships between the upper part of the platform, seismic anomalies and pockmarks were observed. The seismic data strongly suggests that gas emanates from source rocks or breached reservoirs located within the Ordovician platform. Gas may sometimes escape on the seafloor as it migrates through glacially-eroded porous rock layers.

  11. Imaging 3D anisotropic upper mantle shear velocity structure of Southeast Asia using seismic waveform inversion

    Science.gov (United States)

    Chong, J.; Yuan, H.; French, S. W.; Romanowicz, B. A.; Ni, S.

    2011-12-01

    Southeast Asia as a special region in the world which is seismically active and is surrounded by active tectonic belts, such as the Himalaya collision zone, western Pacific subduction zones and the Tianshan- Baikal tectonic belt. Seismic anisotropic tomography can shade light on the complex crust and upper mantle dynamics of this region, which is the subject of much debate. In this study, we applied full waveform time domain tomography to image 3D isotropic and anisotropic upper mantle shear velocity structure of Southeast Asia. Three component waveforms of teleseismic and far regional events (15 degree ≤ Δ≤ 165 degree) with magnitude ranges from Mw6.0 to Mw7.0 are collected from 91 permanent and 438 temporary broadband seismic stations in SE Asia. Wavepackets of both fundamental and overtone modes, filtered between 60 and 400 sec, are selected automatically according to the similarity between data and synthetic waveforms (Panning & Romanowicz, 2006). Wavepackets corresponding to event-station paths that sample the region considered are weighted according to path redundancy and signal to noise ratio. Higher modes and fundamental mode wavepackets are weighted separately in order to enhance the contribution of higher modes which are more sensitive to deeper structure compared to the fundamental mode. Synthetic waveforms and broadband sensitivity kernels are computed using normal mode asymptotic coupling theory (NACT, Li & Romanowicz, 1995). As a starting model, we consider a global anisotropic upper mantle shear velocity model based on waveform inversion using the Spectral Element Method (Lekic & Romanowicz, 2011), updated for more realistic crustal thickness (French et al., 2011) as our starting model, we correct waveforms for the effects of 3D structure outside of the region, and invert them for perturbations in the 3D structure of the target region only. We start with waveform inversion down to 60sec and after several iterations, we include shorter period

  12. Seismic velocity structure of the crust and shallow mantle of the Central and Eastern United States by seismic surface wave imaging

    Science.gov (United States)

    Pollitz, Fred; Mooney, Walter D.

    2016-01-01

    Seismic surface waves from the Transportable Array of EarthScope's USArray are used to estimate phase velocity structure of 18 to 125 s Rayleigh waves, then inverted to obtain three-dimensional crust and upper mantle structure of the Central and Eastern United States (CEUS) down to ∼200 km. The obtained lithosphere structure confirms previously imaged CEUS features, e.g., the low seismic-velocity signature of the Cambrian Reelfoot Rift and the very low velocity at >150 km depth below an Eocene volcanic center in northwestern Virginia. New features include high-velocity mantle stretching from the Archean Superior Craton well into the Proterozoic terranes and deep low-velocity zones in central Texas (associated with the late Cretaceous Travis and Uvalde volcanic fields) and beneath the South Georgia Rift (which contains Jurassic basalts). Hot spot tracks may be associated with several imaged low-velocity zones, particularly those close to the former rifted Laurentia margin.

  13. Characteristics of rubber used in seismic isolation by digital and thermal image analysis

    Science.gov (United States)

    Lewangamage, Chamindalal S.; Abe, Masato; Fujino, Yozo; Yoshida, Junji

    2002-06-01

    The use of seismic isolation rubber bearings in bridges and buildings provides a very effective passive method to suppress hazard from earthquake-induced vibration. Carbons filled natural rubber and high damping rubber (HDR) are smart civil engineering materials especially used in those bearings. This study is to develop algorithms for large strain field measurements in rubber material by image analysis and to experimentally investigate temperature dependency on rubber behavior under cyclic loadings by thermal image analysis. A correlation-based template-matching algorithm is developed in displacement field measurements in continua so that a large strain field can be measured. Possible unrealistic displacement vectors present in measured displacement fields are eliminated by new algorithm in which the deformation should satisfy the continuity condition. The algorithms are successfully employed in strain field measurement of rubber materials reported here as experimental verification. Local deformational characteristics of rubber were also studied; results are shown by the analysis. Finally, a failure criterion was proposed for the rubber. The use of infrared thermographs to measure temperature field is described. This paper will discuss its application in HDR temperature field measurements under cyclic loadings. In HDR, various changes of properties were investigated with respect to the frequencies of loadings and its body temperature; results are shown by the analysis.

  14. New and Evolving Seismic Images of the Central Andes and Subducting Nazca Slab: 20 Years of Portable Seismology Results

    Science.gov (United States)

    Beck, S. L.

    2014-12-01

    Beno Gutenberg first identified a seismic low velocity zone in the upper mantle that we now refer to as the asthenosphere that is still the focus of many studies in active tectonic regions. The upper-most mantle is very heterogeneous and occupies the depth range where much of the tectonic action occurs especially in subduction zones and convergent margins. The central South American convergent margin is the result of the subduction of the Nazca Plate beneath the South American Plate and includes the Andes, one of the largest actively growing mountain ranges on Earth. The South American subduction zone has two regions of "flat" subduction in Peru and central Chile and Argentina separated by a segment of "normal" subduction and an active magmatic arc. The central Andean plateau has an average elevation of 3-4 km and some of the thickest crust on Earth with deformation reaching ~800 km inland. This active margin is characterized by along-strike variations in magmatism, upper crustal shortening, crustal thickness, and slab geometry that make it an ideal region to study the relationship between the subducting slab, the mantle wedge, and the overriding plate. After 20 years of portable seismic deployments in the Central Andes seismologists have generated unprecedented seismic images spanning ~3000 km of the Andean lithosphere, the subducting Nazca slab, and the surrounding mantle. Seismic travel-time, ambient noise and earthquake surface-wave tomography, receiver function imaging, and joint receiver function - surface wave dispersion inversions have produced along strike images of the Central Andes from the surface to a depth of ~700 km. These new images were made possible by PI-driven portable broadband seismic deployments and data sharing by many international groups. I will highlight images of along-strike variations in crustal properties and thickness, mantle lithospheric structure, and slab geometry. These seismic images allow us to more completely evaluate the role

  15. Accurate location of nuclear explosions at Azgir, Kazakhstan, from satellite images and seismic data: Implications for monitoring decoupled explosions

    Science.gov (United States)

    Sykes, Lynn R.; Deng, Jishu; Lyubomirskiy, Paul

    1993-09-01

    The 10 largest tamped nuclear explosions detonated by the Former Soviet Union in and near two salt domes near Azgir were relocated using seismic data and the locations of shot points on a SPOT satellite image taken in 1988. Many of the shot points are clearly recognized on the satellite image and can be located with an accuracy of 60 m even though testing was carried out at those points many years earlier, i. e. between 1966 and 1979. Onsite inspections and a local seismic monitoring network combined with our accurate locations of previous explosions would insure that any cavities that remain standing from those events could not be used for undetected decoupled nuclear testing down to a very small yield. Since the Azgir area, like much of the Pre-Caspian depression, is arid, it would not be a suitable place for constructing large cavities in salt by solution mining and then using them for clandestine nuclear testing.

  16. Seismic-reflection imaging of Tertiary faulting and related post-Eocene deformation 20 km North of Memphis, Tennessee

    Science.gov (United States)

    Williams, R.A.; Stephenson, W.J.; Odum, J.K.; Worley, D.M.

    2001-01-01

    Other than the Crittenden County fault zone (CCFZ), little is known about the seismic hazard from earthquake faults within 50 km of Memphis, Tennessee, a city that contains a large inventory of older buildings that are vulnerable to moderate and strong earthquake ground shaking. To address this lack of knowledge about faulting near Memphis, we acquired a 4.5 km long Mini-Sosie seismic-reflection profile across the boundary between the loess-covered bluffs and modern Mississippi River flood plain in Meeman-Shelby Forest State Park north of Memphis. We imaged a previously unknown reverse/thrust fault that displaces Paleozoic and Cretaceous rocks and upwarps Tertiary deposits on the floodplain portion of the profile about 25 km north of downtown Memphis. The Paleozoic and Cretaceous rocks are vertically faulted about 70 and 40 m, respectively, in an up-to-the-west sense of displacement. The fault displacement apparently terminates in the basal portion of the Paleocene section and causes only an upwarping of the overlying deposits. The overlying Paleocene and Eocene deposits, which are probably the youngest deposits imaged, are upwarped about 50-60 m with the same sense of displacement as the underlying older units. The sense of displacement, amplitude, and appearance of the fault in the seismic data are very similar to that observed in the seismic reflection images of the CCFZ 15 km west of this profile. Although we have imaged this new fault in only one location, its proximity to Memphis and similarities to the CCFZ, leads us to speculate that it may be a parallel structure to the CCFZ and thus warrants further study. ?? 2001 Elsevier Science B.V. All rights reserved.

  17. Coseismic deformation pattern of the Emilia 2012 seismic sequence imaged by Radarsat-1 interferometry

    Directory of Open Access Journals (Sweden)

    Christian Bignami

    2012-10-01

    Full Text Available On May 20 and 29, 2012, two earthquakes of magnitudes 5.9 and 5.8 (Mw, respectively, and their aftershock sequences hit the central Po Plain (Italy, about 40 km north of Bologna. More than 2,000 sizable aftershocks were recorded by the Isti-tuto Nazionale di Geofisica e Vulcanologia (INGV; National Institute of Geophysics and Volcanology National Seismic Network (http://iside.rm.ingv.it/. The sequence was generated by pure compressional faulting over blind thrusts of the western Ferrara Arc, and it involved a 50-km-long stretch of this buried outer front of the northern Apennines. The focal mechanisms of the larger shocks agree with available structural data and with present-day tectonic stress indicators, which show locally a maximum horizontal stress oriented ca. N-S; i.e. oriented perpendicular to the main structural trends. Most of the sequence occurred between 1 km and 12 km in depth, above the local basal detachment of the outer thrust fronts of the northern Apennines. We measured the surface displacement patterns associated with the mainshocks and some of the larger aftershocks (some of which had Mw >5.0 by applying the Interferometric Synthetic Aperture Radar (InSAR technique to a pair of C-Band Radarsat-1 images. We then used the coseismic motions detected over the epicentral region as input information, to obtain the best-fit model fault for the two largest shocks. […

  18. Evidence for Along-Strike Variations in the Crustal Deformation beneath the Bhutan Himalaya from Receiver Function Imaging and Seismicity

    Science.gov (United States)

    Singer, J.; Kissling, E. H.; Diehl, T.; Hetényi, G.

    2015-12-01

    In the Bhutan Himalaya seismicity and geologic surface features like the Kuru Chu Spur (an embayment of the Main Central Thrust) or the Paro window indicate along-strike variations in the collisional structure. The deeper structure of the orogenic wedge and associated deformation processes, however, are poorly understood partly due to the lack of seismic images of the crust. To better understand these differences in structure and deformation, we use data of a temporary seismic broadband network in Bhutan to image the crustal structure with receiver functions (RF). We apply an iterative 3D wave-based migration scheme including a high-frequency ray approximation, which satisfies Snell's law for dipping interfaces. With this approach we image variably dipping intra-crustal interfaces and the Moho topography across the Bhutan Himalaya, and identify lateral variations in the orogenic structure, which we interpret jointly with a new local earthquake catalog. In West Bhutan, RF imaging depicts a northward dipping Moho at ~50 km depth. The low-angle dip steepens north of ~27.6°N which matches well observations by wide-angle seismics in South Tibet and the hypocenter of a deep crustal earthquake recorded by our network. We also identify the Main Himalayan Thrust (MHT) at ~14 km depth in West Bhutan with a ramp-like structure north of ~27.6°N. The ramp is characterized by a negative impedance contrast in the RF signals and coincides with a concentration of seismicity. In the East, the Moho appears to be almost flat at a depth of ~50 km without clear indications of steepening towards north. Beneath the Kuru Chu Spur in East Bhutan, we observe listric-shaped structures reaching from the upper crust beneath the Lesser Himalaya down to the Moho beneath the Greater Himalaya, which we interpret as a stack of crustal material typical for an accretionary wedge. While these structures appear aseismic, a horizontal alignment of seismicity at ~12 km depth suggests an active MHT in

  19. Global imaging of the Earth's deep interior: seismic constraints on (an)isotropy, density and attenuation

    NARCIS (Netherlands)

    Trampert, J.; Fichtner, A.

    2013-01-01

    Seismic tomography is the principal tool to probe the deep interior of the Earth. Models of seismic anisotropy induced by crystal alignment provide insight into the underlying convective motion, and variations of density allow us to discriminate between thermal and compositional heterogeneities. Thi

  20. Seismic imaging of the 2001 Bhuj Mw7.7 earthquake source zone: b-value, fractal dimension and seismic velocity tomography studies

    Science.gov (United States)

    Mandal, Prantik; Rodkin, Mikhail V.

    2011-11-01

    We use precisely located aftershocks of the 2001 Mw7.7 Bhuj earthquake (2001-2009) to explore the structure of the Kachchh seismic zone by mapping the 3-D distributions of b-value, fractal dimension (D) and seismic velocities. From frequency-magnitude analysis, we find that the catalog is complete above Mw = 3.0. Thus, we analyze 2159 aftershocks with Mw ≥ 3.0 to estimate the 3-D distribution of b-value and fractal dimensions using maximum-likelihood and spatial correlation dimension approaches, respectively. Our results show an area of high b-, D- and Vp/Vs ratio values at 15-35 km depth in the main rupture zone (MRZ), while relatively low b- and D values characterize the surrounding rigid regions and Gedi fault (GF) zone. We propose that higher material heterogeneities in the vicinity of the MRZ and/or circulation of deep aqueous fluid/volatile CO 2 is the main cause of the increased b-, D- and Vp/Vs ratio values at 15-35 km depth. Seismic velocity images also show some low velocity zones continuing in to the deep lower crust, supporting the existence of circulation of deep aqueous fluid / volatile CO 2 in the region (probably released from the eclogitasation of olivine rich lower crustal rocks). The presence of number of high and low velocity patches further reveals the heterogeneous and fractured nature of the MRZ. Interestingly, we observe that Aki (1981)'s relation (D = 2b) is not valid for the spatial b-D correlation of the events in the GF (D 2 = 1.2b) zone. However, the events in the MRZ (D 2 = 1.7b) show a fair agreement with the D = 2b relationship while the earthquakes associated with the remaining parts of the aftershock zone (D 2 = 1.95b) show a strong correlation with the Aki (1981)'s relationship. Thus, we infer that the remaining parts of the aftershock zone are probably behaving like locked un-ruptured zones, where larger stresses accumulate. We also propose that deep fluid involvement may play a key role in generating seismic activity in the

  1. Miscellaneous High-Resolution Seismic Imaging Investigations in Salt Lake and Utah Valleys for Earthquake Hazards

    Science.gov (United States)

    Stephenson, W.J.; Williams, R.A.; Odum, J.K.; Worley, D.M.

    2007-01-01

    Introduction In support of earthquake hazards and ground motion studies by researchers at the Utah Geological Survey, University of Utah, Utah State University, Brigham Young University, and San Diego State University, the U.S. Geological Survey Geologic Hazards Team Intermountain West Project conducted three high-resolution seismic imaging investigations along the Wasatch Front between September 2003 and September 2005. These three investigations include: (1) a proof-of-concept P-wave minivib reflection imaging profile in south-central Salt Lake Valley, (2) a series of seven deep (as deep as 400 m) S-wave reflection/refraction soundings using an S-wave minivib in both Salt Lake and Utah Valleys, and (3) an S-wave (and P-wave) investigation to 30 m at four sites in Utah Valley and at two previously investigated S-wave (Vs) minivib sites. In addition, we present results from a previously unpublished downhole S-wave investigation conducted at four sites in Utah Valley. The locations for each of these investigations are shown in figure 1. Coordinates for the investigation sites are listed in Table 1. With the exception of the P-wave common mid-point (CMP) reflection profile, whose end points are listed, these coordinates are for the midpoint of each velocity sounding. Vs30 and Vs100, also shown in Table 1, are defined as the average shear-wave velocities to depths of 30 and 100 m, respectively, and details of their calculation can be found in Stephenson and others (2005). The information from these studies will be incorporated into components of the urban hazards maps along the Wasatch Front being developed by the U.S. Geological Survey, Utah Geological Survey, and numerous collaborating research institutions.

  2. Multi-phase Temporal Seismic Imaging of a Slope Stability Mitigation Project at Newby Island Sanitary Landfill, San Jose, California

    Science.gov (United States)

    Treece, B. J.; Catchings, R.; Reed, D.; Goldman, M.

    2014-12-01

    Without slope stability mitigation, liquefaction-induced settlement in bay mud and Pleistocene alluvial deposits may lead to the collapse of levee walls surrounding sanitary landfills that are located adjacent to the San Francisco Bay. To analyze the effectiveness of a slope stability mitigation project involving deep soil mixing at Newby Island Sanitary Landfill in San Jose, California, we acquired P- and S-wave seismic surveys along a transect through the mitigated region during, and two years after, completion of the mitigation project. Deep soil mixing involves the injection of a cement slurry in augered holes, resulting in groups of soil-cement columns (elements) that are intended to increase the strength and rigidity of the subsurface materials. For our seismic investigations, we used accelerated-weight-drop (AWD) and hammer impacts to generate P- and S-wave seismic sources, respectively, at 57 geophone locations, spaced 5 m apart. The resulting seismic data were recorded using 40-Hz, vertical-component (P-wave) and 4.5-Hz, horizontal-component (S-wave) sensors. Initially, we developed tomographic refraction (velocity) images along a progressive transition from a yet-to-be-mitigated area into a more recently mitigated area, located along the base of a steep slope composed of compacted landfill. The initial survey revealed an increase in seismic velocity in the treated area, seismic velocity increases with curing time for soil-cement elements, and a high-velocity zone beneath the active injection zone. The influence of the mitigation was most apparent from increases in Vp/Vs and Poisson's ratios. To assess the long-term effects of the mitigation project, an identical, follow-up survey was acquired in July 2014, 23 months after the initial survey. We present a comparative analysis of the tomographic images from the two surveys, variations in Vp/Vs and Poisson's ratios over time, and a comparison of in situ, time-varying seismic parameters with laboratory

  3. SHEAR WAVE SEISMIC STUDY COMPARING 9C3D SV AND SH IMAGES WITH 3C3D C-WAVE IMAGES

    Energy Technology Data Exchange (ETDEWEB)

    John Beecherl; Bob A. Hardage

    2004-07-01

    The objective of this study was to compare the relative merits of shear-wave (S-wave) seismic data acquired with nine-component (9-C) technology and with three-component (3-C) technology. The original proposal was written as if the investigation would be restricted to a single 9-C seismic survey in southwest Kansas (the Ashland survey), on the basis of the assumption that both 9-C and 3-C S-wave images could be created from that one data set. The Ashland survey was designed as a 9-C seismic program. We found that although the acquisition geometry was adequate for 9-C data analysis, the source-receiver geometry did not allow 3-C data to be extracted on an equitable and competitive basis with 9-C data. To do a fair assessment of the relative value of 9-C and 3-C seismic S-wave data, we expanded the study beyond the Ashland survey and included multicomponent seismic data from surveys done in a variety of basins. These additional data were made available through the Bureau of Economic Geology, our research subcontractor. Bureau scientists have added theoretical analyses to this report that provide valuable insights into several key distinctions between 9-C and 3-C seismic data. These theoretical considerations about distinctions between 3-C and 9-C S-wave data are presented first, followed by a discussion of differences between processing 9-C common-midpoint data and 3-C common-conversion-point data. Examples of 9-C and 3-C data are illustrated and discussed in the last part of the report. The key findings of this study are that each S-wave mode (SH-SH, SV-SV, or PSV) involves a different subsurface illumination pattern and a different reflectivity behavior and that each mode senses a different Earth fabric along its propagation path because of the unique orientation of its particle-displacement vector. As a result of the distinct orientation of each mode's particle-displacement vector, one mode may react to a critical geologic condition in a more optimal way than

  4. Zero-Offset VSP in the COSC-1 borehole

    Science.gov (United States)

    Krauß, Felix; Simon, Helge; Giese, Rüdiger; Buske, Stefan; Hedin, Peter; Juhlin, Christopher; Lorenz, Henning

    2015-04-01

    As support for the COSC drilling project (Collisional Orogeny in the Scandinavian Caledonides), an extensive seismic survey took place during September and October 2014 in and around the newly drilled borehole COSC-1. The main aim of the COSC project is to better understand orogenic processes in past and recently active mountain belts. For this an approx. 2.5 km deep borehole, with nearly 100% core recovery, was drilled in the Scandinavian Caledonides, close to the town of Åre in western Jämtland/Sweden. The seismic survey consisted of a high resolution zero-offset VSP (vertical seismic profiling) and a multi-azimuthal walkaway VSP experiment with receivers at the surface and in the borehole. For the zero-offset VSP (ZVSP) a hydraulic hammer source (VIBSIST 3000) was used and activated over a period of 20 seconds as a sequence of impacts with increasing hit frequency. For each source point, 25 seconds of data were recorded. The wavefield was recorded in the borehole by 15 three-component receivers using a Sercel Slimwave geophone chain with an inter-tool spacing of 10 meters. The ZVSP was designed to result in a geophone spacing of 2 meters over the whole borehole length. The source was about 30 meters away from the borehole and thus, provides a poor geometry to rotate 3C-data in greater depths. For this reason, a check shot position was defined in about 1.9 km distance to the borehole. With this offset shots, it is possible to rotate the components of the 3C receivers and to concentrate the S-wave energy on one component and thus, increase the signal-to-noise ratio of S-wave events. This offset source point was activated periodically for certain depth positions of the geophone chain. The stacked ZVSP-data show a high signal-to-noise ratio and good data quality. Frequencies up to 150 Hz were recorded. On the vertical component, clear direct P-wave arrivals are visible. Several P-wave reflections occur below 1600 meters depth. After rotating the components

  5. Quantitative Seismic Amplitude Analysis

    NARCIS (Netherlands)

    Dey, A.K.

    2011-01-01

    The Seismic Value Chain quantifies the cyclic interaction between seismic acquisition, imaging and reservoir characterization. Modern seismic innovation to address the global imbalance in hydrocarbon supply and demand requires such cyclic interaction of both feed-forward and feed-back processes. Cur

  6. Seismic VSP Investigations at Olkiluoto, 2005

    International Nuclear Information System (INIS)

    Posiva Oy carries out R and D related tasks for spent nuclear fuel disposal in Finland. The site characterization has been conducted since 1987 in Olkiluoto in western Finland. The ONKALO underground characterization facility has been under construction since 2004. Vibrometric Oy has been contracted to carry out seismic VSP survey in four drillholes in the immediate vicinity of ONKALO, for the characterization of the seismically responsive structures. Four drillholes, KR8, KR27, KR29 and KR38 were included to the project. Seven seismic source locations on ground surface were used for each drillhole. The source locations were optimized with respect to the drillhole and ONKALO and were configured as linear arrays to produce optimum imaging focused on the ONKALO volume. A mechanical Vibsist source, using a hydraulic rock breaker mounted on a 22 t excavator, was used as source of seismic signal. The signal was recorded with downhole 3-component geophones. The recording array was 8-level long, with 5 m spacing between levels. Acquisition was run throughout the drillholes. Processing of the VSP profiles consisted of time decoding of the impact sequences, filtering and image point (IP) transform. The interpretation was carried out interactively, seeking for best match of orientation of each reflection according to different borehole profiles where the features were seen. The interpretations were built as an add-on to a previous seismic model of the site. The most distinct reflectors were interpreted, compiled to as a part of a terrain model composed of 3D surfaces, and transferred digitally together with other results (3D elements of reflector locations) into Posiva's 3D modeling system. Some of the reflectors have already received direct confirmation from ONKALO observations. (orig.)

  7. Crosswell Seismic Amplitude-Versus-Offset for Detailed Imaging of Facies and Fluid Distribution within Carbonate Oil Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Wayne Pennington; Mohamed Ibrahim; Roger Turpening; Sean Trisch; Josh Richardson; Carol Asiala; Walid Mabrouk

    2008-09-30

    Crosswell seismic surveys were conducted at two fields in northern Michigan. One of these, Springdale, included two monitor wells that are located external to the reef, and the other, Coldspring, employed two production wells within the reef. The Springdale wells extended to much greater depths than the reef, and imaging was conducted from above and from beneath the reef. The resulting seismic images provide the best views of pinnacle Niagaran reefs obtained to date. The tops of the reservoirs can be clearly distinguished, and their lateral extent or dipping edges can be observed along the profile. Reflecting events internal to the reef are evident; some of them are fairly continuous across the reef and others are discontinuous. Inversion of the seismic data indicates which events represent zones of higher porosity and which are lower porosity or even anhydrite plugged. The full stacked image includes angles that are beyond critical for many of the interfaces, and some reflections are visible only for a small range of angles, presumably near their critical angle. Stacking these angles in provides an opportunity for these events to be seen on the stacked image, where otherwise they would have been unrecognized. For inversion, however, the complexity associated with phase changes beyond critical can lead to poor results, and elastic inversion of partial angle stacks may be best conducted with restrictions to angles less than critical. Strong apparent attenuation of signals occurs when seismic ray paths pass through the upper part of the Springdale reservoir; this may be due to intrinsic attenuation and/or scattering of events due to the locally strongly varying gas saturation and extremely low fluid pressures. Signal-to-noise limitations become evident far from the source well in the Coldspring study, probably because the raw data were strongly affected by tube-wave noise generated by flow through the perforation of the receiver well. The seismic images obtained, and

  8. Combining satellite and seismic images to analyse the shallow structure of the Dead Sea Transform near the DESERT transect

    Science.gov (United States)

    Kesten, D.; Weber, M.; Haberland, Ch.; Janssen, Ch.; Agnon, A.; Bartov, Y.; Rabba, I.

    2008-02-01

    The left-lateral Dead Sea Transform (DST) in the Middle East is one of the largest continental strike-slip faults of the world. The southern segment of the DST in the Arava/Araba Valley between the Dead Sea and the Red Sea, called Arava/Araba Fault (AF), has been studied in detail in the multidisciplinary DESERT (DEad SEa Rift Transect) project. Based on these results, here, the interpretations of multi-spectral (ASTER) satellite images and seismic reflection studies have been combined to analyse geologic structures. Whereas satellite images reveal neotectonic activity in shallow young sediments, reflection seismic image deep faults that are possibly inactive at present. The combination of the two methods allows putting some age constraint on the activity of individual fault strands. Although the AF is clearly the main active fault segment of the southern DST, we propose that it has accommodated only a limited (up to 60 km) part of the overall 105 km of sinistral plate motion since Miocene times. There is evidence for sinistral displacement along other faults, based on geological studies, including satellite image interpretation. Furthermore, a subsurface fault is revealed ≈4 km west of the AF on two ≈E-W running seismic reflection profiles. Whereas these seismic data show a flower structure typical for strike-slip faults, on the satellite image this fault is not expressed in the post-Miocene sediments, implying that it has been inactive for the last few million years. About 1 km to the east of the AF another, now buried fault, was detected in seismic, magnetotelluric and gravity studies of DESERT. Taking together various evidences, we suggest that at the beginning of transform motion deformation occurred in a rather wide belt, possibly with the reactivation of older ≈N-S striking structures. Later, deformation became concentrated in the region of today’s Arava Valley. Till ≈5 Ma ago there might have been other, now inactive fault traces in the vicinity

  9. Imaging of 3-D seismic velocity structure of Southern Sumatra region using double difference tomographic method

    International Nuclear Information System (INIS)

    Southern Sumatra region has a high level of seismicity due to the influence of the subduction system, Sumatra fault, Mentawai fault and stretching zone activities. The seismic activities of Southern Sumatra region are recorded by Meteorological Climatological and Geophysical Agency (MCGA’s) Seismograph network. In this study, we used earthquake data catalog compiled by MCGA for 3013 events from 10 seismic stations around Southern Sumatra region for time periods of April 2009 – April 2014 in order to invert for the 3-D seismic velocities structure (Vp, Vs, and Vp/Vs ratio). We applied double-difference seismic tomography method (tomoDD) to determine Vp, Vs and Vp/Vs ratio with hypocenter adjustment. For the inversion procedure, we started from the initial 1-D seismic velocity model of AK135 and constant Vp/Vs of 1.73. The synthetic travel time from source to receiver was calculated using ray pseudo-bending technique, while the main tomographic inversion was applied using LSQR method. The resolution model was evaluated using checkerboard test and Derivative Weigh Sum (DWS). Our preliminary results show low Vp and Vs anomalies region along Bukit Barisan which is may be associated with weak zone of Sumatran fault and migration of partial melted material. Low velocity anomalies at 30-50 km depth in the fore arc region may indicated the hydrous material circulation because the slab dehydration. We detected low seismic seismicity in the fore arc region that may be indicated as seismic gap. It is coincides contact zone of high and low velocity anomalies. And two large earthquakes (Jambi and Mentawai) also occurred at the contact of contrast velocity

  10. Imaging of 3-D seismic velocity structure of Southern Sumatra region using double difference tomographic method

    Energy Technology Data Exchange (ETDEWEB)

    Lestari, Titik, E-mail: t2klestari@gmail.com [Meteorological Climatological and Geophysical Agency (MCGA), Jalan Angkasa I No.2 Kemayoran, Jakarta Pusat, 10720 (Indonesia); Faculty of Earth Science and Technology, Bandung Institute of Technology, Jalan Ganesa No.10, Bandung 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology, Jalan Ganesa 10 Bandung 40132 (Indonesia)

    2015-04-24

    Southern Sumatra region has a high level of seismicity due to the influence of the subduction system, Sumatra fault, Mentawai fault and stretching zone activities. The seismic activities of Southern Sumatra region are recorded by Meteorological Climatological and Geophysical Agency (MCGA’s) Seismograph network. In this study, we used earthquake data catalog compiled by MCGA for 3013 events from 10 seismic stations around Southern Sumatra region for time periods of April 2009 – April 2014 in order to invert for the 3-D seismic velocities structure (Vp, Vs, and Vp/Vs ratio). We applied double-difference seismic tomography method (tomoDD) to determine Vp, Vs and Vp/Vs ratio with hypocenter adjustment. For the inversion procedure, we started from the initial 1-D seismic velocity model of AK135 and constant Vp/Vs of 1.73. The synthetic travel time from source to receiver was calculated using ray pseudo-bending technique, while the main tomographic inversion was applied using LSQR method. The resolution model was evaluated using checkerboard test and Derivative Weigh Sum (DWS). Our preliminary results show low Vp and Vs anomalies region along Bukit Barisan which is may be associated with weak zone of Sumatran fault and migration of partial melted material. Low velocity anomalies at 30-50 km depth in the fore arc region may indicated the hydrous material circulation because the slab dehydration. We detected low seismic seismicity in the fore arc region that may be indicated as seismic gap. It is coincides contact zone of high and low velocity anomalies. And two large earthquakes (Jambi and Mentawai) also occurred at the contact of contrast velocity.

  11. NNWSI [Nevada Nuclear Waste Storage Investigations] 51 seismic hole histories

    International Nuclear Information System (INIS)

    This report is a compilation of data from fifty-one shallow boreholes drilled within the Nevada Test Site (NTS) and the adjacent Bureau of Land Management (BLM) lands. The boreholes were drilled to determine the alluvial thickness and subsurface structure. Once drilled the boreholes were used to emplace explosive charges of three seismic refraction surveys conducted in 1981, 1983 and 1984. The information presented in this report includes location maps, daily activities and reviews of hole condition

  12. Seismic imaging of the upper mantle beneath the northern Central Andean Plateau: Implications for surface topography

    Science.gov (United States)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Wagner, L. S.

    2015-12-01

    Extending over 1,800 km along the active South American Cordilleran margin, the Central Andean Plateau (CAP) as defined by the 3 km elevation contour is second only to the Tibetan Plateau in geographic extent. The uplift history of the 4 km high Plateau remains uncertain with paleoelevation studies along the CAP suggesting a complex, non-uniform uplift history. As part of the Central Andean Uplift and the Geodynamics of High Topography (CAUGHT) project, we use surface waves measured from ambient noise and two-plane wave tomography to image the S-wave velocity structure of the crust and upper mantle to investigate the upper mantle component of plateau uplift. We observe three main features in our S-wave velocity model including (1), a high velocity slab (2), a low velocity anomaly above the slab where the slab changes dip from near horizontal to a normal dip, and (3), a high-velocity feature in the mantle above the slab that extends along the length of the Altiplano from the base of the Moho to a depth of ~120 km with the highest velocities observed under Lake Titicaca. A strong spatial correlation exists between the lateral extent of this high-velocity feature beneath the Altiplano and the lower elevations of the Altiplano basin suggesting a potential relationship. Non-uniqueness in our seismic models preclude uniquely constraining this feature as an uppermost mantle feature bellow the Moho or as a connected eastward dipping feature extending up to 300 km in the mantle as seen in deeper mantle tomography studies. Determining if the high velocity feature represents a small lithospheric root or a delaminating lithospheric root extending ~300 km into the mantle requires more integration of observations, but either interpretation shows a strong geodynamic connection with the uppermost mantle and the current topography of the northern CAP.

  13. Seismic reflection imaging of underground cavities using open-source software

    Energy Technology Data Exchange (ETDEWEB)

    Mellors, R J

    2011-12-20

    The Comprehensive Nuclear Test Ban Treaty (CTBT) includes provisions for an on-site inspection (OSI), which allows the use of specific techniques to detect underground anomalies including cavities and rubble zones. One permitted technique is active seismic surveys such as seismic refraction or reflection. The purpose of this report is to conduct some simple modeling to evaluate the potential use of seismic reflection in detecting cavities and to test the use of open-source software in modeling possible scenarios. It should be noted that OSI inspections are conducted under specific constraints regarding duration and logistics. These constraints are likely to significantly impact active seismic surveying, as a seismic survey typically requires considerable equipment, effort, and expertise. For the purposes of this study, which is a first-order feasibility study, these issues will not be considered. This report provides a brief description of the seismic reflection method along with some commonly used software packages. This is followed by an outline of a simple processing stream based on a synthetic model, along with results from a set of models representing underground cavities. A set of scripts used to generate the models are presented in an appendix. We do not consider detection of underground facilities in this work and the geologic setting used in these tests is an extremely simple one.

  14. Characterization of intrabasin faulting and deformation for earthquake hazards in southern Utah Valley, Utah, from high-resolution seismic imaging

    Science.gov (United States)

    Stephenson, William J.; Odum, Jack K.; Williams, Robert A.; McBride, John H.; Tomlinson, Iris

    2012-01-01

    We conducted active and passive seismic imaging investigations along a 5.6-km-long, east–west transect ending at the mapped trace of the Wasatch fault in southern Utah Valley. Using two-dimensional (2D) P-wave seismic reflection data, we imaged basin deformation and faulting to a depth of 1.4 km and developed a detailed interval velocity model for prestack depth migration and 2D ground-motion simulations. Passive-source microtremor data acquired at two sites along the seismic reflection transect resolve S-wave velocities of approximately 200 m/s at the surface to about 900 m/s at 160 m depth and confirm a substantial thickening of low-velocity material westward into the valley. From the P-wave reflection profile, we interpret shallow (100–600 m) bedrock deformation extending from the surface trace of the Wasatch fault to roughly 1.5 km west into the valley. The bedrock deformation is caused by multiple interpreted fault splays displacing fault blocks downward to the west of the range front. Further west in the valley, the P-wave data reveal subhorizontal horizons from approximately 90 to 900 m depth that vary in thickness and whose dip increases with depth eastward toward the Wasatch fault. Another inferred fault about 4 km west of the mapped Wasatch fault displaces horizons within the valley to as shallow as 100 m depth. The overall deformational pattern imaged in our data is consistent with the Wasatch fault migrating eastward through time and with the abandonment of earlier synextensional faults, as part of the evolution of an inferred 20-km-wide half-graben structure within Utah Valley. Finite-difference 2D modeling suggests the imaged subsurface basin geometry can cause fourfold variation in peak ground velocity over distances of 300 m.

  15. Shear Wave Reflection Seismics Image Internal Structure of Quick-Clay Landslides in Sweden

    Science.gov (United States)

    Polom, U.; Krawczyk, C. M.; Malehmir, A.

    2014-12-01

    Covering many different sizes of scale, landslides are widespread and pose a severe hazard in many areas as soon as humans or infrastructure are affected. In order to provide geophysical tools and techniques to better characterize sites prone to sliding, a geophysical assessment working towards a geotechnical understanding of landslides is necessary. As part of a joint project studying clay-related landslides in Nordic countries by a suite of geophysical methods, we therefore tested the use of shear wave reflection seismics to survey shallow structures that are known to be related to quick-clay landslide processes in southern Sweden. On two crossing profiles, a land streamer consisting of 120 SH-geophones with 1 m spacing was deployed, and an ELVIS micro-vibrator was shaking every 4 m to generate the shear wave signal. SH-wave data of high quality were thereby acquired to resolve the gaps between P-wave data and electrical and surface wave based methods of lower resolution. After quality control, correlation, subtractive stack, and geometry setup, single shot gathers already demonstrate the high data quality gained in the region, especially on a gravel road. The migrated depth sections image the structural inventory down to ca. 50 m depth with vertical resolution of less than 1 m. Horizontally layered sediments are visible in the upper 40 m of soft (marine) sediments, followed by top basement with a rough topography varying between ca. 20-40 m depth. The imaged, bowl-shaped basement morphology centres near the profile crossing, and basement is exposed at three sides of the profiles. Three distinct sediment sequences are separated by high-amplitude unconformities. The quick-clay layer may be located above the marked reflection set that lies on top of the more transparent sequence that levels out the basement. Located between 15-20 m depth, this correlates with the height of the last scarp that occurred in the area. In addition, shear wave velocities are determined

  16. High-resolution seismic imaging, Mono Lake fault zone, eastern Sierra region, Walker Lane, California

    Science.gov (United States)

    Jayko, A. S.; Childs, J. R.; Hart, P. E.; Bursik, M. I.; McClain, J. S.

    2012-12-01

    Multiple strands of the Mono Lake fault zone (MLfz), a segment of the Sierra Nevada frontal fault zone, have been imaged on several high-resolution seismic reflection profiles collected during 2009 and 2011 at Mono Lake. The profiles show coherent reflectors to about 30-40 ms depth below the lake bottom (~30 m thick section) in nearshore areas north of the Lee Vining delta. The MLfz is well imaged on 8 lines including 4 lines ~normal to the trend of the fault zone. The fault zone is ~ 0.75 km wide. Deep reflection horizons appear gently tilted and rotated into the fault zone with a prominent clastic wedge overlying the west-tilted horizons. Shallow reflectors above the clastic wedge are generally east-sloping, but noticeably less inclined above the fault zone. At least two ruptures offset Holocene deposits, with ~0.5-1.8 m dip-slip offset around 2.5 ka and ~3.6-6.13 m dip-slip offset around 4.7 to 6.25 ka. The ages of reflection horizons are estimated using published Holocene and late Pleistocene sedimentation rates, as well as correlation with a published nearby shallow core. The short term fault slip rate based on the timing of the most recent event and multiple events in the profile lines suggests fault slip rates of about 0.26 to 0.55 m/ka using ages based only on sedimentation rate and of about 0.31 to 0.34 m/ka using correlation ages from nearby shallow core. This offshore dip-slip rate is significantly lower than previous published 1.0-2.0 m/ka dip-slip rates estimated using cosmogenic dating of Tioga glacial moraines in Lundy Canyon and offset older moraines. The offset on the large scarp in Lundy Canyon (~20 m) decreases both north and south of the canyon and flanking lateral moraines where the scarp is on the order of only ~4-7 m high. A possible explanation for the apparent difference in MLfz slip rates onshore and offshore in this part of Mono Basin may be soft sediment deformation of saturated glacial-deltaic sediment within Lundy Canyon that causes

  17. The Olmsted fault zone, southernmost Illinois: A key to understanding seismic hazard in the northern new Madrid seismic zone

    Science.gov (United States)

    Bexfield, C.E.; McBride, J.H.; Pugin, Andre J.M.; Nelson, W.J.; Larson, T.H.; Sargent, S.L.

    2005-01-01

    Geological deformation in the northern New Madrid seismic zone, near Olmsted, Illinois (USA), is analyzed using integrated compressional-wave (P) and horizontally polarized-wave (SH) seismic reflection and regional and dedicated borehole information. Seismic hazards are of special concern because of strategic facilities (e.g., lock and dam sites and chemical plants on the Ohio River near its confluence with the Mississippi River) and because of alluvial soils subject to high amplification of earthquake shock. We use an integrated approach starting with lower resolution, but deeper penetration, P-wave reflection profiles to identify displacement of Paleozoic bedrock. Higher resolution, but shallower penetration, SH-wave images show deformation that has propagated upward from bedrock faults into Pleistocene loess. We have mapped an intricate zone more than 8 km wide of high-angle faults in Mississippi embayment sediments localized over Paleozoic bedrock faults that trend north to northeast, parallel to the Ohio River. These faults align with the pattern of epicenters in the New Madrid seismic zone. Normal and reverse offsets along with positive flower structures imply a component of strike-slip; the current stress regime favors right-lateral slip on northeast-trending faults. The largest fault, the Olmsted fault, underwent principal displacement near the end of the Cretaceous Period 65 to 70 million years ago. Strata of this age (dated via fossil pollen) thicken greatly on the downthrown side of the Olmsted fault into a locally subsiding basin. Small offsets of Tertiary and Quaternary strata are evident on high-resolution SH-wave seismic profiles. Our results imply recent reactivation and possible future seismic activity in a critical area of the New Madrid seismic zone. This integrated approach provides a strategy for evaluating shallow seismic hazard-related targets for engineering concerns. ?? 2005 Elsevier B.V. All rights reserved.

  18. Control system for borehole tools

    Energy Technology Data Exchange (ETDEWEB)

    Bordon, E.E.

    1987-03-10

    A control assembly is described for use with a tool including one or more subassemblies adapted for controlling and/or monitoring various events within a borehole and actuating instrumentation positioned on the earth's surface for actuating the tool. The assembly comprises: control means connected to the tool for selectively actuating one or more of the subassemblies within the tool, the control means being adapted for operation within the borehole, power supply means connected to the tool for supplying electrical power to the control means for operation thereof independent of the surface actuating instrumentation, communication means connected to the surface actuating instrumentation for communicating therewith, and connection means for selectively connecting the communication means to the control means while the tool and the control means connected thereto are within the borehole to establish communication between the control means and the surface actuating instrumentation. The connection means is adapted for operation within the borehole.

  19. Safety valve for offshore borehole

    Energy Technology Data Exchange (ETDEWEB)

    McGill, H.L.; Randermann, E. Jr.; Musik, O.J.

    1977-10-06

    The invention concerns a new and improved submarine safety valve with a valve element which rotate, which can be used, in emergencies, to separate the wound-up piping which extends into the borehole and to close the production line.

  20. Seismic Fracture Characterization Methodologies for Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Queen, John H. [Hi-Geophysical, Inc., Ponca, OK (United States)

    2016-05-09

    Executive Summary The overall objective of this work was the development of surface and borehole seismic methodologies using both compressional and shear waves for characterizing faults and fractures in Enhanced Geothermal Systems. We used both surface seismic and vertical seismic profile (VSP) methods. We adapted these methods to the unique conditions encountered in Enhanced Geothermal Systems (EGS) creation. These conditions include geological environments with volcanic cover, highly altered rocks, severe structure, extreme near surface velocity contrasts and lack of distinct velocity contrasts at depth. One of the objectives was the development of methods for identifying more appropriate seismic acquisition parameters for overcoming problems associated with these geological factors. Because temperatures up to 300º C are often encountered in these systems, another objective was the testing of VSP borehole tools capable of operating at depths in excess of 1,000 m and at temperatures in excess of 200º C. A final objective was the development of new processing and interpretation techniques based on scattering and time-frequency analysis, as well as the application of modern seismic migration imaging algorithms to seismic data acquired over geothermal areas. The use of surface seismic reflection data at Brady's Hot Springs was found useful in building a geological model, but only when combined with other extensive geological and geophysical data. The use of fine source and geophone spacing was critical in producing useful images. The surface seismic reflection data gave no information about the internal structure (extent, thickness and filling) of faults and fractures, and modeling suggests that they are unlikely to do so. Time-frequency analysis was applied to these data, but was not found to be significantly useful in their interpretation. Modeling does indicate that VSP and other seismic methods with sensors located at depth in wells will be the most

  1. Seismic imaging of the western Hellenic subduction zone: A link between slab buoyancy, differential rollback, and upper-plate deformation?

    Science.gov (United States)

    Pearce, F. D.; Rondenay, S.; Zhang, H.; Olive, J. L.; Royden, L.

    2011-12-01

    The Hellenic subduction zone is located in the east-central Mediterranean region and exhibits large variations in convergence rate along its western edge. Differences in the lithosphere entering the subduction zone are believed to drive the different rates of convergence. While seismic reflection data has shown a transition from continental to oceanic lithosphere along the foreland, no detailed images of the mantle-wedge structure are available to test this hypothesis. Here, we present the results of several seismic imaging studies to constrain the structure of the lower and upper plates along the western Hellenic subduction zone (WHSZ). These studies exploit data from two temporary arrays of 40 broadband seismometers that were deployed across Greece in a northern line (NL, across Northern Greece) and southern line (SL, across Peloponnesus, Attica, and Evia), each roughly perpendicular to the trench axis. Over 50 high-quality teleseismic events were processed from each line using a 2D teleseismic migration algorithm based on the Generalized Radon Transform and a 3D receiver function algorithm that includes dipping interfaces. In addition, a 3D P-wave velocity model was constructed by applying double-difference tomography to ~7000 local earthquakes. Seismic images from each method all show a N60E dipping slab beneath both NL and SL. From the migration images, we interpret a ~10 km thick low-velocity layer beneath SL as subducted oceanic crust and a ~20 km thick low-velocity layer beneath NL as subducted continental crust. The two imaged subducted crusts connect smoothly with results from seismic reflection data obtained updip. However, the ~20 km thick continental crust we observe in the upper mantle beneath NL is less than the ~30 km thick crust observed in seismic reflection data from the foreland, which suggests that ~10 km of continental crust is being scraped off and attached to the upper plate. When compared along strike, the two profiles show that the oceanic

  2. Small scale seismic measurement bench to assess imaging methods - application to Full Waveform Inversion of a shallow structure

    Science.gov (United States)

    Leparoux, D.; Bretaudeau, F.; Brossier, R.; Operto, S.; Virieux, J.

    2011-12-01

    Seismic imaging of subsurface is useful for civil engineering and landscape management topics. The usual methods use surface waves phase velocities or first arrival times of body waves. However, for complex structures, such methods can be inefficient and Full Waveform Inversion (FWI) promises relevant performances because all the signal is taken into account. FWI has been originally developed for deep explorations (Pratt et al. 1999). Heterogeneities and strong attenuation in the near surface make difficult the adaptation of the FWI to shallower media (Bretaudeau et al. 2009). For this reason, we have developed a physical modeling measurement bench that performs small scale seismic recording in well controlled contexts (Bretaudeau et al. 2011). In this paper we assess the capacity of the FWI method (Brossier 2010) for imaging a subsurface structure including a low velocity layer and a lateral variation of interfaces. The analog model is a 180mm long and 50mm thick layered epoxy resin block (fig. 1). Seismic data generated with a punctual piezoelectric source emitting a 120KHz Ricker wavelet at the medium surface were collected by an heterodyne laser interferometer. The laser allows recording the absolute normal particle displacement without contact, avoiding disturbances caused by coupling. The laser interferometer and the piezoelectric source were attached to automated arms that could be moved over the model surface to a precision of 0.01mm (fig. 1). The acquisition survey includes 241 receiver and 37 source positions respectively spaced at 1 and 5 mm. Figure 2 shows 2D maps of the Vs parameter after inversion of data sequentially processed with 13 frequencies. The geometry of the sloped interface is recovered. A low velocity zone is imaged but with a thickness thinner than expected. Moreover, artifacts appear in the near surface. Experimental modeling results showed the capacity of the FWI in this case and provided key issues for further works about inversion by

  3. Multichannel Seismic Imaging of the Rivera Plate Subduction at the Seismogenic Jalisco Block Area (Western Mexican Margin)

    Science.gov (United States)

    Bartolome, Rafael; Górriz, Estefanía; Dañobeitia, Juanjo; Cordoba, Diego; Martí, David; Cameselle, Alejandra L.; Núñez-Cornú, Francisco; Bandy, William L.; Mortera-Gutiérrez, Carlos A.; Nuñez, Diana; Castellón, Arturo; Alonso, Jose Luis

    2016-10-01

    During the TSUJAL marine geophysical survey, conducted in February and March 2014, Spanish, Mexican and British scientists and technicians explored the western margin of Mexico, considered one of the most active seismic zones in America. This work aims to characterize the internal structure of the subduction zone of the Rivera plate beneath the North American plate in the offshore part of the Jalisco Block, to link the geodynamic and the recent tectonic deformation occurring there with the possible generation of tsunamis and earthquakes. For this purpose, it has been carried out acquisition, processing and geological interpretation of a multichannel seismic reflection profile running perpendicular to the margin. Crustal images show an oceanic domain, dominated by subduction-accretion along the lower slope of the margin with a subparallel sediment thickness of up to 1.6 s two-way travel time (approx. 2 km) in the Middle American Trench. Further, from these data the region appears to be prone to giant earthquake production. The top of the oceanic crust (intraplate reflector) is very well imaged. It is almost continuous along the profile with a gentle dip (developed accretionary prism consisting of highly deformed sediments with prominent slumping towards the trench that may be the result of past tsunamis. Also, a bottom simulating reflector (BSR) is identified in the first half a second (twtt) of the section. High amplitude reflections at around 7-8 s twtt clearly image a discontinuous Moho, defining a very gentle dipping subduction plane.

  4. Geology and Geophysics of new boreholes at the FEBEX site

    Energy Technology Data Exchange (ETDEWEB)

    Carbonell, R.; Perez-Estaun, A. [Inst. Jaume Almera, CSIC (Spain); Missana, T.; Buil, B.; Garralon, A.; Gomez, J. [CIEMAT (Spain); Suso, J.; Carretero, G.; Bueno, J.; Martinez, L. [AITEMIN (Spain); Hernan, P. [ENRESA (Spain)

    2007-06-15

    Geophysical data has been acquired to characterized the fracture network of the surrounding volume within the FEBEX gallery. The geophysic data include new borehole logging such as Natural Gamma and Borehole Ground Penetrating radar and cross hole ultrasonic tomography. The preliminary processing and integration of these different data sets indicates that the GPR record can provide images of the fractures, specially if they are fluid filled. The GPR is specially sensitive to the water content as it directly affects the electrical conductivity and the dielectric permittivity Therefore it is adequate for mapping water conductive fractures of the crystalline rock. The correlation of the anomalies measured by the natural gamma can be correlated with the 'diffractions' in the GPR and the fractures imaged by the borehole televiewer. The cross hole ultrasonic tomography data is under processing and no interpretations have been attempted yet.

  5. Exploratory borehole Leuggern: geology

    International Nuclear Information System (INIS)

    The Leuggern borehole was drilled in the Plateau Jura of Canton Aargau. The drill-site lies on land administered by the borough of Leuggern, and is located some 13 km to the north of Brugg. Drilling work lasted from July 9, 1984, until February 10, 1985. Isolated short sections were drilling using a centre-bit, but otherwise a roller-bit was used exclusively and the sedimentary cover and crystalline basement were cored virtually continuously down to the maximum depth of 1688.90 m. The 22.26 m thick sedimentary succession is subdivided into Quarternary, Upper, Middle and Lower Muschelkalk and Buntsandstein. The Upper Muschelkalk includes approximately 10 m of Trigonodus Dolomite in fully dolomitised Plattenkalk-facies. The Lower Muschelkalk is developed in its typical uniform mud-marl facies. The basement lies beneath the Bundsandstein, which rests in sharply discordant contact above the basement. The crystalline basement at Leuggern was overprinted by several post-metamorphic, post-granitic, tectonic-hydrothermal events. Later events are recorded by solution cavities and mineral fracture fillings which grew freely into open fractures. Despite problems with orientation of the core sketches, structural analyses yielded interesting results. The following petrophysical parameters were determined for the various basement lithologies: rock and grain density; total and effective porosity; internal and external specific surface and thermal conductivity. The effect of the hydrothermal alteration on these parameters is generally considerable. The location of water inflow was accomplished by means of 'fluid logging' and core inspection. A total of 35 inflow points were registered, of which 29 were clearly identifiable on the core itself. Four different types of flow systems could be characterised. (author) 22 tabs., 109 refs

  6. Two-dimensional Co-Seismic Surface Displacements Field of the Chi-Chi Earthquake Inferred from SAR Image Matching

    Science.gov (United States)

    Hu, Jun; Li, Zhi-Wei; Ding, Xiao-Li; Zhu, Jian-Jun

    2008-01-01

    The Mw=7.6 Chi-Chi earthquake in Taiwan occurred in 1999 over the Chelungpu fault and caused a great surface rupture and severe damage. Differential Synthetic Aperture Radar Interferometry (DInSAR) has been applied previously to study the co-seismic ground displacements. There have however been significant limitations in the studies. First, only one-dimensional displacements along the Line-of-Sight (LOS) direction have been measured. The large horizontal displacements along the Chelungpu fault are largely missing from the measurements as the fault is nearly perpendicular to the LOS direction. Second, due to severe signal decorrelation on the hangling wall of the fault, the displacements in that area are un-measurable by differential InSAR method. We estimate the co-seismic displacements in both the azimuth and range directions with the method of SAR amplitude image matching. GPS observations at the 10 GPS stations are used to correct for the orbital ramp in the amplitude matching and to create the two-dimensional (2D) co-seismic surface displacements field using the descending ERS-2 SAR image pair. The results show that the co-seismic displacements range from about -2.0 m to 0.7 m in the azimuth direction (with the positive direction pointing to the flight direction), with the footwall side of the fault moving mainly southwards and the hanging wall side northwards. The displacements in the LOS direction range from about -0.5 m to 1.0 m, with the largest displacement occuring in the northeastern part of the hanging wall (the positive direction points to the satellite from ground). Comparing the results from amplitude matching with those from DInSAR, we can see that while only a very small fraction of the LOS displacement has been recovered by the DInSAR mehtod, the azimuth displacements cannot be well detected with the DInSAR measurements as they are almost perpendicular to the LOS. Therefore, the amplitude matching method is obviously more advantageous than the DIn

  7. Imaging the Seismic Cycle in the Central Andean Subduction Zone from Geodetic Observations

    Science.gov (United States)

    Ortega-Culaciati, F.; Becerra-Carreño, V. C.; Socquet, A.; Jara, J.; Carrizo, D.; Norabuena, E. O.; Simons, M.; Vigny, C.; Bataille, K. D.; Moreno, M.; Baez, J. C.; Comte, D.; Contreras-Reyes, E.; Delorme, A.; Genrich, J. F.; Klein, E.; Ortega, I.; Valderas, M. C.

    2015-12-01

    We aim to quantify spatial and temporal evolution of fault slip behavior during all stages of the seismic cycle in subduction megathrusts, with the eventual goal of improving our understanding of the mechanical behavior of the subduction system and its implications for earthquake and tsunami hazards. In this work, we analyze the portion of the Nazca-SouthAmerican plates subduction zone affected by the 1868 southern Peru and 1877 northern Chile mega-earthquakes. The 1868 and 1878 events defined a seismic gap that did not experience a large earthquake for over 124 years. Only recently, the 1995 Mw 8.1 Antofagasta, 2001 Mw 8.4 Arequipa, 2007 Mw 7.7 Tocopilla, and 2014 Mw 8.2 Pisagua earthquakes released only a small fraction of the potential slip budget, thereby raising concerns about continued seismic and tsunami hazard. We use over a decade of observations from continuous and campaign GPS networks to analyze inter-seismic strain accumulation, as well as co-seimic deformation associated to the more recent earthquakes in the in the Central Andean region. We obtain inferences of slip (and back-slip) behavior using a consistent and robust inversion framework that accounts for the spatial variability of the constraint provided by the observations on slip across the subduction megathrust. We present an updated inter-seismic coupling model and estimates of pre-, co- and post- seismic slip behavior associated with the most recent 2014 Mw 8.2 Pisagua earthquake. We analyze our results, along with published information on the recent and historical large earthquakes, to characterize the regions of the megathrust that tend to behave aseismically, and those that are capable to accumulate a slip budget (ultimately leading to the generation of large earthquakes), to what extent such regions may overlap, and discuss the potential for large earthquakes in the region.

  8. A new interpretation of the deep-part of Senegal-Mauritanian Basin in the Diourbel-Thies area by integrating seismic, magnetic, gravimetric and borehole data: Implication for petroleum exploration

    Science.gov (United States)

    Ndiaye, Matar; Ngom, Papa Malick; Gorin, Georges; Villeneuve, Michel; Sartori, Mario; Medou, Joseph

    2016-09-01

    The Diourbel-Thies area is located in the centre of the onshore part of the Senegal-Mauritanian Basin (SMB). The new interpretation of old petroleum data (2-D seismic lines and drilling data of three oil wells) in the deeppart of this poorly evaluated zone, integrating gravimetric and magnetic data, has allowed the distinction of the Hercynian ante-rift phase (U1) which is distinguished from the syn-rift phase (U2) probably of Permo-Triassic to Middle Jurassic age. The syn-rift phase resulted in a series of compartments or grabens infilling aligned in a North-South direction. Tholeiitic volcanism of the Central Atlantic Magmatic Province (CAMP) is present in the syn-rift phase of the Diourbel-Thies area. The syn-rift deposits and associated volcanics allow us to surmise that the Diourbel basin represents a deeper rift basin. In comparison with other Central Atlantic Margins (CAM), the Diourbel rift basin could be one of the numerous rift basins that formed during the Permo-Triassic age. From a petroleum exploration perspective, the existence of the Diourbel rift basin is attractive because of the presence of structures that are excellent for deep gas exploration.

  9. Combining full wavefield migration and full waveform inversion, a glance into the future of seismic imaging

    NARCIS (Netherlands)

    Berkhout, A.J.

    2012-01-01

    The next generation seismic migration and inversion technology considers multiple scattering as vital information, allowing the industry to derive significantly better reservoir models — with more detail and less uncertainty — while requiring a minimum of user intervention. Three new insights have b

  10. A high resolution seismic reflection image for the oceanic LAB (Lithosphere-Asthenosphere Boundary), beneath southern North Island, New Zealand

    Science.gov (United States)

    Stern, T. A.; Henrys, S. A.; Okaya, D. A.; Savage, M. K.; Sato, H.; Iwasaki, T.; Louie, J. N.; Lamb, S. H.

    2014-12-01

    We present the first high-resolution, multichannel, seismic-reflection image for the base of an oceanic plate. Our image is based on an 85 km-long, ~ 900 station deployment across the lower North Island of New Zealand. 12 x 500 kg dynamite shots were used as seismic sources. Strong reflections at a two way travel time of 9-12 s define the top of the plate that dips to the NW at ~ 12-15 degrees. Between 27-32 s we identify a pair of reflections on some shot gathers that are interpreted to come from a reflection 90-100 km deep, that dips to the NW at 15 degrees. We interpret the reflection pair as marking a Lithosphere-Asthenosphere Boundary (LAB) zone at the base of the Pacific plate. Using all 12 shots we made a CDP-stacked image (maximum fold = 15) that shows the LAB as a double event (2-3 s apart) dipping roughly parallel to the top of the plate and Benioff zone. Shot quality varies but the highest frequencies we record from the base of the plate are ~ 18 Hz, suggesting a boundary zone wave speed drops off at least 8% across the LAB boundary. The double reflection at the LAB is interpreted to be a 10 km-thick layer of low seismic wave speed. Because it is so sharp it cannot be a thermal boundary and must represent some form of mechanical change. Previous attempts to explain the abruptness of seismic wave speed changes at the LAB have appealed to layered zones of ponded melt, or anelastic relaxation due to water accumulating beneath the LAB. Both mechanisms may explain our observations and both would point to low viscosity below the LAB. However, the fact we see a ~ 10 km thick channel, with strong acoustic impedances each side of the channel, suggests a shear zone where plate motion ( ~ 9 cm/y in hotspot reference frame) is taken up and strain rates of ~3 x 10-13 s-1 are generated. This interpreted, low wave-speed, low-viscosity, shear zone appears to be a key factor in allowing plates to slide with little resistance and therefore to allow plate tectonics to work.

  11. The 1946 Unimak Tsunami Earthquake Area: revised tectonic structure in reprocessed seismic images and a suspect near field tsunami source

    Science.gov (United States)

    Miller, John J.; von Huene, Roland; Ryan, Holly F.

    2014-01-01

    In 1946 at Unimak Pass, Alaska, a tsunami destroyed the lighthouse at Scotch Cap, Unimak Island, took 159 lives on the Hawaiian Islands, damaged island coastal facilities across the south Pacific, and destroyed a hut in Antarctica. The tsunami magnitude of 9.3 is comparable to the magnitude 9.1 tsunami that devastated the Tohoku coast of Japan in 2011. Both causative earthquake epicenters occurred in shallow reaches of the subduction zone. Contractile tectonism along the Alaska margin presumably generated the far-field tsunami by producing a seafloor elevation change. However, the Scotch Cap lighthouse was destroyed by a near-field tsunami that was probably generated by a coeval large undersea landslide, yet bathymetric surveys showed no fresh large landslide scar. We investigated this problem by reprocessing five seismic lines, presented here as high-resolution graphic images, both uninterpreted and interpreted, and available for the reader to download. In addition, the processed seismic data for each line are available for download as seismic industry-standard SEG-Y files. One line, processed through prestack depth migration, crosses a 10 × 15 kilometer and 800-meter-high hill presumed previously to be basement, but that instead is composed of stratified rock superimposed on the slope sediment. This image and multibeam bathymetry illustrate a slide block that could have sourced the 1946 near-field tsunami because it is positioned within a distance determined by the time between earthquake shaking and the tsunami arrival at Scotch Cap and is consistent with the local extent of high runup of 42 meters along the adjacent Alaskan coast. The Unimak/Scotch Cap margin is structurally similar to the 2011 Tohoku tsunamigenic margin where a large landslide at the trench, coeval with the Tohoku earthquake, has been documented. Further study can improve our understanding of tsunami sources along Alaska’s erosional margins.

  12. High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State

    Science.gov (United States)

    Odum, Jackson K.; Stephenson, William J.; Pratt, Thomas L.; Blakely, Richard J.

    2016-01-01

    Marine seismic reflection data from southern Puget Sound, Washington, were collected to investigate the nature of shallow structures associated with the Tacoma fault zone and the Olympia structure. Growth folding and probable Holocene surface deformation were imaged within the Tacoma fault zone beneath Case and Carr Inlets. Shallow faults near potential field anomalies associated with the Olympia structure were imaged beneath Budd and Eld Inlets. Beneath Case Inlet, the Tacoma fault zone includes an ∼350-m wide section of south-dipping strata forming the upper part of a fold (kink band) coincident with the southern edge of an uplifted shoreline terrace. An ∼2 m change in the depth of the water bottom, onlapping postglacial sediments, and increasing stratal dips with increasing depth are consistent with late Pleistocene to Holocene postglacial growth folding above a blind fault. Geologic data across a topographic lineament on nearby land indicate recent uplift of late Holocene age. Profiles acquired in Carr Inlet 10 km to the east of Case Inlet showed late Pleistocene or Holocene faulting at one location with ∼3 to 4 m of vertical displacement, south side up. North of this fault the data show several other disruptions and reflector terminations that could mark faults within the broad Tacoma fault zone. Seismic reflection profiles across part of the Olympia structure beneath southern Puget Sound show two apparent faults about 160 m apart having 1 to 2 m of displacement of subhorizontal bedding. Directly beneath one of these faults, a dipping reflector that may mark the base of a glacial channel shows the opposite sense of throw, suggesting strike-slip motion. Deeper seismic reflection profiles show disrupted strata beneath these faults but little apparent vertical offset, consistent with strike-slip faulting. These faults and folds indicate that the Tacoma fault and Olympia structure include active structures with probable postglacial motion.

  13. Borehole radar diffraction tomography

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seong Jun; Kim, Jung Ho; Yi, Myeong Jong; Chung, Seung Hwan; Lee, Hee Il [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1997-12-01

    Tomography is widely used as imaging method for determining subsurface structure. Among the reconstruction algorithms for tomographic imaging, travel time tomography is almost applied to imaging subsurface. But isolated small body comparable with the wavelength could not be well recognized by travel time tomography. Other tomographic method are need to improve the imaging process. In the study of this year, diffraction tomography was investigated. The theory for diffraction tomography is based on the 1st-order Born approximation. Multisource holography, which is similar to Kirchihoff migration, is compared with diffraction tomography. To improve 1st-order Born diffraction tomography, two kinds of filter designed from multisource holography and 2-D green function, respectively, applied on the reconstructed image. The algorithm was tested for the numerical modeling data of which algorithm consists of the analytic computation of radar signal in transmitter and receiver regions and 2-D FDM scheme for the propagation of electromagnetic waves in media. The air-filled cavity model to show a typical diffraction pattern was applied to diffraction tomography imaging, and the result shows accurate location and area of cavity. But the calculated object function is not well matched the real object function, because the air-filled cavity model is not satisfied week scattered inhomogeneity for 1st born approximation, and the error term is included in estimating source wavelet from received signals. In spite of the object function error, the diffraction tomography assist for interpretation of subsurface as if conducted with travel time tomography. And the fracture model was tested, 1st born diffraction tomographic image is poor because of limited view angle coverage and violation of week scatter assumption, but the filtered image resolve the fracture somewhat better. The tested diffraction tomography image confirms effectiveness of filter for enhancing resolution. (author). 14

  14. Depth imaging system for seismic reflection data. Part 1. Outline of system; Hanshaho jishin tansa data no tame no shindo imaging system. 1. System no gaiyo

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, N. [Japex Jeoscience Institute, Tokyo (Japan); Matsuoka, T. [Japan Petroleum Exploration Corp., Tokyo (Japan); Tsuru, T. [Japan National Oil Corp., Tokyo (Japan)

    1996-10-01

    Structures of oil and gas fields to be recently explored have changed from simple structures represented by anticline into more complicated and more delicate structures in the deeper underground. In order to discover and develop prospective oil and gas fields among such geological structures, it is indispensable to construct a system which can treat seismic exploration date collectively before stacking and can easily perform imaging of underground structures accurately. Based on the advancement of hardware, Japan National Oil Corporation and Japan Petroleum Exploration Co., Ltd. have developed a depth imaging system as an interactive tool for constructing underground structures accurately through a cooperation of highly accurate imaging technology. Using this system, two-dimensional underground structure models can be easily given and modified by interactively referring to results of depth migration velocity analysis and stacking velocity analysis, well data, cross sections after depth transform, etc. 1 fig.

  15. Imaging the Rivera and Cocos Plates below Jalisco and Michoacan Blocks from Seismicity Data

    Science.gov (United States)

    Nunez-Cornu, F. J.; Gutierrez Pena, Q. J.; Escudero, C. R.; Barba, D. C., Sr.

    2014-12-01

    We review the local seismicity recorded by the project "Mapping the Riviera Subduction Zone" (MARS), a temporary seismic network that was installed in the states of Jalisco, Colima and Michoacán between January 2006 and June 2007, and the data collected by Jalisco Seismic and Accelerometric Network (RESAJ). We did a relocation of all MARS events using Hypo71 and the P-wave velocity model used by the RESAJ. The data comprise more than 2,000 earthquakes with local magnitude between 1.4 and 5.9 and depths between 1.0 and 109 km. Some crustal seismicity alignments are observed on the Jalisco Block. The geometry of the slabs is different; both are clearly separated beneath the Colima Graben. The Cocos plate, residing south of the graben, presents a typical flat slab dipping with an angle of about 21º extending eastward 200 km from the trench. Meanwhile, the more northerly Rivera plate exhibits a curvature or bend, possibly the result of an oblique suduction process, dipping from the trench with an angle of about 10º just south of Bahía Banderas to a dip angle of 25º at the Eastern contact with the Colima Graben. We have produced profiles parallel to the trench, in a profile along the shore line and a second one 50 km inland. A subduction dip angle of 12º towards the SE direction is observed in the Rivera plate in profiles inland from Bahia de Banderas to the Colima Graben, but the seismicity ceases to define the plate for more westerly profiles which enounter the graben.

  16. Broadband Seismic Deployments for Imaging the Upper Mantle Structure in the Lützow-Holm Bay Region, East Antarctica

    Directory of Open Access Journals (Sweden)

    Masaki Kanao

    2011-01-01

    Full Text Available Broadband seismic deployments have been carried out in the Lützow-Holm Bay region (LHB, Dronning Maud Land, East Antarctica. The recorded teleseismic and local events are of sufficient quality to image the structure and dynamics of the crust and mantle of the terrain. Passive seismic studies by receiver functions and shear wave splitting suggest a heterogeneous upper mantle. Depth variations in topography for upper mantle discontinuities were derived from long period receiver function, indicating a shallow depth discontinuity at 660 km beneath the continental area of LHB. These results provide evidence of paleo upwelling of the mantle plume associated with Gondwana break-up. SKS splitting analysis anticipated a relationship between “fossil” anisotropy in lithospheric mantle and past tectonics. Moreover, active source surveys (DSSs imaged lithospheric mantle reflections involving regional tectonic stress during Pan-African and succeeding extension regime at the break-up. By combining the active and passive source studies of the mantle structure, we propose an evolution model of LHB for constructing the present mantle structure.

  17. 3D Seismic Imaging through Reverse-Time Migration on Homogeneous and Heterogeneous Multi-Core Processors

    Directory of Open Access Journals (Sweden)

    Mauricio Araya-Polo

    2009-01-01

    Full Text Available Reverse-Time Migration (RTM is a state-of-the-art technique in seismic acoustic imaging, because of the quality and integrity of the images it provides. Oil and gas companies trust RTM with crucial decisions on multi-million-dollar drilling investments. But RTM requires vastly more computational power than its predecessor techniques, and this has somewhat hindered its practical success. On the other hand, despite multi-core architectures promise to deliver unprecedented computational power, little attention has been devoted to mapping efficiently RTM to multi-cores. In this paper, we present a mapping of the RTM computational kernel to the IBM Cell/B.E. processor that reaches close-to-optimal performance. The kernel proves to be memory-bound and it achieves a 98% utilization of the peak memory bandwidth. Our Cell/B.E. implementation outperforms a traditional processor (PowerPC 970MP in terms of performance (with an 15.0× speedup and energy-efficiency (with a 10.0× increase in the GFlops/W delivered. Also, it is the fastest RTM implementation available to the best of our knowledge. These results increase the practical usability of RTM. Also, the RTM-Cell/B.E. combination proves to be a strong competitor in the seismic arena.

  18. Imagerie sismique d'un réservoir carbonaté : le dogger du Bassin parisien Seismic Imaging a Carbonate Reservoir: the Paris Basin Dogger

    Directory of Open Access Journals (Sweden)

    Mougenot D.

    2006-11-01

    organization of the amplitudes at the top reservoir reflector, which seems to suggest lateral variations in porosity, are a valuable guide for setting up wells and designing horizontal drilling. Three-component seismic (2D-3c and S-wave emissions did not produce any reflections beyond 30 Hz at the level of the target which is a poor reflector (PS & SS. Only borehole seismic (VSP, offset VSP, where high frequencies are much less attenuated than with surface seismic, provides detailed imaging of the reservoir in converted mode (up to 120 Hz in PP and in PS. Despite a deterioration in the signal-to-noise ratio, the anisotropy calculated on the SS sections, by comparing the propagation times in the Kimmeridgian-Bajocian interval surrounding the reservoir, evidences lateral variations which link up consistently with the anisotropy measurements made at the boreholes. Along the 2D-3c profile, the impedances obtained by inversion of the P amplitudes indicate a reduction in porosity and hence an increase in the rigidity of the reservoir where the anisotropy is greatest. Despite these encouraging initial results and given the high cost of threecomponent surface acquisitions, we do not consider this method to be appropriate for describing the Dogger reservoir. As a conclusion, the combination of continuous spatial sampling, such as that obtained in 3D, and a vibroseis emission adapted to frequency attenuation, such as that used in 2D-HR but restricted to 100 Hz, can supply useful information about the thin and discontinuous Dogger reservoir which cannot be provided by mere correlation of the borehole data. In this way, the geometry of the reservoir could be described with accuracy (5 m in addition to a number of heterogeneities corresponding to faults or lateral variations in impedance. Other parameters of significance for production, such as the distribution of drains R1 and R2, which barely alters the acoustic impedances in the reservoir, remain however inaccessible to surface seismic

  19. Seismic imaging of esker structures from a combination of high-resolution broadband multicomponent streamer and wireless sensors, Turku-Finland

    Science.gov (United States)

    Maries, Georgiana; Ahokangas, Elina; Mäkinen, Joni; Pasanen, Antti; Malehmir, Alireza

    2015-04-01

    Eskers and glaciofluvial interlobate formations, mainly composed of sands and gravels and deposited in winding ridges, define the locations of glacial melt-water streams. These sediments, porous and permeable, form the most important aquifers in Finland and are often used as aggregates or for artificial aquifer recharge. The Virttaankangas interlobate suite and artificial aquifer recharge plant provides the entire water supply for the city of Turku and therefore an accurate delineation of the aquifer is critical for long term planning and sustainable use of these natural resources. The study area is part of the Säkylänharju-Virttaankangas Glaciofluvial esker-chain complex and lies on an igneous, crystalline basement rocks. To provide complementary information to existing boreholes and GPR studies at the site, such as identification of potential esker cores, planning for a water extraction, fractured bedrock and possible kettle holes, a new seismic investigation was designed and carried out during summer 2014. Two seismic profiles each about 1 km long were acquired using a newly developed 200 m long prototype, comprising of 80-3C MEMs-based, landstreamer system. To provide velocity information at larger depths (and longer offsets), fifty-two 10-Hz 1C wireless sensors spaced at about every 20 m were used. A Bobcat mounted drop-hammer source, generating three hits per source location, was used as the seismic source. This proved to be a good choice given the attenuative nature of the dry sediments down to about 20 m depth. One of the seismic lines overlaps an existing streamer survey and thus allows a comparison between the system used in this study and the one employed before. Except at a few places where the loose sands mixed with leaves affected the coupling, the data quality is excellent with several reflections identifiable in the raw shot gathers. First arrivals were easily identifiable in almost all the traces and shots and this allowed obtaining velocity

  20. Site Characterization for a Deep Borehole Field Test

    Science.gov (United States)

    Kuhlman, K. L.; Hardin, E. L.; Freeze, G. A.; Sassani, D.; Brady, P. V.

    2015-12-01

    The US Department of Energy Office of Nuclear Energy is at the beginning of 5-year Deep Borehole Field Test (DBFT) to investigate the feasibility of constructing and characterizing two boreholes in crystalline basement rock to a depth of 5 km (16,400 ft). The concept of deep borehole disposal for radioactive waste has some advantages over mined repositories, including incremental construction and loading, the enhanced natural barriers provided by deep continental crystalline basement, and reduced site characterization. Site characterization efforts need to determine an eligible site that does not have the following disqualifying characteristics: greater than 2 km to crystalline basement, upward vertical fluid potential gradients, presence of economically exploitable natural resources, presence of high permeability connection to the shallow subsurface, and significant probability of future seismic or volcanic activity. Site characterization activities for the DBFT will include geomechanical (i.e., rock in situ stress state, and fluid pressure), geological (i.e., rock and fracture infill lithology), hydrological (i.e., quantity of fluid, fluid convection properties, and solute transport mechanisms), and geochemical (i.e., rock-water interaction and natural tracers) aspects. Both direct (i.e., sampling and in situ testing) and indirect (i.e., borehole geophysical) methods are planned for efficient and effective characterization of these site aspects and physical processes. Borehole-based characterization will be used to determine the variability of system state (i.e., stress, pressure, temperature, and chemistry) with depth, and interpretation of material and system parameters relevant to numerical site simulation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE

  1. Utility service entrance in boreholes

    International Nuclear Information System (INIS)

    This study evaluates alternatives for utility service entrances to the repository. We determined the requirements for a repository utility supply. These requirements were defined as safety, maintainability, flexibility, reliability, cost efficiency, voltage regulation, and simplicity of operation. The study showed that repository shafts can best satisfy all requirements for location of the utility supply without the use of borehole penetrations into the repository. It is recommended that the shafts be utilized for utility distribution to the repository, and that the current NWTS program position to minimize the number of boreholes penetrating the repository horizon be maintained. 42 refs., 2 figs., 3 tabs

  2. Borehole camera technology and its application in the Three Gorges Project

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.Y.; Sheng, Q.; Ge, X.R. [Chinese Academy of Sciences, Inst. of Rock and Soil Mechanics, Wuhan (China); Law, K.T. [Carleton Univ., Ottawa, ON (Canada)

    2002-07-01

    The China's Three Gorges Project is the world's largest hydropower project, consisting of a 1,983-meter long and 185-meter high dam and 26 power generating units. Borehole examination has been conducted at the site to ensure stability of the slope of the ship lock used for navigation. This paper describes 2 systems for borehole inspection and viewing. Both methods of camera borehole technology provide a unique way for geologic engineers to observe the condition inside a borehole. The Axial-View Borehole Television (AVBTV) provides real-time frontal view of the borehole ahead of the probe, making it possible to detect where holes are blocked and to see cracks and other distinctive features in the strata. The Digital Panoramic Borehole Camera System (DPBCS) can collect, measure, save, analyze, manage and displace geological information about a borehole. It can also be used to determine the orientation of discontinuity, generate unrolled image and virtual core graph and conduct statistical analysis. Both camera systems have been demonstrated successfully at the Three Gorges Project for qualitative description of the borehole as well as for quantitative analysis of cracks existing in the rock. It has been determined that most of the cracks dip in the same general direction as the northern slope of the permanent ship lock of the Three Gorges Project. 12 refs., 1 tab., 9 figs.

  3. To evaluation of fractured tectonics associated with underground nuclear cavity of 5RTK borehole at Karachaganak salt dome

    International Nuclear Information System (INIS)

    Using of archive material, results of mercury measurements, seismic survey, neutron gamma-logging of the used and control-observation boreholes at Lira object, the morphology evaluation of fractured-permeable zones connected with the underground cavity formed after a peaceful nuclear test conducted in the 5RTK borehole was carried out. Preliminary solid model of fractured zones resulted from explosion in the rock block enclosing the studied underground cavity was made. (author)

  4. Seismic and GPR Imaging of the Springfield Fault System, Canterbury Plains, New Zealand

    Science.gov (United States)

    Carpentier, S.; Dorn, C.; Kaiser, A.; Campbell, F.; Campbell, J.; Green, A.; Horstmeyer, H.; Nobes, D.; Finnemore, M.

    2008-12-01

    The Springfield Fault System is part of a network of splays and overlapping faults that are generally hidden beneath Quaternary sediments of the Canterbury Plains on the South Island of New Zealand. These faults accommodate an important component of motion between the Pacific and Australian tectonic plates. Understanding the connection between local and broader regional tectonics is of major scientific interest. Furthermore, from a practical point of view, insight into the recent fault-related history of differential uplift and seismic hazard is of importance to the local population. Very limited exposures of the faults suggest that they are mostly west facing thrusts that have tilted (by 30°) and displaced Tertiary limestones and volcanics and Jurassic Torlesse basement. In an attempt to map faults of the Springfield Fault System, we have acquired high-resolution seismic reflection and ground-penetrating radar (GPR) data along four nearly parallel lines that range in length from 3 to 18 km. The seismic data were acquired using small explosive and hammer sources at 10 m intervals and a receiver spread comprising two hundred and forty 30-Hz geophones at 5 m intervals, yielding nominal 60-fold data with a CMP spacing of 2.5 m. The GPR data were recorded using 50 MHz antennas separated by 2 m. The processed seismic data reveal many of the features suggested by the limited surface exposures. Clearly visible tilted packets of strong reflections originate from the Tertiary limestone and volcanic sequences and the Jurassic Torlesse basement. Indirect, but convincing evidence is found for the fault strands. They are represented by narrow bands of diminished reflectivity and truncations and vertical offsets of reflections. Active folding is also suspected, given that the folded Tertiary blocks seem to deform the overlying Quaternary sediments. The GPR data should constrain possible continuations of the indicated faults and folds into the overlying Quaternary sediments. An

  5. 基于Gabor滤波器族的地震图像增强算法%Seismic image enhancement algorithm based on Gabor filter bank

    Institute of Scientific and Technical Information of China (English)

    刘天时; 杨雪; 李湘眷

    2015-01-01

    为在增强地震剖面图像时获取纹线的构造及层序信息,提出一种基于地震剖面图像纹线方向的地震图像增强算法。根据地震剖面纹线的方向性,设计一个Gabor滤波器族,用其对低频分量图进行滤波去噪。利用小波变换与Gabor滤波器族各自的优点,实现地震剖面图像纹线的增强,提高整体运算效率。仿真结果表明,该算法对地震剖面图像处理后,均方误差与峰值信噪比均有明显的改善。%To obtain the structure and sequence information of stripe lines accurately while enhancing the seismic profile image ,a seismic image enhancement algorithm was proposed based on the directions of stripe lines on seismic profile image .Based on the directionality of stripe lines on seismic profile image ,a Gabor filter bank was designed ,by which low frequency component figure was filtered and denoised .With the advantages of wavelet transform and Gabor filter bank ,the enhancement of stripe lines on seismic profile was realized ,which improved overall operational efficiency .The simulation results show that the mean square er‐ror and peak signal to noise ratio are improved obviously after the seismic profile image being processed using this algorithm .

  6. Joint Audio-Magnetotelluric and Passive Seismic Imaging of the Cerdanya Basin

    Science.gov (United States)

    Gabàs, A.; Macau, A.; Benjumea, B.; Queralt, P.; Ledo, J.; Figueras, S.; Marcuello, A.

    2016-09-01

    The structure of Cerdanya Basin (north-east of Iberian Peninsula) is partly known from geological cross sections, geological maps and vintage geophysical data. However, these data do not have the necessary resolution to characterize some parts of Cerdanya Basin such as the thickness of soft soil, geometry of bedrock or geometry of geological units and associated faults. For all these reasons, the main objective of this work is to improve this deficiency carrying out a detailed study in this Neogene basin applying jointly the combination of passive seismic methods ( H/V spectral ratio and seismic array) and electromagnetic methods (audio-magnetotelluric and magnetotelluric method). The passive seismic techniques provide valuable information of geometry of basement along the profile. The maximum depth is located near Alp village with a bedrock depth of 500 m. The bedrock is located in surface at both sites of profile. The Neogene sediments present a shear-wave velocity between 400 and 1000 m/s, and the bedrock basement presents a shear-wave velocity values between 1700 and 2200 m/s. These results are used as a priori information to create a 2D resistivity initial model which constraints the inversion process of electromagnetic data. We have obtained a 2D resistivity model which is characterized by (1) a heterogeneous conductivity zone (methods is essential in producing geophysical meaningful models.

  7. Imaging the continental lithosphere: Perspectives from global and regional anisotropic seismic tomography

    Science.gov (United States)

    Lebedev, Sergei; Schaeffer, Andrew

    2016-04-01

    Azimuthal seismic anisotropy, the dependence of seismic wave speeds on propagation azimuth, is largely due to fabrics within the Earth's crust and mantle, produced by deformation. It thus provides constraints on the distribution and evolution of deformation within the upper mantle. Lateral variations in isotropic-average seismic velocities reflect variations in the temperature of the rocks at depth. Seismic tomography thus also provides a proxy for lateral changes in the temperature and thickness of the lithosphere. It can map the deep boundaries between tectonic blocks with different properties and age of the lithosphere. Our new global, anisotropic, 3D tomographic models of the upper mantle and the crust are constrained by an unprecedentedly large global dataset of broadband waveform fits (over one million seismograms) and provide improved resolution of the lithosphere at the global scale, compared to other available models. The most prominent high-velocity anomalies, seen down to around 200 km depths, indicate the cold, thick, stable mantle lithosphere beneath Precambrian cratons. The tomography resolves the deep boundaries of the cratons even where they are not exposed and difficult to map at the surface. Our large waveform dataset, with complementary large global networks and high-density regional array data, also produces improved resolution of azimuthal anisotropy patterns, so that regional-scale variations related to lithospheric deformation and mantle flow can be resolved, in particular in densely sampled regions. The depth of the boundary between the cold, rigid lithosphere (preserving ancient, frozen anisotropic fabric) and the rheologically weak asthenosphere (characterized by fabric developed recently) can be inferred from the depth layering of seismic anisotropy and its comparison to the past and present plate motions. Beneath oceans, the lithosphere-asthenosphere boundary (LAB) is defined clearly by the layering of anisotropy, with a dependence on

  8. The Application of Seismic Array Techniques to Image UXO-Contaminated Littoral Environments

    Science.gov (United States)

    Gritto, R.; Korneev, V.; Nihei, K.; Johnson, L.

    2004-12-01

    We investigate the application of seismic array techniques to increase the energy radiation and resolution of seismic waves in littoral areas to improve the success rate of detecting UXO in contaminated underwater sites. The investigation is carried out based on numerical modeling, including 2-D finite difference modeling and 3-D analytical solutions of the problem. In addition to various UXO orientations, we also modeled the presence of clutter in the subsurface. An array of 31 source and receiver elements was located floating in the water as well as sited on the seafloor, which allowed the comparison between single source-receiver combinations and beam-forming techniques. The numerical forward modeling involved noise-free and noisy data as well as interferences by free surface reflections (off the water-air interface), which produced the strongest phases on the seismograms. The inversion of the scattered seismic energy was performed using a 2-D eikonal solver (curved rays), which stacked and located the recorded amplitudes in space to determine the location of the UXO. The inversion also included the determination of the best fitting velocity model for the bay mud. The results of the 2-D modeling indicated that a single, horizontally oriented, UXO could be well detected as a function of depth and horizontal location. In the case of the source-receiver array being placed on the seafloor, the edges of the UXO were resolved indicating its horizontal extent, while the top of the UXO was correctly located. The cases of a second, vertically oriented, UXO and clutter located 0.1 m next to the first UXO, produced similar results. In each case the two objects produced slight interference in the backscattered seismic signal, yet the resolution of the seismic wave was still good enough to resolve the two objects from each other. The introduction of a rippled water-seafloor interface during the forward modeling didn't change the results for the case of a floating source

  9. Comprehensive observation and modeling of earthquake and temperature-related seismic velocity changes in northern Chile with passive image interferometry

    Science.gov (United States)

    Richter, Tom; Sens-Schönfelder, Christoph; Kind, Rainer; Asch, Günter

    2014-06-01

    We report on earthquake and temperature-related velocity changes in high-frequency autocorrelations of ambient noise data from seismic stations of the Integrated Plate Boundary Observatory Chile project in northern Chile. Daily autocorrelation functions are analyzed over a period of 5 years with passive image interferometry. A short-term velocity drop recovering after several days to weeks is observed for the Mw 7.7 Tocopilla earthquake at most stations. At the two stations PB05 and PATCX, we observe a long-term velocity decrease recovering over the course of around 2 years. While station PB05 is located in the rupture area of the Tocopilla earthquake, this is not the case for station PATCX. Station PATCX is situated in an area influenced by salt sediment in the vicinity of Salar Grande and presents a superior sensitivity to ground acceleration and periodic surface-induced changes. Due to this high sensitivity, we observe a velocity response of several regional earthquakes at PATCX, and we can show for the first time a linear relationship between the amplitude of velocity drops and peak ground acceleration for data from a single station. This relationship does not hold true when comparing different stations due to the different sensitivity of the station environments. Furthermore, we observe periodic annual velocity changes at PATCX. Analyzing data at a temporal resolution below 1 day, we are able to identify changes with a period of 24 h, too. The characteristics of the seismic velocity with annual and daily periods indicate an atmospheric origin of the velocity changes that we confirm with a model based on thermally induced stress. This comprehensive model explains the lag time dependence of the temperature-related seismic velocity changes involving the distribution of temperature fluctuations, the relationship between temperature, stress and velocity change, plus autocorrelation sensitivity kernels.

  10. The application of active-source seismic imaging techniques to transtensional problems the Walker Lane and Salton Trough

    Science.gov (United States)

    Kell, Anna Marie

    The plate margin in the western United States is an active tectonic region that contains the integrated deformation between the North American and Pacific plates. Nearly focused plate motion between the North American and Pacific plates within the northern Gulf of California gives way north of the Salton Trough to more diffuse deformation. In particular a large fraction of the slip along the southernmost San Andreas fault ultimately bleeds eastward, including about 20% of the total plate motion budget that finds its way through the transtensional Walker Lane Deformation Belt just east of the Sierra Nevada mountain range. Fault-bounded ranges combined with intervening low-lying basins characterize this region; the down-dropped features are often filled with water, which present opportunities for seismic imaging at unprecedented scales. Here I present active-source seismic imaging from the Salton Sea and Walker Lane Deformation Belt, including both marine applications in lakes and shallow seas, and more conventional land-based techniques along the Carson range front. The complex fault network beneath the Salton Trough in eastern California is the on-land continuation of the Gulf of California rift system, where North American-Pacific plate motion is accommodated by a series of long transform faults, separated by small pull-apart, transtensional basins; the right-lateral San Andreas fault bounds this system to the north where it carries, on average, about 50% of total plate motion. The Salton Sea resides within the most youthful and northerly "spreading center" in this several thousand-kilometer-long rift system. The Sea provides an ideal environment for the use of high-data-density marine seismic techniques. Two active-source seismic campaigns in 2010 and 2011 show progression of the development of the Salton pull-apart sub-basin and the northerly propagation of the Imperial-San Andreas system through time at varying resolutions. High fidelity seismic imagery

  11. Multichannel Seismic Imaging of the Rivera Plate Subduction at the Seismogenic Jalisco Block Area (Western Mexican Margin)

    Science.gov (United States)

    Bartolome, Rafael; Górriz, Estefanía; Dañobeitia, Juanjo; Cordoba, Diego; Martí, David; Cameselle, Alejandra L.; Núñez-Cornú, Francisco; Bandy, William L.; Mortera-Gutiérrez, Carlos A.; Nuñez, Diana; Castellón, Arturo; Alonso, Jose Luis

    2016-06-01

    During the TSUJAL marine geophysical survey, conducted in February and March 2014, Spanish, Mexican and British scientists and technicians explored the western margin of Mexico, considered one of the most active seismic zones in America. This work aims to characterize the internal structure of the subduction zone of the Rivera plate beneath the North American plate in the offshore part of the Jalisco Block, to link the geodynamic and the recent tectonic deformation occurring there with the possible generation of tsunamis and earthquakes. For this purpose, it has been carried out acquisition, processing and geological interpretation of a multichannel seismic reflection profile running perpendicular to the margin. Crustal images show an oceanic domain, dominated by subduction-accretion along the lower slope of the margin with a subparallel sediment thickness of up to 1.6 s two-way travel time (approx. 2 km) in the Middle American Trench. Further, from these data the region appears to be prone to giant earthquake production. The top of the oceanic crust (intraplate reflector) is very well imaged. It is almost continuous along the profile with a gentle dip (<10°); however, it is disrupted by normal faulting resulting from the bending of the plate during subduction. The continental crust presents a well-developed accretionary prism consisting of highly deformed sediments with prominent slumping towards the trench that may be the result of past tsunamis. Also, a bottom simulating reflector (BSR) is identified in the first half a second (twtt) of the section. High amplitude reflections at around 7-8 s twtt clearly image a discontinuous Moho, defining a very gentle dipping subduction plane.

  12. Exploratory borehole Kaisten. Geology - appendix

    International Nuclear Information System (INIS)

    The Kaisten borehole was the fifth (after Boettstein, Weiach, Riniken and Schafisheim) in Nagra's deep drilling programme in Northern Switzerland. It is located within the community of Kaisten, Canton Aargau, approximately 3 km south-west of Laufenburg railway station. The final depth of the borehole was 1306 m. Drilling began on 13th February 1984, continued up to 27th June 1984 and was carried out almost exclusively using the conventional rotary drilling method. With the exception of a 5.5 m-long section in the Muschelkalk and two shallow centering boreholes, the whole drilled section was cored. From a depth of 321.5 m in the Crystalline, removal of cores was done by wire core drilling. The wide range of field and laboratory investigations carried out included stratigraphic-sedimentological and mineralogical-petrographic programmes, as well as different petrophysical, geochemical and isotope geochemistry investigation. This report is a summary of all data acquired up to the end of December 1986. Beneath a sedimentary cover just 300 m thick, with Muschelkalk at the top and Permian at the base, the Kaisten borehole entered the crystalline basement at a depth of 296.5 m; investigations were carried out down to a depth of 1306 m. (author) 55 figs., 42 tabs

  13. High-resolution seismic-reflection imaging 25 years of change in I-70 sinkhole, Russell County, Kansas

    Science.gov (United States)

    Miller, R.D.; Steeples, D.W.; Lambrecht, J.L.; Croxton, N.

    2006-01-01

    Time-lapse seismic reflection imaging improved our understanding of the consistent, gradual surface subsidence ongoing at two sinkholes in the Gorham Oilfield discovered beneath a stretch of Interstate Highway 70 through Russell and Ellis Counties in Kansas in 1966. With subsidence occurring at a rate of around 10 cm per year since discovery, monitoring has been beneficial to ensure public safety and optimize maintenance. A miniSOSIE reflection survey conducted in 1980 delineated the affected subsurface and successfully predicted development of a third sinkhole at this site. In 2004 and 2005 a high-resolution vibroseis survey was completed to ascertain current conditions of the subsurface, rate and pattern of growth since 1980, and potential for continued growth. With time and improved understanding of the salt dissolution affected subsurface in this area it appears that these features represent little risk to the public from catastrophic failure. However, from an operational perspective the Kansas Department of Transportation should expect continued subsidence, with future increases in surface area likely at a slightly reduced vertical rate. Seismic characteristics appear empirically consistent with gradual earth material compaction/settling. ?? 2005 Society of Exploration Geophysicists.

  14. Seismic imaging and analysis of source and migration within an integrated hydrocarbon system study: Northern Gulf of Mexico Basin

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Oliver P.; Hood, Kenneth C.; Harrison, Stanley C. [Exxon Exploration Co., Houston, TX (United States); Wenger, Lloyd M. [Exxon Production Research Co., Houston, TX (United States)

    1995-12-31

    The sources for hydrocarbons in young Tertiary reservoirs of the offshore Gulf of Mexico have been enigmatic in the past due to the lack of source rock penetration in offshore drilling. Exxon formed a multidisciplinary team to address source, maturation, and migration in the northern Gulf of Mexico. The study was initiated in a pilot area east of the Mississippi River Delta where the complete hydrocarbon system can be seismically imaged, then expanded to the west across much of the shelf and slope. Hydrocarbons from seeps and reservoirs were geochemically characterized across the entire northern Gulf of Mexico Basin, and direct oil to source rock correlations were made both offshore (in pilot area) and onshore. Modern 2-D and 3-D seismic was used to develop a geologic framework and to map potential offshore source intervals. The major sources identified offshore are centered on the Eocene, Turonian, Tithonian, and Oxfordian, and correspond to second-order sequence stratigraphic transgressions. (author). 1 fig., 1 tab

  15. Seismic imaging of glaciomarine sediments of Antarctica: Optimizing the acquisition parameters

    Digital Repository Service at National Institute of Oceanography (India)

    Pandey, D.; Chaubey, A.K.; Rajan, S.

    , Quat. Sci. Rev., 10 (1991) 215-223. 3 Stagg H M J, The structure and origin of Prydz Bay and MacRobertson shelf, East Antarctica, Tectonophysics, 114 (1985) 315-340. 4 Cooper A K, Barrett P J, Hinz K, Traube V, Leitchenkov G & Stagg H M J... of Physics Congress, Paper 0512M, (Hobart, University of Tasmania) 1996. 10 Cooper A K, O’brien P E & ODP LEG 188 Shipboard Scientific Party, Early stages of East Antarctic glaciation– insights from drilling and seismic reflection data in the Prydz Bay...

  16. Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Eisses, A.; Kell, A.; Kent, G. [UNR; Driscoll, N. [UCSD; Karlin, R.; Baskin, R. [USGS; Louie, J. [UNR; Pullammanappallil, S. [Optim

    2016-08-01

    Amy Eisses, Annie Kell, Graham Kent, Neal Driscoll, Robert Karlin, Rob Baskin, John Louie, and Satish Pullammanappallil, 2011, Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada: presented at Geothermal Resources Council Annual Meeting, San Diego, Oct. 23-26.

  17. Preliminary 3d depth migration of a network of 2d seismic lines for fault imaging at a Pyramid Lake, Nevada geothermal prospect

    Energy Technology Data Exchange (ETDEWEB)

    Frary, R.; Louie, J. [UNR; Pullammanappallil, S. [Optim; Eisses, A.

    2016-08-01

    Roxanna Frary, John N. Louie, Sathish Pullammanappallil, Amy Eisses, 2011, Preliminary 3d depth migration of a network of 2d seismic lines for fault imaging at a Pyramid Lake, Nevada geothermal prospect: presented at American Geophysical Union Fall Meeting, San Francisco, Dec. 5-9, abstract T13G-07.

  18. Deblending of seismic data

    NARCIS (Netherlands)

    Mahdad, A.

    2012-01-01

    Seismic imaging is one of the most common geophysical techniques for hydrocarbon exploration. Seismic acquisition is a trade-off between economy and quality. In conventional acquisition, the time intervals between successively firing sources are large enough to avoid interference in time. To obtain

  19. Solvability by semigroup : Application to seismic imaging with complex decomposition of wave equations and migration operators with idempotents

    CERN Document Server

    Lau, August

    2011-01-01

    The classical approach of solvability using group theory is well known and one original motivation is to solve polynomials by radicals. Radicals are square, cube, square root, cube root etc of the original coefficients for the polynomial. A polynomial is solvable by radicals if the permutation group is solvable. This is exact solvability via group theory. With modern computers, we might need to relax our definition of exact solvability and move towards practical solvability. We will address seismic imaging as an example of practical solvability by semigroup theory. The difference between semigroup and group is that the semigroup operators do not have to be invertible as in group operators. Using the metaphor of complex decomposition, we will decompose an operator into simple part and complex part. The simple part of the operator is solvable by numerical methods. The complex part of the operator is interpretable but not numerically solvable. It is sometimes called the evanescent energy in geophysics.

  20. Two-dimensional Co-Seismic Surface Displacements Field of the Chi-Chi Earthquake Inferred from SAR Image Matching

    Directory of Open Access Journals (Sweden)

    Jian-Jun Zhu

    2008-10-01

    Full Text Available The Mw=7.6 Chi-Chi earthquake in Taiwan occurred in 1999 over the Chelungpu fault and caused a great surface rupture and severe damage. Differential Synthetic Aperture Radar Interferometry (DInSAR has been applied previously to study the co-seismic ground displacements. There have however been significant limitations in the studies. First, only one-dimensional displacements along the Line-of-Sight (LOS direction have been measured. The large horizontal displacements along the Chelungpu fault are largely missing from the measurements as the fault is nearly perpendicular to the LOS direction. Second, due to severe signal decorrelation on the hangling wall of the fault, the displacements in that area are un-measurable by differential InSAR method. We estimate the co-seismic displacements in both the azimuth and range directions with the method of SAR amplitude image matching. GPS observations at the 10 GPS stations are used to correct for the orbital ramp in the amplitude matching and to create the two-dimensional (2D co-seismic surface displacements field using the descending ERS-2 SAR image pair. The results show that the co-seismic displacements range from about -2.0 m to 0.7 m in the azimuth direction (with the positive direction pointing to the flight direction, with the footwall side of the fault moving mainly southwards and the hanging wall side northwards. The displacements in the LOS direction range from about -0.5 m to 1.0 m, with the largest displacement occuring in the northeastern part of the hanging wall (the positive direction points to the satellite from ground. Comparing the results from amplitude matching with those from DInSAR, we can see that while only a very small fraction of the LOS displacement has been recovered by the DInSAR mehtod, the azimuth displacements cannot be well detected with the DInSAR measurements as they are almost perpendicular to the LOS. Therefore, the amplitude matching method is obviously more

  1. Imaging fluid channels within the NW Bohemia/Vogtland region using ambient seismic noise and MFP analysis

    Science.gov (United States)

    Umlauft, Josefine; Flores Estrella, Hortencia; Korn, Michael

    2016-04-01

    Presently ongoing geodynamic processes within the intracontinental lithospheric mantle give rise to different natural phenomena in the NW Bohemia/Vogtland region, among others: earthquake swarms, mineral springs and degassing zones of mantle-derived fluids (mofettes). Their interaction mechanisms and relations are not yet fully understood, therefore they are intensively studied using geophysical, geological and biological approaches. We focus on the investigation of near-surface channels that conduct mantle-originating fluids as well as CO2 near the Earth's surface. We aim at the detection, imaging and characterization of the fluid channel structure as well as the observation of their temporal and spatial variability. The Hartoušov Mofette Field within the Cheb Basin (NW Bohemia/Vogtland region) is a key site to study fluid flow as it is characterized by strong surface degassing of CO2. On this field, we applied the noise source localization method Matched Field Processing (MFP) considering the fluid flow as seismic noise source. Within multiple campaigns, we measured ambient seismic noise in continous mode during the night to avoid cultural noise generated by human activity. We used arrays of about 30 randomly distributed stations with 1 to 4 ha extent. We compared the surface position of the MFP output with punctual CO2 flux measurements performed by Nickschick et al. (2015) and observed a strong relation between high CO2 flux values and the position of the MFP maxima. Additionally, we observed surface indicators for CO2 degassing on the same positions of the MFP predicted noise sources: wet and dry mofettes accompanied by bog cotton, bug traps and brown to yellow coloured grass. The MFP maxima can be followed into the subsoil to image the fluid channel structure down to 50 m depth. We analyzed the influence of the array size on the vertical and horizontal MFP resolution as well as the temporal and spatial variability of the flow activity.

  2. Sedimentary underplating at the Cascadia mantle-wedge corner revealed by seismic imaging

    Science.gov (United States)

    Calvert, Andrew J.; Preston, Leiph A.; Farahbod, Amir M.

    2011-08-01

    Earth's largest earthquakes occur in subduction zones, along the boundary between the subducting and overriding plates. Non-volcanic tremor generated by slow slip between the plates is thought to originate on, or near, this boundary. Earthquakes also occur in the down-going plate as fluids are released, and zones of anomalously low seismic velocities observed beneath several subduction zones are interpreted to be the subducting oceanic crust. Yet, the exact location of the plate boundary remains uncertain. Here we interpret a three-dimensional seismic tomography model from the northern Cascadia subduction zone in the northwest USA. We find that the low-velocity zone varies considerably along the Cascadia margin. In places, we observe the low-velocity zone to crop out at the surface and separate from the descending plate at depths of 35-40km. We argue that the low-velocity zone here cannot represent oceanic crust as previously suggested, and instead the zone mostly represents sediments that have been subducted and underplated beneath the North American continent. We also find that tremor signals correlate with the position of the low-velocity zone, implying that slow slip and tremor may be facilitated by trapped fluids and high pore fluid pressures in subducted sedimentary rocks at, or close to the plate boundary. Our results also imply that the plate boundary beneath Cascadia is much deeper than previously thought.

  3. Comparison of seismic sources for imaging geologic structures on the Oak Ridge Reservation, Tennessee

    International Nuclear Information System (INIS)

    In this study, five non-invasive swept sources, three non-invasive impulsive sources and one invasive impulsive source were compared. Previous shallow seismic source tests (Miller and others, 1986, 1992, 1994) have established that site characteristics should be considered in determining the optimal source. These studies evaluated a number of invasive sources along with a few non-invasive impulsive sources. Several sources (particularly the high frequency vibrators) that were included in the ORR test were not available or not practical during previous tests, cited above. This study differs from previous source comparisons in that it (1) includes many swept sources, (2) is designed for a greater target depth, (3) was conducted in a very different geologic environment, and (4) generated a larger and more diverse data set (including high fold CMP sections and walkaway vertical seismic profiles) for each source. The test site is centered around test injection well HF-2, between the southern end of Waste Area Grouping 5 (WAG 5) and the High Flux Isotope Reactor (HFIR)

  4. VSP [Vertical Seismic Profiling] and cross hole tomographic imaging for fracture characterization

    International Nuclear Information System (INIS)

    For the past several years LBL has been carrying out experiments at various fractured rock sites to determine the fundamental nature of the propagation of seismic waves in fractured media. These experiments have been utilizing high frequency (1000 to 10000 Hz.) signals in a cross-hole configuration at scales of several tens of meters. Three component sources and receivers are used to map fracture density, and orientation. The goal of the experiments has been to relate the seismological parameters to the hydrological parameters, if possible, in order to provide a more accurate description of a starting model for hydrological characterization. The work is ultimately aimed at the characterization and monitoring of the Yucca Mountain site for the storage of nuclear waste. In addition to these controlled experiments multicomponent VSP work has been carried out at several sites to determine fracture characteristics. The results to date indicate that both P-wave and S-wave can be used to map the location of fractures. In addition, fractures that are open and conductive are much more visible to seismic waves that non-conductive fractures. The results of these tests indicate direct use in an unsaturated environment. 12 refs., 10 figs

  5. Borehole geophysical investigations of Lavia deep testhole, Finland

    International Nuclear Information System (INIS)

    According to the Goverment's decision in principle in 1983 Industrial Power Company Ltd (TVO) is making preparations for all the steps of final disposal of the spent fuel produced by its power plants. Before the actual site investigation phase, TVO drilled a deep borehole in Lavia, Western Finland. The borehole is used during 1984-85 for testing investigation techniques and methods used for bedrock characterization. Borehole geophysical loggings performed in Lavia consisted of galvanic electrical, transient electromagnetic, radiometric, temperature, seismic and magnetic msurements. This composite survey provided both lithological and structural information of rock mass. The neutron-neutron, density, natural gamma radiation and susceptibility methods characterized rock type. Fracturing and its type could be interpreted most effectively with resistivity, acoustic P-wave velocity and density logs. Temperature and tube-wave measurements revealed several fractured zones related to possible water flow in rock. Lavia investigations indicated that a high quality of instrumentation and careful calibration are necessary for site investigations. The large amount of log data also requires efficient data collection and processing systems both in the field and laboratory. (author)

  6. Seismic VSP and crosshole investigations in Olkiluoto, 2002

    International Nuclear Information System (INIS)

    Vertical Seismic Profiling (VSP) and crosshole seismic surveys were conducted during 2002 at Olkiluoto site in Eurajoki, Finland. The VSP investigations were carried out in three boreholes (KR13, KR14 and KR19) with ten or eleven shot points for each borehole. Additionally, the data from a VSP investigation carried out in 1990 in borehole KR5 had been reprocessed with state of the art tools. One crosshole section (KR14-KR15 at 20 - 240 m interval) was measured and processed. Different receiver types were used for the VSP and crosshole: a 3-component geophone chain for VSP and a hydrophone chain for crosshole. VSP surveys have been carried out with a VIBSIST-1000 source - a time-distributed swept-impact source - instead of explosives. With this source, the seismic signals are produced as rapid series of impacts, the impact intervals being monotonically increased to achieve a nonrepeatable sequence. The VIBSIST-1000 uses a tractor-mounted hydraulic rock-breaker, powered through a computer controlled servo-hydraulic flow regulator. Using standard construction equipment ensures that the VIBSIST sources are safe, non-destructive and environmentally friendly. This also makes the method reliable and cost effective. The new VIBSIST source produces signals with levels of energy comparable to explosives. The VIBSIST appears to be more stable, but its most significant advantages are the low cost of preparation of the shot points and the speed of the acquisition. Crosshole surveys were carried out with a piezoelectric borehole source, the VIBSISTSPH54, which operates on the same principle as the surface VIBSIST source. The wide diversity of reflection angles, the local variations of reflectivity and, generally, the relatively weak seismic response of faults and fractured zones in crystalline rock demand intensive processing. The first stage of the processing sequence focuses on eliminating such wave-fields as the direct P, direct S, tube-waves and ground-roll, so that the

  7. Borehole Water Level Measurements in Kamchatka and Broadband Records of Very Large (M≧7.6) Earthquakes

    Science.gov (United States)

    Kasimova, V.; Kopylova, G.

    2010-12-01

    The impact of seismic waves from distant very large earthquakes can be accompanied by various changes in the groundwater mode. Such effects are observed at distances up to thousands of kilometers from the epicenter and indicate a change in the stress-strain state of geological environment. One of the methods of geophysical monitoring of seismically active regions is the water level observations in the boreholes. Different variations of water level caused by the passage of seismic waves from the very large earthquakes are recorded in piezometric boreholes in Kamchatka. In connection with the very large earthquakes it was observed four types of variations of water level in borehole UZ-5 (Kamchatka, Russia). To quantify the impact of the characteristics of seismic waves on the state of groundwater can be used assess the amplitude and frequency of maximum phase ground motion (velocity, displacement and acceleration) according to the registration of seismic signals of broadband seismic instrumentation. The purpose of this study is to determine the dependence of expression of different types of variations of water level in borehole UZ-5 from the amplitude and frequency of seismic signals from the very large earthquakes recorded by IRIS seismic equipment on the seismic station Petropavlovsk (s/s PET). We used records of earthquakes since 1997, M≧7.6 and 10-minute data of water level meter observations on the borehole UZ-5. Analysis of seismic signals in the time and frequency-time domain with the assessment times, amplitudes and periods of maximum oscillation phases was carried out using the interactive software DIMAS. The restoration of initial ground motion (displacement, acceleration) was carried out. The evaluation of amplitudes and frequency content of maximum oscillation phases of ground and the comparison with the variations of water level in the hole UZ-5 was executed. Dependences of the amplitude-frequency content of maximum oscillation phases of ground

  8. Seismic While Drilling Case Study in Shengli Oilfield, Eastern China

    Science.gov (United States)

    Wang, L.; Liu, H.; Tong, S.; Zou, Z.

    2015-12-01

    Seismic while drilling (SWD) is a promising borehole seismic technique with reduction of drilling risk, cost savings and increased efficiency. To evaluate the technical and economic benefits of this new technique, we carried out SWD survey at well G130 in Shengli Oilfield of Eastern China. Well G130 is an evaluation well, located in Dongying depression at depth more than 3500m. We used an array of portable seismometers to record the surface SWD-data, during the whole drilling progress. The pilot signal was being recorded continuously, by an accelerometer mounted on the top of the drill string. There were also two seismometers buried in the drill yard, one near diesel engine and another near derrick. All the data was being recorded continuously. According to mud logging data, we have processed and analyzed all the data. It demonstrates the drill yard noise is the primary noise among the whole surface wavefield and its dominant frequency is about 20Hz. Crosscorrelation of surface signal with the pilot signal shows its SNR is severely low and there is no any obvious event of drill-bit signals. Fortunately, the autocorrelation of the pilot signal shows clear BHA multiple and drill string multiple. The period of drill string multiple can be used for establishing the reference time (so-called zero time). We identified and removed different noises from the surface SWD-data, taking advantages of wavefield analysis. The drill-bit signal was retrieved from surface SWD-data, using seismic interferometry. And a reverse vertical seismic profile (RVSP) data set for the continuous drilling depth was established. The subsurface images derived from these data compare well with the corresponding images of 3D surface seismic survey cross the well.

  9. MWD tool for deep, small diameter boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Buytaert, J.P.R.; Duckworth, A.

    1992-03-17

    This patent describes an apparatus for measuring a drilling parameters while drilling a borehole in an earth formation, wherein the borehole includes a small diameter deep borehole portion and a large diameter upper borehole portion. It includes small diameter drillstring means for drilling the deep borehole portion; sensor means, disposed within the small diameter drillstring means, for measuring a drilling parameter characteristic of the deep portion of the borehole while drilling the deep portion of the borehole and for providing sensor output signals indicative of the measured parameter; an upper drillstring portion extending between the surface of the formation and the small diameter drillstring means, the upper drillstring portion including a large diameter drillstring portion; data transmission means disposed within the large diameter drillstring portion and responsive to the sensor output.

  10. Seismic images of the base of the gas hydrate stability zone in Northwest walker ridge, Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    McConnell, D.R. [Fugro GeoServices, Inc (United States); Kendall, B.A. [Oil and Gas Development Corp., Kerr-McGee, Islamabad (Pakistan)

    2002-10-01

    The gas hydrate stability zone, the zone below the sea-floor where gas and water should form gas hydrate is predicted to be present in shallow sediments in deep-water areas around the world, including the deep-water Gulf of Mexico. Few, if any, bottom simulating reflectors (BSR) or other manifestations of the gas hydrate stability zone have been interpreted in the Gulf of Mexico. We show convincing images of the base of the gas hydrate stability zone extracted from exploration 3-D data in Northwest Walker Ridge in the Gulf of Mexico. This area is on the margin of an uplifted and compressed mini-basin and in the vicinity of numerous giant gas mounds at the sea-floor. Shallow stratigraphy includes laterally extensive, steeply dipping basin floor silts and silty sands. This paper shows images of hydrate-trapped gas at multiple reflectors at depths that are coincident with the predicted base of the hydrate stability zone if modeled with a geothermal gradient of 19.6{+-}0.5 deg C/km. A BSR is seen in the seismic data in vertical section, but the more convincing images of the base of gas hydrate stability are seen in map view. (authors)

  11. Joint Audio-Magnetotelluric and Passive Seismic Imaging of the Cerdanya Basin

    Science.gov (United States)

    Gabàs, A.; Macau, A.; Benjumea, B.; Queralt, P.; Ledo, J.; Figueras, S.; Marcuello, A.

    2016-06-01

    The structure of Cerdanya Basin (north-east of Iberian Peninsula) is partly known from geological cross sections, geological maps and vintage geophysical data. However, these data do not have the necessary resolution to characterize some parts of Cerdanya Basin such as the thickness of soft soil, geometry of bedrock or geometry of geological units and associated faults. For all these reasons, the main objective of this work is to improve this deficiency carrying out a detailed study in this Neogene basin applying jointly the combination of passive seismic methods (H/V spectral ratio and seismic array) and electromagnetic methods (audio-magnetotelluric and magnetotelluric method). The passive seismic techniques provide valuable information of geometry of basement along the profile. The maximum depth is located near Alp village with a bedrock depth of 500 m. The bedrock is located in surface at both sites of profile. The Neogene sediments present a shear-wave velocity between 400 and 1000 m/s, and the bedrock basement presents a shear-wave velocity values between 1700 and 2200 m/s. These results are used as a priori information to create a 2D resistivity initial model which constraints the inversion process of electromagnetic data. We have obtained a 2D resistivity model which is characterized by (1) a heterogeneous conductivity zone (<40 Ohm m) that corresponds to shallow part of the model up to 500 m depth in the centre of the profile. These values have been associated with Quaternary and Neogene sediments formed by silts, clays, conglomerates, sandstones and gravels, and (2) a deeper resistive zone (1000-3000 Ohm m) interpreted as Palaeozoic basement (sandstones, limestones and slates at NW and conglomerates and microconglomerates at SE). The resistive zone is truncated by a discontinuity at the south-east of the profile which is interpreted as the Alp-La Tet Fault. This discontinuity is represented by a more conductive zone (600 Ohm m approx.) and is explained as

  12. Joint Audio-Magnetotelluric and Passive Seismic Imaging of the Cerdanya Basin

    Science.gov (United States)

    Gabàs, A.; Macau, A.; Benjumea, B.; Queralt, P.; Ledo, J.; Figueras, S.; Marcuello, A.

    2016-09-01

    The structure of Cerdanya Basin (north-east of Iberian Peninsula) is partly known from geological cross sections, geological maps and vintage geophysical data. However, these data do not have the necessary resolution to characterize some parts of Cerdanya Basin such as the thickness of soft soil, geometry of bedrock or geometry of geological units and associated faults. For all these reasons, the main objective of this work is to improve this deficiency carrying out a detailed study in this Neogene basin applying jointly the combination of passive seismic methods ( H/V spectral ratio and seismic array) and electromagnetic methods (audio-magnetotelluric and magnetotelluric method). The passive seismic techniques provide valuable information of geometry of basement along the profile. The maximum depth is located near Alp village with a bedrock depth of 500 m. The bedrock is located in surface at both sites of profile. The Neogene sediments present a shear-wave velocity between 400 and 1000 m/s, and the bedrock basement presents a shear-wave velocity values between 1700 and 2200 m/s. These results are used as a priori information to create a 2D resistivity initial model which constraints the inversion process of electromagnetic data. We have obtained a 2D resistivity model which is characterized by (1) a heterogeneous conductivity zone (<40 Ohm m) that corresponds to shallow part of the model up to 500 m depth in the centre of the profile. These values have been associated with Quaternary and Neogene sediments formed by silts, clays, conglomerates, sandstones and gravels, and (2) a deeper resistive zone (1000-3000 Ohm m) interpreted as Palaeozoic basement (sandstones, limestones and slates at NW and conglomerates and microconglomerates at SE). The resistive zone is truncated by a discontinuity at the south-east of the profile which is interpreted as the Alp-La Tet Fault. This discontinuity is represented by a more conductive zone (600 Ohm m approx.) and is explained

  13. 3D imaging of the Corinth rift from a new passive seismic tomography and receiver function analysis

    Science.gov (United States)

    Godano, Maxime; Gesret, Alexandrine; Noble, Mark; Lyon-Caen, Hélène; Gautier, Stéphanie; Deschamps, Anne

    2016-04-01

    The Corinth Rift is the most seismically active zone in Europe. The area is characterized by very localized NS extension at a rate of ~ 1.5cm/year, the occurrence of frequent and intensive microseismic crises and occasional moderate to large earthquakes like in 1995 (Mw=6.1). Since the year 2000, the Corinth Rift Laboratory (CRL, http://crlab.eu) consisting in a multidisciplinary natural observatory, aims at understanding the mechanics of faulting and earthquake nucleation in the Rift. Recent studies have improved our view about fault geometry and mechanics within CRL, but there is still a critical need for a better knowledge of the structure at depth both for the accuracy of earthquake locations and for mechanical interpretation of the seismicity. In this project, we aim to analyze the complete seismological database (13 years of recordings) of CRL by using recently developed methodologies of structural imaging, in order to determine at the same time and with high resolution, the local 3D structure and the earthquake locations. We perform an iterative joint determination of 3D velocity model and earthquake coordinates. In a first step, P and S velocity models are determined using first arrival time tomography method proposed by Taillandier et al. (2009). It consists in the minimization of the cost function between observed and theoretical arrival times which is achieved by the steepest descent method (e.g. Tarantola 1987). This latter requires computing the gradient of the cost function by using the adjoint state method (Chavent 1974). In a second step, earthquakes are located in the new velocity model with a non-linear inversion method based on a Bayesian formulation (Gesret et al. 2015). Step 1 and 2 are repeated until the cost function no longer decreases. We present preliminary results consisting in: (1) the adjustement of a 1D velocity model that is used as initial model of the 3D tomography and (2) a first attempt of the joint determination of 3D velocity

  14. Seismic imaging of the Cocos plate subduction zone system in central Mexico

    OpenAIRE

    Kim, YoungHee; Miller, Meghan S.; Pearce, Frederick; Clayton, Robert W.

    2012-01-01

    Broadband data from the Meso-America Subduction Experiment (MASE) line in central Mexico were used to image the subducted Cocos plate and the overriding continental lithosphere beneath central Mexico using a generalized radon transform based migration. Our images provide insight into the process of subducting relatively young oceanic lithosphere and its complex geometry beneath continental North America. The converted and reverberated phase image shows complete horizontal tectonic underplatin...

  15. Slant Borehole Demonstration Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    GARDNER, M.G.

    2000-07-19

    This report provides a summary of the demonstration project for development of a slant borehole to retrieve soil samples from beneath the SX-108 single-shell tank. It provides a summary of the findings from the demonstration activities and recommendations for tool selection and methods to deploy into the SX Tank Farm. Daily work activities were recorded on Drilling and Sampling Daily Work Record Reports. The work described in this document was performed during March and April 2000.

  16. Shallow magma chamber under the Wudalianchi Volcanic Field unveiled by seismic imaging with dense array

    Science.gov (United States)

    Li, Zhiwei; Ni, Sidao; Zhang, Baolong; Bao, Feng; Zhang, Senqi; Deng, Yang; Yuen, David A.

    2016-05-01

    The Wudalianchi Volcano Field (WDF) is a typical intraplate volcano in northeast China with generation mechanism not yet well understood. As its last eruption was around 300 years ago, the present risk for volcano eruption is of particular public interest. We have carried out a high-resolution ambient noise tomography to investigate the location of magma chambers beneath the volcanic cones with a dense seismic array of 43 seismometers and ~ 6 km spatial interval. Significant low-velocity anomalies up to 10% are found at 7-13 km depth under the Weishan volcano, consistent with the pronounced high electrical-conductivity anomalies from previous magnetotelluric survey. We propose these extremely low velocity anomalies can be interpreted as partial melting in a shallow magma chamber with volume at least 200 km3 which may be responsible for most of the recent volcanic eruptions in WDF. Therefore, this magma chamber may pose a serious hazard for northeast China.

  17. The preliminary results: Internal seismic velocity structure imaging beneath Mount Lokon

    International Nuclear Information System (INIS)

    Historical records that before the 17th century, Mount Lokon had been dormant for approximately 400 years. In the years between 1350 and 1400, eruption ever recorded in Empung, came from Mount Lokon’s central crater. Subsequently, in 1750 to 1800, Mount Lokon continued to erupt again and caused soil damage and fall victim. After 1949, Mount Lokon dramatically increased in its frequency: the eruption interval varies between 1 – 5 years, with an average interval of 3 years and a rest interval ranged from 8 – 64 years. Then, on June 26th, 2011, standby alert set by the Center for Volcanology and Geological Hazard Mitigation. Peak activity happened on July 4th, 2011 that Mount Lokon erupted continuously until August 28th, 2011. In this study, we carefully analyzed micro-earthquakes waveform and determined hypocenter location of those events. We then conducted travel time seismic tomographic inversion using SIMULPS12 method to detemine Vp, Vs and Vp/Vs ratio structures beneath Lokon volcano in order to enhance our subsurface geological structure. During the tomographic inversion, we started from 1-D seismic velocities model obtained from VELEST33 method. Our preliminary results show low Vp, low Vs, and high Vp/Vs are observed beneath Mount Lokon-Empung which are may be associated with weak zone or hot material zones. However, in this study we used few station for recording of micro-earthquake events. So, we suggest in the future tomography study, the adding of some seismometers in order to improve ray coverage in the region is profoundly justified

  18. The preliminary results: Internal seismic velocity structure imaging beneath Mount Lokon

    Energy Technology Data Exchange (ETDEWEB)

    Firmansyah, Rizky, E-mail: rizkyfirmansyah@hotmail.com [Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Kristianto, E-mail: kris@vsi.esdm.go.id [Center for Volcanology and Geological Hazard Mitigation (CVGHM), Geological Agency, Bandung, 40122 (Indonesia)

    2015-04-24

    Historical records that before the 17{sup th} century, Mount Lokon had been dormant for approximately 400 years. In the years between 1350 and 1400, eruption ever recorded in Empung, came from Mount Lokon’s central crater. Subsequently, in 1750 to 1800, Mount Lokon continued to erupt again and caused soil damage and fall victim. After 1949, Mount Lokon dramatically increased in its frequency: the eruption interval varies between 1 – 5 years, with an average interval of 3 years and a rest interval ranged from 8 – 64 years. Then, on June 26{sup th}, 2011, standby alert set by the Center for Volcanology and Geological Hazard Mitigation. Peak activity happened on July 4{sup th}, 2011 that Mount Lokon erupted continuously until August 28{sup th}, 2011. In this study, we carefully analyzed micro-earthquakes waveform and determined hypocenter location of those events. We then conducted travel time seismic tomographic inversion using SIMULPS12 method to detemine Vp, Vs and Vp/Vs ratio structures beneath Lokon volcano in order to enhance our subsurface geological structure. During the tomographic inversion, we started from 1-D seismic velocities model obtained from VELEST33 method. Our preliminary results show low Vp, low Vs, and high Vp/Vs are observed beneath Mount Lokon-Empung which are may be associated with weak zone or hot material zones. However, in this study we used few station for recording of micro-earthquake events. So, we suggest in the future tomography study, the adding of some seismometers in order to improve ray coverage in the region is profoundly justified.

  19. High-temperature borehole instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, B.R.; Koczan, S.P.; Stephani, E.L.

    1985-10-01

    A new method of extracting natural heat from the earth's crust was invented at the Los Alamos National Laboratory in 1970. It uses fluid pressures (hydraulic fracturing) to produce cracks that connect two boreholes drilled into hot rock formations of low initial permeability. Pressurized water is then circulated through this connected underground loop to extract heat from the rock and bring it to the surface. The creation of the fracture reservior began with drilling boreholes deep within the Precambrian basement rock at the Fenton Hill Test Site. Hydraulic fracturing, flow testing, and well-completion operations required unique wellbore measurements using downhole instrumentation systems that would survive the very high borehole temperatures, 320/sup 0/C (610/sup 0/F). These instruments were not available in the oil and gas industrial complex, so the Los Alamos National Laboratory initiated an intense program upgrading existing technology where applicable, subcontracting materials and equipment development to industrial manufactures, and using the Laboratory resource to develop the necessary downhole instruments to meet programmatic schedules. 60 refs., 11 figs.

  20. Applications of seismic pattern recognition and gravity inversion techniques to obtain enhanced subsurface images of the Earth's crust under the Central Metasedimentary Belt, Grenville Province, Ontario

    Science.gov (United States)

    Roy, Baishali; Mereu, R. F.

    2000-12-01

    Project Lithoprobe's Abitibi-Grenville transect seismic reflection lines 32 and 33 traverse the exposed Central Metasedimentary Belt (CMB) located in the Grenville province of the Precambrian Shield of Canada in southern Ontario. These seismic lines image a zone with a protracted deformational history spanning more than 300Myr. Detailed examination of the commercially processed stacked sections reveals a number of significant deficiencies in some important areas. The image quality in these zones of reduced coherency needs to be enhanced to examine specific features and their relation to the surface geology. Examination of near-vertical seismic data from Lines 32 and 33 revealed that the signal-to-noise ratio was not improved by stacking, due to misalignment of signals even after static, normal moveout corrections and residual static corrections. The presumed reason is that reflected seismic energy following long ray paths in heterogeneous media suffers from relative advances and delays in its propagation, and hence arrives at slightly different times at the receivers, tending to be poorly aligned relative to its theoretical traveltime curves. A pattern recognition (PR) method for signal enhancement followed by energy stacking in moving time windows was used in this study to improve the images in spite of misalignments. Reprocessing has refined the geometry of the reflection profiles. The objective of this paper is to use enhanced images of the seismic reflection data obtained by using a PR approach together with gravity data, using 2.5-D forward and 3-D inversion routines, to give an improved model of subsurface structure in the vicinity of lines 32 and 33. Line 32 is dominated by southeast-dipping reflectors soling into the lower crust. The listric geometry of the strong reflection packages of the CMB boundary thrust zone is interpreted to represent a crustal-scale ramp-flat geometry that accommodated northwest-directed tectonic transport of the CMB. This

  1. Rock stress orientation measurements using induced thermal spalling in slim boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Hakami, Eva [Geosigma AB, Uppsala (Sweden)

    2011-05-15

    In the planning and design of a future underground storage for nuclear waste based on the KBS-3 method, one of the aims is to optimize the layout of deposition tunnels such that the rock stresses on the boundaries of deposition holes are minimized. Previous experiences from heating of larger scale boreholes at the Aespoe Hard Rock Laboratory (AHRL) gave rise to the idea that induced borehole breakouts using thermal loading in smaller diameter boreholes, could be a possible way of determining the stress orientation. Two pilot experiments were performed, one at the Aespoe Hard Rock Laboratory and one at ONKALO research site in Finland. An acoustic televiewer logger was used to measure the detailed geometrical condition of the borehole before and after heating periods. The acoustic televiewer gives a value for each 0.7 mm large pixel size around the borehole periphery. The results from the loggers are presented as images of the borehole wall, and as curves for the maximum, mean and minimum values at each depth. Any changes in the borehole wall geometry may thus be easily detected by comparisons of the logging result images. In addition, using an optical borehole televiewer a good and detailed realistic colour picture of the borehole wall is obtained. From these images the character of the spalls identified may be evaluated further. The heating was performed in a 4 m long section, using a heating cable centred in an 8 m deep vertical borehole, drilled from the floor of the tunnels. For the borehole in the Q-tunnel of AHRL the results from the loggings of the borehole before the heating revealed that breakouts existed even before this pilot test due to previous heating experiments at the site (CAPS). Quite consistent orientation and the typical shape of small breakouts were observed. After the heating the spalling increased slightly at the same locations and a new spalling location also developed at a deeper location in the borehole. At ONKALO three very small changes

  2. Reflection imaging of the Moho and the aseismic Nazca slab in the Malargüe region with global-phase seismic interferometry

    Science.gov (United States)

    Draganov, D.; Nishitsuji, Y.; Ruigrok, E.; Gomez, M.; Wapenaar, C. P. A.

    2015-12-01

    A number of passive seismic methods have been developed over many decades. Still, imaging of aseismical zones of the subducting slabs is one of challenging themes in the geoscience community. Conventional seismological approaches, such as hypocentral mapping, receiver functions, and global tomography, have been providing useful imaging of the Nazca slab, which subducts under the South American plate; however, the aseismic zones remained unclear. Here, we propose to apply global-phase seismic interferometry (GloPSI) for the imaging of the aseismic zones of the Nazca slab beneath the Malargüe region (Mendoza, Argentina). GloPSI uses global phases (epicentral distances ≥ 120°) such as PKP, PKiKP, and PKIKP, recorded on the vertical component of the seismic sensors. These phases illuminate the lithosphere below the receivers with small angles of incidence, which illumination suffices for creating virtual sources that radiate primarily downwards. We then migrate the retrieved virtual responses to obtain a subsurface reflection image with high resolution (< 15 km in depth). We use data recorded in the Malargüe region using an exploration-type receiver array called MalARRgue. This array was recording continuously in 2012 for one year. In this presentation, we show the imaging results from the Moho down to the aseismic Nazca slab, including the upper mantle.

  3. Newly discovered abundant fluid seep indicators off southern Costa Rica, imaged from overlapping multibeam swaths and 3D seismic data

    Science.gov (United States)

    Kluesner, J. W.; Silver, E. A.; Gibson, J. C.; Bangs, N. L.; McIntosh, K.; von Huene, R.; Orange, D.; Ranero, C. R.

    2012-12-01

    Offshore southern Costa Rica we have identified 161 potential fluid seepage sites on the shelf and slope regions within an 11 x 55 km strip where no fluid indicators had been reported previously using conventional deep-water mutlibeam bathymetry (100 m grid cell size) and deep towed side scan sonar. Evidence includes large and small pockmarks, mounds, ridges, and slope failure features with localized anomalous high-amplitude backscatter strength. The majority of seepage indicators are associated with shallow sub-bottom reversed polarity bright spots and flat spots imaged within the CRISP 3D seismic grid. Data were collected ~50 km west of Osa Peninsula, Costa Rica onboard the R/V Marcus G. Langseth during the spring of 2011. We obtained EM122 multibeam data using fixed, closely spaced receiver beams and 9-10 times swath overlap, which greatly improved the signal-to-noise ratio and sounding density and allowed for very small grid and mosaic cell sizes (2-10 m). A gas plume in the water column, seen on a 3.5 kHz profile, is located along a fault trace and above surface and subsurface seep indicators. Fluid indicators on the outer shelf occur largely on a dense array of faults, some of which cut through the reflective basement. Seismic flat spots commonly underlie axes of large anticlines on the shelf and slope. Pockmarks are also located at the foot of mid-slope canyons, very near to the upper end of the BSR. These pockmarks appear to be associated with canyon abandonment and folded beds that channel fluids upward, causing hydrate instability. Our findings suggest that significant amounts of methane are venting into ocean and potentially into the atmosphere across the heavily deformed shelf and slope of Costa Rica.

  4. Elastic-Waveform Inversion with Compressive Sensing for Sparse Seismic Data

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Youzuo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Huang, Lianjie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-01-26

    Accurate velocity models of compressional- and shear-waves are essential for geothermal reservoir characterization and microseismic imaging. Elastic-waveform inversion of multi-component seismic data can provide high-resolution inversion results of subsurface geophysical properties. However, the method requires seismic data acquired using dense source and receiver arrays. In practice, seismic sources and/or geophones are often sparsely distributed on the surface and/or in a borehole, such as 3D vertical seismic profiling (VSP) surveys. We develop a novel elastic-waveform inversion method with compressive sensing for inversion of sparse seismic data. We employ an alternating-minimization algorithm to solve the optimization problem of our new waveform inversion method. We validate our new method using synthetic VSP data for a geophysical model built using geologic features found at the Raft River enhanced-geothermal-system (EGS) field. We apply our method to synthetic VSP data with a sparse source array and compare the results with those obtained with a dense source array. Our numerical results demonstrate that the velocity mode ls produced with our new method using a sparse source array are almost as accurate as those obtained using a dense source array.

  5. Seismically imaging the structural legacy of rifting and collision events in the central and eastern U.S. crust

    Science.gov (United States)

    Schmandt, B.; Lin, F. C.; Karlstrom, K. E.

    2015-12-01

    EarthScope's USArray now provides broadband seismic data across the contiguous U.S. and southeastern Canada. We used teleseismic receiver functions and surface wave tomography to map crustal structure beneath the entire array. Crust thickness was estimated with multi-mode Ps receiver function images using southern end of the mid-continent rift (MCR) in northern Kansas and southern Nebraska, along the Reelfoot rift, and beneath inferred rifts in Michigan, Indiana, and Ohio. The Oklahoma aulacogen is not associated with a coherent change in crust thickness along its length, at least at a scale resolvable by USArray data and our imaging approach. The MCR extending northeast from Nebraska to Lake Superior has locally thicker crust, consistent with other recent results. We suggest that magmatic additions to the lower crust overwhelmed extension in the northern mid-continent rift, but not the rift segments further south and east. Collision events of the Grenville orogeny and Paleozoic orogens that created the Appalachian Mountains are still associated with ~45-55 km thick crust extending from the Grenville front eastward across the Appalachian Mountains to the fall line that marks the abrupt geomorphic transition to the coastal plains. Despite the ~45-55 km crust thickness long-wavelength elevations (>50 km) across this area rarely exceed 1 km. Along the fall line we find ~15-20 km of seaward thinning that is coherent from Alabama to Pennsylvania, with a transition width similar to or less than the ~70 km.

  6. Seismicity in Northern Germany

    Science.gov (United States)

    Bischoff, Monika; Gestermann, Nicolai; Plenefisch, Thomas; Bönnemann, Christian

    2013-04-01

    Northern Germany is a region of low tectonic activity, where only few and low-magnitude earthquakes occur. The driving tectonic processes are not well-understood up to now. In addition, seismic events during the last decade concentrated at the borders of the natural gas fields. The source depths of these events are shallow and in the depth range of the gas reservoirs. Based on these observations a causal relationship between seismicity near gas fields and the gas production is likely. The strongest of these earthquake had a magnitude of 4.5 and occurred near Rotenburg in 2004. Also smaller seismic events were considerably felt by the public and stimulated the discussion on the underlying processes. The latest seismic event occurred near Langwedel on 22nd November 2012 and had a magnitude of 2.8. Understanding the causes of the seismicity in Northern Germany is crucial for a thorough evaluation. Therefore the Seismological Service of Lower Saxony (NED) was established at the State Office for Mining, Energy and Geology (LBEG) of Lower Saxony in January 2013. Its main task is the monitoring and evaluation of the seismicity in Lower Saxony and adjacent areas. Scientific and technical questions are addressed in close cooperation with the Seismological Central Observatory (SZO) at the Federal Institute for Geosciences and Natural Resources (BGR). The seismological situation of Northern Germany will be presented. Possible causes of seismicity are introduced. Rare seismic events at greater depths are distributed over the whole region and probably are purely tectonic whereas events in the vicinity of natural gas fields are probably related to gas production. Improving the detection threshold of seismic events in Northern Germany is necessary for providing a better statistical basis for further analyses answering these questions. As a first step the existing seismic network will be densified over the next few years. The first borehole station was installed near Rethem by BGR

  7. Observation and Scaling of Microearthquakes from TCDP Borehole Seismometers

    Science.gov (United States)

    Lin, Y.; Ma, K.; Oye, V.; Tanaka, H.

    2009-12-01

    Microearthquakes with magnitude down to 0.5 were detected by the Taiwan Chelungpu-ault Drilling Project Borehole Seismometers (TCDPBHS). A location software (MIMO) was used to determine P- and S-wave onset times, incidence and azimuth angles for the locations of the microevents. Regardless of the large co-seismic slip of 12 m at the drill site during the 1999 Chi-Chi earthquake, our studies show very less seismicity near the drill site from the TCDPBHS recording. The microevents clustered at a depth of 8-10 km, where the 30 degree dipping of the Chelungpu thrust fault becomes flat to a decollement of the Taiwan fold-and-thrust tectonic structure. As a continuous GPS survey did not observe post-slip at the large slip region, and as no seismicity was observed near the drill site, we suggest that the thrust belt above the decollement during the interseismic period is locked. A Fluid Injection Test (FIT) pumping high pressure fluid into hole C with hole A as observation well was carried out at the TCDP boreholes in November 2006, and January, March and April 2007. Compared with background seismicity in November 2007, the observation did not show significant correlation of the FIT related seismicity, despite the distinct observations on the arrival of gas and chemical monitoring through FIT. It is possible that the injected fluid rate of FIT experiments is too deficient to trigger microevents. The low fluid rate indicated the low permeability of the fault zone. We also examined the scaling of the source parameters of the small earthquakes in stress drops and seismic moments. The source parameters of 150 microevents were examined from the source spectra using Brune ω-2 model for a constant Q model. The scaling of the magnitude to the Brune stress drop is a significant positive correlation. However, there has been a debate that this positive relationship might be biased for without Q correction. Fortunately, we had observed 65 clusters showing similar waveforms. The path

  8. Study of iron deposit using seismic refraction and resistivity in Carajás Mineral Province, Brazil

    Science.gov (United States)

    Nogueira, Pedro Vencovsky; Rocha, Marcelo Peres; Borges, Welitom Rodrigues; Silva, Adalene Moreira; Assis, Luciano Mozer de

    2016-10-01

    This work comprises the acquisition, processing and interpretation of 2D seismic shallow refraction (P-wave) and resistivity profiles located in the iron ore deposit of N4WS, Carajás Mineral Province (CMP), northern Brazil. The geophysical methods were used to identify the boundaries of the iron ore deposit. Another objective was to evaluate the potentiality of these geophysical methods in that geological context. In order to validate the results, the geophysical lines were located to match a geological borehole line. For the seismic refraction, we used 120 channels, spaced by 10 m, in a line of 1190 m, with seven shot points. The resistivity method used in the acquisition was the electrical resistivity imaging, with pole-pole array, in order to reach greater depths. The resistivity line had a length of 1430 m, with 10 m spacing between electrodes. The seismic results produced a model with two distinct layers. Based on the velocities values, the first layer was interpreted as altered rocks, and the second layer as more preserved rocks. It was not possible to discriminate different lithologies with the seismic method inside each layer. From the resistivity results, a zone of higher resistivity (> 3937 Ω·m) was interpreted as iron ore, and a region of intermediate resistivity (from 816 to 2330 Ω·m) as altered rocks. These two regions represent the first seismic layer. On the second seismic layer, an area with intermediated resistivity values (from 483 to 2330 Ω·m) was interpreted as mafic rocks, and the area with lower resistivity (< 483 Ω·m) as jaspilite. Our results were compared with geological boreholes and show reasonable correlation, suggesting that the geophysical anomalies correspond to the main variations in composition and physical properties of rocks.

  9. Reflection seismic imaging of the end-glacial Pärvie Fault system, northern Sweden

    Science.gov (United States)

    Juhlin, C.; Dehghannejad, M.; Lund, B.; Malehmir, A.; Pratt, G.

    2010-04-01

    Reflection seismic data were acquired along a c. 23 km long profile over the Pärvie Fault system with a nominal receiver and source spacing of 20 m. An hydraulic breaking hammer was used as a source, generating signals with a penetration depth of about 5-6 km. Steeply dipping reflections from the end-glacial faults are observed, as well as sub-horizontal reflections. The location and orientation of the reflections from the faults agree well with surface geological observations of fault geometries. Reflections from a potential fourth end-glacial fault is observed further to the east along the profile. The more sub-horizontal reflections may originate from gabbroic bodies within the granitic basement or from deeper lying greenstones. Our results indicate that the end-glacial faults dip at moderate to steep dips down to at least 2-3 km depth, and possibly continue at this dip to depths of 6 km. This result has significant implications for determining the state of stress required to activate the faults in the past and in the future.

  10. Body-wave retrieval and imaging from ambient seismic fields with very dense arrays

    Science.gov (United States)

    Nakata, N.; Boué, P.; Beroza, G. C.

    2015-12-01

    Correlation-based analyses of ambient seismic wavefields is a powerful tool for retrieving subsurface information such as stiffness, anisotropy, and heterogeneity at a variety of scales. These analyses can be considered to be data-driven wavefield modeling. Studies of ambient-field tomography have been mostly focused on the surface waves, especially fundamental-mode Rayleigh waves. Although the surface-wave tomography is useful to model 3D velocities, the spatial resolution is limited due to the extended depth sensitivity of the surface wave measurements. Moreover, to represent elastic media, we need at least two stiffness parameters (e.g., shear and bulk moduli). We develop a technique to retrieve P diving waves from the ambient field observed by the dense geophone network (~2500 receivers with 100-m spacing) at Long Beach, California. With two-step filtering, we improve the signal-to-noise ratio of body waves to extract P wave observations that we use for tomography to estimate 3D P-wave velocity structure. The small scale-length heterogeneity of the velocity model follows a power law with ellipsoidal anisotropy. We also discuss possibilities to retrieve reflected waves from the ambient field and show other applications of the body-wave extraction at different locations and scales. Note that reflected waves penetrate deeper than diving waves and have the potential to provide much higher spatial resolution.

  11. Comparing plume characteristics inferred from cross-borehole geophysical data

    DEFF Research Database (Denmark)

    Haarder, Eline Bojsen; Binley, Andrew; Zibar, Majken Caroline Looms;

    2012-01-01

    significantly influences results of the moment analysis. We compare results of three cross-borehole geophysical approaches for imaging tracer migration arising from a point injection of water in the unsaturated zone: three-dimensional electrical resistivity tomography (ERT), two-dimensional ground...... of resolution. The flow patterns are compared to geological information from a coring obtained at the site and it is concluded that the diversion of water in the lateral direction can be caused by a few thin layers of contrasting geological composition. Mass balance calculations based on moment analysis......Three cross-borehole geophysical methods are used to image water migration in the unsaturated zone after a point injection of water. Mass balance calculations and moment analysis highlight the differences in resolution between the methods. The choice of moisture content threshold value...

  12. Cross borehole electromagnetic tomography : scoping study and literature review

    OpenAIRE

    P. B. Wilkinson

    2005-01-01

    Cross-borehole electromagnetic tomography is a non-contact geophysical method that can be used to generate images of the electrical properties of the subsurface. It is rather underutilised for site-scale investigation, due to the broad range of frequencies over which it must respond and the complicated nature of the electromagnetic fields in this range. However, such a system would find applications in a wide variety of environments, from fracture characterisation in highly resistive crystall...

  13. Seismic site characterization for the Deep-Fault-Drilling-Project Alpine Fault

    Science.gov (United States)

    Glomb, Vera; Buske, Stefan; Kovacs, Adrienn; Gorman, Andrew

    2013-04-01

    The Alpine Fault in New Zealand (South Island) is one of the largest active plate-bounding continental fault zones on earth with earthquakes of magnitude 7.9 occuring every 200-400 years. Due to the surface exposure and the shallow depth of mechanical and chemical transitions it is a globally significant natural laboratory. Within the ICDP Deep-Fault-Drilling-Project Alpine Fault (DFDP-AF; https://wiki.gns.cri.nz/DFDP) a drill hole shall give insight into the geological structure of the fault zone and its evolution to understand the related deformation and earthquake processes. With the help of advanced seismic imaging techniques the shallow structure of the Alpine Fault is imaged to find the most suitable drill site location. A new seismic reflection profile has been acquired in 2011 by the WhataDUSIE project team consisting of partners from the University of Otago (New Zealand), TU Bergakademie Freiberg (Germany) and the University of Alberta (Canada). The reflection profile, located in the Whataroa river valley, has a total length of about 5 km. Up to 643 geophones with spacings between 4-8 m recorded the approximately 100 shot points along the profile line. Single shot gathers as well as preliminary imaging results will be presented. The high-quality data show various indicators of the Alpine Fault such as strong reflections and distorted first-arrival wavefields which are clearly visible already in single shot gathers. With the help of high resolution seismic images we can study the shallow structures of the subsurface thus gaining information about the location and dip of reflectors. Further detailed processing and intensive interpretative work will enable a seismic site characterization providing important information for the selection of the borehole location. Additionally the high resolution seismic images themselves allow a better understanding of the tectonic and geodynamic settings.

  14. A multi-scale case study of natural fracture systems in outcrops and boreholes with applications to reservoir modelling

    NARCIS (Netherlands)

    Taal-van Koppen, J.K.J.

    2008-01-01

    Fractured reservoirs are notoriously difficult to characterize because the resolution of seismic data is too low to detect fractures whereas borehole data is detailed but sparse. Therefore, outcrops can be of great support in gaining knowledge of the three-dimensional geometry of fracture networks,

  15. Application of High-Density Seismic Image in Nondestructive Exploration of Cut-off Cement-Soil Wall in Earth Dam

    Institute of Scientific and Technical Information of China (English)

    CAI Jing; WANG Jianhua; ZHANG Xianmin

    2005-01-01

    In order to quickly explore the quality of cut-off wall in dams, a new method of high-density seismic image was adopted and estimated by model and in-situ wall tests.The vibration exciter was employed and several parameters such as hypocentral distance, length of signal record and sampling space in signal collection were determined, which are 8 m, 0.25 ms and 128 ms respectively. Through time and frequency field signal analyses, it is concluded that, the smaller arrival times of reflected longitudinal and surface waves, and the higher their main frequencies, the higher the strength of the wall, vice versa. Accordingly the construction quality of the wall can be evaluated quickly by high-density seismic image.

  16. Imaging blended VSP data using full wavefield migration

    OpenAIRE

    Soni, A.K.; Verschuur, D.J.

    2013-01-01

    Blended source and/or simultaneous source acquisition for multi-offset and multi-azimuth VSP measurements can prove significantly beneficial in saving expensive borehole down-time. In the last few years, for the case of surface seismic data, it was proposed to redefine imaging and inversion of the blended data to handle the data directly without any need to separate the blended sources. Recently, we proposed the concept of full wavefield migration (FWM) to image VSP data, where using all the ...

  17. Integrated interpretation of seismic and resistivity images across the «Val d'Agri» graben (Italy

    Directory of Open Access Journals (Sweden)

    E. Ceragioli

    2002-06-01

    Full Text Available Val d'Agri is a «recent SSW - NNE graben» located in the middle of the Southern Apennines thrust belt «chain» and emplaced in Plio-Pleistocene.The recent sedimentation of the valley represents a local critical geophysical problem. Several strong near surface velocity anomalies and scattering degrades seismic data in different ways and compromises the seismic visibility. In 1998, ENI and Enterprise, with the contribution of the European Community (ESIT R & D project - Enhance Seismic In Thrust Belt; EU Thermie fund acquired two «experimental seismic and Resistivity lines» across the valley. The purpose of the project was to look for methods able to enhance seismic data quality and optimize the data processing flow for «thrust belt» areas. During the work, it was clear that some part of the seismic data processing flow could be used for the detailed geological interpretation of the near subsurface too. In fact, the integrated interpretation of the near surface tomography velocity/depth seismic section, built for enhancing the resolution of static corrections, with the HR resistivity profile, acquired for enhancing the seismic source coupling, allowed a quite detailed lithological interpretation of the main shallow velocity changes and the 2D reconstruction of the structural setting of the valley.

  18. High-Resolution Seismicity Image of the Shallow Part of the Subduction Zone Beneath Mejillones in Northern Chile

    Science.gov (United States)

    Kummerow, Jörn; Bloch, Wasja; Salazar, Pablo; Wigger, Peter; Asch, Günter; Shapiro, Serge A.

    2015-04-01

    We analyze slab-related seismicity which has been recorded by a recently (June 2013) installed local seismic monitoring system on the Mejillones peninsula in the forearc region of Northern Chile. The monitoring system consists of 20 seismic stations and is complemented by components of the permanent IPOC (Integrated Plate Boundary Obervatory Chile) seismic network, providing a singular on-shore possibility to study in detail the relatively shallow seismicity of the subducting Nazca slab. To date, about thousand local seismic events have been identified. Precise earthquake relocation involving a local 2.5D velocity model and improved arrival time picks from an iterative cross-correlation based technique allows to trace sharply the slab interface between 25km and 40km depth. Furthermore, we observe distinct and continuous seismic activity on a near-vertical structure which transects the subducting oceanic crust from 40km to 50km depth. Location, orientation and size of this plane correspond to the rupture fault of the MW6.8 Michilla intraslab earthquake which occurred weeks after the MW7.7 Tocopilla earthquake of November 2007. We discuss here particularly the results from cluster analysis and the spatio-temporal signatures of the recorded seismicity.

  19. Seismically imaging the structural legacy of rifting and collision events in the central and eastern U.S. crust

    Science.gov (United States)

    Schmandt, B.; Lin, F. C.; Karlstrom, K. E.

    2015-12-01

    EarthScope's USArray now provides broadband seismic data across the contiguous U.S. and southeastern Canada. We used teleseismic receiver functions and surface wave tomography to map crustal structure beneath the entire array. Crust thickness was estimated with multi-mode Ps receiver function images using lag times. The new results enable large-scale comparison of the structural legacy of multiple rifting and collision events in eastern North America. Some Proterozoic rift segments defined by Bouguer gravity and surface geology maintain locally thin crust while others lack correlated Moho topography or are areas of locally thicker crust. Locally thin crust is found at southern end of the mid-continent rift (MCR) in northern Kansas and southern Nebraska, along the Reelfoot rift, and beneath inferred rifts in Michigan, Indiana, and Ohio. The Oklahoma aulacogen is not associated with a coherent change in crust thickness along its length, at least at a scale resolvable by USArray data and our imaging approach. The MCR extending northeast from Nebraska to Lake Superior has locally thicker crust, consistent with other recent results. We suggest that magmatic additions to the lower crust overwhelmed extension in the northern mid-continent rift, but not the rift segments further south and east. Collision events of the Grenville orogeny and Paleozoic orogens that created the Appalachian Mountains are still associated with ~45-55 km thick crust extending from the Grenville front eastward across the Appalachian Mountains to the fall line that marks the abrupt geomorphic transition to the coastal plains. Despite the ~45-55 km crust thickness long-wavelength elevations (>50 km) across this area rarely exceed 1 km. Along the fall line we find ~15-20 km of seaward thinning that is coherent from Alabama to Pennsylvania, with a transition width similar to or less than the ~70 km.

  20. The Larderello-Travale geothermal field (Tuscany, central Italy): seismic imaging as a tool for the analysis and assessment of the reservoir

    Science.gov (United States)

    Anselmi, M.; Piccinini, D.; Casini, M.; Spinelli, E.; Ciuffi, S.; De Gori, P.; Saccorotti, G.; chiarabba, C.

    2013-12-01

    The Larderello-Travale is a geothermal field with steam-dominated reservoirs (1300 kg/s of steam and running capacity of 700 MWatt), which is exploited by Enel Green Power, the electric company involved in the renewable energy and resources. The area is located in the pre-Apennine belt of southern Tuscany and has been characterized by extensional tectonics and sporadic events of compression. The result of these tectonic phases is a block-faulting structure with NW-SE trending horsts and basins. Small post-orogenic granitic stocks were emplaced along the main axes of the uplifted structures, causing the anomalous heat flow that marks the area. Results from seismic reflection lines crossing the study area show the presence of the top of a discontinuous reflector in the 3-8 km depth range and with thickness up to ~1 km, referred to as the ';K-horizon'. In this framework we present the results obtained by the processing of a high-quality local earthquake dataset, recorded during the 1977-2005 time interval by the seismic network managed by Enel Green Power. The geothermal target volume was parameterized using a 3-D grid for both Vp (P-wave velocities) and Qp (quality factor of P-waves). Grid nodes are spaced by 5 and 2 km along the two horizontal and vertical directions, respectively. The tomographic Vp images show an overall velocity increase with depth down to the K-horizon. Conversely, some characteristic features are observed in the distribution of Qp anomalies, with high Qp values in the 300-600 range located just below the K-horizon. The relationship between K-horizon and the seismicity distribution doesn't show a clear and homogeneous coupling: the bulk of re-located earthquakes are placed either above or below the top of the K-horizon in the shallower 8 km depth, with an abrupt cut-off at depth greater than 10 km. We then present the preliminary result from the G.A.P.S.S. (Geothermal Area Passive Seismic Sources) experiment, a project that the Istituto

  1. Seismic Imaging of the Waltham Canyon Fault, California: Comparison of Ray-Theoretical and Fresnel Volume Prestack Migration

    Science.gov (United States)

    Bauer, K.; Ryberg, T.; Fuis, G. S.; Lueth, S.

    2011-12-01

    Steep faults can be imaged by migration of reflected refractions observed in controlled-source seismic data. The processing can be focussed on the enhancement of the reflected refractions and simultaneous suppression of undesired phases. The Kirchhoff prestack migration is then applied where migration noise is suppressed by constructive stacking of multi-fold data. The Fresnel volume migration is an efficient alternative method, where smearing along isochrones (potential reflection points, partly migration noise) is limited to the first Fresnel zone in this technique. This makes the Fresnel volume migration particularly interesting for the imaging of steep faults using only low-fold data. We depeloped a ray-theroretical line drawing migration, which can be considered as the high-frequency approximation of the Fresnel volume migration. The ray-theoretical migration is less time consuming, and, hence, can be used to optimize the migration parameters before the final application of Fresnel volume migration. Another advantage of our ray-theoretical migration is possible wave field separation before and after migration. This feature can be used to optimize the pre-processing of the data before migration. We tested the prestack migration techniques with synthetic data. The methods were then applied to low-fold data collected across the SAFOD drill site near Parkfield, California. We chose five shot gathers with clear phases interpreted as reflected refractions. The phases are not obvious in shot gathers apart from the five shot locations. The resulting images show near-vertical reflector segments at 1-5 km depth, which project close to the surface track of the Waltham Canyon fault running approximately 10 km eastward and parallel to the San Andreas fault. Some more details were resolved in comparison with previous investigations. Based on modeling studies, the imaged features can be interpreted as reflections from a fault with lower internal velocities compared with the

  2. SNG-log in borehole Ermelund-208

    DEFF Research Database (Denmark)

    Korsbech, Uffe C C

    1996-01-01

    A Spectral Natural Gamma-ray log has been run in a borehole in Ermelunden. The vertical distribution of Th, U, and K is similar to that observed in neighbouring boreholes. A new measuring and data processing technique was used and the probes own background signal was determined. Surprisingly...

  3. Acoustic and seismic imaging of the Adra Fault (NE Alboran Sea: in search of the source of the 1910 Adra earthquake

    Directory of Open Access Journals (Sweden)

    E. Gràcia

    2012-11-01

    Full Text Available Recently acquired swath-bathymetry data and high-resolution seismic reflection profiles offshore Adra (Almería, Spain reveal the surficial expression of a NW–SE trending 20 km-long fault, which we termed the Adra Fault. Seismic imaging across the structure depicts a sub-vertical fault reaching the seafloor surface and slightly dipping to the NE showing an along-axis structural variability. Our new data suggest normal displacement of the uppermost units with probably a lateral component. Radiocarbon dating of a gravity core located in the area indicates that seafloor sediments are of Holocene age, suggesting present-day tectonic activity. The NE Alboran Sea area is characterized by significant low-magnitude earthquakes and by historical records of moderate magnitude, such as the Mw = 6.1 1910 Adra Earthquake. The location, dimension and kinematics of the Adra Fault agree with the fault solution and magnitude of the 1910 Adra Earthquake, whose moment tensor analysis indicates normal-dextral motion. The fault seismic parameters indicate that the Adra Fault is a potential source of large magnitude (Mw ≤ 6.5 earthquakes, which represents an unreported seismic hazard for the neighbouring coastal areas.

  4. Seismic Endoscopy: Design of New Instruments

    Science.gov (United States)

    Conil, F.; Nicollin, F.; Gibert, D.

    2003-04-01

    In order to perform 3D images around shallow-depth boreholes, in conditions in the field and within reasonable times of data acquisitions, several instrumental developments have been performed. The first development concerns the design of a directional probe working in the 20-100 kHz frequency range; the idea is to create a tool composed of multiple elementary piezoelectric entities able to cover the whole space to explore; made of special polyurethane rigid foam with excellent attenuation performances, the prototypes are covered by flexible polyurethane electric resin. By multiplying the number of elementary receptors around the vertical axes and piling up each elementary sensor, a complete design of multi-azimuth and multi-offset has been concepted. In addition to this, a test site has been built in order to obtain a controlled medium at typical scales of interest for seismic endoscopy and dedicated to experiment near the conditions in the field. Various reflectors are placed in well known positions and filled in an homogeneous cement medium; the whole edifice (2.2 m in diameter and 8 metres in depth) also contains 4 PVC tubes to simulate boreholes. The second part of this instrumental developments concern the synthesis of input signals; indeed, many modern devices used in ultrasonic experiment have non linear output response outside their nominal range: this is especially true in geophysical acoustical experiments when high acoustical power is necessary to insonify deep geological targets. Thanks to the high speed electronic and computerised devices now available, it is possible to plug in experimental set-ups into non linear inversions algorithms like simulated annealing. First experiments showed the robustness of the method in case of non linear analogic architecture. Large wavelet families have or example been constructed thanks to the method and multiscale Non Destructive Testing Method have been performed as an efficient method to detect and characterise

  5. Joint inversion of multichannel seismic reflection and wide-angle seismic data: Improved imaging and refined velocity model of the crustal structure of the north Ecuador-south Colombia convergent margin

    Science.gov (United States)

    Agudelo, W.; Ribodetti, A.; Collot, J.-Y.; Operto, S.

    2009-02-01

    Improving seismic imaging of the crust is essential for understanding the structural factors controlling subduction zones processes. We developed a processing work flow based on the combined analysis of multichannel seismic reflection (MCS) and wide angle (WA) reflection/refraction data to derive both shallow and deep velocities suitable for prestack depth migration and to construct a blocky velocity model integrating all identifiable seismic phases contained in MCS and WA data. We apply this strategy to the study of the north Ecuador-SW Colombia subduction margin to improve the imaging and geostructural interpretation of a splay fault and surrounding outer and inner margin wedges. Results show improvements over tomographic inversion of WA data only, such as (1) sediment velocity variation across the trench and margin slope that correlates with lateral lithologic changes, tectonic compaction and effect of mass wasting processes; (2) a two-layer velocity structure of the inner wedge basement that is consistent with the crust of an oceanic plateau; (3) a complex velocity structure of the outer wedge basement that consists of a deep, high-velocity (5.0-5.5 km s-1) core and a low-velocity zone (3.8-5.0 km s-1) associated with the major splay fault; (4) a ˜1.3-km-thick, low-velocity (3.5-4.0 km s-1) subduction channel that extends beneath the margin outer wedge. Both the splay fault and subduction channel are expected to direct fluid flows; and (5) downdip velocity increase (5-6 km s-1) in the subducting oceanic crust associated with a low (7.8 km s-1) upper mantle velocity, possibly reflecting changes in rock nature or properties.

  6. Backtracking urbanization from borehole temperature

    Science.gov (United States)

    Bayer, Peter; Rivera, Jaime A.; Blum, Philipp; Rybach, Ladislaus

    2016-04-01

    The thermal regime in shallow ground is influenced by various factors such as short and long term climatic variations, atmospheric urban warming, land use change and geothermal energy use. Temperature profiles measured in boreholes represent precious archives of the past thermal conditions at the ground surface. Changes at the ground surface induce time-dependent variations in heat transfer. Consequently, instantaneous and persistent changes such as recent atmospheric climate change or paving of streets cause perturbations in temperature profiles, which now can be found in depths of hundred meters and even more. In our work, we focus on the influence of urbanization on temperature profiles. We inspect profiles measured in borehole heat exchanger (BHE) tubes before start of energy extraction. These were obtained at four locations in the city and suburbs of Zurich, Switzerland, by lowering a specifically developed temperature logging sensor in the 200-400 m long tubes. Increased temperatures indicate the existence of a subsurface urban heat island (SUHI). At the studied locations groundwater flow can be considered negligible, and thus conduction is the governing heat transport process. These locations are also favorable, as long-term land use changes and atmospheric temperature variations are well documented for more than the last century. For simulating transient land use changes and their effects on borehole temperature profiles, a novel analytical framework based on the superposition of Green's functions is presented. This allows flexible and fast computation of the long term three-dimensional evolution of the thermal regime in shallow ground. It also facilitates calibration of unknown spatially distributed parameter values and their correlation. With the given spatial and temporal discretization of land use and background atmospheric temperature variations, we are able to quantify the heat contribution by asphalt and buildings. By Bayesian inversion it is

  7. Seismic basement in Poland

    Science.gov (United States)

    Grad, Marek; Polkowski, Marcin

    2016-06-01

    The area of contact between Precambrian and Phanerozoic Europe in Poland has complicated structure of sedimentary cover and basement. The thinnest sedimentary cover in the Mazury-Belarus anteclize is only 0.3-1 km thick, increases to 7-8 km along the East European Craton margin, and 9-12 km in the Trans-European Suture Zone (TESZ). The Variscan domain is characterized by a 1- to 2-km-thick sedimentary cover, while the Carpathians are characterized by very thick sediments, up to c. 20 km. The map of the basement depth is created by combining data from geological boreholes with a set of regional seismic refraction profiles. These maps do not provide data about the basement depth in the central part of the TESZ and in the Carpathians. Therefore, the data set is supplemented by 32 models from deep seismic sounding profiles and a map of a high-resistivity (low-conductivity) layer from magnetotelluric soundings, identified as a basement. All of these data provide knowledge about the basement depth and of P-wave seismic velocities of the crystalline and consolidated type of basement for the whole area of Poland. Finally, the differentiation of the basement depth and velocity is discussed with respect to geophysical fields and the tectonic division of the area.

  8. AcquisitionFootprintAttenuationDrivenbySeismicAttributes

    OpenAIRE

    Cuellar-Urbano Mayra; Chávez-Pérez Sergio

    2014-01-01

    Acquisition footprint, one of the major problems that PEMEX faces in seismic imaging, is noise highly correlated to the geometric array of sources and receivers used for onshore and offshore seismic acquisitions. It prevails in spite of measures taken during acquisition and data processing. This pattern, throughout the image, is easily confused with geological features and misguides seismic attribute computation. In this work, we use seismic data from PEMEX Exploración y Producción to show th...

  9. A new model for estimating subsurface ice content based on combined electrical and seismic data sets

    Directory of Open Access Journals (Sweden)

    C. Hauck

    2011-06-01

    Full Text Available Detailed knowledge of the material properties and internal structures of frozen ground is one of the prerequisites in many permafrost studies. In the absence of direct evidence, such as in-situ borehole measurements, geophysical methods are an increasingly interesting option for obtaining subsurface information on various spatial and temporal scales. The indirect nature of geophysical soundings requires a relation between the measured variables (e.g. electrical resistivity, seismic velocity and the actual subsurface constituents (rock, water, air, ice. In this work, we present a model which provides estimates of the volumetric fractions of these four constituents from tomographic electrical and seismic images. The model is tested using geophysical data sets from two rock glaciers in the Swiss Alps, where ground truth information in form of borehole data is available. First results confirm the applicability of the so-called 4-phase model, which allows to quantify the contributions of ice-, water- and air within permafrost areas as well as detecting solid bedrock. Apart from a similarly thick active layer with enhanced air content for both rock glaciers, the two case studies revealed a heterogeneous distribution of ice and unfrozen water within Muragl rock glacier, where bedrock was detected at depths of 20–25 m, but a comparatively homogeneous ice body with only minor heterogeneities within Murtèl rock glacier.

  10. Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-10-01

    Many basins in the Rocky Mountains contain naturally fractured gas reservoirs. Production from these reservoirs is controlled primarily by the shape, orientation and concentration of the natural fractures. The detection of gas filled fractures prior to drilling can, therefore, greatly benefit the field development of the reservoirs. The objective of this project was to test and verify specific seismic methods to detect and characterize fractures in a naturally fractured reservoir. The Upper Green River tight gas reservoir in the Uinta Basin, Northeast Utah was chosen for the project as a suitable reservoir to test the seismic technologies. Knowledge of the structural and stratigraphic geologic setting, the fracture azimuths, and estimates of the local in-situ stress field, were used to guide the acquisition and processing of approximately ten miles of nine-component seismic reflection data and a nine-component Vertical Seismic Profile (VSP). Three sources (compressional P-wave, inline shear S-wave, and cross-line, shear S-wave) were each recorded by 3-component (3C) geophones, to yield a nine-component data set. Evidence of fractures from cores, borehole image logs, outcrop studies, and production data, were integrated with the geophysical data to develop an understanding of how the seismic data relate to the fracture network, individual well production, and ultimately the preferred flow direction in the reservoir. The multi-disciplinary approach employed in this project is viewed as essential to the overall reservoir characterization, due to the interdependency of the above factors.

  11. New CHIRP Seismic Images of Submarine Terraces Around San Clemente Island Constrain its Tectonic Evolution and Geomorphology

    Science.gov (United States)

    Derosier, B.; Driscoll, N. W.; Graves, L. G.; Holmes, J. J.; Nicholson, C.

    2015-12-01

    New High-resolution CHIRP data acquired on the R/V Point Loma in 2015 imaged flights of submarine Terraces off of San Clemente Island. Outboard terraces at ~90 to 115 m below sea level (using a nominal water column velocity of 1500 m/s) may correlate with the Marine Isotope Stage 2 (MIS2); the last glacial maximum (LGM). Submarine terraces were mapped on both the gentle sloping windward (west) and the steeper sloping leeward (east) sides of San Clemente Island. The submarine terrace's depths are roughly the same on both sides of the island and suggest uniform uplift. These findings are consistent with the onshore mapping of terraces on San Clemente Island. The island exhibits a marked asymmetry both onshore and offshore, with a steeply dipping eastern margin and a gentle dipping western margin. This marked asymmetry cannot be explained by the uniform uplift of San Clemente Island based on the observed onshore and offshore terraces. In our model, the asymmetry of San Clemente Island records an early phase of predominantly extensional deformation during the middle to late Miocene, with San Clemente Island being the footwall block. Such asymmetry is also observed across the 30-mile bank and the Coronado Bank with steeply dipping eastern margins and gently dipping western margins. New regional multichannel seismic data and reprocessed industry data show no sediment divergence along the hangingwall blocks, which suggests that extensional deformation predated sedimentation. Finally, the elevations of the terraces on San Clemente Island are similar to those observed on the mainland from Baja California to Newport Beach, requiring any tectonic model fitting the uplift pattern of mainland terraces to account for the similar elevations not only along the margin but also across the margin out to 70 nautical miles offshore.

  12. Techniques for Surveying Urban Active Faults by Seismic Methods

    Institute of Scientific and Technical Information of China (English)

    Xu Mingcai; Gao Jinghua; Liu Jianxun; Rong Lixin

    2005-01-01

    Using the seismic method to detect active faults directly below cities is an irreplaceable prospecting technique. The seismic method can precisely determine the fault position. Seismic method itself can hardly determine the geological age of fault. However, by considering in connection with the borehole data and the standard geological cross-section of the surveyed area, the geological age of reflected wave group can be qualitatively (or semi-quantitatively)determined from the seismic depth profile. To determine the upper terminal point of active faults directly below city, it is necessary to use the high-resolution seismic reflection technique.To effectively determine the geometric feature of deep faults, especially to determine the relation between deep and shallow fracture structures, the seismic reflection method is better than the seismic refraction method.

  13. 2D and 3D imaging of the metamorphic carbonates at Omalos plateau/polje, Crete, Greece by employing independent and joint inversion on resistivity and seismic data

    Directory of Open Access Journals (Sweden)

    Pangratis Pangratis

    2012-07-01

    Full Text Available A geophysical survey carried out at Omalos plateau in Chania, Western Crete, Greece employed seismic as well as electrical tomography methods in order to image karstic structures and the metamorphic carbonates (Tripali unit and Plattenkalk group which are covered by post-Mesozoic deposits (terra rossa, clays, sands and gravels. The geoelectrical sections image the metamorphic carbonates which exhibit a highly irregular relief. At the central part of the plateau the thickness of post-Mesozoic deposits (terra rossa, clays, sands and gravels ranges from 40-130 m. A 3D resistivity image was generated by inverting resistivity data collected on a grid to the south west at the Omalos plateau. The 3D resistivity image delineated a karstic structure at a depth of 25 to 55 m. On the same grid the depth to the top of the karstified carbonates ranges from 25-70 m. This is also verified on the resistivity sections and seismic velocity sections along lines 5 and 7 of the above mentioned grid which are derived from the cross-gradients joint inversion.

  14. Seismic images under the Beijing region inferred from P and PmP data

    Science.gov (United States)

    Lei, Jianshe; Xie, Furen; Lan, Congxin; Xing, Chengqi; Ma, Shizhen

    2008-07-01

    In this study a new tomographic method is applied to over 1500 high-quality PmP (Moho reflected wave) travel-time data as well as over 38,500 high-quality first P-wave arrivals to determine a detailed 3D crustal velocity structure under Beijing and adjacent areas. Results of detailed resolution analyses show that the PmP data can significantly improve the resolution of the model in the middle and lower crust. After the PmP data are included in the tomographic inversion, our new model not only displays the tectonic feature appeared in the previous studies, but also reveals some new features. The Zhangjiakou-Bohai Sea fault zone (Zhang-Bo zone) is imaged as prominent and continuous low-velocity (low-V) anomalies in the shallower crust, while in the middle and lower crust it shows intermittent low-V anomalies extending down to the uppermost mantle. Furthermore, the pattern of low-V anomalies is different along the Zhang-Bo zone from the southeast to the northwest, indicating that there exist large differences in the dynamic evolution of Taihangshan and Yanshan uplifts and North China depression basin. Prominent low-V anomalies are visible under the source area of the 4 July 2006 Wen-An earthquake (M 5.1), suggesting that the occurrence of the Wen-An earthquake is possibly related to the effect of the crustal fluids probably caused by the upwelling of the hot and wet asthenospheric materials due to the deep dehydration of the stagnant Pacific slab in the mantle transition zone. The fluids in the lower crust may cause the weakening of the seismogenic layer in the upper and middle crust and thus contribute to the initiation of the Wen-An earthquake. This is somewhat similar to the cause of the 1695 Sanhe-Pinggu earthquake and the 1976 Tangshan earthquake in the region, as well as the 1995 Kobe earthquake in Japan and the 2001 Bhuj earthquake in India.

  15. Geophysical borehole logging test procedure: Final draft

    International Nuclear Information System (INIS)

    The purpose of geophysical borehole logging from the At-Depth Facility (ADF) is to provide information which will assist in characterizing the site geologic conditions and in classifying the engineering characteristics of the rock mass in the vicinity of the ADF. The direct goals of borehole logging include identification of lithologic units and their correlation from hole to hole, identification of fractured or otherwise porous or permeable zones, quantitative or semi-quantitative estimation of various formation properties, and evaluation of factors such as the borehole diameter and orientation. 11 figs., 4 tabs

  16. A directional antenna for borehole radar

    International Nuclear Information System (INIS)

    The borehole radar system developed during phase II of the International Stripa Project has been successfully applied to mapping fracture zones up to 100 meters from the borehole in granite. The techniques previously used to determine the orientation of fracture zones (single hole reflection, crosshole reflection, crosshole tomography) have been supplemented with a directional antenna, which makes it possible to determine the orientation from measurements in a single borehole. The antenna works by synthesizing four signals to produce directional information. Tests performed in Stripa show that the resolution of the antenna is about 50

  17. 3-D structure below Aevroe Island from high-resolution reflection seismic studies, southeastern Sweden

    International Nuclear Information System (INIS)

    Reflection seismology has served as a useful tool for imaging and mapping of fracture zones in crystalline rock along 2-D lines in nuclear waste disposal studies. Two 1-km-long perpendicular seismic reflection lines were acquired on Aevroe Island, southeast Sweden, in October 1996 in order to (1) test the seismic reflection method for future site investigations, (2) map known fracture zones, and (3) add to the Swedish database of reflection seismic studies of the shallow crystalline crust. An east-west line was shot with 5-m geophone and shot-point spacing, and a north-south line was shot with 10-m geophone and shotpoint spacing. An explosive source with a charge size of 100 g was used along both lines. The data clearly image three major dipping reflectors and one subhorizontal one in the upper 200 ms (600 m). The dipping reflectors (to the south, east, and northwest) intersect or project to the surface at or close to where surface-mapped fracture zones exist. The south-dipping reflector correlates with the top of a heavily fractured interval observed in a borehole (KAV01) at about 400 m. The subhorizontal zone at about 100--200 m correlates with a known fracture zone in the same borehole (KAV01). 3-D effects are apparent in the data, and only where the profiles cross can the true orientation of the reflecting events be determined. To properly orient and locate all events observed on the lines requires acquisition of 3-D data

  18. Imaging the Ferron Member of the Mancos Shale formation using reprocessed high-resolution 2-D seismic reflection data: Emery County, Utah

    Science.gov (United States)

    Taylor, D.J.

    2003-01-01

    Late in 1982 and early in 1983, Arco Exploration contracted with Rocky Mountain Geophysical to acquired four high-resolution 2-D multichannel seismic reflection lines in Emery County, Utah. The primary goal in acquiring this data was an attempt to image the Ferron Member of the Upper Cretaceous Mancos Shale. Design of the high-resolution 2-D seismic reflection data acquisition used both a short geophone group interval and a short sample interval. An explosive energy source was used which provided an input pulse with broad frequency content and higher frequencies than typical non-explosive Vibroseis?? sources. Reflections produced by using this high-frequency energy source when sampled at a short interval are usually able to resolve shallow horizons that are relatively thin compared to those that can be resolved using more typical oil and gas exploration seismic reflection methods.The U.S. Geological Survey-Energy Resources Program, Geophysical Processing Group used the processing sequence originally applied by Arco in 1984 as a guide and experimented with processing steps applied in a different order using slightly different parameters in an effort to improve imaging the Ferron Member horizon. As with the Arco processed data there are sections along all four seismic lines where the data quality cannot be improved upon, and in fact the data quality is so poor that the Ferron horizon cannot be imaged at all.Interpretation of the seismic and core hole data indicates that the Ferron Member in the study area represent a deltaic sequence including delta front, lower delta plain, and upper delta plain environments. Correlating the depositional environments for the Ferron Member as indicated in the core holes with the thickness of Ferron Member suggests the presence of a delta lobe running from the northwest to the southeast through the study area. The presence of a deltaic channel system within the delta lobe complex might prove to be an interesting conventional

  19. IODP Expedition 340T: Borehole Logging at Atlantis Massif Oceanic Core Complex

    Directory of Open Access Journals (Sweden)

    Donna Blackman

    2013-03-01

    Full Text Available Integrated Ocean Drilling Program (IODP Expedition 340T returned to the 1.4-km-deep Hole U1309D at Atlantis Massif to carry out borehole logging including vertical seismic profiling (VSP. Seismic, resistivity, and temperature logs were obtained throughout the geologic section in the footwall of this oceanic core complex. Reliable downhole temperature measurements throughout and the first seismic coverage of the 800–1400 meters below seafloor (mbsf portionof the section were obtained. Distinct changes in velocity, resistivity, and magnetic susceptibility characterize the boundaries of altered, olivine-rich troctolite intervals within the otherwise dominantly gabbroic se-quence. Some narrow fault zones also are associated with downhole resistivity or velocity excursions. Small deviations in temperature were measured in borehole fluid adjacent to known faults at 750 mbsf and 1100 mbsf. This suggests that flow of seawater remains active along these zones of faulting and rock alteration. Vertical seismic profile station coverage at zero offsetnow extends the full length of the hole, including the uppermost 150 mbsf, where detachment processes are expected to have left their strongest imprint. Analysis of wallrock properties, together with alteration and structural characteristics of the cores from Site U1309, highlights the likely interplay between lithology, structure, lithospheric hydration, and core complex evolution.

  20. Multiple Suppression and Imaging of Marine Seismic Data from The Shallow Water Area in Southern East China Sea Shelf Basin

    Science.gov (United States)

    Shi, J.; Luan, X.; Yang, C.

    2015-12-01

    Neither surface-related multiple elimination(SRME) nor predictive de-convolution method is effective to suppress the multiple of marine seismic data from the shallow water area. The former method needs the accurate reflection of seafloor, which is mixed with the direct wave in the near offset range. The other one could probably lose the primary wave when applied to the shallow water seismic data. We introduced the new method: deterministic water-layer de-multiple method (DWD) which is capable for the poor extrapolate result of near-offset traces. Firstly, the data shifts as downward continuation in tau-p domain with a water-layer period and the multiple model will be obtained. Then, the original seismic subtracts adaptively with the multiple model. Finally, we would get the de-multiple data after inverse tau-p transform. Marine seismic real data is from southern part of East China Sea Shelf Basin. This area has become the potential target for marine hydrocarbon exploration, it is located in the junction of the Eurasian plate pacific plate and Indian plate. Because the average water depth is less than 100 meters, seismic data contains abundant of multiple, especially the surface-related multiple. As a result it is difficult to distinguish the strata structure clearly. We used DWD approach to remove the water-layer multiple, cut off the seafloor reflection events and then suppressed the residual surface-related multiple by the traditional SRME. At last , the radon transform was applied to eliminate the multiple with long period . With these steps, we suppressed the multiple of marine seismic data from this area effectively. After multiple is removed , we acquired more accurate velocity to build the velocity model of migration. With the pre-stack migration technique, reflections from each geological period are shown clearly in the seismic section. This work was supported by the National Science Foundation of China(grant no. 41476053).

  1. Fractal analysis of INSAR and correlation with graph-cut based image registration for coastline deformation analysis: post seismic hazard assessment of the 2011 Tohoku earthquake region

    Directory of Open Access Journals (Sweden)

    P. K. Dutta

    2012-04-01

    Full Text Available Satellite imagery for 2011 earthquake off the Pacific coast of Tohoku has provided an opportunity to conduct image transformation analyses by employing multi-temporal images retrieval techniques. In this study, we used a new image segmentation algorithm to image coastline deformation by adopting graph cut energy minimization framework. Comprehensive analysis of available INSAR images using coastline deformation analysis helped extract disaster information of the affected region of the 2011 Tohoku tsunamigenic earthquake source zone. We attempted to correlate fractal analysis of seismic clustering behavior with image processing analogies and our observations suggest that increase in fractal dimension distribution is associated with clustering of events that may determine the level of devastation of the region. The implementation of graph cut based image registration technique helps us to detect the devastation across the coastline of Tohoku through change of intensity of pixels that carries out regional segmentation for the change in coastal boundary after the tsunami. The study applies transformation parameters on remotely sensed images by manually segmenting the image to recovering translation parameter from two images that differ by rotation. Based on the satellite image analysis through image segmentation, it is found that the area of 0.997 sq km for the Honshu region was a maximum damage zone localized in the coastal belt of NE Japan forearc region. The analysis helps infer using matlab that the proposed graph cut algorithm is robust and more accurate than other image registration methods. The analysis shows that the method can give a realistic estimate for recovered deformation fields in pixels corresponding to coastline change which may help formulate the strategy for assessment during post disaster need assessment scenario for the coastal belts associated with damages due to strong shaking and tsunamis in the world under disaster risk

  2. Near Surface Structure of the Frijoles Strand of the San Gregorio Fault, Point Año Nuevo, San Mateo County, California, from Seismic Imaging

    Science.gov (United States)

    Campbell, L.; Catchings, R. D.; Rymer, M. J.; Goldman, M.; Weber, G. E.

    2012-12-01

    The San Gregorio Fault Zone (SGFZ) is one of the major faults of the San Andreas Fault (SAF) system in the San Francisco Bay region of California. The SGFZ is nearly 200 km long, trends subparallel to the SAF, and is located primarily offshore with two exceptions- between Point Año Nuevo and San Gregorio Beach and between Pillar Point and Moss Beach. It has a total width of 2 to 3 km and is comprised of seven known fault strands with Quaternary activity, five of which also demonstrate late Holocene activity. The fault is clearly a potential source of significant earthquakes and has been assigned a maximum likely magnitude of 7.3. To better understand the structure, geometry, and shallow-depth P-wave velocities associated with the SGFZ, we acquired a 585-m-long, high-resolution, combined seismic reflection and refraction profile across the Frijoles strand of the SGFZ at Point Año Nuevo State Park. Both P- and S-wave data were acquired, but here we present only the P-wave data. We used two 60-channel Geometrics RX60 seismographs and 120 40-Hz single-element geophones connected via cable to record Betsy Seisgun seismic sources (shots). Both shots and geophones were approximately co-located and spaced at 5-m intervals along the profile, with the shots offset laterally from the geophones by 1 m. We measured first-arrival refractions from all shots and geophones to develop a seismic refraction tomography velocity model of the upper 70 m. P-wave velocities range from about 600 m/s near the surface to more than 2400 m/s at 70 m depth. We used the refraction tomography image to infer the depth to the top of the groundwater table on the basis of the 1500 m/s velocity contour. The image suggests that the depth, along the profile, to the top of groundwater varies by about 18 m, with greater depth on the west side of the fault. At about 46 m depth, a 60- to 80-m-wide, low-velocity zone, which is consistent with faulting, is observed southwest of the Frijoles strand of the

  3. Anatomy of a megathrust: The 2010 M8.8 Maule, Chile earthquake rupture zone imaged using seismic tomography

    Science.gov (United States)

    Hicks, Stephen P.; Rietbrock, Andreas; Ryder, Isabelle M. A.; Lee, Chao-Shing; Miller, Matthew

    2014-11-01

    Knowledge of seismic velocities in the seismogenic part of subduction zones can reveal how material properties may influence large ruptures. Observations of aftershocks that followed the 2010 Mw 8.8 Maule, Chile earthquake provide an exceptional dataset to examine the physical properties of a megathrust rupture zone. We manually analysed aftershocks from onshore seismic stations and ocean bottom seismometers to derive a 3-D velocity model of the rupture zone using local earthquake tomography. From the trench to the magmatic arc, our velocity model illuminates the main features within the subduction zone. We interpret an east-dipping high P-wave velocity anomaly (>6.9 km/s) as the subducting oceanic crust and a low P-wave velocity (physical heterogeneity in governing megathrust behaviour. Greatest slip during the Maule earthquake occurred in areas of moderate P-wave velocity (6.5-7.5 km/s), where the interface is structurally more uniform. At shallow depths, high fluid pressure likely influenced the up-dip limit of seismic activity. The high velocity bodies lie above portions of the plate interface where there was reduced coseismic slip and minimal postseismic activity. The northern velocity anomaly may have acted as a structural discontinuity within the forearc, influencing the pronounced crustal seismicity in the Pichilemu region. Our work provides evidence for how the ancient geological structure of the forearc may influence the seismic behaviour of subduction megathrusts.

  4. Geophysical logging of the Harwell boreholes

    International Nuclear Information System (INIS)

    A comprehensive geophysical borehole logging survey was carried out on each of three deep boreholes drilled at the Harwell research site. KOALA and PETRA computer programs were used to analyse and interpret the logs to obtain continuous quantitative estimates of the geological and hydrogeological properties of the sequences penetrated at the Harwell site. Quantitative estimates of the mineral composition and porosity of the cores samples were made. (UK)

  5. Working programme for MIU-4 borehole investigations

    Energy Technology Data Exchange (ETDEWEB)

    Ota, Kunio; Nakano, Katsushi; Metcalfe, R.; Ikeda, Koki; Goto, Jun-ichi; Amano, Kenji; Takeuchi, Shinji; Hama, Katsuhiro; Matsui, Hiroya [Japan Nuclear Cycle Development Inst., Toki, Gifu (Japan). Tono Geoscience Center

    1999-08-01

    Surface-based investigations have now been carried out since 1997 according to the Master Plan of the Mizunami Underground Research Laboratory (MIU) (PNC, 1996). The specific goals of the surface-based investigations are: To acquire information necessary for understanding the undisturbed deep geological environment as a background of the MIU and for predicting the effects of the construction of underground facilities. To establish methodologies for evaluating predictions. To formulate detailed design concepts for underground facilities and to plan scientific investigations during the construction of the MIU. In addition, appropriate, systematic methodologies for investigating the deep subsurface should be developed through the surface-based investigations. It is expected that the surface-based investigations with further borehole investigations will last until March 2002. However, the construction of the MIU was provisionally planned to commence in the 2000 financial year. JNC has drilled four 1,000m-deep boreholes and one 400m-deep borehole at the MIU site (JNC's land of about 140,000m{sup 2}) in Akeyo-cho, Mizunami City, Gifu Prefecture. In the surface-based investigations, specifically three 1,000m-deep boreholes, MIU-1, MIU-2 and MIU-3, have been drilled. Investigations in these boreholes have characterised mainly the geological structure and hydrogeological features of the deep geological environment. In addition, JNC has been developing investigation techniques and improving equipment for these investigations. At the time of writing, a series of borehole investigations are being carried out in the MIU-3 borehole. The MIU-3 borehole investigations aim mainly at characterising the Tsukiyoshi fault that intersects the crystalline basement in the site. (J.P.N.)

  6. Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Eisses, A.; Kell, A.; Kent, G. [UNR; Driscoll, N. [UCSD; Karlin, R.; Baskin, R. [USGS; Louie, J. [UNR; Pullammanappallil, S. [Optim

    2016-08-01

    Amy Eisses, Annie Kell, Graham Kent, Neal Driscoll, Robert Karlin, Rob Baskin, John Louie, and Satish Pullammanappallil, 2011, Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada: Geothermal Resources Council Transactions, 35, 7 pp. Preprint at http://crack.seismo.unr.edu/geothermal/Eisses-GRCpaper-sm.pdf The Pyramid Lake fault zone lies within a vitally important area of the northern Walker Lane where not only can transtension can be studied through a complex arrangement of strike-slip and normal faults but also geothermal activity can be examined in the extensional regime for productivity. This study used advanced and economical seismic methods in attempt to develop the Paiute Tribe’s geothermal reservoir and to expand upon the tectonics and earthquake hazard knowledge of the area. 500 line-kilometers of marine CHIRP data were collected on Pyramid Lake combined with 27 kilometers of vibrator seismic on-land data from the northwest side of the basin were collected in 2010 that highlighted two distinct phases of faulting. Preliminary results suggest that the geothermal fluids in the area are controlled by the late Pleistoceneto Holocene-aged faults and not through the mid-Miocene-aged conduits as originally hypothesized.

  7. Borehole stability in densely welded tuffs

    International Nuclear Information System (INIS)

    The stability of boreholes, or more generally of underground openings (i.e. including shafts, ramps, drifts, tunnels, etc.) at locations where seals or plugs are to be placed is an important consideration in seal design for a repository (Juhlin and Sandstedt, 1989). Borehole instability or borehole breakouts induced by stress redistribution could negate the effectiveness of seals or plugs. Breakout fractures along the wall of repository excavations or exploratory holes could provide a preferential flowpath for groundwater or gaseous radionuclides to bypass the plugs. After plug installation, swelling pressures exerted by a plug could induce radial cracks or could open or widen preexisting cracks in the rock at the bottom of the breakouts where the tangential compressive stresses have been released by the breakout process. The purpose of the work reported here is to determine experimentally the stability of a circular hole in a welded tuff sample subjected to various external boundary loads. Triaxial and biaxial borehole stability tests have been performed on densely welded Apache Leap tuff samples and Topopah Spring tuff samples. The nominal diameter of the test hole is 13.3 or 14.4 mm for triaxial testing, and 25.4 mm for biaxial testing. The borehole axis is parallel to one of the principal stress axes. The boreholes are drilled through the samples prior to applying external boundary loads. The boundary loads are progressively increased until breakouts occur or until the maximum load capacity of the loading system has been reached. 74 refs

  8. Development and testing of a two-dimensional ultrasonic laboratory model system for seismic imaging of heterogeneous structures

    Science.gov (United States)

    Mo, Yike; Karaman, Hakki; Greenhalgh, Stewart

    2014-05-01

    dispersion curves were experimentally determined for both modes in aluminium, brass and perspex plates. For the heterogeneous models, we collected reflection data for various source positions and applied various processing techniques such as AGC, filtering, deconvolution, and pre-stack Kirchhoff migration. Some muting and pre-processing was necessary to attenuate the refractions, guided waves and surface waves produced by the low velocity near surface layer (perspex) which has a large impedance contrast with the host rock (aluminium). Pre-stack migration was able to resolve the two main buried interfaces when the surface layer was flat but for the variable thickness irregular surface layer the interfaces could not be properly imaged. First-arrival tomography was implemented to the crosshole seismic data set and yielded the correct velocity distribution. Unfortunately, the presence of anti-symmetric Lamb waves in this data precluded the application of 2D full waveform inversion. The VSP data enhanced the imaging of the near-surface layer as well as providing additional control for the reflection experiments.

  9. ONKALO 3D tunnel seismic investigations, Olkiluoto 2013

    Energy Technology Data Exchange (ETDEWEB)

    Enescu, N.; Cosma, C.; Crawford, J. [Vibrometric Oy Cosma, Perttula (Finland)

    2014-10-15

    POSIVA Oy conducts bedrock investigations at the spent nuclear fuel final disposal site at Olkiluoto, in western Finland. The purpose of these efforts, which include a significant R and D component, is to ensure compliance with the requirements set forth for the long-term safety of final disposal. The excavation of the access tunnel to the repository hosts the ONKALO underground rock characterization facility. The investigations carried out in ONKALO focus on the bedrock and groundwater conditions prevailing on the final disposal site and how construction work affects them. Deformation zones and hydraulically conductive zones can limit the areas which are suitable for a deposition hole to be placed. The main objective of the tunnel seismic investigations presented here is to develop a seismic investigation technique for deposition area characterization. The field work consisted of 3 receiver lines using 3-component geophones and sources locations using the Vibsist-500 for 6 profiles, the Vibsist-20 for 1 profile (sparse), and a mechanical borehole hammer, MH-70, for 5 profiles for a total of 12 profiles. This investigation took place in the ONKALO demonstration area. Design of the seismic field work is based on previous tunnel seismic works in ONKALO (Cosma et al. 2008 and 2011) and pre-survey numerical modeling for field data and processing (Heinonen et al. 2013). The fieldwork was carried out in June 2013. Tomographic inversion of P-wave first arrival times was done on combined data sets, containing data from several shot-receiver configurations along tunnels and boreholes. The velocity distributions derived by tomographic inversion were verified by comparison with the forward modeled profiles. The Image Point (IP) migration method is characterized by is its ability to accumulate reflection events measured in the time distance data sets into points in the IP domain, which permits the enhancement of coherent backscattered events. The result of the 3D IP migration

  10. ONKALO 3D tunnel seismic investigations, Olkiluoto 2013

    International Nuclear Information System (INIS)

    POSIVA Oy conducts bedrock investigations at the spent nuclear fuel final disposal site at Olkiluoto, in western Finland. The purpose of these efforts, which include a significant R and D component, is to ensure compliance with the requirements set forth for the long-term safety of final disposal. The excavation of the access tunnel to the repository hosts the ONKALO underground rock characterization facility. The investigations carried out in ONKALO focus on the bedrock and groundwater conditions prevailing on the final disposal site and how construction work affects them. Deformation zones and hydraulically conductive zones can limit the areas which are suitable for a deposition hole to be placed. The main objective of the tunnel seismic investigations presented here is to develop a seismic investigation technique for deposition area characterization. The field work consisted of 3 receiver lines using 3-component geophones and sources locations using the Vibsist-500 for 6 profiles, the Vibsist-20 for 1 profile (sparse), and a mechanical borehole hammer, MH-70, for 5 profiles for a total of 12 profiles. This investigation took place in the ONKALO demonstration area. Design of the seismic field work is based on previous tunnel seismic works in ONKALO (Cosma et al. 2008 and 2011) and pre-survey numerical modeling for field data and processing (Heinonen et al. 2013). The fieldwork was carried out in June 2013. Tomographic inversion of P-wave first arrival times was done on combined data sets, containing data from several shot-receiver configurations along tunnels and boreholes. The velocity distributions derived by tomographic inversion were verified by comparison with the forward modeled profiles. The Image Point (IP) migration method is characterized by is its ability to accumulate reflection events measured in the time distance data sets into points in the IP domain, which permits the enhancement of coherent backscattered events. The result of the 3D IP migration

  11. Tomographic Imaging of a New Seismic Zone in Northern Taiwan: Implications for Crustal Magnetism and Tectonic Inheritance

    Science.gov (United States)

    Cheng, Win-Bin; Chang, Gen-Sin; Hsu, Shu-Kun

    2016-04-01

    To the west of 121°E, we found that the northern South China Sea magnetic anomaly in central Taiwan is coincident with high seismic velocity zone derived from a joint analysis of gravity anomaly and seismic travel time data. To the east of 121°E, we found a new seismic zone which remains enigmatic because of its apparent relationship with both the emplacement of high magnetic anomaly and termination of Okinawa Trough. In order to understand the new seismic zone and breakup of the high magnetic anomaly, a joint analysis of gravity anomaly and seismic travel time data have been used to construct three-dimensional velocity structure for the study area. Earthquake data were collected by the Central Weather Bureau Seismological Network from 2000 to 2012. A modified velocity model obtained by previously local earthquake tomography, was used to construct an initial three-dimensional gravity model, using a linear velocity-density relationship. To derive a crustal velocity-density model that accounts for both types of observations, this study performed a sequential inversion of traveltime and gravity data. The main features of our three-dimensional velocity model are: (1) an uplifted zone with velocity greater than 6.5 km/s is observed in the lower crust, (2) the width and the shape of the uplifted zone is found strongly correlated with the high magnetic belt, (3) the trend of the high-velocity zone turns from NE to N in central Taiwan, where the feature of high magnetic was truncated. This study suggested that integration of seismic data with new perspectives on crustal magnetism will provide a better understanding of terrane accretion, rifting processes, and passive margin formation in the Taiwan region.

  12. Characterization of the Hontomín Research Facility for Geological Storage of CO2: 3D Seismic Imaging Results

    Science.gov (United States)

    Alcalde, J.; Martí, D.; Juhlin, C.; Malehmir, A.; Calahorrano, A.; Ayarza, P.; Pérez-Estaún, A.; Carbonell, R.

    2012-04-01

    A technological research facility dedicated to the underground geological storage of CO2 is currently being developed by the Spanish research program on Carbon Capture and Storage (CCS) in Hontomin (Burgos). This research program is being developed by the CIUDEN Foundation, an initiative launched by 3 Spanish state departments (Science & Innovation, Environment and Industry). An extensive multidisciplinary site characterization phase has been carried out, including a multiseismic data acquisition experiment. Within this effort, a 36 km2 3D seismic reflection survey was acquired in the summer of 2010. Its aim was to provide high resolution images of the subsurface of the storage complex, as well as to provide a baseline model for all the disciplines involved in the project. The target reservoir is a saline aquifer located at 1400 m, approximately, within Lower Jurassic carbonates (Lias). The main seal is formed by inter-layered marls and marly limestones of Early to Middle Jurassic age (Dogger and Lias). The main acquisition characteristics of the survey included (1) a mixed source of vibroseis and explosives with 74% and 26% of each used, respectively, (2) 5000 source points distributed along 22 source lines (separated 250 m) and (3) 22 lines of receivers (separated 275 m). Shot and receiver spacing along the source and receiver lines was 25 m, resulting in a nominal CDP-fold of 36 for 13 m2 bins. The 3D-data have been fully processed to post stack migration. The most critical processing steps included static correction calculations, time variant frequency filtering, rms velocity analysis, F-XY deconvolution, dip move-out correction, residual statics calculations and post stack migration. The final high-resolution 3D-volume shows the shape and depth of the primary reservoir-seal system, the main faults of the area and the secondary reservoir-seal sequence. It allows us to characterize the main tectonic structure of the dome complex, the fault system of the area and

  13. Subduction-to-Strike-Slip-Transition in the Southeastern Caribbean Imaged Using Deeply-Penetrating Seismic Reflection Lines and Tomography

    Science.gov (United States)

    Alvarez, T.; Vargas, C. A.; Mann, P.; Latchman, J.

    2010-12-01

    The subduction-to-strike-slip transition (SSST) zone of the southeastern Caribbean is one of thirty identified locations where active subduction and strike-slip tectonic styles transition along strongly curved and seismogenic plate boundaries. This SSST zone provides a field laboratory for understanding how sedimentary basins, faults, basement areas and subducted slabs change from an area of dominantly westward-directed subduction beneath the Lesser Antilles arc to an area of dominantly east-west strike-slip faulting along northern South America. We use two geophysical data types to image the lithosphere and study the relationships between lithospheric scale deformation and basin scale response to the transitional tectonic configuration. Interpretation of deeply-penetrating seismic reflection lines recorded down to 16 seconds two-way time, or depths of about 18 km, is combined with tomographic slices of the upper mantle and lower crust which were constructed using the coda method on ~ 700 earthquakes in the depth range of 70-250 km. Results from the tomographic study are compared with nine seismogenic zones in the southeast Caribbean SSST zone which are defined based on the depth, and focal mechanism of earthquake events. These zones include: (1) the Paria slab tear region; (2) Caribbean/South American strike-slip zone; (3) Hinge area separating continental margin in Trinidad from Tobago forearc basin; (4) Central Range -strike-slip fault zone, onshore Trinidad; (5) Underthrust zone of South American beneath southern onshore and offshore eastern Trinidad, including the prolific hydrocarbon-bearing Columbus Basin; (6) Venezuela foreland and fold-thrust belt; (7) flexural bulge area of oceanic crust located east of Barbados accretionary prism (BAP); (8) Subducted slab beneath the stabilized and supracomplex zones of the BAP; (9) Inner accretionary prism of the BAP. Primary controls on the seismogenic character of each curving tectonic belt include the strike of the

  14. Mantle-Crust Volcanics and Geodynamics of the Yellowstone Hotspot from Seismic and GPS Imaging and Earthquake Swarm Magmatic Interaction

    Science.gov (United States)

    Smith, R. B.; Farrell, J.; Puskas, C. M.

    2015-12-01

    The Yellowstone hotspot is the product of plume-plate interaction that has produced a large and active silicic volcanic field within the N. American Plate. Our newest research on Yellowstone includes: 1) A recent discovery by seismic imaging that the Yellowstone volcanic system extends as a connected magmatic system from at least 1000 km deep in the mantle with melt ascending upward in a WNW tilted plume to a newly discovered lower-crustal magma body at 20-45 km depth and 4x larger than the shallow crustal reservoir 5-15 km deep. Moreover the shallow 70 km NE-SW crustal magma body unexpectedly extends 15 km NE well beyond Yellowstone's volcanic field a distance that N. American Plate would advance in 640,000 years, i.e., the time of the last Yellowstone super eruption and hence reflecting plate motion over the Yellowstone mantle plume; 2) Yellowstone's giant mantle-crust connected magma system represents ~48,000 km3 with ~1800 km3 of melt that fuels Yellowstone's extraordinarily high heat flux of up to ~ 3 Watts/meter2 that in turn drives Yellowstone's world renown hydrothermal system; and 3) How migration of magma vertically into and laterally out of the crustal magma reservoir, measured by GPS and earthquake correlation, reveals the mechanics of Yellowstone's "natural volcano pressure relief valve" that retards volcanic eruptions for thousands of years, but that occasionally breach the brittle-ductile transition in volcanic eruptions. We will also discuss the most recent and largest earthquake in Yellowstone in over 30 years, a magnitude 4.8 event, on March 30, 2014 near Norris Geyser Basin. This earthquake was part of a larger sequence of swarm activity in the Norris area that began in September 2013 and continued into June 2014. GPS derived deformation at Norris revealed unusually high uplift rates at ~15 cm/yr. attaining 60 mm of uplift at the time of the MW4.8 event and that dramatically reversed to subsidence at rates of ~17 cm/yr. Notably, however the much

  15. Seismic surveying for coal mine planning

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, B. [CMTE/CSIRO Exploration and Mining, Kenmore, Qld. (Australia)

    2002-07-01

    More and more coal in Australia is extracted by underground mining methods especially by longwall mining. These methods can be particularly sensitive to relatively small-scale structural discontinuities and variations in roof and floor rock character. Traditionally, information on these features has been obtained through drilling. However, this is an expensive process and its relevance is limited to the immediate neighbourhood of the boreholes. Seismic surveying, especially by 3D seismic, is an alternative tool for geological structure delineation. It is one of the most effective geophysical methods available for identification of geological structures such as faults, folds, washouts, seam splits and thickness changes which are normally associated with potential mining hazards. Seismic data even can be used for stratigraphic identification. The information extracted from seismic data can be integrated into mine planning and design. In this paper, computer aided interpretation techniques for maximising the information from seismic data are demonstrated and the ability of seismic reflection methods to resolve localised geological features illustrated. Both synthetic and real seismic data obtained in recent 2D and 3D seismic surveys from Australian coal mines are used. 7 refs., 9 figs.

  16. Geostatistical methods for rock mass quality prediction using borehole and geophysical survey data

    Science.gov (United States)

    Chen, J.; Rubin, Y.; Sege, J. E.; Li, X.; Hehua, Z.

    2015-12-01

    For long, deep tunnels, the number of geotechnical borehole investigations during the preconstruction stage is generally limited. Yet tunnels are often constructed in geological structures with complex geometries, and in which the rock mass is fragmented from past structural deformations. Tunnel Geology Prediction (TGP) is a geophysical technique widely used during tunnel construction in China to ensure safety during construction and to prevent geological disasters. In this paper, geostatistical techniques were applied in order to integrate seismic velocity from TGP and borehole information into spatial predictions of RMR (Rock Mass Rating) in unexcavated areas. This approach is intended to apply conditional probability methods to transform seismic velocities to directly observed RMR values. The initial spatial distribution of RMR, inferred from the boreholes, was updated by including geophysical survey data in a co-kriging approach. The method applied to a real tunnel project shows significant improvements in rock mass quality predictions after including geophysical survey data, leading to better decision-making for construction safety design.

  17. Constraints on mantle convection from seismic tomography

    NARCIS (Netherlands)

    Kárason, H.; Hilst, R.D. van der

    2000-01-01

    Since the advent of global seismic tomography some 25 years ago, advances in technology, seismological theory, and data acquisition have allowed spectacular progress in our ability to image seismic heterogeneity in Earth's mantle. We briefly review some concepts of seismic tomography, such as parame

  18. Compressing and Coding Method of Seismic Data

    Institute of Scientific and Technical Information of China (English)

    赵学军; 郑宇; 宁书年; 郭俊霞; 岳俊梅

    2002-01-01

    Aiming at the characteristics of the seismic exploration signals, the paper studies the image coding technology, the coding standard and algorithm, brings forward a new scheme of admixing coding for seismic data compression. Based on it, a set of seismic data compression software has been developed.

  19. Borehole geophysical investigation of a formerly used defense site, Machiasport, Maine, 2003-2006

    Science.gov (United States)

    Johnson, Carole D.; Mondazzi, Remo A.; Joesten, Peter K.

    2011-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, collected borehole geophysical logs in 18 boreholes and interpreted the data along with logs from 19 additional boreholes as part of an ongoing, collaborative investigation at three environmental restoration sites in Machiasport, Maine. These sites, located on hilltops overlooking the seacoast, formerly were used for military defense. At each of the sites, chlorinated solvents, used as part of defense-site operations, have contaminated the fractured-rock aquifer. Borehole geophysical techniques and hydraulic methods were used to characterize bedrock lithology, fractures, and hydraulic properties. In addition, each geophysical method was evaluated for effectiveness for site characterization and for potential application for further aquifer characterization and (or) evaluation of remediation efforts. Results of borehole geophysical logging indicate the subsurface is highly fractured, metavolcanic, intrusive, metasedimentary bedrock. Selected geophysical logs were cross-plotted to assess correlations between rock properties. These plots included combinations of gamma, acoustic reflectivity, electromagnetic induction conductivity, normal resistivity, and single-point resistance. The combined use of acoustic televiewer (ATV) imaging and natural gamma logs proved to be effective for delineating rock types. Each of the rock units in the study area could be mapped in the boreholes, on the basis of the gamma and ATV reflectivity signatures. The gamma and mean ATV reflectivity data were used along with the other geophysical logs for an integrated interpretation, yielding a determination of quartz monzonite, rhyolite, metasedimentary units, or diabase/gabbro rock types. The interpretation of rock types on the basis of the geophysical logs compared well to drilling logs and geologic mapping. These results may be helpful for refining the geologic framework at depth. A stereoplot of all fractures

  20. Grimsel Test Site. Further Development of Seismic Tomography

    International Nuclear Information System (INIS)

    Experience gained by NAGRA and its partner organisations in the Grimsel underground rock laboratory has led to the identification of two main areas of investigation: The first part of the present project deals with the evaluation and testing of underground seismic sources suitable for large measurement distances. Various high-frequency seismic sources have been tested at the Grimsel Test Site (GTS) (Buehnemann, 1996; Buehnemann and Holliger, 1998). The tests were designed to facilitate future tomographic studies of potential radioactive waste disposal sites. A key objective was to identify borehole and tunnel seismic sources capable of generating and sustaining high-frequency signals over distances of up to 1000 m. Seismic sources were located in both water-filled boreholes (sparker, two piezo-electric sources, explosives) and at the tunnel wall (accelerated weight drop, minivibrator, bolt gun, buffalo gun, explosives). The second focal point of the project was dealing with improvement (and development) of analysis techniques in terms of stability, quality and resolution. 3 inversion techniques were tested and developed using the dataset US85 (Gelbke, 1988). Two travel time inversions - anisotropic velocity tomography - AVT (Pratt and Chapman, 1992) and coupled inversion - CI (Maurer, 1996; Maurer and Green, 1997) - and a wave field inversion (WFI Song et al., 1995) were used. Several problems occurred in the first inversion of the US85 dataset using the Simultaneous Iterative Reconstruction Technique (SIRT); these were due to the velocity anisotropy of the rock, the triggering inaccuracy of the shots and uncertainties regarding the source/receiver locations in the boreholes. In the AVT, the velocity anisotropy of the rock is taken into account as a free parameter. In addition to an 'isotropic' velocity image, this involves producing tomograms of anisotropy. Taking into account the anisotropy of the rock allows the artefacts of the SIRT inversion to be explained

  1. Study on sealing of boreholes

    International Nuclear Information System (INIS)

    A bibliographical research on the problem of the backfilling and sealing of boreholes, shafts and tunnels for radioactive waste disposal has been carried out. Various materials - both natural and artificial - like clay, industrial cement, polymer concrete, geothermical and magnesium cement have been examined. Their main physico-chemical and durability characteristics have been examined. The problem of the interaction between the sealing and the geological environment has been also dealt. The final subject discussed in the bibliography is the damage caused to the host formation by the excavation of shafts and tunnels. The laboratory tests have been performed on a natural clay and other types of material (cement grout, cement grout with expansive additive, cement mortar and remoulded clay) which have been used as plug materials. The main conclusions obtained from the tests are the following: - The permeability of the cement is lower than the permeability of the clay; - no adhesion was observed between clay and cement mortar, with or without expansive additive, when cured under different ambient conditions, but without any application of load; - When curing took place under load, good adhesion was observed between the clay and the cement mortar; - The flow of water in a specimen consisting of a clay core surrounded by remoulded clay is larger than in the natural clay. These results seem to be caused by the different permeabilities of the remoulded and undisturbed clay and not to depend on flow at the contact between the two materials. A remote instrumentation package for the in situ evaluation of the performance of a plug, has been developed. In order to get rid of the uncertainty associated with the infiltration of the cables through the plug a wireless data transmission system, based on acoustic waves, has been developed

  2. Newberry Volcano EGS Demonstration Induced Seismicity Modeling

    Science.gov (United States)

    Cladouhos, T. T.; Petty, S.; Osborn, W.; Clyne, M.; Nichols, M. L.; Nofziger, L.

    2011-12-01

    An Enhanced Geothermal System (EGS) reservoir is created by injecting water under pressure into a geothermal well which induces shear slip on existing fractures ("hydroshearing"). The shear slip increases fracture permeability and induces microseismicity that can be detected by seismometers and used to map EGS reservoir growth. Most induced seismic events have a magnitude less than 2.0 and are not felt at the surface. However, some EGS projects have generated events large enough to be felt and cause minor damage. As a part of Phase I of the Newberry Volcano EGS Demonstration project, several data sets were collected to characterize the rock volume around the target well (NWG 55-29 on the NW flank of the volcano) and understand the induced seismicity potential. Fracture, fault, stress, and seismicity data has been collected by a borehole televiewer (BHTV), LiDAR elevation maps, and microseismic monitoring. Well logs and cuttings from the well and core from a nearby core hole (Geo N-2) have been analyzed to develop geothermal, geochemical, mineralogical and strength models of the rock matrix, altered zones, and fracture fillings. These characterization data sets provide inputs to AltaStim, a proprietary software model developed by AltaRock to plan and predict EGS induced seismicity, reservoir creation and productivity. The software is used to create a discrete fracture network (DFN) model, visualize EGS stimulation scenarios, and provide guidance for final planning. The process of creating an AltaStim model requires synthesis of geologic observations at the well, the modeled stress conditions, and the stimulation plan. The open-hole portion of the well was divided into five distinct zones defined by the contacts between various extrusive and intrusive volcanic units and variations in fracture intensity. The DFN model was constructed with fracture orientations and intensities bootstrapped from data interpreted from BHTV images and sliding friction coefficients based

  3. PROGRESS REPORT. ADVANCED HIGH RESOLUTION SEISMIC IMAGING, MATERIAL PROPERTIES ESTIMATION AND FULL WAVEFIELD INVERSION FOR THE SHALLOW SUBSURFACE

    Science.gov (United States)

    In July and August 2000, we conducted 3-D reflection, tomography, and downhole seismic studies at Operable Unit 2 (OU2) at Hill Air Force Base (HAFB) in Ogden, Utah. OU2 has been the subject of ongoing remediation efforts to remove dense nonaqueous phase liquids (DNAPLs) that con...

  4. Real Time Seismic Prediction while Drilling

    Science.gov (United States)

    Schilling, F. R.; Bohlen, T.; Edelmann, T.; Kassel, A.; Heim, A.; Gehring, M.; Lüth, S.; Giese, R.; Jaksch, K.; Rechlin, A.; Kopf, M.; Stahlmann, J.; Gattermann, J.; Bruns, B.

    2009-12-01

    Efficient and safe drilling is a prerequisite to enhance the mobility of people and goods, to improve the traffic as well as utility infrastructure of growing megacities, and to ensure the growing energy demand while building geothermal and in hydroelectric power plants. Construction within the underground is often building within the unknown. An enhanced risk potential for people and the underground building may arise if drilling enters fracture zones, karsts, brittle rocks, mixed solid and soft rocks, caves, or anthropogenic obstacles. Knowing about the material behavior ahead of the drilling allows reducing the risk during drilling and construction operation. In drilling operations direct observations from boreholes can be complemented with geophysical investigations. In this presentation we focus on “real time” seismic prediction while drilling which is seen as a prerequisite while using geophysical methods in modern drilling operations. In solid rocks P- and S-wave velocity, refraction and reflection as well as seismic wave attenuation can be used for the interpretation of structures ahead of the drilling. An Integrated Seismic Imaging System (ISIS) for exploration ahead of a construction is used, where a pneumatic hammer or a magnetostrictive vibration source generate repetitive signals behind the tunneling machine. Tube waves are generated which travel along the tunnel to the working face. There the tube waves are converted to mainly S- but also P-Waves which interact with the formation ahead of the heading face. The reflected or refracted waves travel back to the working front are converted back to tube waves and recorded using three-component geophones which are fit into the tips of anchor rods. In near real time, the ISIS software allows for an integrated 3D imaging and interpretation of the observed data, geological and geotechnical parameters. Fracture zones, heterogeneities, and variations in the rock properties can be revealed during the drilling

  5. Joint 3D seismic travel time and full channel electrical resistivity inversion with cross gradient structure constraint

    Science.gov (United States)

    Gao, J.; Zhang, H.

    2015-12-01

    Near surface geophysical exploration for the purpose of engineering design or construction For this reason, geophysical imaging demands a higher resolution and a better quantitative interpretation. Seismic travel time tomography and direct current resistivity tomography are two main methods for the near surface survey. Because of the limited coverage of observation system and the complex physical relationship between physical parameters and observations, individual geophysical method suffers issues of non-uniqueness and resolution limitation to some degree. We have developed a joint inversion method to combine seismic travel time tomography and full channel resistivity tomography. For the full channel resistivity survey, it uses two electrodes for power supply and all the other electrodes for recording. Compared with the traditional resistivity method, it collects more data and has a better model converge. Our joint inversion strategy relies on the structure constraint enforced through minimizing cross gradients between seismic velocity and resistivity models (Gallardo, 2003). For resistivity tomography, sensitivity kernels are obtained through the adjoint method by solving the electrostatic field equation with the finite-difference method. For seismic travel time tomography, ray paths and travel times are calculated using the fast marching method. We have tested our joint inversion method for a 2D cross-hole problem where two small zones with high and low velocity/resistivity anomalies. Seismic/electrical sources/receivers are installed in two boreholes. For separate seismic inversion, the smearing effect is evident and two anomaly zones are distorted and misplaced. For separate electric resistivity inversion, although two anomaly zones are positioned correctly their values are not accurate. By joint inversion, two velocity anomaly zones are clearly imaged and the smearing effect is greatly reduced. In comparison, for the resistivity model, the two anomaly zones

  6. Near-Surface Structure and Velocities of the Northeastern Santa Cruz Mountains and the Western Santa Clara Valley, California, From Seismic Imaging

    Science.gov (United States)

    Catchings, R.D.; Gandhok, G.; Goldman, M.R.; Steedman, Clare

    2007-01-01

    reservoirs, pipelines, and flood-protection facilities maintained by SCVWD. As one component of these joint studies, the USGS acquired an approximately 10-km-long, high-resolution, combined seismic reflection/refraction transect from the Santa Cruz Mountains to the central SCV in December 2000 (Figs. 1 and 2a,b). The overall seismic investigation of the western Santa Clara Valley also included an ~18-km-long, lower-resolution (~50-m sensor) seismic imaging survey from the central Santa Cruz Mountains to the central part of the valley (Fig. 1). Collectively, we refer to these seismic investigations as the 2000 western Santa Clara Seismic Investigations (SCSI). Results of the high-resolution investigation, referred to as SCSI-HR, are presented in this report, and Catchings et al. (2006) present results of the low-resolution investigation (SCSI-LR) in a separate report. In this report, we present data acquisition parameters, unprocessed and processed seismic data, and interpretations of the SCSI-HR seismic transect.

  7. Elastic Wavespeed Images of Northern Chile Subduction Zone from the Joint Inversion of Body and Surface Waves: Structure of the Andean Forearc and the Double Seismic Zone

    Science.gov (United States)

    Comte, D.; Carrizo, D.; Roecker, S. W.; Peyrat, S.; Arriaza, R.; Chi, R. K.; Baeza, S.

    2015-12-01

    Partly in anticipation of an imminent megathrust earthquake, a significant amount of seismic data has been collected over the past several years in northern Chile by local deployments of seismometers. In this study we generate elastic wavespeed images of the crust and upper mantle using a combination of body wave arrival times and surface wave dispersion curves. The body wave data set consists of 130000 P and 108000 S wave arrival times generated by 12000 earthquakes recorded locally over a period of 25 years by networks comprising about 360 stations. The surface wave data set consists of Rayleigh wave dispersion curves determined from ambient noise recorded by 60 broad band stations from three different networks over a period of three years. Transit time biases due to an uneven distribution of noise were estimated using a technique based on that of Yao and van der Hilst (2009) and found to be as high as 5% for some station pairs. We jointly invert the body and surface wave observations to both improve the overall resolution of the crustal images and reduce the trade-off between shallow and deep structures in the images of the subducted slab. Of particular interest in these images are three regions of anomalous Vp/Vs: (1) An extensive zone of low Vp/Vs (1.68) correlates with trench-parallel magmatic belts emplaced in the upper continental crust. In the region of the coast and continental slope, low Vp/Vs corresponds to batholithic structures in the Jurassic-Cretaceous magmatic arc. Between the central depression and Domeyko Cordillera, low Vp/Vs correlates with the distribution of magmatic arcs of Paleocene-Oligocene and Eocene-Oligocene age. Low Vp/Vs also correlates with the location of the Mejillones Peninsula. (2) A region of high Vp/Vs occurs in what is most likely the serpentinized wedge of the subduction zone. (3) An additional zone of low Vp/Vs is located in the middle of the double seismic zone at depths of 90-110 km. This region may exist all along the

  8. BASIMO - Borehole Heat Exchanger Array Simulation and Optimization Tool

    Science.gov (United States)

    Schulte, Daniel; Rühaak, Wolfram; Welsch, Bastian; Bär, Kristian; Sass, Ingo

    2016-04-01

    Borehole heat exchangers represent a well-established technology, which pushes for new fields of applications and novel modifications. Current simulation tools cannot - or only to some extent - describe features like inclined or partly insulated boreholes unless they run fully discretized models of the borehole heat exchangers. However, fully discretized models often come at a high computational cost, especially for large arrays of borehole heat exchangers. We present a tool, which uses one dimensional thermal resistance and capacity models for the borehole heat exchangers coupled with a numerical finite element model for the subsurface heat transport. An unstructured tetrahedral mesh bypasses the limitations of structured grids for borehole path geometries, while the thermal resistance and capacity model is improved to account for borehole heat exchanger properties changing with depth. The presented tool benefits from the fast analytical solution of the thermal interactions within the boreholes while still allowing for a detailed consideration of the borehole heat exchanger properties.

  9. LAqui-core, a 150 m deep borehole into the depocenter of the basin controlled by the 2009 Mw=6.1 L'Aquila earthquake fault

    Science.gov (United States)

    Porreca, M.; Mochales Lopez, T.; Smedile, A.; Buratti, N.; Macri', P.; Di Chiara, A.; Nicolosi, I.; D'ajello Caracciolo, F.; Carluccio, R.; Di Giulio, G.; Vassallo, M.; Amoroso, S.; Villani, F.; Tallini, M.; Sagnotti, L.; Speranza, F.

    2013-12-01

    INSAR images showed that the 2009 Mw=6.1 normal faulting L'Aquila earthquake produced a maximum co-seismic subsidence of ca. 15 cm in the depocenter of the Middle Aterno basin (Abruzzi, central Italy), on the hanging-wall of the Paganica fault. This continental basin is one of the several fault-controlled extensional basins of the central Apennines and its sedimentation history is poorly known due to the scarcity of outcrops in the weakly incised infilling cover. During May-June 2013, a 151 m deep borehole was drilled in the basin depocenter, as shown by INSAR images. The recovered core (LAqui-core) consists of continental Holocene and Pleistocene clastic sediments and it do not reach the basin substrate. In the same area, we have also performed preliminary geological and geophysical (electrical resistivity tomography and seismic noise survey) investigations in order to select the best drilling location. We have also taken into account recently published high-resolution seismic tomographic data acquired in the same area, showing an evident thickening of low Vp sediments in correspondence of the depocenter. These approaches have been useful to infer the geometry and sedimentary facies architecture of the basin. A first general stratigraphic setting has been defined by means of lithostratigraphic description of the core. It can be subdivided in two main sequences. The upper sequence is composed by 41 meters of silt and sand deposits, interbedded with m-thick rounded gravel intervals. This sequence is interpreted as related to fluvial-alluvial fan depositional environments. An erosional discontinuity separates this upper sequence from the lower clay and sand sequence, typical of a lacustrine depositional environment. The lacustrine sequence continues till the bottom of the borehole and is interrupted in the middle by a 30 m thick coarse gravel deposit. On this stratigraphic record we have collected samples for different kind of analyses (now in progress), involving

  10. Seismic investigation of gas hydrates in the Gulf of Mexico: 2013 multi-component and high-resolution 2D acquisition at GC955 and WR313

    Science.gov (United States)

    Haines, Seth S.; Hart, Patrick E.; Shedd, William W.; Frye, Matthew

    2014-01-01

    The U.S. Geological Survey led a seismic acquisition cruise at Green Canyon 955 (GC955) and Walker Ridge 313 (WR313) in the Gulf of Mexico from April 18 to May 3, 2013, acquiring multicomponent and high-resolution 2D seismic data. GC955 and WR313 are established, world-class study sites where high gas hydrate saturations exist within reservoir-grade sands in this long-established petroleum province. Logging-while-drilling (LWD) data acquired in 2009 by the Gulf of Mexico Gas Hydrates Joint Industry Project provide detailed characterization at the borehole locations, and industry seismic data provide regional- and local-scale structural and stratigraphic characterization. Significant remaining questions regarding lithology and hydrate saturation between and away from the boreholes spurred new geophysical data acquisition at these sites. The goals of our 2013 surveys were to (1) achieve improved imaging and characterization at these sites and (2) refine geophysical methods for gas hydrate characterization in other locations. In the area of GC955 we deployed 21 ocean-bottom seismometers (OBS) and acquired approximately 400 km of high-resolution 2D streamer seismic data in a grid with line spacing as small as 50 m and along radial lines that provide source offsets up to 10 km and diverse azimuths for the OBS. In the area of WR313 we deployed 25 OBS and acquired approximately 450 km of streamer seismic data in a grid pattern with line spacing as small as 250 m and along radial lines that provide source offsets up to 10 km for the OBS. These new data afford at least five times better resolution of the structural and stratigraphic features of interest at the sites and enable considerably improved characterization of lithology and the gas and gas hydrate systems. Our recent survey represents a unique application of dedicated geophysical data to the characterization of confirmed reservoir-grade gas hydrate accumulations.

  11. Seismic VSP and HSP surveys on preliminary investigation areas in Finland for final disposal of spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Keskinen, J.; Cosma, C.; Heikkinen, P. (Vibrometric Oy, Helsinki (Finland))

    1992-10-01

    Seismic reflection surveys in boreholes were carried out for Teollisuuden Voima Oy at five sites in Finland (Eurajoki Olkiluoto, Hyrynsalmi Veitsivaara, Konginkangas Kivetty, Kuhmo Romuvaara and Sievi Syyry). The vertical Seismic Profiling (VSP) surveys were a part of the investigation programme for the final disposal of spent nuclear fuel. The purpose was to detect fractured zones, lithological contacts and other anomalies in the structure of the rockmass and to determine their position and orientation. Horizontal Seismic Profiling (HSP) was used at the Olkiluoto site, additionally to VSP. The data has been organized in profiles containing seismograms recorded from the same shotpoint (shot gathers). One of the most powerful processing methods used with this project has been the Image Space Filtering, a new technique, which has been developed (in the project) for seismic reflection studies in crystalline rock. The method can be applied with other rock types where steeply inclined or vertical anomalies are of interest. It acts like a multichannel filter, enhancing the reflected events and also as an interpretation tool, to estimate the strength and position of the reflectors. This approach has been of great help in emphasizing the weak reflections from uneven and sometimes vanishing interfaces encountered in crystalline.

  12. Seismic velocities, anisotropy and elastic properties of crystalline rocks and implications for interpretation of seismic data

    Science.gov (United States)

    Sun, Shengsi

    the strength of this thesis, which provides a detailed study of seismic properties (P- and S-wave velocities, hysteresis, anisotropy and shear wave splitting) on a unique suite of deep borehole core samples from the Chinese Continental Scientific Drilling (CCSD) project. The data show that the velocity-pressure data can successfully provide important hints about the preferred orientation of microcracks that causes P-wave velocity anisotropy and shear wave splitting in cracked rocks, and that the effect of compression on the Vp/Vs ratios is negligible for crack-free compacted rocks. The seismic velocities of equivalent isotropic (fabric-free) and crack-free crystalline aggregates calculated from room pressure single crystal elastic constants using the Voigt average are in agreement with laboratory data at ˜200 MPa. Comparison of the seismic reflection image from the vicinity of the borehole with the normal-incidence reflection coefficient profile computed from the laboratory-measured velocities and densities infers that the seismic reflections originate from mafic (eclogite and retrograde eclogite) or ultramafic units within dominantly felsic rocks. Chapter 4 is devoted to the characterization of Lamé constants for common types of crystalline rocks in the Earth's crust and upper mantle and their variations with pressure (P), temperature (T) and mineralogical composition. The analysis was based on the equivalent isotropic elastic data of 475 natural rocks, reported in the literature. Lamé parameter (λ) and shear modulus (μ) are the most important, intrinsic, elastic properties of rocks. When no partial melting, metamorphic reaction, dehydration or phase transformation occurs, λ of a crystalline rock as a function of P and T can be described by λ=a+(dλ/dP)P- cexp(-kP)-(dλ/dT)T, where a is the projected λ value at zero pressure if microcracks were fully closed; dλ/dP is the pressure derivative in the linear elastic regime; c is the initial λ drop caused by the

  13. Source Mechanism of Explosive Degassing at Kilauea Volcano Imaged From Inversion of Very Long Period Seismic Waveforms

    Science.gov (United States)

    Chouet, B. A.; Dawson, P. B.

    2008-12-01

    Following the opening of a new vent in the Halemaumau pit crater on 19 March 2008, summit activity at Kilauea has been marked by emissions of volcanic gases and ash from this vent, occasionally disrupted by explosive degassing bursts. The source mechanisms of very long period (VLP) signals accompanying the degassing bursts are analyzed in the 10 - 50 s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium. The waveforms of five explosions (19 March, 9 and 16 April, and 9 July 2008) are well reproduced by our inversions, which take into account volcano topography. All explosions originate from the same point source positioned 1000 m below the eastern perimeter of Halemaumau. The source mechanisms include both moment-tensor and single-force components. The principal axes of the moment tensor have amplitude ratios 1:1.4:1.5, which can be interpreted as representative of either a pipe, or two intersecting cracks, if one assumes the rock matrix at the source to have a Poisson ratio ν = 1/3, a value appropriate for hot rock. The imaged pipe dips 64° northeast, while the two-crack model features an east-striking crack (dike) dipping 80° north, intersecting a north-striking crack (another dike) dipping 65° east. Each explosion is marked by a similar sequence of deflation, inflation, deflation of the volumetric source, reflecting a cycle of depressurization, pressurization, depressurization within a time interval of ~1 min. Maximum volume changes range from 400 to 1500 m3 in the pipe model, and from 500 to 1900 m3 split roughly evenly among both cracks in the dual-crack model. Accompanying these volumetric components is a dominantly vertical single-force component with magnitude of 109 N. The force is initially upward, synchronous with source deflation, followed by a downward force synchronous with the subsequent source inflation. This combination of force and volume change is suggestive of a

  14. Excess plutonium disposition: The deep borehole option

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, K.L.

    1994-08-09

    This report reviews the current status of technologies required for the disposition of plutonium in Very Deep Holes (VDH). It is in response to a recent National Academy of Sciences (NAS) report which addressed the management of excess weapons plutonium and recommended three approaches to the ultimate disposition of excess plutonium: (1) fabrication and use as a fuel in existing or modified reactors in a once-through cycle, (2) vitrification with high-level radioactive waste for repository disposition, (3) burial in deep boreholes. As indicated in the NAS report, substantial effort would be required to address the broad range of issues related to deep bore-hole emplacement. Subjects reviewed in this report include geology and hydrology, design and engineering, safety and licensing, policy decisions that can impact the viability of the concept, and applicable international programs. Key technical areas that would require attention should decisions be made to further develop the borehole emplacement option are identified.

  15. High-Resolution Seismic Reflection and Refraction Imaging of the Hayward Fault in Fremont, Alameda County, California

    Science.gov (United States)

    Everson, E. D.; Rymer, M. J.; Goldman, M. R.; Catchings, R. D.

    2007-12-01

    In July 2007, the U.S. Geological Survey acquired a 60-m-long seismic reflection and refraction profile across the main trace of the Hayward fault in Fremont Central Park, Fremont, California. The profile was designed to determine the geometry, seismic velocities, and possible structural complexities of the fault. The study was along a part of the surface rupture of the 1868 M 7.0 Hayward earthquake. We used single-element, 40-Hz vertical geophones placed at 1-m intervals along the profile with 0.5-m lateral offset from the shot points, also with 1-m intervals. Seismic sources were generated by multiple sledgehammer blows at each shot point. Data were recorded unfiltered in the field on a Geometrics Strataview RX-60 seismograph at a sampling rate of 0.5 ms for 2 s. Geophone locations were measured in 3D using differential GPS. We developed a velocity model using the Hole (1992) code to invert P-wave first arrivals of the refraction data. Seismic P-wave velocities range from about 200 m/s near the surface to approximately 800 m/s at a depth of 13 to 16 m. The velocity model was then applied to the reflection data to develop an unmigrated common depth point (CDP) stack. The reflection data indicate the presence of at least three fault strands in an approximately 20-m-wide zone. We believe the three strands define an upwardly flaring 'flower structure', with the central strand being the main strand of the Hayward fault. The three strands project to merge at a depth of about 150 m; the overall dip of the fault zone in the upper 100 m is to the northeast, at about 88 degrees.

  16. A Sparse Bayesian Imaging Technique for Efficient Recovery of Reservoir Channels With Time-Lapse Seismic Measurements

    KAUST Repository

    Sana, Furrukh

    2016-06-01

    Subsurface reservoir flow channels are characterized by high-permeability values and serve as preferred pathways for fluid propagation. Accurate estimation of their geophysical structures is thus of great importance for the oil industry. The ensemble Kalman filter (EnKF) is a widely used statistical technique for estimating subsurface reservoir model parameters. However, accurate reconstruction of the subsurface geological features with the EnKF is challenging because of the limited measurements available from the wells and the smoothing effects imposed by the \\\\ell _{2} -norm nature of its update step. A new EnKF scheme based on sparse domain representation was introduced by Sana et al. (2015) to incorporate useful prior structural information in the estimation process for efficient recovery of subsurface channels. In this paper, we extend this work in two ways: 1) investigate the effects of incorporating time-lapse seismic data on the channel reconstruction; and 2) explore a Bayesian sparse reconstruction algorithm with the potential ability to reduce the computational requirements. Numerical results suggest that the performance of the new sparse Bayesian based EnKF scheme is enhanced with the availability of seismic measurements, leading to further improvement in the recovery of flow channels structures. The sparse Bayesian approach further provides a computationally efficient framework for enforcing a sparse solution, especially with the possibility of using high sparsity rates through the inclusion of seismic data.

  17. Borehole radar and BIPS investigations in boreholes at the Boda area

    Energy Technology Data Exchange (ETDEWEB)

    Carlsten, S.; Straahle, A. [GEOSIGMA AB, Uppsala (Sweden)

    2000-12-01

    As part of the studies conducted in the Boda area, measurements with borehole radar, borehole TV (BIPS) and deviation measurements were performed during May 2000. The investigations were carried out in four percussion-drilled boreholes with a total length of 514 m. Two boreholes are vertical and two are directed into and below the cave area. The BIPS measurement showed the presence of 14 open fractures. Largest apparent aperture width of open fractures was 133 mm. In the lowest part in boreholes 2, 3, and 4, particles in suspension deteriorated the visibility. BIPS has revealed a dominating subhorizontal fracture set and another striking NW to N-S with a dip close to vertical. Possible but very uncertain is a third fracture set striking NE and dipping steeply towards S. The open and partly open fractures forms an average block size 11 m wide and 6 m high, while the length of the block is uncertain. Of 98 borehole radar reflectors interpreted to intersect within BIPS-mapped sections, 90 were possible to combine with BIPS-mapped structures, i.e. 92% of the radar reflectors. The fractured rock around Boda is a shallow feature, since borehole radar and BIPS measurements shows no evidence of increased fracturing or the presence of caves at larger depth in the Boda area. The result indicates that the formation of the superficial fracture system (with caves included) at Boda in all probability is connected to glacial action, such as banking.

  18. Characterization of crystalline rocks in deep boreholes. The Kola, Krivoy Rog and Tyrnauz boreholes

    International Nuclear Information System (INIS)

    SKB studies, as one alternative, the feasibility of disposing of spent nuclear fuel in very deep boreholes. As a part of this work NEDRA has compiled geoscientific data from three superdeep boreholes within the former Soviet Union. The holes considered were: the Kola borehole, 12261 m deep and located on the Kola Peninsula, the Krivoy Rog borehole, 5000 m deep and located in Ukraine, and the Tyrnauz borehole, 4001 m deep and located between the Black Sea and the Caspian Sea. These boreholes all penetrate crystalline formations, but major differences are found when their tectonic environments are compared. Excluding the uppermost horizon affected by surface phenomena, data do not indicate any general correlation between depth and the state of rock fracturing, which is instead governed by site specific, lithological and tectonical factors. This applies also to fracture zones, which are found at similar frequencies at all depths. As opposed to the structural data, the hydrogeological and hydrochemical information reveals a vertical zonation, with clear similarities between the three boreholes. An upper zone with active circulation and fresh or slightly mineralized groundwaters reaches down 1000-2000 m. The interval from 1000-2000 m down to 4000-5000 m can be characterized as a transition zone with lower circulation rates and gradually increasing mineralisation. Below 4000-5000 m, strongly mineralized, stagnant, juvenile or metamorphogenic waters are found. Geothermal data verify the existence of this zonation. 28 figs, 30 tabs

  19. Seismic images of the mantle transition zone beneath Northeast China and the Sino-Korean craton from P-wave receiver functions

    Science.gov (United States)

    Zhang, Ruiqing; Gao, Zhanyong; Wu, Qingju; Xie, Zhenxing; Zhang, Guangcheng

    2016-04-01

    Seismic data from northeast (NE) China and the Sino-Korean craton were combined to image the upper mantle discontinuities at 410 and 660 km. Fine-scale topographic variations on these two discontinuities provide important clues for both delineating geometry of the subducting Pacific slab particularly at arc-arc junction and interpreting regional Cenozoic intraplate volcanism. We used over 90,000 receiver functions from 1916 teleseismic earthquakes recorded by 584 broadband seismic stations, primary those of temporary seismic arrays. We found the average depths of the two discontinuities to be 410 km and 672 km, respectively, beneath the study area. Results show that the 660-km discontinuity is strongly depressed by about 20-30 km in a narrow region beneath and around the Changbaishan volcano, consistent with the results of previous receiver function studies. In contrast, much of the Sino-Korean craton exhibits typical transition zone thickness (~ 260 km) and thus offers no evidence of a stagnated Pacific slab. Our results also reveal an elevated 660-km discontinuity and a thinner transition zone both to the west of the observed depression region and beneath the Kuril-Japan arc junction. This feature is most likely due to a tearing of the descending Pacific plate at both its leading and junction edges. An additional elevated 660-km discontinuity together with a thinner transition zone appears in the vicinity of the Dariganga lava field, supporting interpretations of a deep-rooted mantle plume. Our observations of an elevated 410-km discontinuity and a thicker transition zone correlate spatially with the diffuse distribution of volcanism around Hannuoba, Aershan and Wudalianchi. This correlation may suggest lithospheric removal as a mechanism for these magmatic activities.

  20. Seismic Prediction While Drilling (SPWD): Seismic exploration ahead of the drill bit using phased array sources

    Science.gov (United States)

    Jaksch, Katrin; Giese, Rüdiger; Kopf, Matthias

    2010-05-01

    In the case of drilling for deep reservoirs previous exploration is indispensable. In recent years the focus shifted more on geological structures like small layers or hydrothermal fault systems. Beside 2D- or 3D-seismics from the surface and seismic measurements like Vertical Seismic Profile (VSP) or Seismic While Drilling (SWD) within a borehole these methods cannot always resolute this structures. The resolution is worsen the deeper and smaller the sought-after structures are. So, potential horizons like small layers in oi