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Sample records for borehole seismic imaging

  1. Mapping permeable fractures at depth in crystalline metamorphic shield rocks using borehole seismic, logging, and imaging

    Science.gov (United States)

    Chan, J.; Schmitt, D. R.; Nieuwenhuis, G.; Poureslami Ardakani, E.; Kueck, J.; Abasolo, M. R.

    2012-04-01

    The presence of major fluid pathways in subsurface exploration can be identified by understanding the effects of fractures, cracks, and microcracks in the subsurface. Part of a feasibility study of geothermal development in Northern Alberta consists of the investigation of subsurface fluid pathways in the Precambrian basement rocks. One of the selected sites for this study is in the Fort McMurray area, where the deepest well drilled in the oilsands region in Northeastern Alberta is located. This deep borehole has a depth of 2.3 km which offers substantial depth coverage to study the metamorphic rocks in the Precambrian crystalline basement of this study area. Seismic reflection profiles adjacent to the borehole reveal NW-SE dipping reflectors within the metamorphic shield rocks some of which appear to intersect the wellbore. An extensive logging and borehole seismic program was carried out in the borehole in July, 2011. Gamma ray, magnetic susceptibility, acoustic televiewer, electrical resistivity, and full-waveform sonic logs were acquired to study the finer scale structure of the rock formations, with vertical resolutions in the range of 0.05 cm to 80 cm. These logs supplement earlier electrical microscanner images obtained by the well operator when it was drilled. In addition, we are also interested in identifying other geological features such as zones of fractures that could provide an indication of enhanced fluid flow potential - a necessary component for any geothermal systems to be viable. The interpretation of the borehole logs reveals a highly conductive 13 m thick zone at 1409 m depth that may indicate communication of natural brines in fractures with the wellbore fluid. The photoelectric factor and magnetic susceptibility also appear anomalous in this zone. Formation MicroImager (FMI) log was used to verify the presence of fractures in the borehole in this conductive zone. This fracture zone may coincide with the dipping seismic reflectors in the

  2. Borehole seismic modeling

    Science.gov (United States)

    Zhen, Tao

    In many borehole seismic experiments, the velocity of the tube wave is higher than that of the surrounding rock shear wave. This fast tube wave creates a strong conical shear wave in the surrounding rock, similar to the Mach wave in supersonic aviation and the Cherenkov radiation in electrodynamics. Many geophysicists have tried to utilize the conical signal in VSP (vertical seismic profiling) and cross borehole data interpretation, using quasi static approximations to model the borehole effect. Two popular quasi static approximations are: the effective source array method for source borehole modeling and the squeeze strain method for receiver borehole modeling. These quasi static approximations are sensible as they qualitatively conform to Hueygen's principle and the typical wavelength of a VSP or a cross borehole seismic experiment is much larger than the borehole radius. However, they have not been quantitatively benchmarked against other non approximation method such as the frequency wave number method. The frequency wave number method is a rigorous, non approximation method for modeling straight boreholes without lengthwise variation. The boreholes may consist of many coaxial, homogeneous and axially symmetric shells. In this thesis, the results of the quasi static approximations are compared to the results obtained from the frequency wave number method. The comparison demonstrates that both the effective source array method and squeeze strain method gives the correct arrival time. The effective source array method gives incorrect amplitude and waveform for direct arrivals and tube waves due to its arbitrary assumption of the elementary source radiation pattern. The squeeze strain method gives fairly accurate amplitude and waveform for P and S direct arrivals but it fails to match the tube wave results obtained from the frequency wave number method. The omission of tube wave dispersion and amplitude loss by the quasi static approximation methods also

  3. Combination of surface and borehole seismic data for robust target-oriented imaging

    Science.gov (United States)

    Liu, Yi; van der Neut, Joost; Arntsen, Børge; Wapenaar, Kees

    2016-05-01

    A novel application of seismic interferometry (SI) and Marchenko imaging using both surface and borehole data is presented. A series of redatuming schemes is proposed to combine both data sets for robust deep local imaging in the presence of velocity uncertainties. The redatuming schemes create a virtual acquisition geometry where both sources and receivers lie at the horizontal borehole level, thus only a local velocity model near the borehole is needed for imaging, and erroneous velocities in the shallow area have no effect on imaging around the borehole level. By joining the advantages of SI and Marchenko imaging, a macrovelocity model is no longer required and the proposed schemes use only single-component data. Furthermore, the schemes result in a set of virtual data that have fewer spurious events and internal multiples than previous virtual source redatuming methods. Two numerical examples are shown to illustrate the workflow and to demonstrate the benefits of the method. One is a synthetic model and the other is a realistic model of a field in the North Sea. In both tests, improved local images near the boreholes are obtained using the redatumed data without accurate velocities, because the redatumed data are close to the target.

  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

    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

  5. Integrating Ground Penetrating Radar, Electrical Resistivity, Seismic Refraction, and Borehole Data to Image an Alluvial Aquifer in Three Dimensions

    Science.gov (United States)

    Bailey, B. L.; Marshall, S. T.; Anderson, W. P.

    2010-12-01

    In this study we image the subsurface of a mountain stream floodplain in order to determine the three-dimensional aquifer geometry and degree of hydrologic connectivity. On site borehole data provides detailed information about the subsurface including direct measurements of depth to the water table; however, boreholes are not cost effective over a large area, the existing boreholes only have a penetration depth of ~3 meters, and subsurface stratigraphic features may only be locally present. We therefore combine borehole data with ground-penetrating radar (GPR), electrical resistivity, and seismic refraction data collected in linear transects perpendicular to the stream in order to effectively image a larger portion of the subsurface in three-dimensions. GPR data images several buried/abandoned channels, but no significant hydrologic barriers, such as clay lenses, have been found. Strong shallow reflectors in GPR data correlate to borehole measurements of water table depth and indicate a relatively flat water table surface. Furthermore, the GPR data show strong reflectors at the bedrock/sedimentary basin interface, which appears to dip towards the river mimicking the nearby surface topography. Resistivity transects also clearly delineate the water table and bedrock interface, reinforcing the GPR results. Seismic refraction data successfully resolves the dipping nature of the bedrock interface beyond the GPR penetration depth. Because bedrock was only encountered in one borehole, integrating the geophysical data provides constraints on overall aquifer volume. Future modeling studies of groundwater dynamics will better represent realistic aquifer properties by utilizing the data gathered here. Our continuing work will involve comparing the effectiveness of each geophysical technique for specific geologic targets, determining which techniques have the best resolution, and expanding the survey region.

  6. 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.

  7. 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

  8. 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.

  9. Development of a hydraulic borehole seismic source

    Energy Technology Data Exchange (ETDEWEB)

    Cutler, R.P.

    1998-04-01

    This report describes a 5 year, $10 million Sandia/Industry project to develop an advanced borehole seismic source for use in oil and gas exploration and production. The development Team included Sandia, Chevron, Amoco, Conoco, Exxon, Raytheon, Pelton, and GRI. The seismic source that was developed is a vertically oriented, axial point force, swept frequency, clamped, reaction-mass vibrator design. It was based on an early Chevron prototype, but the new tool incorporates a number of improvements which make it far superior to the original prototype. The system consists of surface control electronics, a special heavy duty fiber optic wireline and draw works, a cablehead, hydraulic motor/pump module, electronics module, clamp, and axial vibrator module. The tool has a peak output of 7,000 lbs force and a useful frequency range of 5 to 800 Hz. It can operate in fluid filled wells with 5.5-inch or larger casing to depths of 20,000 ft and operating temperatures of 170 C. The tool includes fiber optic telemetry, force and phase control, provisions to add seismic receiver arrays below the source for single well imaging, and provisions for adding other vibrator modules to the tool in the future. The project yielded four important deliverables: a complete advanced borehole seismic source system with all associated field equipment; field demonstration surveys funded by industry showing the utility of the system; industrial sources for all of the hardware; and a new service company set up by their industrial partner to provide commercial surveys.

  10. 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.

  11. Borehole Summary Report for Waste Treatment Plant Seismic Borehole C4993

    Energy Technology Data Exchange (ETDEWEB)

    Rust, Colleen F.; Barnett, D. BRENT; Bowles, Nathan A.; Horner, Jake A.

    2007-02-28

    A core hole (C4998) and three boreholes (C4993, C4996, and C4997) were drilled to acquire stratigraphic and downhole seismic data to model potential seismic impacts and to refine design specifications and seismic criteria for the Waste Treatment Plant (WTP) under construction on the Hanford Site. Borehole C4993 was completed through the Saddle Mountains Basalt, the upper portion of the Wanapum Basalt, and associated sedimentary interbeds, to provide a continuous record of the rock penetrated by all four holes and to provide access to the subsurface for geophysical measure¬ment. Presented and compiled in this report are field-generated records for the deep mud rotary borehole C4993 at the WTP site. Material for C4993 includes borehole logs, lithologic summary, and record of rock chip samples collected during drilling through the months of August through early October. The borehole summary report also includes documentation of the mud rotary drilling, borehole logging, and sample collection.

  12. Borehole Summary Report for Waste Treatment Plant Seismic Borehole C4996

    Energy Technology Data Exchange (ETDEWEB)

    Adams , S. C.; Ahlquist, Stephen T.; Fetters, Jeffree R.; Garcia, Ben; Rust, Colleen F.

    2007-01-28

    This report presents the field-generated borehole log, lithologic summary, and the record of samples collected during the recent drilling and sampling of the basalt interval of borehole C4996 at the Waste Treatment Plant (WTP) on the Hanford Site. Borehole C4996 was one of four exploratory borings, one core hole and three boreholes, drilled to investigate and acquire detailed stratigraphic and down-hole seismic data. This data will be used to define potential seismic impacts and refine design specifications for the Hanford Site WTP.

  13. 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

  14. Imaging systems for geotechnical boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Scott Thomson; S. Adam [CoalBed Concepts Pty Ltd. (Australia)

    2009-05-15

    The objective of this project was to develop a new system for evaluating geotechnical boreholes in underground mining. This approach was predicated on the demonstration of a commercial prototype imaging system (the Slim Borehole Scanner (SBS)) which is designed to be suitable for application in all standard geotechnical boreholes and is certified Intrinsically Safe (IS) in Europe. This project was designed to test this new imaging system in Australian conditions and critically compare the outcomes from the work with currently available technologies. A key aspect of the project was the assessment of the likely impact the imaging system has on current practices and recommendations for improved methods of geotechnical assessment in underground operations. A comprehensive field-testing program of the SBS was undertaken to evaluate its suitability for application in Australian conditions. Test work was completed at BHPB Illawarra Appin Colliery and Xstrata Coal Tahmoor Colliery. The Slim Borehole Scanner (SBS) was found to be a useful tool for enhancing the capability of Australian underground mine operators to assess roof conditions. The SBS is a significant advance on existing qualitative assessment methods such as the Borescope, and is complementary to existing direct measurement methods such as Tel-tales and Gel-extensometers. It is recommended that the SBS system undergo Australian intrinsic safety approval and be adopted as a routine part of the geotechnical engineer's arsenal in assessing roof control issues in Australian mines.

  15. 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.

  16. 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

  17. 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.

  18. 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

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

    Science.gov (United States)

    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.

  20. 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.

  1. 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)

  2. 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

  3. 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.

  4. Rupture Process for Hayward Microearthquakes Inferred from Borehole Seismic Recordings

    Science.gov (United States)

    Taira, T.; Dreger, D. S.; Nadeau, R. M.

    2014-12-01

    The Hayward fault (HF) in the San Francisco Bay Area, California is one of the major strands of the San Andreas fault system, extending for about 70 km. Crustal deformation along the HF is characterized by a wide variety of fault slip behaviors from aseismic creep to stick-slip earthquake including a Mw ~6.8 earthquake in 1868. We here document the high-resolution imaging of the rupture models for the recent M 3+ HF earthquakes by making use of waveforms from the Hayward Fault Network (HFN). The HFN is an array of borehole seismic instrumentation and provides an unprecedented high-resolution coverage of the earthquake source study for HF earthquakes. Using the finite-source rupture inversion with an empirical Green's function approach, we find a variety of rupture propagations including subevents, directivity, and high stress drop. Our finite-source modeling reveals a complex slip distribution for the 2013 Mw 3.2 Orinda earthquake that is characterized by a patch of slip with a maximum slip of 4 cm concentrated near the hypocenter at about 6.6 km depth, with a large secondary patch of slip (peak slip of 2 cm) centered up-dip and southeast from the hypocenter at a distance of about 400 m away. The two subevents release 43% and 23% of the total seismic moment (6.7 x 1013 N m) and the inferred peak stress drops are 18 MPa and 10 MPa. The 2011 Mw 4.0 Berkeley and 2012 Mw 4.0 El Cerrito earthquakes are marked by high stress drop. The inferred peak and mean stress drops are about 130-165 MPa and 45 MPa, respectively, which suggests that there are locally high levels of the fault strength on the HF. Our finite-source modeling suggests that the radiation efficiency determined for these two earthquakes is very low (< 0.1) and implies that majority of energy is dissipated during the earthquake rupture process.

  5. 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

  6. 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.

  7. Improvement of high resolution borehole seismics. Part 1: Development of processing methods for VSP surveys. Part 2: Piezoelectric signal transmitter for seismic measurements

    International Nuclear Information System (INIS)

    The purpose of the high resolution borehole seismics project has been to improve the reliability and resolution of seismic methods in the particular environment of nuclear waste repository sites. The results obtained, especially the data processing and interpretation methods developed, are applicable also to other geophysical methods (e.g. Georadar). The goals of the seismic development project have been: the development of processing and interpretation techniques for mapping fractured zones, and the design and construction of a seismic source complying with the requirements of repository site characterization programs. Because these two aspects of the work are very different in nature, we have structured the report as two self contained parts. Part 1 describes the development of interpretive techniques. We have used for demonstrating the effect of different methods a VSP data set collected at the SCV site during Stage 1 of the project. Five techniques have been studied: FK-filtering, three versions of Tau-p filtering and a new technique that we have developed lately, Image Space filtering. Part 2 refers to the construction of the piezoelectric source. Earlier results obtained over short distances with low energy piezoelectric transmitters let us believe that the same principle could be applied for seismic signal transmitters, if solutions for higher energy and lower frequency output were found. The instrument which we have constructed is a cylindrical unit which can be placed in a borehole and is able to produce a radial strain when excited axially. The minimum borehole diameter is 56 mm. (au)

  8. 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

  9. 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.

  10. 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).

  11. 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.

  12. OGS improvements in 2012 in running the Northeastern Italy Seismic Network: the Ferrara VBB borehole seismic station

    Science.gov (United States)

    Pesaresi, Damiano; Romanelli, Marco; Barnaba, Carla; Bragato, Pier Luigi; Durì, Giorgio

    2013-04-01

    The Centro di Ricerche Sismologiche (CRS, Seismological Research Center) 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 Northeastern Italy Seismic Network: it currently consists of 17 very sensitive broad band and 18 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS-CRS data center in Udine. Real time data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of about 100 seismic stations acquired in real time, which makes the OGS the reference institute for seismic monitoring of Northeastern Italy. The southwestern edge of the OGS seismic network stands on the Po alluvial basin: earthquake localization and characterization in this area is affected by the presence of soft alluvial deposits. OGS ha already experience in running a local seismic network in high noise conditions making use of borehole installations in the case of the micro-seismicity monitoring of a local gas storage site for a private company. Following the ML=5.9 earthquake that struck the Emilia region around Ferrara in Northern Italy on May 20, 2012 at 02:03:53 UTC, a cooperation of Istituto Nazionale di Geofisica e Vulcanologia, OGS, the Comune di Ferrara and the University of Ferrara lead to the reinstallation of a previously existing very broad band (VBB) borehole seismic station in Ferrara. The aim of the OGS intervention was on one hand to extend its real time seismic monitoring capabilities toward South-West, including Ferrara and its surroundings, and on the other hand to evaluate the seismic response at the site. We will describe improvements in running the Northeastern Italy Seismic Network, including details of the Ferrara VBB

  13. 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.

  14. SURFACE AND BOREHOLE ELECTROMAGNETIC IMAGING OF CONDUCTING CONTAMINANT PLUMES

    Science.gov (United States)

    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 ma...

  15. 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

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

    Science.gov (United States)

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

    2014-07-01

    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 stations, all telemetered to and acquired in real time at the OGS-CRS data centre in Udine. Real time data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of about 100 seismic stations acquired in real time, which makes the OGS the reference institute for seismic monitoring of North-eastern Italy. The south-western edge of the OGS seismic network (Fig. 1) stands on the Po alluvial basin: earthquake localization and characterization in this area is affected by the presence of soft alluvial deposits. OGS ha already experience in running a local seismic network in high noise conditions making use of borehole installations in the case of the micro-seismicity monitoring of a local gas storage site for a private company. Following the ML = 5.9 earthquake that struck the Emilia region around Ferrara in Northern Italy on 20 May 2012 at 02:03:53 UTC, a cooperation of Istituto Nazionale di Geofisica e Vulcanologia, OGS, the Comune di Ferrara and the University of Ferrara lead to the reinstallation of a previously existing very broad band (VBB) borehole seismic station in Ferrara. The aim of the OGS intervention was on one hand to extend its real time seismic monitoring capabilities toward South-West, including Ferrara and its surroundings, and on the other hand to evaluate the seismic response at the site. We will describe improvements in running the North-eastern Italy Seismic Network, including details of

  17. 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

  18. Automating Shallow Seismic Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Steeples, Don W.

    2004-12-09

    This seven-year, shallow-seismic reflection research project had the aim of improving geophysical imaging of possible contaminant flow paths. Thousands of chemically contaminated sites exist in the United States, including at least 3,700 at Department of Energy (DOE) facilities. Imaging technologies such as shallow seismic reflection (SSR) and ground-penetrating radar (GPR) sometimes are capable of identifying geologic conditions that might indicate preferential contaminant-flow paths. Historically, SSR has been used very little at depths shallower than 30 m, and even more rarely at depths of 10 m or less. Conversely, GPR is rarely useful at depths greater than 10 m, especially in areas where clay or other electrically conductive materials are present near the surface. Efforts to image the cone of depression around a pumping well using seismic methods were only partially successful (for complete references of all research results, see the full Final Technical Report, DOE/ER/14826-F), but peripheral results included development of SSR methods for depths shallower than one meter, a depth range that had not been achieved before. Imaging at such shallow depths, however, requires geophone intervals of the order of 10 cm or less, which makes such surveys very expensive in terms of human time and effort. We also showed that SSR and GPR could be used in a complementary fashion to image the same volume of earth at very shallow depths. The primary research focus of the second three-year period of funding was to develop and demonstrate an automated method of conducting two-dimensional (2D) shallow-seismic surveys with the goal of saving time, effort, and money. Tests involving the second generation of the hydraulic geophone-planting device dubbed the ''Autojuggie'' showed that large numbers of geophones can be placed quickly and automatically and can acquire high-quality data, although not under rough topographic conditions. In some easy

  19. 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

  20. Empirical Study Of Tube Wave Suppression For Single Well Seismic Imaging

    Energy Technology Data Exchange (ETDEWEB)

    West, P.B.; Weinberg, D.M.; Fincke, J.R.

    2002-05-31

    This report addresses the Idaho National Engineering and Environmental Laboratory's portion of a collaborative effort with Lawrence Berkeley National Laboratory and Sandia National Laboratories on a borehole seismic project called Single Well Seismic Imaging. The INEEL's role was to design, fabricate, deploy, and test a number of passive devices to suppress the energy within the borehole. This energy is generally known as tube waves. Heretofore, tube waves precluded acquisition of meaningful single-well seismic data. This report addresses the INEEL tests, theories, observations, and test results.

  1. Empirical Study Of Tube Wave Suppression For Single Well Seismic Imaging

    Energy Technology Data Exchange (ETDEWEB)

    West, Phillip Bradley; Weinberg, David Michael; Fincke, James Russell

    2002-05-01

    This report addresses the Idaho National Engineering and Environmental Laboratory's portion of a collaborative effort with Lawrence Berkeley National Laboratory and Sandia National Laboratories on a borehole seismic project called Single Well Seismic Imaging. The INEEL's role was to design, fabricate, deploy, and test a number of passive devices to suppress the energy within the borehole. This energy is generally known as tube waves. Heretofore, tube waves precluded acquisition of meaningful single-well seismic data. This report addresses the INEEL tests, theories, observations, and test results.

  2. 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...

  3. 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

  4. Geophysical borehole logging and optical imaging of the boreholes KR34, KR35 and KR36, at Olkiluoto 2005

    Energy Technology Data Exchange (ETDEWEB)

    Majapuro, J. [Suomen Malmi Oy, Espoo (Finland)

    2005-09-15

    Suomen Malmi Oy conducted geophysical borehole logging and optical imaging surveys of the boreholes KR34, KR35 and KR36 at the Olkiluoto site in Eurajoki during May - June 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 magnetic susceptibility, natural gamma radiation, gamma-gamma density, single point resistance, Wenner-resistivity, borehole radar, full waveform sonic and optical imaging. The assignment included the field work of all surveys, interpretation and processing of the acoustic and borehole radar 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.)

  5. Geophysical borehole logging and optical imaging of the boreholes KR34, KR35 and KR36, at Olkiluoto 2005

    International Nuclear Information System (INIS)

    Suomen Malmi Oy conducted geophysical borehole logging and optical imaging surveys of the boreholes KR34, KR35 and KR36 at the Olkiluoto site in Eurajoki during May - June 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 magnetic susceptibility, natural gamma radiation, gamma-gamma density, single point resistance, Wenner-resistivity, borehole radar, full waveform sonic and optical imaging. The assignment included the field work of all surveys, interpretation and processing of the acoustic and borehole radar 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.)

  6. 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

  7. 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.

  8. Construction of System for Seismic Observation in Deep Borehole (SODB) - Overview and Achievement Status of the Project

    International Nuclear Information System (INIS)

    The seismic responses of each unit at the Kashiwazaki-Kariwa NPP differed greatly during the 2007 Niigata-ken Chuetsu-oki Earthquake; the deep sedimentary structure around the site greatly affected these differences. To clarify underground structure and to evaluate ground motion amplification and attenuation effects more accurately in accordance with deep sedimentary structure, JNES initiated the SODB project. Deployment of a vertical seismometer array in a 3000-meter deep borehole was completed in June 2012 on the premises of NIIT. Horizontal arrays were also placed on the ground surface. Experiences and achievements in the JNES project were introduced, including development of seismic observation technology in deep boreholes, site amplification measurements from logging data, application of borehole observation data to maintenance of nuclear power plant safety, and so on. Afterwards, the relationships of other presentations in this WS, were explained. (authors)

  9. Delineation of tunnel valley across the North Sea coastline, Denmark based on reflection seismic data, boreholes, TEM and Schlumberger soundings

    DEFF Research Database (Denmark)

    Andersen, Theis Raaschou; Jørgensen, Flemming; Christensen, Steen

    2016-01-01

    on- and offshore 2D seismic data, TEM (Transient Electro-Magnetic) soundings, Schlumberger soundings, and boreholes. The valleys are observed as discrete incisions with three overall orientations: SSE – NNW, ESE – WNW, and SSW – NNE. They have depths between 75 and 185 m, widths up to 1.8 km, and...

  10. Exploring anisotropic seismic property of the seismogenic plate boundary in the Nankai Trough using a seafloor borehole observatory

    Science.gov (United States)

    Araki, E.; Kimura, T.; Kodaira, S.; Miura, S.; Takaesu, M.; Takahashi, N.; Nakano, M.; Kaneda, Y.

    2014-12-01

    Stress state in the vicinity of a seismogenic fault would be a key parameter governing its fault dynamics. Stress analysis in a borehole such as breakout may give stress information, but drilling seismogenic fault at depth is still challenging and it is even more difficult to perform repeated stress measurements for temporal evolution of stress state. Here we consider applying seismic anisotropy as an index of stress state and by observing its temporal change to identify change of stress around the seismogenic fault. In this study, we explored techniques to assess seismic anisotropy in the Nankai Trough accretionary prism, using a borehole seismometer deployed in IODP borehole C0002G, which is located just above the Tonankai earthquake fault. The borehole seismometer is situated at about 900 m below 1966 m deep seafloor, and is operational since January 2013 when the observatory was connected to DONET seafloor cable network. We developed a technique to analyze seismic anisotropy on converted S-wave from microseismic noise records and applied the technique on the borehole seismometer records, by which we expect to evaluate temporal change of anisotropy continuously. We obtained anisotropy of a few percent. We further evaluated depth dependency of anisotropy direction and obtained the difference between the uppermost sedimentary basin and accretionary prism near the plate boundary. We also performed airgun array shooting around the borehole in November 2013 to check validity of the anisotropy result. We applied two different analysis on the airgun records, the one was P-wave seismic anisotropy from the travel time, and the other was S-wave anisotropy using converted S-wave from airgun P-wave. Preliminary results from these analysis were consistent with the microseismic noise analysis. Repeated airgun shooting is planned at the interval of a year or so to evaluate our ability to detect its temporal change.

  11. 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

  12. Seismic imaging of the oil and geothermal reservoirs using the induced seismicity

    Science.gov (United States)

    Zhang, H.; Toksoz, M. N.; Fehler, M.

    2011-12-01

    It is known that microseismicity can be induced in the oil field due to the stress change caused by oil/gas production. Similarly, injection of high-pressure fluids into the reservoir can also induce microseismicity. Due to the proximity of induced seismicity to the reservoir, in some cases, it may be advantageous to use induced seismicity to image the reservoir. The seismic stations for monitoring the induced seismicity are usually sparse. Conventional travel time tomography using travel times from seismic events to stations may not be applicable because of poor ray coverage outside the source region. In comparison, the double-difference tomography method of Zhang and Thurber (2003) that uses the differential travel times is able to image the reservoir by avoiding determining the velocity structure outside the source region. In this study, we present two case studies of applying double-difference tomography to induced seismicity monitored by borehole stations. In the case of an oil field in Oman, five closely spaced monitoring wells are used to monitor microseismicity induced by gas production. In each well, multiple seismic sensors are positioned from depths 750 m - 1250 m and about 2000 events are selected for tomography. Reservoir imaging shows encouraging results in identifying structures and velocity changes within reservoir layers. Clear velocity contrast was seen across the major northeast-southwest faults. Low Vp, low Vs and low Vp/Vs anomalies are mainly associated with the gas production layer. For the case of the Soultz Enhanced Geothermal System at Soultz-sous-Forets, France, we used travel time data from the September and October 1993 hydraulic stimulations, where only four borehole stations are available. The results showed that the S-wave velocity structure correlated well with seismicity and showed low velocity zones at depths between 2900 and 3300 meters, where fluid was believed to have infiltrated the reservoir. We also attempt time

  13. 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

  14. Rupture process for micro-earthquakes inferred from borehole seismic recordings

    Science.gov (United States)

    Taira, Taka'aki; Dreger, Douglas S.; Nadeau, Robert M.

    2015-09-01

    We investigate the spatial extent of rupture and variability in fault slip for micro-earthquakes by inverting seismic moment rate functions derived from empirical Green's function deconvolution. By using waveforms from an array of borehole seismometers, we determine the spatial distributions of fault slip for M 3+ earthquakes that occurred along the Hayward fault in central California and identify a variety of slip behaviors including subevents, directivity, and high stress drop. The 2013 M w 3.2 Orinda earthquake exhibits a complex rupture process involving two subevents with northwest and up-dip directivity. The two subevents release 43 and 18 % of the total seismic moment (6.7 × 1013 N m), and their inferred peak stress drops are 18 and 8 MPa. The 2011 M w 4.0 Berkeley and 2012 M w 4.0 El Cerrito earthquakes are marked by high stress drop. The inferred peak and mean stress drops are about 100-130 and 40 MPa, respectively, which suggests that there are locally high levels of fault strength on the Hayward fault. Our finite-source modeling suggests that the radiation efficiency determined for these two earthquakes is very low (<0.1) and implies that most energy is dissipated during the earthquake rupture process.

  15. 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)

  16. 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

  17. 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.)

  18. Anomalous fluid emission of a deep borehole in a seismically active area of Northern Apennines (Italy)

    International Nuclear Information System (INIS)

    The Miano borehole, 1047 m deep, is located close to the river Parma in the Northern Apennines, Italy. A measuring station has been installed to observe the discharge of fluids continuously since November 2004. The upwelling fluid of this artesian well is a mixture of thermal water and CH4 as main components. In non-seismogenic areas, a relatively constant fluid emission would be expected, perhaps overlaid with long term variations from that kind of deep reservoir over time. However, the continuous record of the fluid emission, in particular the water discharge, the gas flow rate and the water temperature, show periods of stable values interrupted by anomalous periods of fluctuations in the recorded parameters. The anomalous variations of these parameters are of low amplitude in comparison to the total values but significant in their long-term trend. Meteorological effects due to rain and barometric pressure were not detected in recorded data probably due to reservoir depth and relatively high reservoir overpressure. Influences due to the ambient temperature after the discharge were evaluated by statistical analysis. Our results suggest that recorded changes in fluid emission parameters can be interpreted as a mixing process of different fluid components at depth by variations in pore pressure as a result of seismogenic stress variation. Local seismicity was analyzed in comparison to the fluid physico-chemical data. The analysis supports the idea that an influence on fluid transport conditions due to geodynamic processes exists. Water temperature data show frequent anomalies probably connected with possible precursory phenomena of local seismic events.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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...

  5. 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.

  6. Site study plan for EDBH [Engineering Design Boreholes] seismic surveys, Deaf Smith County site, Texas: Revision 1

    International Nuclear Information System (INIS)

    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

  7. Geophysical borehole logging and optical imaging of the pilot hole ONK-PH2

    Energy Technology Data Exchange (ETDEWEB)

    Lahti, M. [Suomen Malmi Oy, Espoo (Finland); Heikkinen, E. [JP-Fintact Oy, Vantaa (Finland)

    2005-01-15

    Suomen Malmi Oy conducted geophysical borehole logging and optical imaging surveys of pilot hole ONK-PH2 in ONKALO tunnel at the Olkiluoto site in December 2004. The survey is a part of Posiva Oy's detailed investigation program for the final disposal of spent nuclear fuel. The methods applied are magnetic susceptibility, natural gamma radiation, gamma-gamma density, single point resistance, Wenner-resistivity, borehole radar, full waveform sonic and optical imaging. The assignment included the field work of all the surveys, integration of the data as well as interpretation of the acoustic and borehole radar data. The report describes the field operation, equipment, processing procedures, interpretation results and shows the obtained geophysical and image data. The data as well as the interpretation results are delivered digitally in WellCAD and Excel format. (orig.)

  8. Geophysical borehole logging and optical imaging of the pilot hole ONK-PH2

    International Nuclear Information System (INIS)

    Suomen Malmi Oy conducted geophysical borehole logging and optical imaging surveys of pilot hole ONK-PH2 in ONKALO tunnel at the Olkiluoto site in December 2004. The survey is a part of Posiva Oy's detailed investigation program for the final disposal of spent nuclear fuel. The methods applied are magnetic susceptibility, natural gamma radiation, gamma-gamma density, single point resistance, Wenner-resistivity, borehole radar, full waveform sonic and optical imaging. The assignment included the field work of all the surveys, integration of the data as well as interpretation of the acoustic and borehole radar data. The report describes the field operation, equipment, processing procedures, interpretation results and shows the obtained geophysical and image data. The data as well as the interpretation results are delivered digitally in WellCAD and Excel format. (orig.)

  9. 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

  10. 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.

  11. The Application of Borehole Seismic Techniques in Mine Development at the Millennium Uranium Deposit, Northern Saskatchewan, Canada

    International Nuclear Information System (INIS)

    The Millennium uranium deposit is located within the Athabasca Basin of northern Saskatchewan, Canada. The deposit is situated in metasedimentary rocks, is controlled by multiple sub-vertical faults, and crossfaults and is overlain by over 500 m of intensely altered, porous Manitou Falls group sandstones. The rock quality directly surrounding the deposit is greatly reduced because of alteration and post-Athabasca sandstone structures, which provide conduits for the migration of basinal and meteoric fluids. This leads to significant risk for mine development and shaft sinking, because of the increased potential for water inflow into mine workings. To mitigate the risk involved with mining in such complex geology several projects were proposed as part of a pre-feasibility study. Of these, seismic methods were identified as the best tool to potentially identify alteration and structurally compromised zones. Subsequently, a comprehensive surface and borehole seismic program was completed in an attempt to delineate these engineering hazards and to provide assurance of success of the shaft sinking and mine development. This was the first time a seismic program of this scale was undertaken for geotechnical studies during mine development in the Athabasca Basin. (author)

  12. 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...

  13. Construction of System for Seismic Observation in Deep Borehole (SODB) - Development of Multi-depth, High-temperature/pressure resistance seismometer

    International Nuclear Information System (INIS)

    The development of a high quality system for seismic observation in deep boreholes, the installation process at the NIIT site, and the data sharing plan for this observation were explained. The key points of the development were high temperature resistance (150 degrees Celsius), high pressure resistance (30 MPa), and a high dynamic/wide frequency range seismometer which allows for observation of micro-tremor to strong motions as well as a cascade-connection-type borehole seismometer, which allows multiple probes to be set at several depths in a single borehole. The developed system consists of broadband (0.1-50 Hz) and high dynamic range (up to 1000 gal) seismometer with electronic parts on the ground and only the pendulum part in the borehole (it became a servo-type seismometer). Durability and maintenance may be issues in the future. (author)

  14. 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...

  15. 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

  16. Determination of in-situ fracture apertures from digital borehole images

    International Nuclear Information System (INIS)

    Imaging methods applied to borehole investigations have become common for mapping and characterisation of the rock mass. Today we have access to detailed information about the rock, but we lack some methods for analysis. In this study we develop a methodology for measurements of in-situ fracture geometry, from optical borehole images (BIP-system). We focus on the detailed information about fracture geometry, available thanks to the high image resolution. We have decided to perform the measurements using digital image processing, to avoid bias from the human analyst, and we present on-going work on the image processing methodology. Our method is based on iterative intensity thresholding. We work on grey-scale images, of open fractures that fully intersect the borehole. The fracture trace comes out as a dark sinusoidal in the borehole image. First, the darkest pixels in the image are extracted. Then the pixels, which are immediate neighbours to the first set, are included, under the condition that they are darker than a somewhat lower threshold. The including of neighbours is repeated until the fracture trace is filled. The resulting sinusoidal fracture trace is then used for finding an approximation of the fracture plane. The fracture plane orientation is used for determination of true aperture from the apparent aperture seen in the image. After this, fracture aperture statistics can be determined. The method works well for images of open fractures of simple geometry (sine wave). It needs to be improved to handle more complex geometry, e.g. crossing fracture traces. Today, some minor interaction from the analyst is needed, but slight modifications will minimise this

  17. 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

  18. 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...

  19. 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

  20. Seismic imaging: From classical to adjoint tomography

    Science.gov (United States)

    Liu, Q.; Gu, Y. J.

    2012-09-01

    Seismic tomography has been a vital tool in probing the Earth's internal structure and enhancing our knowledge of dynamical processes in the Earth's crust and mantle. While various tomographic techniques differ in data types utilized (e.g., body vs. surface waves), data sensitivity (ray vs. finite-frequency approximations), and choices of model parameterization and regularization, most global mantle tomographic models agree well at long wavelengths, owing to the presence and typical dimensions of cold subducted oceanic lithospheres and hot, ascending mantle plumes (e.g., in central Pacific and Africa). Structures at relatively small length scales remain controversial, though, as will be discussed in this paper, they are becoming increasingly resolvable with the fast expanding global and regional seismic networks and improved forward modeling and inversion techniques. This review paper aims to provide an overview of classical tomography methods, key debates pertaining to the resolution of mantle tomographic models, as well as to highlight recent theoretical and computational advances in forward-modeling methods that spearheaded the developments in accurate computation of sensitivity kernels and adjoint tomography. The first part of the paper is devoted to traditional traveltime and waveform tomography. While these approaches established a firm foundation for global and regional seismic tomography, data coverage and the use of approximate sensitivity kernels remained as key limiting factors in the resolution of the targeted structures. In comparison to classical tomography, adjoint tomography takes advantage of full 3D numerical simulations in forward modeling and, in many ways, revolutionizes the seismic imaging of heterogeneous structures with strong velocity contrasts. For this reason, this review provides details of the implementation, resolution and potential challenges of adjoint tomography. Further discussions of techniques that are presently popular in

  1. 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

  2. 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.)

  3. 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

  4. 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

  5. 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.

  6. 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., Jr.; 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. High-resolution reflection seismic imaging of the upper crust at Laxemar, southeastern Sweden

    Science.gov (United States)

    Bergman, B.; Juhlin, C.; Palm, H.

    2002-09-01

    A major cost in exploring the upper 1-2 km of crystalline crust with reflection seismics is the drilling required for explosive sources. By reducing the charge size to a minimum, shallow inexpensive shotholes can be drilled with handheld equipment. Here, we present results from a full-scale test using small charges for high-resolution seismic surveying over a nuclear waste disposal study site (not an actual site). Two 2-2.5-km-long crossing profiles were acquired in December 1999 with 10-m shot and geophone spacing in the Laxemar area, near Oskarshamn in southeastern Sweden. After standard processing, including dip moveout (DMO), several subhorizontal to moderately dipping reflections are imaged. Many of the dipping ones can be correlated to fracture zones observed in a ca. 1700-m-deep borehole where the profiles cross and/or to fracture zones mapped on the surface. The imaged fracture zones form a complex 3D pattern illustrating the necessity of having 3D control before interpreting seismic reflection data. Analyses of sonic and density logs from the borehole show that greenstones have significantly higher impedances than the more dominant granite found in the borehole (granite/greenstone reflection coefficient is +0.065). These greenstones may contribute to the reflectivity when associated with fracture zones. In some cases, where they are present as larger subhorizontal lenses, they may be the dominant source of reflectivity. A set of north-dipping (10°) reflectors at 3-3.5-km depth can be correlated to a similar set observed below the island of Ävrö about 3 km to the east.

  12. 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.

  13. 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.

  14. 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...

  15. Combined analysis of surface reflection imaging and vertical seismic profiling at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    This report presents results from surface and borehole seismic profiling performed by the Lawrence Berkeley Laboratory (LBL) on Yucca Mountain. This work was performed as part of the site characterization effort for the potential high-level nuclear waste repository. Their objective was to provide seismic imaging from the near surface (200 to 300 ft. depth) to the repository horizon and below, if possible. Among the issues addressed by this seismic imaging work are location and depth of fracturing and faulting, geologic identification of reflecting horizons, and spatial continuity of reflecting horizons. The authors believe their results are generally positive, with tome specific successes. This was the first attempt at this scale using modem seismic imaging techniques to determine geologic features on Yucca Mountain. The principle purpose of this report is to present the interpretation of the seismic reflection section in a geologic context. Three surface reflection profiles were acquired and processed as part of this study. Because of environmental concerns, all three lines were on preexisting roads. Line 1 crossed the mapped surface trace of the Ghost Dance fault and it was intended to study the dip and depth extent of the fault system. Line 2 was acquired along Drill Hole wash and was intended to help the ESF north ramp design activities. Line 3 was acquired along Yucca Crest and was designed to image geologic horizons which were thought to be less faulted along the ridge. Unfortunately, line 3 proved to have poor data quality, in part because of winds, poor field conditions and limited time. Their processing and interpretation efforts were focused on lines 1 and 2 and their associated VSP studies

  16. 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.

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

    Directory of Open Access Journals (Sweden)

    Zeinab Asry

    2012-01-01

    Full Text Available 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 connected to a multicore cable. The refraction seismic was conducted using 24 channel ABEM Mark6 signal enhancement seismograph with 5 m geophone spacing. The resistivity layer is associated with the residual soil with thickness of about 0.5-3 m. The high velocity layer is an average depth of about 9.4 m. The intermediate velocity zone is associated with weathered schist with thickness of about 2.5 m. The low velocity zone is with thickness of about 6 m. The thickness of residual soil obtained by seismic refraction survey appears to agree very well with the borehole data. Resistivity and the seismic refraction data have been successfully used to determine the thickness of residual soil layer and depth of bedrock. Approach: In this survey, electrodes were arranged in a straight line with constant spacing and connected to a multicore cable. The refraction seismic was conducted using 24 channel ABEM Mark6 signal enhancement seismograph with 5 m geophone spacing. The seismic data have been interpreted using SeisOpt@2D which automatically produced 2-D seismic velocity sections of the subsurface. Results: The resistivity results showed that the subsurface layers are associated with variable resistivity (296-2600Ω. m. The resistivity layer is associated with the residual soil with thickness of about 0.5-3 m. The interpreted 2-D seismic sections showed three different velocity layers. The high velocity layer (1600-2000 m sec-1 is interpreted to be associated with bedrock

  18. 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.

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

    International Nuclear Information System (INIS)

    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 angle and

  20. 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.

  1. The application of borehole seismic techniques in mine development at the millennium uranium deposit, Northern Saskatchewan, Canada

    International Nuclear Information System (INIS)

    Full text: The Millennium uranium deposit (indicated resource of 469 500 t at 4.53% U3O8) is located within the Athabasca basin of northern Saskatchewan, Canada. The deposit is hosted within steeply dipping Lower Proterozoic basement rocks, unconformably overlain by 500 m to 625 m of flat lying Athabasca Group sandstones. The deposit is associated with multiple graphitic faults, some of which are associated with post-Athabasca movement that has contributed to over 100 m of unconformity offset proximal to the deposit. The mineralization process has also resulted in intense hydrothermal alteration of the host rocks, and to a lesser extent the sandstone units located above the mineralization. All of these factors complicate the hydrological setting around the deposit, a factor that has to be accounted for in mine development. The pre-feasibility study for mine development commenced in 2007. In an attempt to minimize costs related to shaft sinking the proposed mine development was located to the east of the deposit, hanging wall to the mineralization. Two shaft pilot holes (CX-62 and CX-63) and an inclined exploration drill hole (CX-61) were completed in this area early in 2007. Single hole (Side-scan) seismic surveys were then completed in the shaft pilot holes and a multi-offset VSP (Vertical Seismic Profiling) survey in drill hole CX-61 in an attempt to: 1) map vertical to sub-vertical structure in the vicinity of the proposed mine shafts; 2) map unconformity offsets located in proximity of the proposed mine infrastructure and; 3) add to the geotechnical knowledge of the sandstone within the study area. The surveys successfully imaged subvertical structures and unconformity offset, adding insight into the hydrological controls within the study area. These surveys are now accepted by Cameco Corporation as a prerequisite for shaft sinking given the cost implications related to recent water inflow at minesites located within the Athabasca basin. (author)

  2. 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

  3. Global optimization for multisensor fusion in seismic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Barhen, J.; Protopopescu, V.; Reister, D. [Oak Ridge National Lab., TN (United States). Center for Engineering Systems Advanced Research

    1997-06-01

    The accurate imaging of subsurface structures requires the fusion of data collected from large arrays of seismic sensors. The fusion process is formulated as an optimization problem and yields an extremely complex energy surface. Due to the very large number of local minima to be explored and escaped from, the seismic imaging problem has typically been tackled with stochastic optimization methods based on Monte Carlo techniques. Unfortunately, these algorithms are very cumbersome and computationally intensive. Here, the authors present TRUST--a novel deterministic algorithm for global optimization that they apply to seismic imaging. The excellent results demonstrate that TRUST may provide the necessary breakthrough to address major scientific and technological challenges in fields as diverse as seismic modeling, process optimization, and protein engineering.

  4. Tectonics of North-Central Switzerland: interpretation on the basis on regional seismics, surface geology and deep boreholes

    International Nuclear Information System (INIS)

    This report presents the methodology and results of a geological interpretation of Nagra's reflection seismic data (1982-1984) for North-Central Switzerland. The area under investigation, which is covered by the entire network of reflection seismics lines, is outlined by the towns of Schaffhausen/ Zuerich in the east and Saeckingen/Olten in the west. (author) figs., tabs., 439 refs

  5. 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...

  6. 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 (Germany, where crosshole electrical resistivity imaging is used for CO2 migration

  7. Application of Seismic Observation Data in Borehole for the Development of Attenuation Equation of Response Spectra on Bedrock

    International Nuclear Information System (INIS)

    Ground motion data on seismic bedrock is important, but it is very difficult to obtain such data directly. The data from KiK-net and JNES/SODB is valuable and very useful in developing the attenuation relationship of response spectra on seismic bedrock. NIED has approximately 200 observation points on seismic bedrock with S-wave velocity of more than 2000 m/s in Japan. Using data from observation at these points, a Ground Motion Prediction Equation (GMPE) is under development. (author)

  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. The microstructure of sediment-hosted hydrates: evidence from effective medium modelling of laboratory and borehole seismic data

    OpenAIRE

    Minshull, T.A.; Chand, S

    2009-01-01

    Much of our knowledge of hydrate distribution in the subsurface comes from interpretations of remote seismic measurements. A key step in such interpretations is an effective medium theory that relates the seismic properties of a given sediment to its hydrate content. A variety of such theories have been developed; these theories generally give similar results if the same assumptions are made about the extent to which hydrate contributes to the load-bearing sediment frame. We ha...

  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. 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

  12. 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.

  13. 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

  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. 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

  16. Application of remote sensing image interpretation in seismic safety evaluation

    Science.gov (United States)

    Li, Feng; Wei, Wen-xia; Wang, Gang

    2005-10-01

    As one of essential design gist in important engineering projects, the seismic safety evaluation on choosing engineering site has been applied widely. Using remote sensing images, the analysis to regional seismotectonic environment can bring macroscopic, integrative, dynamic and high efficiency information, so the application of remote sensing technology in seismic safety evaluation of engineering site has fine prospect and will bring great benefit. In this paper, based on remote sensing interpretation to Landsat7 ETM images, also using GIS and field geological investigations, as a case study in Qingdao City, we analyze the physiognomy environment, new tectonic movement, faults activities, and the distributing of deleterious geological objects around the site. Then we find this method can provide good basic geological information for seismic safety evaluation.

  17. Borehole image analysis of the Nankai Accretionary Wedge, ODP Leg 196: Structural and stress studies

    Science.gov (United States)

    Ienaga, Masanori; McNeill, Lisa C.; Mikada, Hitoshi; Saito, Saneatsu; Goldberg, David; Moore, J. Casey

    2006-10-01

    Electrical images recorded with Resistivity-At-Bit (RAB) from two sites drilled during Ocean Drilling Program (ODP) Leg 196 were analyzed to study the effects of subduction at the Nankai margin. For the first time in the history of scientific deep-sea drilling in ODP, in situ complete borehole images of the décollement zone were obtained. Analyses of all drilling-induced fracture data indicated that the maximum horizontal compressive stress ( SHmax) axes have an azimuth of 303°, and analyses of breakout data from RAB images indicated an azimuth of 310°. These azimuths approximate the convergence direction of the Philippine Sea plate towards the Eurasian plate. The frontal thrust at Site 808 was encountered at about 389 mbsf. Density, porosity, resistivity, and gamma ray data change across the frontal thrust. The décollement zone at the deformation front was identified between 937 and 965 mbsf. The base of the décollement is sharply defined as the maximum extent of conductive fracturing and is marked by abrupt changes in physical properties [Mikada, H., Becker, K., Moore, J.C., Klaus, A., Austin, G.L., Bangs, N.L., Bourlange, S., Broilliard, J., Brückmann, W., Corn, E.R., Davis, E.E., Flemings, P.B., Goldberg, D.B., Gulick, S.S., Hansen, M.B., Hayward, N., Hills, D.J., Hunze, S., Ienaga, M., Ishiguro, H., Kinoshita, M., Macdonald, R.D., McNeill, L., Obana, S., Hong, O.S., Peacock, S., Pettigrew, T.L., Saito, S., Sawa, T., Thaiprasert, N., Tobin, H.J., Tsurumi, H., 2002. Proc. ODP, Initial Rep., 196, College Station, TX, (Ocean Drilling Program)]. The upper boundary of the décollement is marked by several sets of conductive fractures and by high variability in physical properties. The décollement zone is characterized by intense brittle fracturing. These fractures are considered to be the consequence of cyclic stresses and high fluid pressures in this zone. We analyzed fracture dips and their orientations at both sites and found that they are all consistent

  18. 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

  19. 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.

  20. 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

  1. Rock mass seismic imaging around the ONKALO tunnel, Olkiluoto 2007

    Energy Technology Data Exchange (ETDEWEB)

    Cosma, C.; Cozma, M.; Balu, L.; Enescu, N. (Vibrometric Oy, Vantaa (Finland))

    2008-11-15

    Posiva Oy prepares for disposal of spent nuclear fuel in bedrock focusing in Olkiluoto, Eurajoki. This is in accordance of the application filed in 1999, the Decision-in-Principle of the State Council in 2000, and ratification by the Parliament in 2001. Vibrometric Oy has performed a tunnel seismic survey in ONKALO access tunnel on a 100 m line in December 2007. Tunnel length (chainage) was 1720 - 1820 m (vertical depth 170 - 180 m). Measurement applied 120 source positions at 1 m spacing, and on the both ends at 4 m spacing. Electromechanical Vibsist-20 tool was used as the source. Hammer produced 15.36 s sweeps. Signal was recorded with 2-component geophone assemblies, installed in 400 mm long, 45 mm drillholes in the tunnel wall. Sweeps were recorded with Summit II seismograph and decoded to seismic traces. Also percussion drill rig, which is used in drilling the blasting holes in tunnel excavation, was tested from a 100-m distance as a seismic source. Signal is equally good as from actual seismic source, and may be applied later on for production. Obtained seismic results were processed with tomographic reconstruction of the first arrivals to P and S wave refraction tomograms, and to tomograms of Young's modulus and Shear Modulus. The obtained values correspond the typical levels known from Olkiluoto. There are indications of lower velocity near tunnel wall, but resolution is not adequate for further interpretation. Some variation of velocity is detected in the rock mass. Seismic data was also processed with normal reflection profile interpretation and migrated. As a result there was obtained reflection images to a 100-m distance from the tunnel. Several reflecting events were observed in the rock mass. Features making an angle of 30 deg or more with tunnel axis can be imaged from distances of tens of metres. Vertical fractures perpendicular to tunnel can be imaged only near the tunnel. Gently dipping features can be imaged below and above. Images are 2D

  2. Bandung seismic experiment: Towards tomographic imaging by using ambient seismic noise

    Science.gov (United States)

    Pranata, Bayu; Yudistira, Tedy; Saygin, Erdinc; Cummins, Phil R.; Widiyantoro, Sri; Zulfakriza, Nugraha, Andri D.

    2016-05-01

    Bandung is one of the most densely populated cities in Indonesia with vital infrastructures. On the other hand, this area is surrounded by potential sources of earthquakes that make Bandung vulnerable to earthquakes. Structure of seismic velocity and sediment thickness are crucially needed in the earthquake hazard reduction program for Bandung. Based on this consideration, we deployed 64 seismic stations over the Bandung basin to record seismic ambient noise. In this study, we employed a cross-correlation method to the simultaneously recorded data to retrieve interstation Green's functions. We measured group velocity of the retrieved Green's functions by using frequency-time analysis technique. By the end of this project, the set of interstation group velocity will be inverted to image the shallow seismic velocity structure of the Bandung basin and its surrounding areas including Mt. Tangkuban Parahu and Lembang fault. As the first stage of this work, currently we focus on Green ' s function calculation as well as the interstation group velocity measurements. The general characteristics of group velocity can be evaluated from the plot of cross-correlation function as a function of its interstation distance.

  3. 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

  4. 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...

  5. Synergy use of satellite images for Vrancea seismic area analysis

    Science.gov (United States)

    Zoran, Maria A.; Ninomiya, Yoshiki; Zoran, Liviu Florin V.

    2004-10-01

    The seismic hazard of Romania is relatively high, mainly due to the subcrustal earthquakes located at the sharp bend of the Southeast Carpathians, in Vrancea region, one of the most seismically active area in Europe. It is crossed by a series of principal and secondary faults. Vrancea area is assumed to be a conjunction of 4 tectonic blocks which lie on the edge of the Eurasian plate. Several GPS monitoring data revealed the motion of the blocks both in horizontal direction (relative motion of 5- 6 millimeters/year), as well as in vertical direction(of a few millimeters/ year).All data information available on the study area have been integrated in a unique database of geologic maps, thematic maps from cartography, land use maps provided by satellite images acquired in different spectral wavelengths by Landsat MSS, TM and ETM, SAR ERS and ASTER during a long term period (1975-2002). Satellite data are excellent for recognizing the continuity and regional relationships of faults . Synergy use of satellite data and image analysis techniques is essential for neotectonic applications, improving greatly the interpretability of the images and subsequent more accurate terrain features and lineament analysis of geologic structures in active seismic areas.

  6. 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.

  7. 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...

  8. 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.

  9. Interwell seismic imaging at the Savannah River Site, South Carolina

    International Nuclear Information System (INIS)

    Crosswell and continuity logging seismic measurements were made beneath a large tank (27 m diameter) used for processing radioactive waste at the Department of Energy (DOE) Savannah River Site in the Atlantic Coastal Plain of South Carolina. The authors used the data to delineate a low-velocity zone (soft materials) and image the connectivity of a clay unit between wells. The low-velocity zone depicted on the crosswell seismic tomogram integrated with data from cores and well logs revealed soft materials in the region between 150 and 180 ft (46--55 m). The bottom boundary of this low-velocity zone correlates with a reflection observed in the crosswell seismic image at a depth of 180 ft (55 m). This reflection corresponds to the impedance contrast between the soft materials and the more rigid Tinker Formation. The low-velocity zone of soft materials indicates a dissolution margin of a carbonate unit (which is part of the Utley limestone) and the presence of loose sands of the Griffins Landing Member. Ray tracing and common source seismograms show that the rigid part of the Utley limestone extends horizontally about 12.5 ft (4 m) west of the receiver well. The continuity logging data showed leaky and normal modes in the region between 140 and 150 ft (43--46 m). The computed group velocity contours of leaky and normal modes are consistent with waveguide models based on well logs and crosswell seismic data. This indicates that the low-velocity tan clay (confining unit) within the Griffins Landing Member is connected between wells

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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

  15. Imaging natural fractures with the microseismic data by using seismic interferometry

    Science.gov (United States)

    Tak, H.; Kim, M.; Byun, J.; Seol, S.

    2012-12-01

    Hydraulic fracturing treatments have been widely applied to the stimulation of low-permeability oil and gas reservoirs such as shale gas or tight gas reservoirs. In hydraulic fracturing treatments, it is very important to locate not only hydraulic fractures but also natural fractures and faults pre-existed in a reservoir because pre-existed faults or natural factures can cause drilling failure and also they can be propagated toward water-bearing zone during the hydraulic fracturing. An additional technique is required to identify the location of the natural fracture, whereas hydraulic fractures can be tracked by locating microseismic events. In this paper, we present a new method which can produce RVSP data or single-well data from the measurement of microseismic events at surface and borehole by using seismic interferometry. The RVSP and single-well data can be generated with virtual sources by cross-correlating between microseismic data. These RVSP and single-well data contain the reflections from natural fractures which do not cut through the well. To verify our method, first, we generated synthetic microseismic data using a finite-difference time domain modeling method for a velocity model containing two fractures. Next, we created virtual source data using by seismic interferometry and compared them to those with real source data. The reflection traveltime from the fractures in virtual source data agree well with those from real source data. By applying the migration to these virtual source data, we could obtain the images of natural fractures with accurate locations. However, since the imaging zone of fractures has strong dependence on the locations of the microseismic events used in creating virtual source and fractures themselves, microseismic events occurred at various locations are indispensable in order to image more existing natural fractures. This method can provide more accurate images of natural fractures around the well as the recorded microseismic

  16. 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

  17. 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)

    Sukop, Michael C.; Cunningham, Kevin J.

    2014-11-01

    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.

  18. 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.

  19. 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.

  20. 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.

  1. Seismic images of the continental Moho of the Indian shield

    Science.gov (United States)

    Reddy, P. R.; Vijaya Rao, V.

    2013-12-01

    Deep seismic reflection profiling has imaged different patterns of the Moho across the Indian shield with a variety of tectonic environments from Archean to Recent. The character of the Moho varies from a discrete strong event, the base of strong coherent lower crustal sub-horizontal reflections, the base of dipping lower crustal reflections into mantle, to no clear reflection boundary. The seismic reflection data suggest a laminated lower crust in several places and offsets in the Moho at others. Kinematic and dynamic modeling of wide-angle reflection data across the Mesoproterozoic South Delhi Fold Belt and the Central Indian Tectonic zone suggests a laminated lower crust for these regions. In general, the lower crust of the Indian shield is heterogeneous. A clear Moho is identified in some of the Precambrian orogenic belts and sedimentary basins along with reflective lower-crust, whereas the cratonic areas exhibit a diffused Moho. Post-collisional extensional process, such as orogenic collapse, delamination, magmatic intrusions, low-viscosity ordering and underplating might have played a role in the generation of lower crustal laminated zone and formation of a younger Moho. The termination of lower-crustal reflectivity at the Moho with a transparent upper mantle need not necessarily indicate homogeneous upper mantle.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Ice-Borehole Probe

    Science.gov (United States)

    Behar, Alberto; Carsey, Frank; Lane, Arthur; Engelhardt, Herman

    2006-01-01

    An instrumentation system has been developed for studying interactions between a glacier or ice sheet and the underlying rock and/or soil. Prior borehole imaging systems have been used in well-drilling and mineral-exploration applications and for studying relatively thin valley glaciers, but have not been used for studying thick ice sheets like those of Antarctica. The system includes a cylindrical imaging probe that is lowered into a hole that has been bored through the ice to the ice/bedrock interface by use of an established hot-water-jet technique. The images acquired by the cameras yield information on the movement of the ice relative to the bedrock and on visible features of the lower structure of the ice sheet, including ice layers formed at different times, bubbles, and mineralogical inclusions. At the time of reporting the information for this article, the system was just deployed in two boreholes on the Amery ice shelf in East Antarctica and after successful 2000 2001 deployments in 4 boreholes at Ice Stream C, West Antarctica, and in 2002 at Black Rapids Glacier, Alaska. The probe is designed to operate at temperatures from 40 to +40 C and to withstand the cold, wet, high-pressure [130-atm (13.20-MPa)] environment at the bottom of a water-filled borehole in ice as deep as 1.6 km. A current version is being outfitted to service 2.4-km-deep boreholes at the Rutford Ice Stream in West Antarctica. The probe (see figure) contains a sidelooking charge-coupled-device (CCD) camera that generates both a real-time analog video signal and a sequence of still-image data, and contains a digital videotape recorder. The probe also contains a downward-looking CCD analog video camera, plus halogen lamps to illuminate the fields of view of both cameras. The analog video outputs of the cameras are converted to optical signals that are transmitted to a surface station via optical fibers in a cable. Electric power is supplied to the probe through wires in the cable at a

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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...

  14. From Geodetic Imaging of Seismic and Aseismic Fault Slip to Dynamic Modeling of the Seismic Cycle

    Science.gov (United States)

    Avouac, Jean-Philippe

    2015-05-01

    Understanding the partitioning of seismic and aseismic fault slip is central to seismotectonics as it ultimately determines the seismic potential of faults. Thanks to advances in tectonic geodesy, it is now possible to develop kinematic models of the spatiotemporal evolution of slip over the seismic cycle and to determine the budget of seismic and aseismic slip. Studies of subduction zones and continental faults have shown that aseismic creep is common and sometimes prevalent within the seismogenic depth range. Interseismic coupling is generally observed to be spatially heterogeneous, defining locked patches of stress accumulation, to be released in future earthquakes or aseismic transients, surrounded by creeping areas. Clay-rich tectonites, high temperature, and elevated pore-fluid pressure seem to be key factors promoting aseismic creep. The generally logarithmic time evolution of afterslip is a distinctive feature of creeping faults that suggests a logarithmic dependency of fault friction on slip rate, as observed in laboratory friction experiments. Most faults can be considered to be paved with interlaced patches where the friction law is either rate-strengthening, inhibiting seismic rupture propagation, or rate-weakening, allowing for earthquake nucleation. The rate-weakening patches act as asperities on which stress builds up in the interseismic period; they might rupture collectively in a variety of ways. The pattern of interseismic coupling can help constrain the return period of the maximum- magnitude earthquake based on the requirement that seismic and aseismic slip sum to match long-term slip. Dynamic models of the seismic cycle based on this conceptual model can be tuned to reproduce geodetic and seismological observations. The promise and pitfalls of using such models to assess seismic hazard are discussed.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Electrical resistivity imaging of seismically active frontal Himalaya

    International Nuclear Information System (INIS)

    Complete text of publication follows. Given the sensitivity of resistivity to rheology, magnetotelluric measurement are undertaken to study deep crustal electrical structures and their possible linkage to the space-depth distribution of seismicity. Magnetotelluric investigations at Thirty three sites along Bijnaur-Mallari profile cutting across major litho tectonic units of Himalaya starting from Indo Ganges plain, Siwalik, Lesser, Higher Himalaya to Tethys Himalaya. Observing the low solar activity during the survey period each site was occupied for five days. Longer occupancy allowed estimation of impedance tensor at periods greater than 500 sec at most of the stations. However at few stations electric field recordings were very noisy perhaps due to unbalanced power network of the region. This is reflected in larger error bars in estimated impedance tensors. Skewness and other dimensionality parameter indicate the validity of 2-D regional model. Robust impedance decomposition for the period band of 10 Hz- 1000 sec of eleven stations reveal that EM strike coincides with the geologic fabric. Considering regional strike EM field were decoupled in TE, TM mode and then inverted for frequency dependent conductivity distribution along the profile. The most conspicuous feature of the inverted resistivity section is the low resistivity zone at a shallow depth of 10 km beneath the Indo-Gangetic Plains that dips down at a low-angle and extends as a continuous plane right up to the northern limit of the profile. The geometry of this layer is correlated with the basement thrust separating the top of the under thrusting Indian Plate from the over-riding sedimentary wedge of lesser Himalaya. The paper will discuss the tectonic and rheological significance of the results of resistivity imaging using magnetotelluric method along the profile from Bijnaur to Mallari.

  1. 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.

  2. 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.)

  3. 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.

  4. High resolution imaging of vadose zone transport using crosswell radar and seismic methods; TOPICAL

    International Nuclear Information System (INIS)

    The summary and conclusions are that overall the radar and seismic results were excellent. At the time of design of the experiments we did not know how well these two methods could penetrate or resolve the moisture content and structure. It appears that the radar could easily go up to 5, even 10 meters between boreholes at 200 Mhz and even father (up to 20 to 40 m) at 50 Mhz. The seismic results indicate that at several hundred hertz propagation of 20 to 30 meters giving high resolution is possible. One of the most important results, however is that together the seismic and radar are complementary in their properties estimation. The radar being primarily sensitive to changes in moisture content, and the seismic being primarily sensitive to porosity. Taken in a time lapse sense the radar can show the moisture content changes to a high resolution, with the seismic showing high resolution lithology. The significant results for each method are: Radar: (1) Delineated geological layers 0.25 to 3.5 meters thick with 0.25 m resolution; (2) Delineated moisture movement and content with 0.25 m resolution; (3) Compared favorably with neutron probe measurements; and (4) Penetration up to 30 m. Radar results indicate that the transport of the riverwater is different from that of the heavier and more viscous sodium thiosulfate. It appears that the heavier fluids are not mixing readily with the in-situ fluids and the transport may be influenced by them. Seismic: (1) Delineated lithology at .25 m resolution; (2) Penetration over 20 meters, with a possibility of up to 30 or more meters; and (3) Maps porosity and density differences of the sediments. Overall the seismic is mapping the porosity and density distribution. The results are consistent with the flow field mapped by the radar, there is a change in flow properties at the 10 to 11 meter depth in the flow cell. There also appears to be break through by looking at the radar data with the denser sodium thiosulfate finally

  5. 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.

  6. 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...

  7. ISIS : a formation flying ionospheric seismic imaging experiment

    Science.gov (United States)

    Mimoun, D.; Lognonné, Ph; Garcia, R.; Occhipinti, G.; Abbondanza, S.

    Today, available techniques for the lithosphere tomography are limited by the number of seismic stations that we can deploy : it is sometimes difficult to access to some remote regions, but foremost the number of stations that are deployable over the oceans is strongly reduced. If we can dispose of some sites on islands (which are all characterized by a strong background noise), and on the measurements on coastal areas borders, it is therefore difficult to inverse the fine structure of the oceanic lithosphere. A promising idea is to use a long known idea, that earthquakes have a measurable impact on the ionosphere. As a matter of fact, the decrease of the atmosphere density with respect to altitude implies an amplification of the Rayleigh waves in the atmosphere, up to a maximum at about 250 km. This effect has been quantified for the Denali earthquake (Ducic et al, 2003) though its impact on the TEC content on the ionosphere. We therefore propose to detect this effect from space, thanks to a spaceborne multistatic SAR. Our concept includes 3 satellites in formation (along the same orbit) in a MEO orbit (about 19000 km). The master satellite payload is a slightly modified SAR, which operates around two main frequencies, in order to allow the computation of the delay induced by ionospheric fluctuations. The two other satellites have a passive payload which is time-synchronized with the master SAR: the use of their crossing rays will allow a 3D reconstruction of the ionosphere. A preliminary design of the space segment proposes an implementation on a MEO-orbit compatible bus, with high peak power capabilities. In order to allow the compatibility of the payload concept with the on-board available power, we have assumed that the satellite will enter in its alert mode on ground request. When an earthquake occurs, we dispose of a ten minutes delay to "wake-up" the satellite. When not in alert mode, its nominal imaging frequency will be reduced to allow the detection of

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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.

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

    International Nuclear Information System (INIS)

    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

  14. 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.

  15. Fuzzy logic and image processing techniques for the interpretation of seismic data

    International Nuclear Information System (INIS)

    Since interpretation of seismic data is usually a tedious and repetitive task, the ability to do so automatically or semi-automatically has become an important objective of recent research. We believe that the vagueness and uncertainty in the interpretation process makes fuzzy logic an appropriate tool to deal with seismic data. In this work we developed a semi-automated fuzzy inference system to detect the internal architecture of a mass transport complex (MTC) in seismic images. We propose that the observed characteristics of a MTC can be expressed as fuzzy if-then rules consisting of linguistic values associated with fuzzy membership functions. The constructions of the fuzzy inference system and various image processing techniques are presented. We conclude that this is a well-suited problem for fuzzy logic since the application of the proposed methodology yields a semi-automatically interpreted MTC which closely resembles the MTC from expert manual interpretation

  16. 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.

  17. 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

  18. 2-D traveltime and waveform inversion for improved seismic imaging: Naga Thrust and Fold Belt, India

    Science.gov (United States)

    Jaiswal, Priyank; Zelt, Colin A.; Bally, Albert W.; Dasgupta, Rahul

    2008-05-01

    Exploration along the Naga Thrust and Fold Belt in the Assam province of Northeast India encounters geological as well as logistic challenges. Drilling for hydrocarbons, traditionally guided by surface manifestations of the Naga thrust fault, faces additional challenges in the northeast where the thrust fault gradually deepens leaving subtle surface expressions. In such an area, multichannel 2-D seismic data were collected along a line perpendicular to the trend of the thrust belt. The data have a moderate signal-to-noise ratio and suffer from ground roll and other acquisition-related noise. In addition to data quality, the complex geology of the thrust belt limits the ability of conventional seismic processing to yield a reliable velocity model which in turn leads to poor subsurface image. In this paper, we demonstrate the application of traveltime and waveform inversion as supplements to conventional seismic imaging and interpretation processes. Both traveltime and waveform inversion utilize the first arrivals that are typically discarded during conventional seismic processing. As a first step, a smooth velocity model with long wavelength characteristics of the subsurface is estimated through inversion of the first-arrival traveltimes. This velocity model is then used to obtain a Kirchhoff pre-stack depth-migrated image which in turn is used for the interpretation of the fault. Waveform inversion is applied to the central part of the seismic line to a depth of ~1 km where the quality of the migrated image is poor. Waveform inversion is performed in the frequency domain over a series of iterations, proceeding from low to high frequency (11-19 Hz) using the velocity model from traveltime inversion as the starting model. In the end, the pre-stack depth-migrated image and the waveform inversion model are jointly interpreted. This study demonstrates that a combination of traveltime and waveform inversion with Kirchhoff pre-stack depth migration is a promising approach

  19. 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.

  20. First images and orientation of fine structure from a 3-D seismic oceanography data set

    Directory of Open Access Journals (Sweden)

    T. M. Blacic

    2010-04-01

    Full Text Available We present 3-D images of ocean fine structure from a unique industry-collected 3-D multichannel seismic dataset from the Gulf of Mexico that includes expendable bathythermograph casts for both swaths. 2-D processing reveals strong laterally continuous reflections throughout the upper ~800 m as well as a few weaker but still distinct reflections as deep as ~1100 m. We interpret the reflections to be caused by reversible fine structure from internal wave strains. Two bright reflections are traced across the 225-m-wide swath to produce reflection surface images that illustrate the 3-D nature of ocean fine structure. We show that the orientation of linear features in a reflection can be obtained by calculating the orientations of contours of reflection relief, or more robustly, by fitting a sinusoidal surface to the reflection. 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 fine structure in 3-D and shows that, beyond simply providing a way visualize oceanic fine structure, quantitative information such as the spatial orientation of features like fronts 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.

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

    2016-03-01

    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.

  9. 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.

  10. 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.

  11. 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.

  12. High-Resolution Active Source Seismic Investigation of the Alpine Fault at Gaunt Creek, central Westland, New Zealand

    Science.gov (United States)

    Eccles, J. D.; Sutherland, R.; Townend, J.; Toy, V. G.; Malin, P. E.

    2012-12-01

    Two shallow (101 m and 151 m) boreholes were drilled in early 2011 through the Alpine Fault at Gaunt Creek in the first phase of the Deep Fault Drilling Project (DFDP). Both holes are located close to a well-known fault outcrop where hanging wall mylonites and cataclasites, exhumed from c. 30 km depth, are thrust over Quaternary gravels. The boreholes DFDP-1A and 1B terminated in footwall gravel and Australian Plate continental footwall material respectively and were both cored and logged using wireline tools. Following drilling a borehole observatory was installed including two borehole seismometers within 20 m of the principal slip zone (PSZ). In April 2012, a multi-purpose explosive seismic survey was undertaken to bridge the gap between the detailed observations of fault zone properties made in the boreholes and the larger-scale seismic response. A string of eight borehole geophones were installed in the DFDP-1A borehole and 126 additional channels deployed on the surface. This experiment was the first field-trial of REF TEK 160 'GOES' systems for seismic; each of the eighteen 'GOES' consisted of a standalone unit with GPS timing, an internal three-component 2 Hz sensor and capacity to record six external channels (for twelve units this was cabled 15 Hz vertical geophones). These units enabled the profile to straddle physiographic obstacles such as Gaunt Creek and facilitated straightforward correlation of shot timing. Moreover, standalone units proved easy to transport upriver into rough terrain to extend the profile azimuth. Forty-one explosive shots, 0.15-1.2 kg in size, were detonated along a 2D profile perpendicular to the Alpine Fault's strike for seismic reflection imaging, vertical seismic profiling and tomography. The preliminary findings based on this data set are presented here.

  13. 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.

  14. 3D seismic imaging of the subsurface for underground construction and drilling

    International Nuclear Information System (INIS)

    3D seismic imaging of underground structure has been carried out in various parts of the world for various purposes. Examples shown below were introduced in the presentation. - CO2 storage in Ketzin, Germany; - Mine planning at the Millennium Uranium Deposit in Canada; - Planned Forsmark spent nuclear fuel repository in Sweden; - Exploring the Scandinavian Mountain Belt by Deep Drilling: the COSC drilling project in Sweden. The author explained that seismic methods provide the highest resolution images (5-10 m) of deeper (1-5 km) sub-surfaces in the sedimentary environment, but further improvement is required in crystalline rock environments, and the integration of geology, geophysics, and drilling will provide an optimal interpretation. (author)

  15. 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...

  16. 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.

  17. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Juhlin, C.; Bergman, B. [Uppsala Univ. (Sweden); Cosma, C.; Keskinen, J.; Enescu, N. [Vibrometric Oy, Helsinki (Finland)

    2002-02-01

    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

  19. 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

  20. 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.

  1. 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...

  2. 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.

  3. 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

  4. High resolution seismic imaging of complex structures: a case study of the South China Sea data

    Science.gov (United States)

    Zhang, Hao; Wang, Jun; Fu, Geping

    2016-03-01

    Seismic imaging is an effective way for marine geophysical investigation. Different types of imaging schemes, such as pre-stack time migration (PSTM) and pre-stack depth migration (PSDM), are often used to reveal subsurface structures. Theoretically, the PSDM method, which better honors the wave field propagation, can produce more accurate subsurface images compared with PSTM. However, it is challenging for PSDM to obtain a proper velocity model. In the South China Sea basin, the presence of complex structures such as carbonate pinnacles makes velocity model building more difficult due to the complex geometry and strong velocity variation. We have developed a seismic processing work flow which aims to circumvent these difficulties and can improve the PSDM velocity model via iterative updating. In order to improve the data quality and obtain optimal results, a proper pre-processing is required. In this workflow, we use the full waveform inversion to update the velocity model, followed by the application of the tomography inversion. In this way, a geologically plausible velocity model for PSDM is obtained. Afterwards, we use the Q-tomography approach to estimate the Earth quality factor (Q), which numerically quantifies the earth absorption and attenuation effect. Finally we use a de-absorption pre-stack depth migration scheme to compensate for the Earth absorption and attenuation effect in the process of imaging. The amplitudes are balanced and a high quality subsurface image is obtained.

  5. 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.

  6. 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.

  7. Analysis of ocean internal waves imaged by multichannel reflection seismics, using ensemble empirical mode decomposition

    International Nuclear Information System (INIS)

    Research on ocean internal waves using seismic oceanography is a frontier issue both for marine geophysicists and physical oceanographers. Images of the ocean water layer obtained by conventional processing of multichannel seismic reflection data can show the overall patterns of internal waves. However, in order to extract more information from the seismic data, new tools need to be developed. Here, we use the ensemble empirical mode decomposition (EEMD) method to decompose vertical displacement data from seismic sections and apply this method to a seismic section from the northeastern South China Sea, where clear internal waves are observed. Compared with the conventional empirical mode decomposition method, EEMD has greatly reduced the scale mixing problems induced in the decomposition results. The results obtained show that the internal waves in this area are composed of different characteristic wavelengths at different depths. The depth range of 200–1050 m contains internal waves with a wavelength of 1.25 km that are very well coupled in the vertical direction. The internal waves with a wavelength of 3 km, in the depth range of 200–600 m, are also well coupled, but in an oblique direction; this suggests that the propagation speed of internal waves of this scale changes with depth in this area. Finally, the internal waves with a wavelength of 6.5 km, observed in the depth range of 200–800 m, are separated into two parts with a phase difference of about 90°, by a clear interface at a depth of 650 m; this allows us to infer an oblique propagation of wave energy of this scale. (paper)

  8. 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.

  9. TV-2 test borehole

    International Nuclear Information System (INIS)

    A new test borehole was drilled for testing logging radiometers for uranium surveying and for dimensioning logging cables. The borehole is 660 m deep and located in it are 4 artificial radioactivity anomalies. The uncased interval is 120 m long, it has significant differences in resistance (200 to 14 000 Ωm) and makes it possible to test all types of electric logging probes. The test borehole makes possible the control of logging instruments after repair in the field, the testing of new probes prior to their being put into operation, the quality and quick dimensioning of logging cables and the performing of developmental and methodological measurements. (A.K.)

  10. 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

  11. 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.

  12. Reflection seismic methods applied to locating fracture zones in crystalline rock

    International Nuclear Information System (INIS)

    The reflection seismic method is a potentially powerful tool for identifying and localising fracture zones in crystalline rock if used properly. Borehole sonic logs across fracture zones show that they have reduced P-wave velocities compared to the surrounding intact rock. Diagnostically important S-wave velocity log information across the fracture zones is generally lacking. Generation of synthetic reflection seismic data and subsequent processing of these data show that structures dipping up towards 70 degrees from horizontal can be reliably imaged using surface seismic methods. Two real case studies where seismic reflection methods have been used to image fracture zones in crystalline rock are presented. Two examples using reflection seismic are presented. The first is from the 5354 m deep SG-4 borehole in the Middle Urals, Russia where strong seismic reflectors dipping from 25 to 50 degrees are observed on surface seismic reflection data crossing over the borehole. On vertical seismic profile data acquired in the borehole, the observed P-wave reflectivity is weak from these zones, however, strong converted P to S waves are observed. This can be explained by the source of the reflectors being fracture zones with a high P wave to S wave velocity ratio compared to the surrounding rock resulting in a high dependence on the angle of incidence for the reflection coefficient. A high P wave to S wave velocity ratio (high Poisson's ratio) is to be expected in fluid filled fractured rock. The second case is from Aevroe, SE Sweden, where two 1 km long crossing high resolution seismic reflection lines were acquired in October 1996. An E-W line was shot with 5 m geophone and shotpoint spacing and a N-S one with 10 m geophone and shotpoint spacing. An explosive source with a charge size of 100 grams was used along both lines. The data clearly image three major dipping reflectors in the upper 200 ms (600 m). The dipping ones intersect or project to the surface at/or close to

  13. 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

  14. 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.

  15. 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.

  16. High Resolution Seismic Reflection Imaging of the Southern Whidbey Island fault, Northwest Washington State

    Science.gov (United States)

    Pape, K. M.; Liberty, L. M.; Pratt, T. L.

    2006-12-01

    The Southern Whidbey Island fault (SWIF) is an active fault between the Seattle and Everett Basins in northwest Washington State. Marine seismic and geologic data characterize the SWIF as sub-parallel, northwest trending reverse faults that may extend over a 100 km distance and may be capable of producing M 7 or greater earthquakes. We acquired two land-based seismic transects crossing LIDAR and magnetic lineaments associated with the SWIF near Woodinville, WA, to relate surface scarps to subsurface structures and to characterize deformation in the upper 0.5 km of strata. Nearby borehole data place Pleistocene and younger deposits at depths less than 0.2 km, with Tertiary and older strata identified below. The 2 km, north-south Crystal Lake transect crosses the surface locations of LIDAR and magnetic lineaments and shows reverse faulting that offsets Tertiary and younger strata in a zone that extends more than 1.25 km. In contrast, we interpret relatively undeformed, flat lying Tertiary strata at depths of 0.1 to 0.2 km south of the observed surface lineaments. In the 3 km, east-west Woodinville transect, we identify reverse faulting and folding that forms a small 0.75 km-wide graben within a broader deformation zone. These anomalies are on strike with the LIDAR and magnetic lineaments identified near Crystal Lake. The presence of a small graben in the SWIF is consistent with models that hypothesize strike-slip motion on the fault system, with curvature of adjacent fault strands forming a small pull-apart basin. Our observations suggest that other magnetic lineaments in the region also are likely associated with fault strands. We acquired three additional transects upwards of 30 km southeast of Woodinville to determine whether the SWIF extends beyond surface lineaments and potentially merging with the Seattle Fault. Our preliminary analysis shows faulted Tertiary and younger strata on these profiles. If the observed fault strands on these transects are related to

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods

    Science.gov (United States)

    Kelly, C. L.; Lawrence, J. F.; Ebinger, C. J.

    2013-12-01

    Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods Cyndi Kelly1, Jesse F. Lawrence1, Cindy Ebinger2 1Stanford University, Department of Geophysics, 397 Panama Mall, Stanford, CA 94305, USA 2University of Rochester, Department of Earth and Environmental Science, 227 Hutchison Hall, Rochester, NY 14627, USA Low-magnitude seismic signals generated by processes that characterize volcanic and hydrothermal systems and their plumbing networks are difficult to observe remotely. Seismic records from these systems tend to be extremely 'noisy', making it difficult to resolve 3D subsurface structures using traditional seismic methods. Easily identifiable high-amplitude bursts within the noise that might be suitable for use with traditional seismic methods (i.e. eruptions) tend to occur relatively infrequently compared to the length of an entire eruptive cycle. Furthermore, while these impulsive events might help constrain the dynamics of a particular eruption, they shed little insight into the mechanisms that occur throughout an entire eruption sequence. It has been shown, however, that the much more abundant low-amplitude seismic 'noise' in these records (i.e. volcanic or geyser 'tremor') actually represents a series of overlapping low-magnitude displacements that can be directly linked to magma, fluid, and volatile movement at depth. This 'noisy' data therefore likely contains valuable information about the processes occurring in the volcanic or hydrothermal system before, during and after eruption events. In this study, we present a new method to comprehensively study how the seismic source distribution of all events - including micro-events - evolves during different phases of the eruption sequence of Sierra Negra Volcano in the Galapagos Islands. We apply a back-projection search algorithm to image sources of seismic 'noise' at Sierra Negra Volcano during a proposed intrusion event. By analyzing

  2. 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.

  3. Development of a multi-scale seismic imaging method and its application to Newberry volcano

    Science.gov (United States)

    Heath, B.; Toomey, D. R.; Hooft, E. E.; Bezada, M. J.

    2013-12-01

    While some shallow magma reservoirs beneath land volcanoes have been seismically imaged, our understanding of their mid-to lower-crustal magma plumbing systems remains limited. Active source techniques allow for optimizing source geometry to image shallow crustal magmatic systems, but typically do not resolve depths greater than ~6-10 km, since the velocity gradient in the mid-to lower crust limits the energy that turns at these depths. For closely spaced seismic stations, teleseismic data provide constraints on deeper crustal heterogeneity, particularly its lateral variation. On the other hand, teleseismic studies do not resolve vertical variations in crustal structure well because their ray paths are almost vertical, which results in limited crossing rays within the crust. Furthermore, due to the generally lower frequency content of teleseismic arrivals, these data primarily image longer wavelength heterogeneity. Here we develop a multi-scale seismic imaging method that combines high-frequency active source data with lower frequency teleseismic data, and test its usefulness for imaging the crustal structure beneath Newberry Volcano in central Oregon. To constrain the P wave structure throughout the crust, we develop an iterative method that includes 3-D sensitivity kernels and 3-D raytracing. The use of sensitivity kernels provides a physically motivated method that accounts for the different resolving capability of teleseismic and active source data. Various approximations to the sensitivity kernel are explored, with the goal of maximizing both computational efficiency and inversion accuracy. 3-D raytracing determines an accurate ray path, which is important in the highly heterogeneous crust. We verify our approach with synthetic data calculated using finite difference waveform modeling. We discuss our inversion results and our ability to resolve the velocity structure throughout the crust. We will investigate the presence of high and low velocity regions that

  4. 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

  5. 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

  6. Reassessment of seismic reflection data from the Finnsjoen study site and prospectives for future surveys

    International Nuclear Information System (INIS)

    Reprocessing of data from the seismic reflection survey performed at Finnsjoen in 1987 show that reflection seismics is a viable technique for mapping fracture zones in crystalline rock. Application of state of the art processing algorithms clearly image a gently dipping fracture zone located in the depth interval 200-400 m. In addition, several other reflectors were imaged in the reprocessed section, both gently and steeply dipping ones. Correlations with borehole data indicate that the origin of these reflections are also fractures zones. The data acquisition procedures used at the Finnsjoen survey were basically sound and could, with minor modifications, be applied at other sites. The results indicate that both sources and receivers in future surveys should be placed in boreholes a few meter below the ground surface. 30 refs

  7. Imaging Seismic Source Variations Using Back-Projection Methods at El Tatio Geyser Field, Northern Chile

    Science.gov (United States)

    Kelly, C. L.; Lawrence, J. F.

    2014-12-01

    During October 2012, 51 geophones and 6 broadband seismometers were deployed in an ~50x50m region surrounding a periodically erupting columnar geyser in the El Tatio Geyser Field, Chile. The dense array served as the seismic framework for a collaborative project to study the mechanics of complex hydrothermal systems. Contemporaneously, complementary geophysical measurements (including down-hole temperature and pressure, discharge rates, thermal imaging, water chemistry, and video) were also collected. Located on the western flanks of the Andes Mountains at an elevation of 4200m, El Tatio is the third largest geyser field in the world. Its non-pristine condition makes it an ideal location to perform minutely invasive geophysical studies. The El Jefe Geyser was chosen for its easily accessible conduit and extremely periodic eruption cycle (~120s). During approximately 2 weeks of continuous recording, we recorded ~2500 nighttime eruptions which lack cultural noise from tourism. With ample data, we aim to study how the source varies spatially and temporally during each phase of the geyser's eruption cycle. We are developing a new back-projection processing technique to improve source imaging for diffuse signals. Our method was previously applied to the Sierra Negra Volcano system, which also exhibits repeating harmonic and diffuse seismic sources. We back-project correlated seismic signals from the receivers back to their sources, assuming linear source to receiver paths and a known velocity model (obtained from ambient noise tomography). We apply polarization filters to isolate individual and concurrent geyser energy associated with P and S phases. We generate 4D, time-lapsed images of the geyser source field that illustrate how the source distribution changes through the eruption cycle. We compare images for pre-eruption, co-eruption, post-eruption and quiescent periods. We use our images to assess eruption mechanics in the system (i.e. top-down vs. bottom-up) and

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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)

  16. High resolution seismic imaging of an active normal fault in the Agri Valley, Southern Apennines, Italy

    Science.gov (United States)

    Improta, L.; Bruno, P.; di Fiore, V.; Mariani, S.

    2004-12-01

    The Agri Valley is an intermontane basin located in the Southern Apennine seismic belt (Italy) whose formation in tied to large NW-trending trastensional and extensional faults active since Early Pleistocene. Recent faulting activity in the area is documented by faulted paleosoils and suggested by a M7 earthquake that struck the basin in 1857. On the contrary, present-day background seismicity in the area is extremely low. Despite intense geomorphic investigations, the identification of the source responsible for this historical event and of further large seismogenic faults in the area is still a matter of debate. A new NW trending normal faulting system has been recently recognized based on subtle geomorphic expressions on the ridge bounding the basin westward. Recent faulting activity along this structure is locally documented by a trench. Aimed at yielding new information about the shallow structure of the fault, we conducted a high resolution seismic experiment in a small lacustrine basin, located 4 km south of the trench, in which the presence of the fault is inferred by a linear surface warping but trench excavation is impractical. Both multi-fold wide-angle data and multichannel near vertical reflection data have been collected along a 220-m-long profile in order to obtain an accurate model of the basin combining seismic velocity and reflectivity images. About 3600 first arrival traveltimes picked on 36 wide-angle record sections have been inverted by a non-linear tomographic technique that is specially designed to image complex structures. The tomographic inversion provides a high-resolution velocity model of the basin down to 60 m depth. The model is strongly heterogeneous and displays sharp lateral velocity variations. Seismic reflection processing has been applied to both data sets. Data have been edited for trace quality and first (refracted and direct) arrivals have been muted. A following FK dip filtering on the shot gathers reduced the energy

  17. Cleaning of boreholes

    International Nuclear Information System (INIS)

    In terms of long-term safety it is a risk that the boreholes can eventually function as short-circuits between the repository and ground surface. Therefore sealing of investigation boreholes is an important issue for the long- term safety of high-level nuclear waste repositories. In order to seal a borehole properly, the conditions of the borehole have to meet certain predetermined requirements. One of the requirements is that no instruments or materials endangering the plugging operation or the long-term function of the sealing materials, are allowed to be left in the borehole. Sometimes drilling equipment will be left in the hole or it cannot be recovered from the hole with the given constraints of time, cost and resources in spite of attempts. Additionally various measurements may be carried out in the holes after the drilling has been completed and measuring devices may get stuck in holes. Consequently cleaning of the borehole is carried out as an essential activity before sealing can be implemented. There are two common reasons identified for the drill strings to get stuck in holes. First the drill string may get stuck due to acute drilling problems. The second case is where rods are left as casing in a hole either based on the structure of the upper part of the hole or in order to support the hole. To remove the drilling or measuring equipment lost in a borehole, special techniques and professional skill must be applied. Removing measuring equipment from a hole is often demanding and time consuming work. A vital part of the cleaning operation is planning the work in advance. In order to make the plan and to select the suitable methods it is important to know the condition of the stuck material. It is also important to know the exact depth where the equipment are stuck and to have an estimate of the reasons why they have got stuck. It is also very important to know the correct dimensions of the equipment or drill string before commencing the cleaning work

  18. The Antillean-South American Collision Zone as Imaged by BOLIVAR Seismic Data

    Science.gov (United States)

    Levander, A.; Bezada, M. J.; Niu, F.; Miller, M. S.; Masy, J.; Clark, S. A.; Magnani, M.; Ave Lallemant, H. G.; Pindell, J. L.

    2009-12-01

    Most models for the evolution of the southeastern Caribbean plate boundary invoke a time transgressive collision of the Antilles arc against northern South America (SA) as the Antillean subduction zone rolled back from Colombia to its present location east of Trindad during the Cenozoic. We present seismic images from the BOLIVAR experiment that detail crustal, lithospheric, and upper mantle structures across northern Venezuela resulting from this collision between the Caribbean and South American plates. A combination of seismicity, active seismic profiles, receiver functions, shear wave splits, and surface wave inversions image crustal, lithospheric and upper most mantle structures, while receiver functions and finite-frequency body-wave tomography provide control on deeper structures through the transition zone. We observe a number of first order structures that relate to Caribbean-South American collision: 1) The right-lateral San Sebastian-El Pilar strike-slip system originates at the southeastern corner of the Antillean subduction zone at about (10.75oN, 62.25oW) offshore eastern Venezuela as a subduction-transform edge propagator fault system. As the Atlantic plate descends into the mantle, tearing from the South American plate, it also depresses the edge of the SA continental margin, providing room for coastal mountain building and massive sedimentary basins. 2) After tearing from South America, the Atlantic slab descends rapidly to the transition zone as seen in body wave tomography and receiver function images. 3) The Caribbean plate has been underthrust beneath Colombia and western Venezuela from the west, and now extends as far east as the foreland of the Merida Andes, its western edge roughly paralleling the Bocono fault. 4) The mountains of central and western Venezuela owe much of their elevation to the Caribbean slab lying beneath them. In particular east-directed flat-slab Caribbean subduction beneath westernmost Venezuela has produced the Merida

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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...

  6. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hoversten, G.M.; Gritto, Roland; Washbourne, John; Daley, Tom

    2002-06-10

    This paper presents a method for combining seismic and electromagnetic measurements to predict changes in water saturation, pressure, and CO{sub 2} gas/oil ratio in a reservoir undergoing CO{sub 2} flood. Crosswell seismic and electromagnetic data sets taken before and during CO{sub 2} flooding of an oil reservoir are inverted to produce crosswell images of the change in compressional velocity, shear velocity, and electrical conductivity during a CO{sub 2} 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 CO{sub 2} 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 CO{sub 2}/oil ratio. Resulting images of the CO{sub 2}/oil ratio show CO{sub 2}-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 CO{sub 2}. The images produced by this process are better correlated to the location and amount of

  10. 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...

  11. 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)

  12. 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

  13. Quantifying the similarity of seismic polarizations

    Science.gov (United States)

    Jones, Joshua P.; Eaton, David W.; Caffagni, Enrico

    2016-02-01

    Assessing the similarities of seismic attributes can help identify tremor, low signal-to-noise (S/N) signals and converted or reflected phases, in addition to diagnosing site noise and sensor misalignment in arrays. Polarization analysis is a widely accepted method for studying the orientation and directional characteristics of seismic phases via computed attributes, but similarity is ordinarily discussed using qualitative comparisons with reference values or known seismic sources. Here we introduce a technique for quantitative polarization similarity that uses weighted histograms computed in short, overlapping time windows, drawing on methods adapted from the image processing and computer vision literature. Our method accounts for ambiguity in azimuth and incidence angle and variations in S/N ratio. Measuring polarization similarity allows easy identification of site noise and sensor misalignment and can help identify coherent noise and emergent or low S/N phase arrivals. Dissimilar azimuths during phase arrivals indicate misaligned horizontal components, dissimilar incidence angles during phase arrivals indicate misaligned vertical components and dissimilar linear polarization may indicate a secondary noise source. Using records of the Mw = 8.3 Sea of Okhotsk earthquake, from Canadian National Seismic Network broad-band sensors in British Columbia and Yukon Territory, Canada, and a vertical borehole array at Hoadley gas field, central Alberta, Canada, we demonstrate that our method is robust to station spacing. Discrete wavelet analysis extends polarization similarity to the time-frequency domain in a straightforward way. Time-frequency polarization similarities of borehole data suggest that a coherent noise source may have persisted above 8 Hz several months after peak resource extraction from a `flowback' type hydraulic fracture.

  14. 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

  15. Quaternary extensional growth folding beneath Reno, Nevada, imaged by urban seismic profiling

    Science.gov (United States)

    Stephenson, William J.; Frary, Roxy N.; Louie, John; Odum, Jackson K.

    2013-01-01

    We characterize shallow subsurface faulting and basin structure along a transect through heavily urbanized Reno, Nevada, with high‐resolution seismic reflection imaging. The 6.8 km of P‐wave data image the subsurface to approximately 800 m depth and delineate two subbasins and basin uplift that are consistent with structure previously inferred from gravity modeling in this region of the northern Walker Lane. We interpret two primary faults that bound the uplift and deform Quaternary deposits. The dip of Quaternary and Tertiary strata in the western subbasin increases with greater depth to the east, suggesting recurrent fault motion across the westernmost of these faults. Deformation in the Quaternary section of the western subbasin is likely evidence of extensional growth folding at the edge of the Truckee River through Reno. This deformation is north of, and on trend with, previously mapped Quaternary fault strands of the Mt. Rose fault zone. In addition to corroborating the existence of previously inferred intrabasin structure, these data provide evidence for an active extensional Quaternary fault at a previously unknown location within the Truckee Meadows basin that furthers our understanding of both the seismotectonic framework and earthquake hazards in this urbanized region.

  16. 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.

  17. Borehole sealing method and apparatus

    International Nuclear Information System (INIS)

    A method and apparatus is described for sealing boreholes in the earth. The borehole is blocked at the sealing level, and a sealing apparatus capable of melting rock and earth is positioned in the borehole just above seal level. The apparatus is heated to rock-melting temperature and powdered rock or other sealing material is transported down the borehole to the apparatus where it is melted, pooling on the mechanical block and allowed to cool and solidify, sealing the hole. Any length of the borehole can be sealed by slowly raising the apparatus in the borehole while continuously supplying powdered rock to the apparatus to be melted and added to the top of the column of molten and cooling rock, forming a continuous borehole seal. The sealing apparatus consists of a heater capable of melting rock, including means for supplying power to the heater, means for transporting powdered rock down the borehole to the heater, means for cooling the apparatus and means for positioning the apparatus in the borehole. 5 claims, 1 figure

  18. Borehole stability on Yme

    OpenAIRE

    Vikeså, Dan Ole

    2007-01-01

    The main object of this thesis it to perform an in-situ stress and borehole stability evaluation of the wells in the Yme field. The Inversion technique was used find the maximum and minimum horizontal stresses. The stresses were found for the whole well and for the location around each casing shoe. The field was found to be anisotropic. The outcome of the analysis was used together with data form each well to calculate fracture and collapse gradients for the wells. The fracturin...

  19. 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.

  20. Imaging preeruptive and coeruptive structural and mechanical changes of a volcano with ambient seismic noise

    Science.gov (United States)

    Obermann, A.; Planès, T.; Larose, E.; Campillo, M.

    2013-12-01

    Forecasting the location of an eruption is of primary importance for risk management in volcanic regions. Locating the underground structural changes associated with a potential eruption is also a key issue to better understand the dynamics at work in a volcano. Using recent results in wave physics, we develop an imaging procedure that is based on the sensitivity of multiply scattered waves to weak changes in heterogeneous media. This procedure allows to locate changes in both mechanical and scattering properties of the studied medium. We study ambient seismic noise from 19 broadband stations at the active volcano Piton de la Fournaise on Reunion Island, recorded from June to December 2010. During this period, two volcanic eruptions occurred at two different locations. We calculate the noise cross correlations and study two types of changes in the coda: apparent velocity variations related to changes in the elastic properties of the medium; and, waveform decoherence associated with variations in the scattering, and thus the geological structures. We observe that the temporal variations of both of these parameters provide potential precursors of volcanic eruptions at Piton de la Fournaise. The locations determined from the preeruptive and coeruptive changes in both parameters are in good agreement with the actual eruptive activities. These data demonstrate that the coda of ambient noise correlations contains deterministic information on the locations of the eruptive processes in an active volcano. Our analysis offers an original and significant constraint for the localization of forthcoming volcanic eruptions.

  1. 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

  2. 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

  3. Borehole Gravity Meter Surveys at the Waste Treatment Plant, Hanford, Washington.

    Energy Technology Data Exchange (ETDEWEB)

    MacQueen, Jeffrey D.; Mann, Ethan

    2007-04-06

    Microg-LaCoste (MGL) was contracted by Pacfic Northwest National Laboratories (PNNL) to record borehole gravity density data in 3 wells at the HanfordWaste Treatment Plant (WTP) site. The survey was designed to provide highly accurate density information for use in seismic modeling. The borehole gravity meter (BHGM) tool has a very large depth of investigation (hundreds of feet) compared to other density tools so it is not influenced by casing or near welbore effects, such as washouts.

  4. 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

  5. Seismic and magnetic images at the Sumatra-Andaman mega thrust subduction zone earthquake (MW 9.3)

    International Nuclear Information System (INIS)

    Complete text of publication follows. The December 26, 2004 Sumatra-Andaman earthquake (MW 9.3), the fourth largest event (M≥9.0) in the world during the last 100 years, occurred by thrust faulting at the subducting India plate. The main shock rupture, ∼1200 km long and ∼200 km wide, propagated from north of Sumatra to Andaman-Nicobar Islands; the slow rupture generated Tsunami which killed about 300,000 people. The mega thrust event was followed by an intense aftershock activity spreading over the rupture area. Seismotectonic processes suggest predominant thrust faulting in the fore arc region, and normal/strike slip faulting in the back arc region, consistent with the regional tectonics. Pre- and Post- earthquake marine geophysics surveys show changes in magnetic (100 - 150 nT) as well as in bathymetry (15-25 m) of the ocean floor. The transient geomagnetic filed variations and the seismic tomography results are reviewed to shed a new light on the regional seismic structures of the Andaman-Sumatra subduction zone. The sediment filled fore arc basin as well as the volcanic arc is well reflected as high conducting and low seismic velocity zone compared to outer non-volcanic island arc. The high conductivity and low seismic velocity are attributed to conducting magma materials and or trapped fluid due to subduction process, and the images revealed the subducting tectonic features.

  6. 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

  7. Seismic reflection imaging in the ruptured area of The Tohoku-Oki Earthquake - Results from rapid response seismic reflection surveys -

    Science.gov (United States)

    Nakamura, Y.; No, T.; Fujie, G.; Kaiho, Y.; Sato, T.; Barnes, J.; Boston, B.; Yamashita, M.; Park, J.; Miura, S.; Takahashi, N.; Kodaira, S.; Kaneda, Y.; Moore, G. F.

    2011-12-01

    The 2011 off the Pacific coast of Tohoku Earthquake is one of the largest earthquakes ever observed and generated devastating Tsunamis. Seismological analysis revealed that the large slip occurred beneath the lower trench slope area, close to the Japan trench axis, (e.g. Ide et al. 2011), which seems to be related with the Tsunami generation. We conducted rapid response reflection seismic surveys using R/V Kairei after the main shock to delineate the structure of the ruptured area off Miyagi. Ten E-W lines with at least 120 km of length were surveyed using a 6 km-long, 444 channel streamer cable and a 7800 inch^3 tuned air gun array. The line spacing was 10-20 km. Preliminary processed data and their interpretation demonstrate that the structure considerably varies from south to north in the survey area. Normal faults dominate in the deep sea terrace. Those faults cut sedimentary sequence in this area, and sometimes offset the reflector at the top of cretaceous sequence. Beneath the trench slope, there are few reflectors especially in the shallower depth below the seafloor. Low angle landward dipping reflectors are observed in most of the survey area, some of them coincides with the backstop interface pointed out by Tsuru et al. (2000), but apparent shape and location of these reflectors are not consistent through the survey area. These reflectors may represent faults, but it is difficult to determine the sense of faulting. In the northern part of the survey area, prominent seaward dipping normal faults are observed in the upper to middle slope. Similar normal faults in small scale can be also recognized in some other lines, and should be one of key features offshore Tohoku region.

  8. 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.)

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. Seismic velocity structures of Southern Italy from tomographic imaging of the Ionian slab and petrological inferences

    OpenAIRE

    Calo, M.; C. Dorbath; D. Luzio; Rotolo, SG; D' Anna G

    2012-01-01

    In this study we have determined detailed Vp and Vs seismic velocity models of the Ionian lithosphere subducting beneath the Tyrrhenian basin and of the surrounding mantle, by applying a post-processing technique to a large sample of local earthquake tomography studies. Our seismic velocity models permit us to infer the presence of low velocity anomalies within the slab, which we interpret as regions that are partially hydrated by fluids released during the subduction process. A petrological ...

  16. 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.

  17. Co-seismic surface effects from very high resolution panchromatic images: the case of the 2005 Kashmir (Pakistan earthquake

    Directory of Open Access Journals (Sweden)

    M. Chini

    2011-03-01

    Full Text Available The use of Very High Resolution (VHR satellite panchromatic image is nowadays an effective tool to detect and investigate surface effects of natural disasters. We specifically examined the capabilities of VHR images to analyse earthquake features and detect changes based on the combination of visual inspection and automatic classification tools. In particular, we have used Quickbird (0.6 m spatial resolution images for detecting the three main co-seismic surface features: damages, ruptures and landslides. The present approach has been applied to the 8 October 2005, Mw7.6 Kashmir, Pakistan, earthquake. We have focused our study in and around the main urban areas hit by the above earthquake specifically at Muzaffarabad and Balakot towns. The automatic classification techniques provided the best results wherever dealing with the damage to man-made structures and landslides. On the other hand, the visual inspection method demonstrated in addressing the identification of rupture traces and associated features. The synoptic view (concerning landslide, more than 190 millions of pixels have been automatically classified, the spatiotemporal sampling and the fast automatic damage detection using satellite images provided a reliable contribution to the prompt response during natural disaster and for the evaluation of seismic hazard as well.

  18. 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

  19. Seismoelectric waves in a borehole excited by an external explosive source

    International Nuclear Information System (INIS)

    The conversion of energy between seismic and electromagnetic wave fields has been described by Pride's coupled equations in porous media. In this paper, the seismoelectric field excited by the explosive point source located at the outside of the borehole is studied. The scattering fields inside and outside a borehole are analyzed and deduced under the boundary conditions at the interface between fluid and porous media. The influences of the distance of the point source, multipole components of the eccentric explosive source, and the receiving position along the axis of vertical borehole, on the converted waves inside the borehole are all investigated. When the distance from the acoustic source to the axis of a borehole is far enough, the longitudinal and coseismic longitudinal wave packets dominate the acoustic and electric field, respectively. The three components of both electric field and magnetic field can be detected, and the radial electric field is mainly excited and converted by the dipole component. Owing to the existence of borehole, the electric fields and magnetic fields in the borehole are azimuthal. The distance from the point where the maximum amplitude of the axial components of electric field is recorded, to the origin of coordinate indicates the horizontal distance from the explosive source to the axis of vertical borehole. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  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. Time-lapse crosswell seismic and VSP monitoring of injected CO2 ina brine aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Daley, Thomas M.; Myer, Larry R.; Peterson, J.E.; Majer, E.L.; Hoversten,G.M.

    2006-05-30

    Seismic surveys successfully imaged a small scale C02injection (1,600 tons) conducted in a brine aquifer of the Frio Formationnear Houston, Texas. These time-lapse bore-hole seismic surveys,crosswell and vertical seismic profile (VSP), were acquired to monitorthe C02 distribution using two boreholes (the new injection well and apre-existing well used for monitoring) which are 30 m apart at a depth of1500 m. The crosswell survey provided a high-resolution image of the C02distribution between the wells via tomographic imaging of the P-wavevelocity decrease (up to 500 mls). The simultaneously acquired S-wavetomography showed little change in S-wave velocity, as expected for fluidsubstitution. A rock physics model was used to estimate C02 saturationsof 10-20 percent from the P-wave velocity change. The VSP survey resolveda large (-70 percent) change in reflection amplitude for the Friohorizon. This C02 induced reflection amplitude change allowed estimationof the C02 extent beyond the monitor well and on 3 azimuths. The VSPresult is compared with numerical modeling of C02 saturations and isseismically modeled using the velocity change estimated in the crosswellsurvey.

  2. Neural network analysis of crosshole tomographic images: The seismic signature of gas hydrate bearing sediments in the Mackenzie Delta (NW Canada)

    Science.gov (United States)

    Bauer, K.; Pratt, R. G.; Haberland, C.; Weber, M.

    2008-10-01

    Crosshole seismic experiments were conducted to study the in-situ properties of gas hydrate bearing sediments (GHBS) in the Mackenzie Delta (NW Canada). Seismic tomography provided images of P velocity, anisotropy, and attenuation. Self-organizing maps (SOM) are powerful neural network techniques to classify and interpret multi-attribute data sets. The coincident tomographic images are translated to a set of data vectors in order to train a Kohonen layer. The total gradient of the model vectors is determined for the trained SOM and a watershed segmentation algorithm is used to visualize and map the lithological clusters with well-defined seismic signatures. Application to the Mallik data reveals four major litho-types: (1) GHBS, (2) sands, (3) shale/coal interlayering, and (4) silt. The signature of seismic P wave characteristics distinguished for the GHBS (high velocities, strong anisotropy and attenuation) is new and can be used for new exploration strategies to map and quantify gas hydrates.

  3. 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.

  4. Drilling a borehole for LEP

    CERN Multimedia

    1981-01-01

    Boreholes were drilled along the earlier proposed line of the LEP tunnel under the Jura to find out the conditions likely to be encountered during the construction of the LEP tunnel (Annual Report 1981 p. 106, Fig. 10).

  5. 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

  6. High-resolution 3D seismic imaging of a pull-apart basin in the Gulf of Cadiz

    Science.gov (United States)

    Crutchley, G.; Berndt, C.; Klaeschen, D.; Gutscher, M.

    2009-12-01

    In 2006, high-resolution 3D seismic data were acquired in the Gulf of Cadiz and the Mediterranean Sea aboard the RRS Charles Darwin as part of the HERMES (Hotspot Ecosystem Research on the Margins of European Seas) project. The P-Cable system, a cost-efficient set-up for fast acquisition of 3D seismic data on 12 single-channel streamers, was utilized to acquire seismic cubes at four different targets. Here, we present results from the second target - a WNW-ESE-oriented pull-apart basin in the southeastern Gulf of Cadiz. Initial processing has included: 1) spatial positioning of each recording channel from GPS data acquired on the outer two channels, 2) improved positioning of shot points and channels from the inversion of first arrival times, 3) application of a swell filter to improve reflection coherency, 4) CDP binning and stacking and 5) migration. The new data confirm that the southeastern Gulf of Cadiz north of the Rharb submarine valley is structurally controlled by numerous strike slip faults that were active until quite recently (within the resolution of the data). Given the location of this basin, between the extensional domain on the upper slope and the compressional toe of the accretionary wedge, we interpret the origin to be gravitational sliding on a detachment layer, possibly containing salt, but at this stage not imaged by our profiles.

  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. Using Resistivity and Seismic Refraction to Image Surface-Ground Water Interaction in the Snowy Range, Wyoming

    Science.gov (United States)

    Provart, M.; Holbrook, W.; Carr, B.; Miller, S. N.; Traver, E.; Hall, R.

    2013-12-01

    Closing the water balance in mountain watersheds is often difficult due to uncertainties about the role of surface/groundwater interactions. We have initiated a combined hydrological/geophysical study of a mountain watershed in the Snowy Range of Wyoming in order to test the efficacy of near-surface geophysical techniques in assessing the pathways that connect surface water to groundwater. Here we present initial results of subsurface structure inferred from electrical resistivity and seismic refraction data. The Snowy Range represents the northern extent of the Medicine Bow Mountains, a subset of the Rockies, that originated from the Laramide Orogeny. Bedrock varies from quartzite, to metasedimentary gneisses and schists, to igneous rock. Our data set consists of DC-resistivity and seismic refraction surveys in a valley containing a spring, as well as a saline tracer experiment in the No Name watershed consisting of time-lapse resistivity profiles along both banks of the stream. Our resistivity transects show highly conductive regions immediately below the spring with resistivities ionized water that has filtered downwards through the ridgelines to the north and south of the valley. Seismic refraction surveys along the same profiles show P-velocities <1500 m/s (the seismic velocity of water) in the upper 10 meters. One possible explanation is that water occupies discrete fracture systems in an otherwise partially saturated subsurface. A saline tracer experiment also shows clear evidence for surface/groundwater interactions. We injected a salt water mixture into the stream and conducted time-lapse resistivity profiling on stream-parallel profiles downstream over five hours to test for hyporheic flow from the stream into the adjacent banks. We imaged increasing conductivity in sections of our profiles which we attribute to saline water infiltrating the subsurface. Our results will lend insight into surface/groundwater interactions in mountainous regions.

  9. 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.

  10. 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

  11. Seismic Velocity Structure and Improved Seismic Image of the Southern Depression of the Tainan Basin from Pre-Stack Depth Migration

    Directory of Open Access Journals (Sweden)

    Qunshu Tang and Chan Zheng

    2010-01-01

    Full Text Available In this paper, a velocity model of the Southern Depression of the Tainan Basin is obtained along with its migrated image from an iterative pre-stack depth migration approach. The Cenozoic strata are uniformly layered with velocities varying from ~1.8 to ~3.6 km s-1. However, the general velocity is slightly lower in the NW segment than the SE. Both fractures and burial depth might be the controls of their seismic velocities. There is an unconformable contact between the Cenozoic and underlying Mesozoic strata with an abrupt velocity jump from ~3.2 to ~4.3 km s-1. The Mesozoic strata are recognized with acoustically distinct reflection patterns (chaotic, deformed and discontinuous and complex internal structures (uplift, folds and faults. Their interval velocities range from ~4.3 to ~4.7 km s-1 within a depth from ~3.5 down to ~12.5 km, and the maximum depositional thickness reaches up to 6.5 km. Multiple tectonic events such as collision, subsidence and uplift might be responsible for the complexity of the Mesozoic strata.

  12. Application of Mixture of Gaussian Clustering on Joint Facies Interpretation of Seismic and Magnetotelluric Sections

    Science.gov (United States)

    Shahrabi, Mohammad Ali; Hashemi, Hosein; Hafizi, Mohammad Kazem

    2016-02-01

    Seismic and magnetotelluric (MT) methods are the most applicable geophysical methods in exploration of hydrocarbon resources. In this paper, mixture of Gaussian clustering is used to combine seismic and MT images under the scheme of Expectation/Maximization (EM) algorithm. Pre-Stack Depth Migration (PSDM) velocity, Root Mean Square (RMS) velocity and vertical gradient of RMS velocity of seismic and resistivity model of MT along 19.3 km MUN-21 profile in Munir Block that has been located in Southwest of Iran in Dezful embayment over the Seh-Qanat anticline are applied. The anticline is the most important oil trap of this area. The Expectation/Maximization (EM) method that has been applied includes: (1) creation of data vectors from the seismic and MT images using image processing techniques, (2) normalizing and mapping using Principal Component Analysis (PCA) procedure (3) unsupervised learning of dataset matrix, (4) setting the matrix in Expectation/Maximization (EM) iteration algorithm (5) remapping to physical space. The final model consists fof six classes which could be given to eight formations that belong to Eocene to Neocomian geological age. Pre-Stack Depth Migration (PSDM) velocity model obtained from seismic study on Seh-Qanat anticline only detected 2 horizons of formations, Asmari and Sarvak Formations; however, the current methodology introduces subdivision anticline into six classes by matching it to the log information of Seh-Qanat Deep-1 (SQD-1) borehole where it was excavated over the anticline with total depth of 2876 m.

  13. 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

  14. 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.

    is important. Hydrophones have a resonance frequency and below resonance the response decays at about 12 dB/octave. High-frequency phones are used in shallow seismic survey in order to boost the recording of high frequencies. The next important parameter...

  15. Shallow seismic reflection profiling of waste disposal sites

    International Nuclear Information System (INIS)

    Conventional approaches to environmental site characterization usually involve drilling of relatively dense networks of continuously sampled and geophysically logged boreholes. In glaciated terrains, problems are often encountered in determining the lateral continuity and three-dimensional subsurface geometry of sediments between borehole locations. An improved and potentially more cost-effective approach combines drilling and borehole sampling with high-resolution shallow seismic reflection profiling. This approach is illustrated with case studies from candidate landfill sites. Seismic data provide critical information regarding the lateral continuity and geometry of sediments and pathways for ground water and contaminants. (author). 38 refs., 11 figs

  16. 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.

  17. 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.

  18. Forsmark site investigation. Geophysical, radar and BIPS logging in boreholes HFM01, HFM02, HFM03 and the percussion drilled part of KFM01A

    International Nuclear Information System (INIS)

    This document reports the data gained during logging operations, which is one of the activities performed within the site investigation at Forsmark. The logging operations presented here include geophysical logging with Wellmac, RAMAC and BIPS. In total, 430 metres of logging was carried out in four percussion drilled boreholes. The boreholes in question are; KFM01A (c. 100 m deep of which 50 m were logged/diameter 165 mm), HFM01 (200 m/140 mm), HFM02 (100 m/140 mm) and HFM03 (30 m/140 mm). The borehole referred to as KFM01A is the uppermost, percussion drilled part of a c 1000 m deep telescopic drilled borehole of which the section 1001000 metres is core drilled. All measurements were conducted in June 2002. Instruments used: Borehole radar (RAMAC) system with dipole radar antennas. Borehole TV system (Borehole Image Processing System BIPS), a high resolution, side viewing, colour borehole TV system. Borehole geophysical logging system (WELLMAC)

  19. 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.

  20. 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.

  1. Development of borehole sealing technology

    International Nuclear Information System (INIS)

    As a part of the geoscientific research in JNC Tono Geoscience Center, we are conducting the borehole investigation as a method of surveying techniques to gain an understanding of geological environment characterization (geology/geological structure, rock hydraulic characteristics, ground water geochemical characteristics and rock mechanics) from surface to deep underground. The borehole for the borehole investigation is used for monitoring hole after the borehole investigation. Since the borehole may act as a passage of groundwater flow and disturb the geological environment artificially, it has to be sealed in finally. Moreover, the hydraulic testing and the geochemical analysis of groundwater that be conducted in the zones injected some kind of lost circulation materials might be impacted on the accuracy of test result. The actual technologies regarding to these themes was researched and evaluated. In the second step, clarification of problems and procedure of R and D for solution of these problems was examined. In order to estimate the effect of lost circulation materials on hydraulic testing, a laboratory test of borehole behavior was performed using a scale model that consisted of a borehole and a water-loss zone. In this test, we found out that the lost circulation material was desorbed from the water-loss zone by back-flow action. It was proved by the test that there is little influence from lost circulation materials on hydraulic testing. Investigation regarding borehole sealing technology was conducted in literature search and interview to overseas researchers. In consequent, three kinds of materials - bentonite clay, bentonite pellet, and ethanol bentonite, were selected as effective sealing material. Moreover, five kinds of methods were selected as effective sealing methods. In water permeability test of sealing material, three kinds of sealing materials indicated lower permeability - order of 10-11 m/sec, and it was evaluated that it could be worked as

  2. 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

  3. Seismic testing

    International Nuclear Information System (INIS)

    This lecture deals with: qualification methods for seismic testing; objectives of seismic testing; seismic testing standards including examples; main content of standard; testing means; and some important elements of seismic testing

  4. Seismic reflection surveys at Horonobe coastal land area

    International Nuclear Information System (INIS)

    We carried out a series of seismic surveys at the coastal land area of Horonobe district. Hokkaido to clarify subsurface structure of the shallow zone around Horonobe town located at the west coast of northern part of the Teshio plain. The series of surveys included a P-wave reflection survey targeting relatively shallow zone and an S-wave reflection survey targeting extremely shallow zone. We interpreted subsurface geological structure by comparing the seismic survey results with the borehole data acquired in a borehole drilled at the research area. P-wave reflection survey clarified that each Quaternary to Neogene layer thickly deposited at west end of survey line makes deposition depth shallower while making its layer thickness rapidly thinner toward the Sarobetsu fold located at the eastern part of a survey line. S-wave reflection survey clearly images two major reflection events. The former one is the reflection from the boundaries between nearshore sediments and lower sediments at the depth range of about 30-40 m. The lower sediments are composed with clayey to silty deposits at the most part of the survey line, and with lagoon deposits at the central part of the survey line. The latter one is the reflection from the basement of the alluvial deposit at a depth of about 80 m. From those results, we can conclude that we revealed the sedimental environment of approximately the last 10,000 years in detail. (author)

  5. 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

  6. Stratigraphy of the Harwell boreholes

    International Nuclear Information System (INIS)

    Seven boreholes, five of them partially cored, were drilled at the Atomic Energy Research Establishment at Harwell as part of a general investigation to assess the feasibility of storing low- and intermediate-level radioactive waste in underground cavities. Two of the deeper boreholes were almost wholly cored to provide samples for hydrogeological, hydrochemical, mineralogical, geochemical, geotechnical, sedimentological and stratigraphical studies to enable variations in lithology and rock properties to be assessed, both vertically and laterally, and related to their regional geological setting. This report describes the lithologies, main faunal elements and stratigraphy of the Cretaceous, Jurassic, Triassic and Carboniferous sequences proved in the boreholes. More detailed stratigraphical accounts of the late Jurassic and Cretaceous sequences will be prepared when current studies of the faunal assemblages are complete. (author)

  7. DeepNet: An Ultrafast Neural Learning Code for Seismic Imaging

    International Nuclear Information System (INIS)

    A feed-forward multilayer neural net is trained to learn the correspondence between seismic data and well logs. The introduction of a virtual input layer, connected to the nominal input layer through a special nonlinear transfer function, enables ultrafast (single iteration), near-optimal training of the net using numerical algebraic techniques. A unique computer code, named DeepNet, has been developed, that has achieved, in actual field demonstrations, results unattainable to date with industry standard tools

  8. 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.

  9. Location Capability and Site Characterization Installing a Borehole VBB Seismometer: the OGS Experience in Ferrara (Italy)

    Science.gov (United States)

    Pesaresi, D.; Barnaba, C.

    2014-12-01

    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 Northeastern Italy Seismic Network: it currently consists of 19 very sensitive broad band and 17 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS CRS data centre in Udine. The southwestern edge of the OGS seismic network stands on the Po alluvial basin: earthquake localization and characterization in this area is affected by the presence of soft alluvial deposits. Following the ML=5.9 earthquake that struck the Emilia region around Ferrara in Northern Italy on May 20, 2012, a cooperation of Istituto Nazionale di Geofisica e Vulcanologia, OGS, the Comune di Ferrara and the University of Ferrara lead to the reinstallation of a previously existing very broad band (VBB) borehole seismic station in Ferrara and to the deployment of a temporary seismographic network consisting of eight portable seismological stations, to record the local earthquakes that occurred during the seismic sequence. The aim of the OGS intervention was on one hand to extend its real time seismic monitoring capabilities toward South-West, including Ferrara and its surroundings, and on the other hand to evaluate seismic site responses in the area. We will introduce details of the Ferrara VBB borehole station and the OGS temporary seismographic network configuration and installation. We will then illustrate the location capability performances, and finally we will shortly describe seismic site characterization with surface/borehole comparisons in terms of seismic noise, site amplification and resonance frequencies.

  10. 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

  11. 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)

  12. 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.

  13. 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

  14. Seismic Images of the Crust across the northern Beata Ridge (NE Caribbean)

    Science.gov (United States)

    Nuñez, Diana; Córdoba, Diego; Pazos, Antonio; Martín-Dávila, José; Carbó, Andrés.; Granja-Bruña, José Luis; Payero, Juan; Octavio Cotilla, Mario

    2010-05-01

    The Beata Ridge is a NE-SW trending structure located in the interior of the Caribbean plate, between the extended Colombian and Venezuelan basins. The northern part of the ridge is ~100 km-wide and emerged (Sierra de Bahoruco in the southern Hispaniola Island) and the southern part is ~3500 km- wide and > 4000 m below sea level. It has been suggested that northern part of the ridge is colliding with the E-W tending island arc. In summary, the Hispaniola island arc is being impacted by collision with the Bahamas Bank in the north and by collision with the Beata Ridge in the south. This collision processes jointly with the main E-W component of left-lateral strike-slip have yielded the basin and range physiography observed in the Hispaniola island. To study the macro-structure of the Beata Ridge has likely the key to understand the controversial origin and evolution of the Caribbean plate. A recent combined onshore-offshore CARIBE NORTE survey has been carried out in the Dominican Republic region to study the subduction and collision processes in this area. The marine geophysical cruise aboard the Spanish R/V Hespérides was carried out in spring of 2009. The cruise collected multibeam bathymetry, gravity, magnetic, high-resolution seismic and three-channel seismic reflection data. In the frame of that experiment, a wide angle seismic profile was carried out across the Beata Ridge along a near NW-SE trending line of 200 km length. A set of 5 OBS were anchored along that transect on both sides of the Beata Ridge and 2 seismic land stations at the Beata and Alto Velo Islands, recorded continuously the airgun shots provided by the R/V Hespérides. Processing of the whole dataset is still ongoing, but available results, improve significantly spatial P-wave velocity variations in the upper and middle crust on both sides of the Beata Ridge. In this work, the more recent results from wide angle seismic data across the Beata Ridge are presented.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. Seismic Imaging of Crustal Faults in Kutch - A Requirement for Understanding Intraplate Earthquakes.

    Science.gov (United States)

    Parvatareddy, R. R.; Sarkar, D.; Sain, K.

    2001-12-01

    Kutch could be a continental shield, but hardly a stable one. The presence of predominantly E-W rift/fault systems is well known. There are also some faults that strike transverse to this trend. That this fractured landmass is periodically rocked by a few great and several moderate but destructive earthquakes show that neotectonic reactivation along these faults is still on. The scenario is further complicated by the presence of a triple junction formed by Indian, African and Arabian plates about 400 km west of this region. The stress distribution and its direction get affected and become more complicated here than at a one-to-one plate boundary. Perhaps because of this, unlike interplate earthquakes, which show some trends of alignments, Kutch seismicity is rather scattered. The great 1819 earthquake is ascribed due to Allah Bund fault in the Great Rann far in north, but the focus of recent 2001 mega event lies at a depth of 23 km in the lower crust just north of Kutch Mainland Fault. This earthquake is perhaps associated with another nearly E-W blind shear. The 1956 Anjar earthquake lies near Katrol fault (KF), which coincides with the southern boundary of Kutch Mainland Uplift (KMU). The aftershock distribution of 2001 earthquake also shows that their foci also scatter over a much larger volume, several tens of kilometers away from the south dipping causative thrust plane. This picture points to the fact that many known and blind crustal scale faults are either already neotectonically active or have been reactivated due to the elastic energy released by the 2001 event. Many of them have the potential of causing damaging, if not great, earthquakes in this region. Mapping of blind faults and the depth extents of known faults with seismic tools therefore acquire importance. Though Kutch region is geophysically well explored by oil industry, hardly any information is available below the granitic basement. NGRI carried out seismic refraction studies mostly in

  1. Seismic Reflection Image Across the Izu-Bonin Island Arc System

    Science.gov (United States)

    Park, J.; Tsuru, T.; Takahashi, N.; Kodaira, S.; Kaneda, Y.

    2002-12-01

    The Izu-Bonin island arc system occupies almost a northern half of the Izu-Bonin-Island (IBM) arc system extending 2500 km south from near Tokyo, which is one of the largest convergent margins on earth. This Izu-Bonin island arc system is a typical intra-oceanic island arc system involving trench-arc-backarc basin system, i.e., the Izu-Bonin trench, the Izu-Bonin arc, and the backarc Shikoku basin. In order to figure out the past 50 m.y. development history of the entire Izu-Bonin intra-oceanic island arc system, we collected marine multichannel seismic (MCS) reflection data across the island arc system on board the R/V Kairei of the Japan Marine Science and Technology Center (JAMSTEC) in May 2002. We used a ~5-km, 204-channel streamer and a 12,000 cubic inch (~200 L) air-guns array. Receiver spacing was 25-m, yielding 51-fold coverage at 12.5-m CDP spacing. We acquired the MCS data on two different lines: ~560-km-long Line 1 and ~1140-km-long Line 3. The MCS data were migrated in depth domain. Velocity-depth models for the depth migration were iteratively constructed by prestack depth migration velocity analysis. Wide-angle data guided the velocity analysis. In this paper, we show the two MCS profiles and discuss the development process of the Izu-Bonin island arc system from viewpoints of seismic stratigraphy and structure. We identify a clear seismic reflector of the subducting Pacific plate with several horst-and-graben structures, which can be observed beneath the arc more than 60 km landward from the trench axis. Forearc basin is characterized by several buried normal faults and vigorous intra-oceanic sedimentation. In the arc rifting zone, we observe many seismic hyperbolic signatures indicative of active volcanic intrusions, which are related to active magmatism. The topmost sedimentary cover sequences are obviously tilted and cut by many normal faults. It is noticeable that reflectors of the middle crust in the arc-backarc transition zone appear to pinch

  2. Waste Isolation Pilot Plant borehole data

    International Nuclear Information System (INIS)

    Data pertaining to all the surface boreholes used at the WIPP site for site characterization hydrological testing and resource evaluation exist in numerous source documents. This project was initiated to develop a comprehensive data base that would include the data on all WIPP related surface boreholes from the Atomic Energy Commission, Waste Isolation Pilot Plant Energy Research and Development Administration, Department of Energy, and Hydrologic Test Borehole Programs. The data compiled from each borehole includes: operator, permit number, location, total depth, type of well, driller, drilling record, casing record, plugging schedule, and stratigraphic summary. There are six groups of boreholes contained in this data base, they are as follows: Commercially Drilled Potash Boreholes, Energy Department Wells, Geologic Exploration Boreholes, Hydrologic Test Boreholes, Potash Boreholes, and Subsurface Exploration Boreholes. There were numerous references which contained borehole data. In some cases the data found in one document was inconsistent with data in another document. In order to ensure consistency and accuracy in the data base, the same references were used for as many of the boreholes as possible. For example, all elevations and locations were taken from Compilation and Comparison of Test-Hole Location Surveys in the Vicinity of the WIPP Site. SAND 88-1065, Table 3-5. There are some sections where a data field is left blank. In this case, the information was either not applicable or was unavailable

  3. Burar seismic station: evaluation of seismic performance

    International Nuclear Information System (INIS)

    A new seismic monitoring system, the Bucovina Seismic Array (BURAR), has been established since July 2002, in the Northern part of Romania, in a joint effort of the Air Force Technical Applications Center, USA, and the National Institute for Earth Physics (NIEP), Romania. The small-aperture array consists of 10 seismic sensors (9 vertical short-period and one three-component broad band) located in boreholes and distributed in a 5 x 5 km2 area. At present, the seismic data are continuously recorded by the BURAR and transmitted in real-time to the Romanian National Data Center in Bucharest and National Data Center of the USA, in Florida. Based on the BURAR seismic information gathered at the National Data Center, NIEP (ROMNDC), in the August 2002 - December 2004 time interval, analysis and statistical assessments were performed. Following the preliminary processing of the data, several observations on the global performance of the BURAR system were emphasized. Data investigation showed an excellent efficiency of the BURAR system particularly in detecting teleseismic and regional events. Also, a statistical analysis for the BURAR detection capability of the local Vrancea events was performed in terms of depth and magnitude for the year 2004. The high signal detection capability of the BURAR resulted, generally, in improving the location solutions for the Vrancea seismic events. The location solution accuracy is enhanced when adding BURAR recordings, especially in the case of low magnitude events (recorded by few stations). The location accuracy is increased, both in terms of constraining hypocenter depth and epicentral coordinates. Our analysis certifies the importance of the BURAR system in NIEP efforts to elaborate seismic bulletins. Furthermore, the specific procedures for array data processing (beam forming, f-k analysis) increase significantly the signal-to-noise ratio by summing up the coherent signals from the array components, and ensure a better accuracy of

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Log response of ultrasonic imaging and its significance for deep mineral prospecting of scientific drilling borehole-2 in Nanling district, China

    International Nuclear Information System (INIS)

    The hole NLSD-2, one of the deepest scientific drilling projects in the metallic ore districts of China, is the second scientific drilling deep hole in the Nanling district. Its ultimate depth is 2012.12 m. This hole was created through the implementation of continuous coring, and the measuring of a variety of geophysical well logging methods was performed over the course of the drilling process. This paper analyzes the characteristic responses of the fracture and fractured zone by ultrasonic imaging log data, and characterizes various rules of fracture parameters which change according to drilling depth. It then discusses the denotative meaning of the log results of polymetallic mineralization layers. The formation fractures develop most readily in a depth of 100∼200 m, 600∼850 m and 1450∼1550 m of the hole NLSD-2, and high angle fractures develop most prominently. The strike direction of the fractures is mainly NW-SE, reflecting the orientation of maximum horizontal principal stress. For the polymetallic mineralization layer that occurred in the fractured zone, the characteristic response of ultrasonic imaging log is a wide dark zone, and the characteristic responses of conventional logs displayed high polarizability, high density, high acoustic velocity and low resistivity. All the main polymetallic mineralization layers are developed in fractures or fractured zones, and the fractures and fractured zones can be identified by an ultrasonic imaging log, thus the log results indirectly indicate the occurrence of polymetallic mineralization layers. Additionally, the relationship between the dip direction of fractures and the well deviation provides guidance for straightening of the drilling hole. (paper)

  9. 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.

  10. 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)

  11. 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

  12. 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)

  13. 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

  14. 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.

  15. 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)

  16. 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 (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 a combination of fractured rock and a fluid

  17. 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

  18. 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...

  19. 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.

  20. 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.

  1. 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

  2. From the Atlas to the Rif a Crustal seismic image across Morocco: The SIMA & RIFSEIS control source wide-angle seismic reflection data

    Science.gov (United States)

    Carbonell, Ramon; Ayarza, Puy; Gallart, Josep; Diaz, Jordi; Harnafi, Mimoun; Levander, Alan; Teixell, Antonio

    2014-05-01

    The velocity structure of the crust and the geometry of the Moho across Morocco has been the main target of two recently acquired wide-angle seismic reflection transects. One is the SIMA experiment which provided seismic constraints beneath the Atlas Mountains and the second has been the RIFSEIS experiment which sampled the RIF orogen. Jointly these controlled source wide-angle seismic reflection data results in an almost 700 km, seismic profile going from the the Sahara craton across the High and Middle Atlas and Rif Mountain till the Gibraltar-Arc (Alboran). Current work on the interpretation of the seismic data-set is based on forward modeling, ray-tracing, as well as low fold wide-angle stacking. The data has resulted in a detailed crustal structure and velocity model for the Atlas Mountains and a 700 km transect revealing the irregular topography of the Moho beneath these two mountain orogens. Results indicate that the High Atlas features a moderate crustal thickness and that shortening is resolved at depth through a crustal root where the Saharan crust under-thrusts below the Moroccan crust, defining a lower crust imbrication which locally places the Moho boundary at, approximately, 40 km depth. The P-wave velocity model is characterized, in averaged, by relatively low velocities. These low deep crustal velocities together with other geophysical observables such as: conductivity estimates derived from Mt measurements; moderate Bouguer gravity anomaly; surface exposures of recent alkaline volcanics; lead the interpretation to propose that partial melts are currently emplaced in the deep crustal levels and in the upper mantle. The Moho discontinuity defines a crust which is in average relatively thin beneath the Atlas which is almost a 4000 m high orogenic belt. The resulting model supports existence of mantle upwelling as a possible mechanism that contributes, significantly, to maintain the High Atlas topography.

  3. Seismic imaging of the Waltham Canyon fault, California: comparison of ray‐theoretical and Fresnel volume prestack depth migration

    Science.gov (United States)

    Bauer, Klaus; Ryberg, Trond; Fuis, Gary S.; Lüth, Stefan

    2013-01-01

    Near‐vertical faults can be imaged using reflected refractions identified in controlled‐source seismic data. Often theses phases are observed on a few neighboring shot or receiver gathers, resulting in a low‐fold data set. Imaging can be carried out with Kirchhoff prestack depth migration in which migration noise is suppressed by constructive stacking of large amounts of multifold data. Fresnel volume migration can be used for low‐fold data without severe migration noise, as the smearing along isochrones is limited to the first Fresnel zone around the reflection point. We developed a modified Fresnel volume migration technique to enhance imaging of steep faults and to suppress noise and undesired coherent phases. The modifications include target‐oriented filters to separate reflected refractions from steep‐dipping faults and reflections with hyperbolic moveout. Undesired phases like multiple reflections, mode conversions, direct P and S waves, and surface waves are suppressed by these filters. As an alternative approach, we developed a new prestack line‐drawing migration method, which can be considered as a proxy to an infinite frequency approximation of the Fresnel volume migration. The line‐drawing migration is not considering waveform information but requires significantly shorter computational time. Target‐oriented filters were extended by dip filters in the line‐drawing migration method. The migration methods were tested with synthetic data and applied to real data from the Waltham Canyon fault, California. The two techniques are applied best in combination, to design filters and to generate complementary images of steep faults.

  4. CO2 gas/oil ratio prediction in a multi-component reservoir bycombined seismic and electromagnetic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hoversten, G.M.; Gritto, Roland; Washbourne, John; Daley, Tom

    2002-08-28

    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 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. The electrical conductivity changes are directly mapped to changes in water saturation. The estimated changes in water saturation are used 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. The residual compressional velocity change is then interpreted in terms of increases in the CO2 /oil ratio. Resulting images of CO2/oil ratio show CO2 rich zones that are well correlated with 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 geophysical parameters.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Origin and nature of crystal reflections: Results from integrated seismic measurements at the KTB superdeep drilling site

    Science.gov (United States)

    Harjes, H.-P.; Bram, K.; Dürbaum, H.-J.; Gebrande, H.; Hirschmann, G.; Janik, M.; KlöCkner, M.; Lüschen, E.; Rabbel, W.; Simon, M.; Thomas, R.; Tormann, J.; Wenzel, F.

    1997-08-01

    For almost 10 years the KTB superdeep drilling project has offered an excellent field laboratory for adapting seismic techniques to crystalline environments and for testing new ideas for interpreting seismic reflections in terms of lithological or textural properties of metamorphic rock units. The seismic investigations culminated in a three-dimensional (3-D) reflection survey on a 19×19 km area with the drill site at its center. Interpretation of these data resulted in a detailed, structural model of the German Continental Deep Drilling Program (KTB) location with dominant, steep faults in the upper crust. The 3-D reflection survey was part of a suite of seismic experiments, ranging from wide-angle reflection and refraction profiles to standard vertical seismic profiles (VSP) and more sophisticated surface-to-borehole observations. It was predicted that the drill bit would meet the most prominent, steeply dipping, crustal reflector at a depth of about 6500-7000 m, and indeed, the borehole penetrated a major fault zone in the depth interval between 6850 and 7300 m. This reflector offered the rare opportunity to relate logging results, reflective properties, and geology to observed and modeled data. Post-Variscan thrusting caused cataclastic deformation, with partial, strong alterations within a steeply dipping reverse fault zone. This process generated impedance contrasts within the fault zone on a lateral scale large enough to cause seismic reflections. This was confirmed by borehole measurements along the whole 9.1 km deep KTB profile. The strongest, reflected signals originated from fluid-filled fractures and cataclastic fracture zones rather than from lithological boundaries (i.e., first-order discontinuities between different rock types) or from texture- and/or foliation-induced anisotropy. During the interpretation of seismic data at KTB several lessons were learned: Conventional processing of two-dimensional (2-D) reflection data from a presite survey

  10. New Insights from Seismic Imaging over the Youanmi Terrane, Western Australia

    Science.gov (United States)

    Ahmadi, Omid; Juhlin, Christopher

    2014-05-01

    The Youanmi terrane is located in the central parts of the Yilgarn craton, Western Australia, an Archean granite-greenstone unit containing numerous mineral deposits such as gold, base metals, nickel, uranium and gemstones. The terrane is surrounded by the Kalgoorlie and Narryer terranes to the east and west, respectively. To the southwest it is bounded by the South West terrane. In order to study the transitions between the Youanmi terrane and the surrounding terranes, as well as identifying potential mineral rich areas, the Geological Survey of Western Australia acquired three deep crustal 2D seismic profiles with a total length of about 700 km in 2010. Correlated record lengths of 20 seconds allow the deep structure of the crust to be investigated with the data, down to Moho depths and greater. Initial processing using a conventional 2D flow show a highly reflective crust with several interesting features. We have now reprocessed the data following mainly the previous processing flow, but with a focus on the shallower crust, less than 10 seconds (about 27 km). Due to the complex geology in the region, 3D aspects of the structures need to be considered in the data processing. Therefore, we investigated the effect of cross-dip corrections to the data. The cross-dip correction has two advantages; (i) reflections are more coherent and enhanced after the correction and (ii) the orientation and dip angle of the geological structures of the corresponding reflections can be identified in the cross-line direction. Where the profiles intersect each other sparse 3D processing can be performed. First arrival travel-time tomography was also tested on parts of the dataset. Travel-time inversion may provide better velocity models at shallow depths than standard reflection seismic processing provides. Preliminary results show that the travel-time tomography has a depth of investigation of about 1 km, a depth that is of interest for mining purposes. Therefore, the tomography

  11. Simpevarp site investigation. Geophysical, radar and BIPS logging in borehole KSH01A, HSH01, HSH02 and HSH03

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Per; Gustafsson, Christer [RAYCON, Malaa (Sweden)

    2003-04-01

    The objective of the surveys is to both receive information of the borehole itself, and from the rock mass around the borehole. Bore hole radar was used to investigate the nature and the structure of the rock mass located around the boreholes, and BIPS for geological surveying and fracture mapping and orientation. Geophysical logging was used to measure changes in physical properties in the borehole fluid and the bedrock surrounding the boreholes. This field report describes the equipment used as well the measurement procedures. For the BIPS survey, the result is presented as images. Radar data is presented in radargrams and identified reflectors in each borehole are listed in tables. Geophysical logging data is presented in graphs as a function of depth.

  12. Simpevarp site investigation. Geophysical, radar and BIPS logging in borehole KSH01A, HSH01, HSH02 and HSH03

    International Nuclear Information System (INIS)

    The objective of the surveys is to both receive information of the borehole itself, and from the rock mass around the borehole. Bore hole radar was used to investigate the nature and the structure of the rock mass located around the boreholes, and BIPS for geological surveying and fracture mapping and orientation. Geophysical logging was used to measure changes in physical properties in the borehole fluid and the bedrock surrounding the boreholes. This field report describes the equipment used as well the measurement procedures. For the BIPS survey, the result is presented as images. Radar data is presented in radargrams and identified reflectors in each borehole are listed in tables. Geophysical logging data is presented in graphs as a function of depth

  13. 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.

  14. 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.

  15. 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

  16. 3D Seismic Reflection Imaging of Crustal Formation Processes on the East Pacific Rise, 9°57-42'N

    Science.gov (United States)

    Purdy, G. M.; Mutter, J. C.; Carbotte, S. M.; Canales, J. P.; Nedimovic, M. R.; Carton, H.; Newman, K. R.; Marjanovic, M.; Xu, M.; Aghaei, O.; Stowe, L. C.

    2008-12-01

    Between June 29th and August 19th 2008 the research vessel Marcus G Langseth carried out its first multi- streamer 3D seismic reflection imaging cruise, MGL08-12, by conducting a program research on the East Pacific Rise centered around 9°50'N. The primary goals were to create an accurate 3D seismic reflection image of the magmatic-hydrothermal system at this Integrated Study Site of the Ridge2000 program by imaging the structure of the axial magma chamber (AMC) lid and oceanic crust at a resolution, accuracy, and scale comparable to seafloor observations. The vessel acquired data with four, 6-kilometer solid streamers each comprising 468 active channels deployed with a total separation of 450 meters. Four gun strings with total volume of 3300 cubic inches in two groups fired alternately provide the source for a shot spacing of 37.5 meters. This configuration yields eight CMP lines for each of the sail lines that were spaced 300 m apart, and a static bin size of 6.25 m × 37.5 m in the along-track and across-track directions, respectively, providing a nominal fold of 40. The cruise accomplished the acquisition of ~3,782 km of sail line data. There are 111 across axis lines that required 10 repeated lines and 14 infills. Average feathering during the cruise was 0° ± 5° (one standard deviation), with maximum values of up to 11°. This means that 18% of the total cross axis acquisition was needed for reshoots and infilling. A 25% multiplier on planned lines for a 3D grid is probably a useful figure to use in cruise planning and is fairly standard in the seismic industry. Data quality meets or exceeds industry standards. 3D coverage was achieved in two areas. The larger comprises a set of 93 equally spaced lines forming the 3D grid between 9°57'N and 9°42'N. This grid is made up of lines from all of racetracks #1 and #2 and the northern lines of racetrack#3 and covers two principal hydrothermal vent areas in a continuous fashion. The second 3D area is comprised

  17. 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

    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...... 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...

  18. 3-D Seismic Images of Mud Volcano North Alex, West-Nile Delta, Egypt

    Science.gov (United States)

    Bialas, Joerg; Klaeschen, Dirk; Papenberg, Cord; Gehrmann, Romina; Sommer, Malte

    2010-05-01

    Mud volcanoes within shelf areas are the bathymetric expression of mobilized overpressured sediments causing a feature of possible instability within the slope. Such a scene is given in the West-Nile Delta offshore Alexandria, Egypt at 700 m water depth, ,which was studied during a RWE Dea funded research project. The West Nile Delta forms part of the source of the large turbiditic Nile Deep Sea Fan. Since the late Miocene sediments have formed an up to 10 km thick pile, which includes about 1 - 3 km of Messinian evaporates. The sediment load of the overburden implies strong overpressures and salt-related tectonic deformation. Both are favourable for fluid migration towards the seafloor guided by the fractured margin. Deep-cutting channel systems like the Rosetta channel characterize the continental slope. Bathymetric expressions of slides and numerous mud volcanoes in the area are expressions of active processes, which contribute to the ongoing modification of the slope. The western deltaic system, Rosetta branch, has formed an 80 km wide continental shelf. Here at 700 m water depth the mud volcano North Alex developed his circular bathymetric feature, which proved to be an active gas and mud-expelling structure. A grid of 2-D seismic profiles did reveal a large set of faults located within the main mud volcano as well as surrounding the structure. Internal faults are mainly related to episodic mud expulsion processes and continuous gas and fluid production. Deep cutting external faults surround the structure in a half circle shape. They can be tracked up to the seafloor indicating ongoing tectonic activity of the slope area. A recently build 3-D acquisition system (funded by RWE Dea) suitable for mid-size research vessels was applied to collect an active seismic cube of the mud volcano. Based on the P-Cable design 11 parallel streamers (each 12.5 m long with 1.5 m group interval) were used to record shots of a single 210 cinch GI airgun. Based on GPS positions of

  19. NCSRR digital seismic network in Romania

    International Nuclear Information System (INIS)

    Digital seismic instrumentation donated by Japan International Cooperation Agency (JICA) to the National Center for Seismic Risk Reduction (NCSRR, Romania) allowed the installation in 2003 of a new Romanian seismic network. In 2005-2006 the network was developed by investments from NCSRR within the budget ensured by Ministry of Transports, Construction and Tourism (MTCT). The NCSRR seismic network contains three types of instrumentation: (i) free-field stations - outside the capital city Bucharest (8 accelerometers), (ii) instrumented buildings - in Bucharest (5 buildings), and (iii) stations with free-field and borehole sensors - in Bucharest (8 sites with ground surface sensor and sensors in 15 boreholes with depths up to 153 m). Since its installation, the NCSRR network recorded more than 170 seismic motions from 26 earthquakes with moment magnitudes ranging from 3.2 to 6.0. The seismic instrumentation was accompanied by investigations of ground conditions and site response: PS logging tests, single-station and array microtremor measurements. The development of seismic monitoring in Romania is a major contribution of JICA Project, creating the premises for a better understanding and modelling of earthquake ground motion, site effects and building response. (authors)

  20. 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...

  1. 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.

  2. Borehole radar surveying for orebody delineation

    Science.gov (United States)

    Turner, G.; Mason, I. M.; Hargreaves, J. E.; Wellington, A.

    2000-04-01

    The Arcolabs borehole radar system was developed to assist detailed orebody delineation particularly for mines extracting thin vein ore deposits. The probes are 32 mm and therefore fit in most common exploration and mining drillholes. The system has been successfully used at a number of mine sites to assist with ore delineation at a range of scales. Images from holes drilled alongside the extension of a massive sulphide orebody downdip from current development clearly showed the extent of the orebody and changes in thickness and dip of the orebody. The costs of these surveys were considerably less than the cost of delineation by drilling alone and the resulting image provided more detailed data which could be used to optimize the position of development. Estimates of potential savings from using the system to define the bottom of the orebody were of the order of hundreds of thousands of dollars. Images from short holes drilled at short intervals beneath the footwall of another orebody enabled a detailed wireframe of the orebody contact to be constructed. Better knowledge of the contact location helped to maximize ore extraction and minimize dilution.

  3. Device for geophysical borehole investigations

    International Nuclear Information System (INIS)

    Electronic circuits for an improved system for the determination of uranium, thorium and potassium in geological structures penetrated by a borehole are described. Previous methods have only considered the main characteristic gamma peaks for these elements and have given poor statistical accuracy. The system described covers the whole energy range from 0.15 to 3 MeV using a sodium iodide scintillator counter, with the energy range divided into five windows. The spectra are analysed by an analogue computer which has previously been calibrated against samples of known concentration. (JIW)

  4. 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.

  5. 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.

  6. High resolution seismic reflection profiling at Aberdeen Proving Grounds, Maryland

    International Nuclear Information System (INIS)

    The effectiveness of shallow high resolution seismic reflection (i.e., resolution potential) to image geologic interfaces between about 70 and 750 ft at the Aberdeen Proving Grounds, Maryland (APG), appears to vary locally with the geometric complexity of the unconsolidated sediments that overlay crystalline bedrock. The bedrock surface (which represents the primary geologic target of this study) was imaged at each of three test areas on walkaway noise tests and CDP (common depth point) stacked data. Proven high resolution techniques were used to design and acquire data on this survey. Feasibility of the technique and minimum acquisition requirements were determined through evaluation and correlation of walkaway noise tests, CDP survey lines, and a downhole velocity check shot survey. Data processing and analysis revealed several critical attributes of shallow seismic data from APG that need careful consideration and compensation on reflection data sets. This survey determined: (1) the feasibility of the technique, (2) the resolution potential (both horizontal and vertical) of the technique, (3) the optimum source for this site, (4) the optimum acquisition geometries, (5) general processing flow, and (6) a basic idea of the acoustic variability across this site. Source testing involved an accelerated weight drop, land air gun, downhole black powder charge, sledge hammer/plate, and high frequency vibrator. Shallow seismic reflection profiles provided for a more detailed picture of the geometric complexity and variability of the distinct clay sequences (aquatards), previously inferred from drilling to be present, based on sparse drill holes and basewide conceptual models. The seismic data also reveal a clear explanation for the difficulties previously noted in correlating individual, borehole-identified sand or clay units over even short distances

  7. System and method to estimate compressional to shear velocity (VP/VS) ratio 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

    2012-10-16

    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.

  8. Exploratory borehole Riniken. Geology. Text volume

    International Nuclear Information System (INIS)

    The Riniken well was the third borehole of the NAGRA deep drilling programme, drilled after the wells of Boettstein and Weiach. Located in the borough of Riniken (Canton Aargau) at an altitude of 385.07 m above sea level it lies approximately 3 km NNW of Brugg railway station. The well reached a total depth of 1800 m. Drilling at Riniken started on June 23, 1983 and continued until January 12, 1984. The comprehensive drillsite and laboratory studies included stratigraphic, sedimentological, mineralogical, petrographic and structural analyses in addition to a variety of petrophysical and geochemical investigations. This report presents all the data collected up until the end of September 1985. The Riniken well penetrated the ca. 800 m thick Mesozoic Tafeljura sedimentary cover, and then drilled through ca. 1000 m of the clastic fill of the N Swiss Permo-Carboniferous trough. The succession encountered extended from the Effinger Beds (Malm) down to the Upper Rotliegendes. The crystalline basement was not penetrated, but interpretation of the seismic data indicates its presence at depths between 3 and 7 km. The cored sediments display occasional fissures. Most of these fissures are filled with clay minerals, calcite and quartz. Open fissures were encountered only in the Buntsandstein and in the Rotliegendes, at a depth of around 1005 m. Water-saturated zones were recorded in the Schilfsandstein (Keuper), in the Trigonodus-Dolomit, in the Buntsandstein, and in the Rotliegendes between 950 and 1010 m. Water circulation is controlled partly by the presence of high porosity lithologies (e.g. Trigonodus-Dolomit, Buntsandstein) and partly by the occurrence of open fissures (e.g. in the Rotliegendes). However, most of the sedimentary sequence shows low permeabilities (K-10 m/s). 162 refs., 2 figs., 6 tabs

  9. Exploratory borehole Riniken. Geology. Supplement volume

    International Nuclear Information System (INIS)

    The Riniken well was the third borehole of the NAGRA deep drilling programme, drilled after the wells of Boettstein and Weiach. Located in the borough of Riniken (Canton Aargau) at an altitude of 385.07 m above sea level it lies approximately 3 km NNW of Brugg railway station. The well reached a total depth of 1800 m. Drilling at Riniken started on June 23, 1983 and continued until January 12, 1984. The comprehensive drillsite and laboratory studies included stratigraphic, sedimentological, mineralogical, petrographic and structural analyses in addition to a variety of petrophysical and geochemical investigations. This report presents all the data collected up until the end of September 1985. The Riniken well penetrated the ca. 800 m thick Mesozoic Tafeljura sedimentary cover, and then drilled through ca. 1000 m of the clastic fill of the N Swiss Permo-Carboniferous trough. The succession encountered extended from the Effinger Beds (Malm) down to the Upper Rotliegendes. The crystalline basement was not penetrated, but interpretation of the seismic data indicates its presence at depths between 3 and 7 km. The cored sediments display occasional fissures. Most of these fissures are filled with clay minerals, calcite and quartz. Open fissures were encountered only in the Buntsandstein and in the Rotliegendes, at a depth of around 1005 m. Water-saturated zones were recorded in the Schilfsandstein (Keuper), in the Trigonodus-Dolomit, in the Buntsandstein, and in the Rotliegendes between 950 and 1010 m. Water circulation is controlled partly by the presence of high porosity lithologies (e.g. Trigonodus-Dolomit, Buntsandstein) and partly by the occurrence of open fissures (e.g. in the Rotliegendes). However, most of the sedimentary sequence shows low permeabilities (K-10 m/s). 34 figs

  10. High-resolution seismic imaging of the western Hellenic subduction zone using teleseismic scattered waves

    Science.gov (United States)

    Suckale, J.; Rondenay, S.; Sachpazi, M.; Charalampakis, M.; Hosa, A.; Royden, L. H.

    2009-08-01

    The active Hellenic subduction system has long been considered an ideal setting for studying subduction dynamics because it is easily accessible and of limited spatial extent. It has been the focus of numerous seismological studies over the last few decades but, nonetheless, the detailed structure of both the slab and the surrounding mantle remain poorly constrained in an intermediate depth range from 30 to 150 km. The objective of this paper is to fill this gap. The intermediate depth regime is of particular interest because it is pivotal for improving our understanding of the dynamic interaction between subducting lithosphere and the surrounding mantle. An interdisciplinary effort aimed at addressing this challenge is currently undertaken by the `Multidisciplinary Experiments for Dynamic Understanding of Subduction under the Aegean Sea' (MEDUSA) project. As part of the MEDUSA initiative, a temporary array consisting of 40 densely spaced broad-band seismometers from the IRIS-PASSCAL pool has been deployed in southern Greece. We process the teleseismic data recorded by this array with a migration algorithm based on the generalized radon transform to obtain high-resolution images of the subduction zone in 2-D. The images reveal a sharp Mohorovičić discontinuity (Moho) at depths ranging from 30 km beneath the western margin of the Aegean Sea to 40 km beneath the central Peloponnesus, where it outlines the crustal root of the Hellenides. To the west of the Hellenides, the continental Moho is not identified, but we interpret a pronounced discontinuity imaged at ~20 km depth as the contact between low-velocity sediments and high-velocity crystalline basement. The images also show the subducted oceanic crust as a low-velocity layer that plunges at a constant angle of 21° from west to east. The oceanic crust exhibits low velocities to at least 90 km depth, indicating that the bulk of fluid transfer from the subducted slab into the mantle wedge occurs below this depth

  11. 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.

  12. 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

  13. Importance of borehole deviation surveys for monitoring of hydraulic fracturing treatments

    Czech Academy of Sciences Publication Activity Database

    Bulant, P.; Eisner, L.; Pšenčík, Ivan; Le Calvez, J. H.

    2007-01-01

    Roč. 55, č. 6 (2007), s. 891-899. ISSN 0016-8025 Grant ostatní: GA ČR(CZ) GA205/07/0032; EC(XE) MTKI-CT-2004-517242 Institutional research plan: CEZ:AV0Z30120515 Source of funding: R - rámcový projekt EK Keywords : hydraulic fracture * borehole deviation * seismic rays Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.731, year: 2007

  14. 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.

  15. 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

  16. Characterization of a complex near-surface structure using well logging and passive seismic measurements

    Science.gov (United States)

    Benjumea, Beatriz; Macau, Albert; Gabàs, Anna; Figueras, Sara

    2016-04-01

    We combine geophysical well logging and passive seismic measurements to characterize the near-surface geology of an area located in Hontomin, Burgos (Spain). This area has some near-surface challenges for a geophysical study. The irregular topography is characterized by limestone outcrops and unconsolidated sediments areas. Additionally, the near-surface geology includes an upper layer of pure limestones overlying marly limestones and marls (Upper Cretaceous). These materials lie on top of Low Cretaceous siliciclastic sediments (sandstones, clays, gravels). In any case, a layer with reduced velocity is expected. The geophysical data sets used in this study include sonic and gamma-ray logs at two boreholes and passive seismic measurements: three arrays and 224 seismic stations for applying the horizontal-to-vertical amplitude spectra ratio method (H/V). Well-logging data define two significant changes in the P-wave-velocity log within the Upper Cretaceous layer and one more at the Upper to Lower Cretaceous contact. This technique has also been used for refining the geological interpretation. The passive seismic measurements provide a map of sediment thickness with a maximum of around 40 m and shear-wave velocity profiles from the array technique. A comparison between seismic velocity coming from well logging and array measurements defines the resolution limits of the passive seismic techniques and helps it to be interpreted. This study shows how these low-cost techniques can provide useful information about near-surface complexity that could be used for designing a geophysical field survey or for seismic processing steps such as statics or imaging.

  17. Monitoring borehole flow dynamics using heated fiber optic DTS in a fractured rock aquifer

    Science.gov (United States)

    Coleman, Thomas; Chalari, Athena; Parker, Beth; Munn, Jonathan; Mondanos, Michael

    2014-05-01

    Temperature profiles in fractured rock have long been used to identify and characterize flow in the rock formation or in the borehole. Fiber optic distributed temperature sensing (DTS) is a tool that allows for continuous borehole temperature profiling in space and time. Recent technology advancements in the spatial, temperature, and temporal resolutions of DTS systems now allow temperature profiling methods to offer improved insight into fractured rock hydrogeologic processes. An innovation in shallow borehole temperature logging utilizes high resolution DTS temperature profiling in sealed and heated boreholes to identify fractures with natural gradient groundwater flow by creating a thermal disequilibrium and monitoring the temperature response. This technique can also be applied to open well conditions to monitor borehole flow distributions caused by hydraulic perturbations such as pumping or injection. A field trial was conducted in Guelph, Ontario, Canada to determine the capabilities of heated DTS for flow monitoring in both open and sealed wells. Intelligent distributed acoustic sensing (iDAS) measurements for vertical seismic profiling were carried out simultaneously with the DTS measurements to assist with characterization of the fractured aquifer system. DTS heat pulse tests were conducted in a single well under sealed conditions for natural gradient flow measurements and open conditions to monitor flow distributions during injection and pumping. The results of these tests indicate that borehole flow distributions can be monitored using DTS and that active heating allows for further information about the hydrogeologic system to be determined than from the passive measurements alone. Depth-continuous transmissivity data from the borehole correlate well with the DTS testing results. DTS based flow monitoring systems may be useful for monitoring transient production and injection processes for a variety of applications including groundwater remediation

  18. Induced Seismicity Monitoring System

    Science.gov (United States)

    Taylor, S. R.; Jarpe, S.; Harben, P.

    2014-12-01

    There are many seismological aspects associated with monitoring of permanent storage of carbon dioxide (CO2) in geologic formations. Many of these include monitoring underground gas migration through detailed tomographic studies of rock properties, integrity of the cap rock and micro seismicity with time. These types of studies require expensive deployments of surface and borehole sensors in the vicinity of the CO2 injection wells. Another problem that may exist in CO2 sequestration fields is the potential for damaging induced seismicity associated with fluid injection into the geologic reservoir. Seismic hazard monitoring in CO2 sequestration fields requires a seismic network over a spatially larger region possibly having stations in remote settings. Expensive observatory-grade seismic systems are not necessary for seismic hazard deployments or small-scale tomographic studies. Hazard monitoring requires accurate location of induced seismicity to magnitude levels only slightly less than that which can be felt at the surface (e.g. magnitude 1), and the frequencies of interest for tomographic analysis are ~1 Hz and greater. We have developed a seismo/acoustic smart sensor system that can achieve the goals necessary for induced seismicity monitoring in CO2 sequestration fields. The unit is inexpensive, lightweight, easy to deploy, can operate remotely under harsh conditions and features 9 channels of recording (currently 3C 4.5 Hz geophone, MEMS accelerometer and microphone). An on-board processor allows for satellite transmission of parameter data to a processing center. Continuous or event-detected data is kept on two removable flash SD cards of up to 64+ Gbytes each. If available, data can be transmitted via cell phone modem or picked up via site visits. Low-power consumption allows for autonomous operation using only a 10 watt solar panel and a gel-cell battery. The system has been successfully tested for long-term (> 6 months) remote operations over a wide range

  19. Revealing a strike-slip plate boundary: Drill-bit seismic imaging of the San Andreas Fault at the SAFOD site

    Science.gov (United States)

    Taylor, Stewart Thomas

    2006-12-01

    The San Andreas Fault at the San Andreas Fault Observatory at Depth (SAFOD) near Parkfield, CA forms the contact between the Pacific and North American tectonic plates. The hypotheses tested in this dissertation are that this boundary (1) is not located beneath the currently recognized surface trace of the SAF, (2) is not composed of a single active strand, but at least two overlapping, positive and negative flower structures, and (3) has juxtaposed, severely folded, and then buried Tertiary to pre-Cretaceous strata not previously known to exist in the Parkfield area. These hypotheses were tested through the construction, analysis, and interpretation of a new type of drill-bit seismic reflection imaging at the SAFOD drill site. Drill-bit seismic (DBS) imaging uses the drill bit as a seismic source. Previous DBS experiments have used geophone receiver arrays laid on the earth's surface. At SAFOD, a vertical receiver array supplemented a surface receiver array, to record the Stage 1 drilling of SAFOD well which was completed in 2004. This dissertation expands the DBS method by utilizing both the vertical and surface arrays to record the drill bit vibrations and produce two types of reverse vertical seismic profiles. A major portion of this dissertation includes research and development of DBS data signal processing techniques for industrial applications and the special case of the SAFOD observations. These observations include downhole geophone recordings which represent a new approach not previously reported in the seismic reflection literature. The application of algorithms produced by these studies has resulted in improved methods for estimating the drill bit seismic source signature. These methods also determine optimal deconvolution operators for DBS signals which produce estimates of the "pilot signal". It is shown that processing of DBS data is possible without drill string pilot accelerometers. This allows more economic deployment of equipment at the drill

  20. Seismic Fault Preserving Diffusion

    OpenAIRE

    Lavialle, Olivier; Pop, Sorin; Germain, Christian; Donias, Marc; Guillon, Sebastien; Keskes, Naamen; Berthoumieu, Yannick

    2007-01-01

    This paper focuses on the denoising and enhancing of 3-D reflection seismic data. We propose a pre-processing step based on a non linear diffusion filtering leading to a better detection of seismic faults. The non linear diffusion approaches are based on the definition of a partial differential equation that allows us to simplify the images without blurring relevant details or discontinuities. Computing the structure tensor which provides information on the local orientation of the geological...

  1. 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.

  2. BOLIVAR: the Caribbean-South America plate boundary between 60W and 71W as imaged by seismic reflection data

    Science.gov (United States)

    Magnani, M.; Mann, P.; Clark, S. A.; Escalona, A.; Zelt, C. A.; Christeson, G. L.; Levander, A.

    2007-12-01

    We present the results of ~6000km of marine multi-channel seismic (MCS) reflection data collected offshore Venezuela as part of the Broadband Ocean Land Investigation of Venezuela and the Antilles arc Region project (BOLIVAR). The imaged area spans almost 12 degrees of longitude and 5 degrees of latitude and encompasses the diffuse plate boundary between South America (SA) and the SE Caribbean plate (CAR). This plate boundary has been evolving for at least the past 55My when the volcanic island arc that borders the CAR plate started colliding obliquely with the SA continent: the collision front has migrated from west to east. BOLIVAR MCS data show that the crustal architecture of the present plate boundary is dominated by the eastward motion of the Caribbean plate with respect to SA and is characterized by a complex combination of convergent and strike-slip tectonics. To the north, the reflection data image the South Caribbean Deformed Belt (SCDB) and the structures related to the thrusting of the CAR plate under the Leeward Antilles volcanic arc region. The data show that the CAR underthrusting continues as far east as the southern edge of the Aves ridge and detailed stratigraphic dating of the Venezuela basin and trench deposits suggests that the collision began in the Paleogene. The amount of shortening along the SCDB decreases toward the east, in part due to the geometry of plate motion vectors and in part as a result of the NNE escape of the Maracaibo block in western Venezuela. South of the SCDB the MCS profiles cross the Leeward Antilles island arc and Cenozoic sedimentary basins, revealing a complex history of Paleogene-Neogene multiphase extension, compression, and tectonic inversion, as well as the influence of the tectonic activity along the right-lateral El Pilar - San Sebastian fault system. East of the Bonaire basin the MCS data image the southern end of the Aves Ridge abandoned volcanic island arc and the southwestern termination of the Grenada basin

  3. 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...

  4. 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.

  5. 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.

  6. 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.

  7. Seismic imaging of a convergent continental margin and plateau in the central Andes (Andean Continental Research Project 1996 (ANCORP'96))

    Science.gov (United States)

    Oncken, O.; Asch, G.; Haberland, C.; Metchie, J.; Sobolev, S.; Stiller, M.; Yuan, X.; Brasse, H.; Buske, S.; Giese, P.; GöRze, H.-J.; Lueth, S.; Scheuber, E.; Shapiro, S.; Wigger, P.; Yoon, M.-K.; Bravo, P.; Vieytes, H.; Chong, G.; Gonzales, G.; Wilke, H.-G.; Lüschen, E.; Martinez, E.; RöSsling, R.; Ricaldi, E.; Rietbrock, A.

    2003-07-01

    A 400-km-long seismic reflection profile (Andean Continental Research Project 1996 (ANCORP'96)) and integrated geophysical experiments (wide-angle seismology, passive seismology, gravity, and magnetotelluric depth sounding) across the central Andes (21°S) observed subduction of the Nazca plate under the South American continent. An east dipping reflector (Nazca Reflector) is linked to the down going oceanic crust and shows increasing downdip intensity before gradual breakdown below 80 km. We interpret parts of the Nazca Reflector as a fluid trap located at the front of recent hydration and shearing of the mantle, the fluids being supplied by dehydration of the oceanic plate. Patches of bright (Quebrada Blanca Bright Spot) to more diffuse reflectivity underlie the plateau domain at 15-30 km depth. This reflectivity is associated with a low-velocity zone, P to S wave conversions, the upper limits of high conductivity and high Vp/Vs ratios, and to the occurrence of Neogene volcanic rocks at surface. We interpret this feature as evidence of widespread partial melting of the plateau crust causing decoupling of the upper and lower crust during Neogene shortening and plateau growth. The imaging properties of the continental Moho beneath the Andes indicate a broad transitional character of the crust-mantle boundary owing to active processes like hydration of mantle rocks (in the cooler parts of the plate margin system), magmatic underplating and intraplating under and into the lowermost crust, mechanical instability at Moho, etc. Hence all first-order features appear to be related to fluid-assisted processes in a subduction setting.

  8. NON-INVASIVE DETERMINATION OF THE LOCATION AND DISTRIBUTION OF FREE-PHASE DENSE NONAQUEOUS PHASE LIQUIDS (DNAPL) BY SEISMIC REFLECTION TECHNIQUES

    International Nuclear Information System (INIS)

    The Earth Sciences and Resources Institute, University of South Carolina is conducting a 14 month proof of concept study to determine the location and distribution of subsurface Dense Nonaqueous Phase Liquid (DNAPL) carbon tetrachloride (CCl4) contamination at the 216-Z-9 crib, 200 West area, Department of Energy (DOE) Hanford Site, Washington by use of two-dimensional high resolution seismic reflection surveys and borehole geophysical data. The study makes use of recent advances in seismic reflection amplitude versus offset (AVO) technology to directly detect the presence of subsurface DNAPL. The techniques proposed are a noninvasive means towards site characterization and direct free-phase DNAPL detection. This report covers the results of Task 3 and change of scope of Tasks 4-6. Task 1 contains site evaluation and seismic modeling studies. The site evaluation consists of identifying and collecting preexisting geological and geophysical information regarding subsurface structure and the presence and quantity of DNAPL. The seismic modeling studies were undertaken to determine the likelihood that an AVO response exists and its probable manifestation. Task 2 is the design and acquisition of 2-D seismic reflection data designed to image areas of probable high concentration of DNAPL. Task 3 is the processing and interpretation of the 2-D data. Task 4, 5, and 6 were designing, acquiring, processing, and interpretation of a three dimensional seismic survey (3D) at the Z-9 crib area at 200 west area, Hanford

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

    Science.gov (United States)

    Dutta, P. K.; Mishra, O. P.

    2012-04-01

    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 mitigation programs.

  17. 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.

  18. Seismic Fault Preserving Diffusion

    CERN Document Server

    Lavialle, Olivier; Germain, Christian; Donias, Marc; Guillon, Sebastien; Keskes, Naamen; Berthoumieu, Yannick

    2007-01-01

    This paper focuses on the denoising and enhancing of 3-D reflection seismic data. We propose a pre-processing step based on a non linear diffusion filtering leading to a better detection of seismic faults. The non linear diffusion approaches are based on the definition of a partial differential equation that allows us to simplify the images without blurring relevant details or discontinuities. Computing the structure tensor which provides information on the local orientation of the geological layers, we propose to drive the diffusion along these layers using a new approach called SFPD (Seismic Fault Preserving Diffusion). In SFPD, the eigenvalues of the tensor are fixed according to a confidence measure that takes into account the regularity of the local seismic structure. Results on both synthesized and real 3-D blocks show the efficiency of the proposed approach.

  19. 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

  20. 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.

  1. Which boreholes do we need to resolve the Common Era in borehole paleoclimatology?

    Science.gov (United States)

    Rath, V.; Smerdon, J. E.; González-Rouco, J. F.; Beltrami, H.

    2012-04-01

    The global database of borehole temperature profiles used to estimate paleoclimatic ground surface temperature histories (GSTHs) has typically focused on the last 500 years. his is mainly due to the fact that the borehole database is dominated by shallow boreholes (~200-300 m). Nevertheless, it has been shown that these boreholes may be too shallow for proper separation of the downwelling climatic transient and the long-term background steady-state signal associated with heat loss from the earth's interior. The mere inclusion of deeper boreholes, however, does not necessarily mitigate the problem. Borehole temperature profiles of any depth show the signatures of earlier climatic changes, including the strong warming following the last glacial maximum (LGM). In shallow boreholes this effect is very similar to a linear trend, usually cannot be discriminated from a steady-state geotherm, and is unlikely to strongly impact estimates of GSTHs spanning common-era timescales. In deeper boreholes, however, the signature of the LGM cannot be approximated linearly, and biases associated with the LGM may impact GSTH reconstructions during the Common Era. The combined incentive to employ deep boreholes for reliable estimation of the background steady-state signal, while limiting the LGM impacts on reconstructions of Common-Era GSTHs thus leads to an multi-objective optimization problem seeking a trade-off between the impacts of the two effects. Such an optimization of the borehole maximum depth criterion is investigated in this study using numerical models. A Monte Carlo ensemble approach is used to quantify the impact of various reconstruction decisions as temperature histories, error characteristics, thermophysical properties, and maximum borehole depths. The findings have implications for interpretations of current global reconstruction products and future efforts to analyze the global borehole database for Common-Era GSTH reconstructions. (http://palma.fis.ucm.es/~volker/)

  2. Three-dimensional seismic reflection images of axial melt lens and seismic layer 2A between 9°42'N and 9°57'N on the East Pacific Rise

    Science.gov (United States)

    Carton, H. D.; Carbotte, S. M.; Mutter, J. C.; Canales, J.; Nedimovic, M. R.; Aghaei, O.; Marjanovic, M.; Newman, K. R.

    2010-12-01

    We present results from 3D time-domain processing of the dual-source, four-streamer seismic dataset acquired in 2008 by R/V Langseth at the 9°50’N Integrated Study Site (ISS) on the East Pacific Rise. The survey was designed with a main goal to determine the fine-scale geometry of the magmatic system across three fourth-order ridge axis discontinuities (at 9°45.2’N, 9°48.7’N, and 9°51.5’N), and to study relationships with the hydrothermal system and eruptive/intrusive processes, in particular related to the 2005-06 eruption. Seismic processing included flexible binning to regularize the fold coverage, CMP stacking within 6.25m x 37.5m bins using velocity functions derived from constant-velocity stack analyses, post-stack interpolation to 6.25m x 18.75m bin size, and 3D post-stack time migration, resulting in a fully migrated area of 18km across-axis by 27km along-axis. The axial melt lens is ~500-600m wide at 9°50’N beneath the northern vent cluster, and up to 1km wide beneath the southern vent cluster. The fourth-order segment boundaries, as defined from seafloor morphology and structure of the axial summit trough (AST), coincide with geometrically complex regions of the magmatic system, with cross-axis views showing two separate magma bodies distant by up to a few hundreds of meters. Discontinuities in the axial magma lens thus appear like mini-overlap basins encircled by north and south lens segments, which may trend at a slightly oblique angle to the average ridge axis direction. A deeper magma body, likely also part of the axial system, is imaged near 9°51’N at ~125m from the western edge of the axial melt lens, while near 9°47.5’N a bright near-axis magma body is imaged at ~1360m from the eastern edge of the axial melt lens, at a shorter travel time below seafloor. Seismic layer 2A is imaged both as a basal reflection-refraction event, spatially continuous but variable in brightness, and through shallow layering (reflections at ~30ms i

  3. Crosshole investigations - results from borehole radar investigations

    International Nuclear Information System (INIS)

    A new borehole radar system has been designed, built and tested. The system consists of borehole transmitter and receiver probes, a signal control unit for communication with the borehole probes, and a computer unit for storage and display of data. The system can be used both in singlehole and crosshole modes and probing ranges of 115 m and 300 m, respectively, have been obtained at Stripa. The borehole radar is a short pulse system which uses center frequencies in the range 20 to 60 MHz. Single hole reflection measurements have been used to identify fracture zones and to determine their position and orientation. The travel time and amplitude of the first arrival measured in a crosshole experiment can be used as input data in a tomographic analysis. (orig./DG)

  4. 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.)

  5. Working programme for MIU-4 borehole investigations

    International Nuclear Information System (INIS)

    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 140,000m2) 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. 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)

  7. 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

  8. 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

  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. Near surface characterisation of a limestone site using borehole and surface geophysics.

    Science.gov (United States)

    Sénéchal, G.; Hollender, F.; Rousset, D.

    2003-04-01

    The paper deals with the analysis of the respective performances and the optimization of geophysical methods used for the non-destructive imagery of rocks, from the surface to a depth of approximately 100 m. Different techniques, carried out from the surface or from boreholes, have been tested on the \\char`&{uml;}Médecin Hill\\char`&{uml;} (Centre d'Etude de Cadarache - 13108 St. Paul lez Durance - France). This test site consists in a low fractured limestone, crossed by several faults characterized by a near-vertical dip. The site was previously investigated by numerous other characterization methods (boreholes, surface geology, structural analysis, well logging, etc.): a well known structural 3D model is available. Each tested geophysical method is based on the determination of different physical parameters (elastic parameters, density, electrical resistivity, dielectric permittivity, etc.). In terms of resolution and depth of investigation, every geophysical method has its own drawbacks and advantages. High resolution seismic focuses between 20 and some hundred of meters of depth with a metric to decametric vertical resolution. GPR has a decimetric resolution but electromagnetic waves are strongly attenuated after a few meters of propagation. DC resistivity is a potential method so, resolution dramatically decreases with depth of investigation. The acquisition pattern of this last study leads to a depth of investigation around 15 m and a resolution of one to several meters. Several surface acquisitions have been performed within a 400 m line along which seven boreholes are located. From the high resolution reflection seismic data, we calculated a depth migrated section which displays the main interfaces affected by some near vertical faults. These results are compared to seismic data obtained from a borehole survey interpreted with the help of log data. A radar borehole survey, using tomographic and reflection pattern surveys provided improved information but

  12. 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

  13. 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.

  14. Borehole stability in densely welded tuffs

    Energy Technology Data Exchange (ETDEWEB)

    Fuenkajorn, K.; Daemen, J.J.K. [Arizona Univ., Tucson, AZ (United States). Dept. of Mining and Geological Engineering

    1992-07-01

    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.

  15. 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

  16. Geophysical siting of boreholes in crystalline basement areas of Africa

    Science.gov (United States)

    Olayinka, A. I.

    1992-02-01

    This paper assesses the effectiveness of surface geophysical methods namely electrical resistivity, electromagnetic, seismic refraction, magnetic, gravity and induced polarization for groundwater exploration in crystalline basement complex areas. Most of these geophysical techniques can provide quantitative information on the characteristics of the weathered zone which relate to the occurrence of an economic aquifer. The critical factors in the choice of a particular method include the local geological setting, the initial and maintenance costs of the equipment, the speed of surveying, the manpower required as field crew, the degree of sophistication entailed in data processing to enable a geologically meaningful interpretation, and anomaly resolution. The particular advantages and limitations of each technique are highlighted. Several case histories from Nigeria and the rest of Africa indicate that electrical resistivity (both vertical sounding and horizontal profiling) is the most widely used, followed by electromagnetic traversing. These are often employed in combination to improve upon the percentage of successful boreholes. Due to the high cost of equipment, large scale of the field operations and difficulties in data interpretation, seismic refraction is not widely adopted in commercial-type surveys. Similarly, magnetic, gravity and induced polarization are used only sparingly.

  17. Borehole strainmeter measurements spanning the 2014 Mw6.0 South Napa Earthquake, California: The effect from instrument calibration

    Science.gov (United States)

    Langbein, John

    2015-10-01

    The 24 August 2014 Mw6.0 South Napa, California earthquake produced significant offsets on 12 borehole strainmeters in the San Francisco Bay area. These strainmeters are located between 24 and 80 km from the source, and the observed offsets ranged up to 400 parts per billion (ppb), which exceeds their nominal precision by a factor of 100. However, the observed offsets of tidally calibrated strains differ by up to 130 ppb from predictions based on a moment tensor derived from seismic data. The large misfit can be attributed to a combination of poor instrument calibration and better modeling of the strain field from the earthquake. Borehole strainmeters require in situ calibration, which historically has been accomplished by comparing their measurements of Earth tides with the strain tides predicted by a model. Although the borehole strainmeter accurately measures the deformation within the borehole, the long-wavelength strain signals from tides or other tectonic processes recorded in the borehole are modified by the presence of the borehole and the elastic properties of the grout and the instrument. Previous analyses of surface-mounted, strainmeter data and their relationship with the predicted tides suggest that tidal models could be in error by 30%. The poor fit of the borehole strainmeter data from this earthquake can be improved by simultaneously varying the components of the model tides up to 30% and making small adjustments to the point source model of the earthquake, which reduces the RMS misfit from 130 ppb to 18 ppb. This suggests that relying on tidal models to calibrate borehole strainmeters significantly reduces their accuracy.

  18. 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

  19. 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.

  20. 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

  1. 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...

  2. 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

  3. Seismic detection of meteorite impacts on Mars

    OpenAIRE

    Teanby, N. A.; Wookey, J.

    2011-01-01

    Abstract Meteorite impacts provide a potentially important seismic source for probing Mars? interior. It has recently been shown that new craters can be detected from orbit using high resolution imaging, which means the location of any impact-related seismic event could be accurately determined thus improving the constraints that could be placed on internal structure using a single seismic station. This is not true of other seismic sources on Mars such as sub-surface faulting, whic...

  4. 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

  5. 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

  6. Subsurface fracture surveys using a borehole television camera and an acoustic televiewer

    International Nuclear Information System (INIS)

    Borehole television survey and acoustic televiewer logging provide rapid, cost-effective, and accurate methods of surveying fractures and their characteristics within boreholes varying in diameter from 7.6 to 15.3 cm. In the television survey, a camera probe is used to inspect the borehole walls. Measurements of location, orientation, infilling width, and aperture of fractures are made on the television screen and recorded on computer data record sheets. All observations are recorded on video cassette tapes. With the acoustic televiewer, oriented images of fractures in the borehole walls are recorded on a strip-chart log and also on video cassette tapes. The images are displayed as if the walls were split vertically along magnetic north and spread out horizontally. Measurements of fracture characteristics are made on the strip-chart log, using a digitizing table and a microcomputer, and the data recorded on floppy diskettes. In both surveys, an inclined fracture is displayed as a sinusoidal curve, from which the apparent orientation of the fracture can be measured. Once the borehole orientation is known, the true orientation of the fracture can be computed from its apparent orientation. Computer analysis of the fracture data, provides a rapid assessment of fracture occurrence, fracture aperture, and statisically significant concentrations of fracture orientations

  7. 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.

  8. 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

  9. Extracting near-borehole P and S reflections from array sonic logging data

    International Nuclear Information System (INIS)

    There has been widespread interest in acoustic reflection logging recently due to its higher resolution compared to seismic exploration and larger lateral extension compared to logging techniques. Acoustic reflection logging is particularly useful for delineating near-borehole subtle structures and fractured reservoirs. The primary data processing of acoustic reflection logging is to extract the reflection signals from the full waveform records which are overwhelmingly dominated by the borehole direct modes. We present in this paper a method combining a frequency–wavenumber (f–k) filter with a modified parametric prediction to separate the direct and reflection waves. Afterwards, we apply dip stacking to enhance and to further separate P–P and S–S reflection signals, and suppress the residual direct waves and other noises. Processing examples obtained with synthetic and real data show the capabilities of the proposed workflow and algorithms

  10. Phase 1 report: the 4D seismic market from 2000 to 2003

    International Nuclear Information System (INIS)

    This report synthesizes the phase 1 results of the joint industrial project, called ''4D Seismic: Technologies, Economics and Issues''. This project was conducted by IFP between November 2003 and April 2004, in collaboration with Compagnie Generale de Geophysique (CGG) and sponsored by Gaz de France and 4. Wave Imaging. Phase 1 offers an objective view of the 4D seismic market over the period 2000-2003. The market has been assessed from IFP extensive databases, gathering 115 4D projects conducted worldwide and from interviews of seven oil companies, both representing 90% of the activity in time-lapse seismic. This study provides sales estimation and sales/projects breakdown by: in-house/subcontracted activity, geography, onshore/offshore, reservoir rocks and recovery methods, technology/methodology, oil companies and service companies. The market of 4D seismic has been split into 4 segments: acquisition, processing, reservoir studies - feasibility, interpretation and seismic history matching -, borehole seismic (acquisition and processing). In addition, the market of passive seismic monitoring, another technique of seismic reservoir monitoring has also been estimated. The main sources, used to build the IFP databases, were: Worldwide Global E and P Service Reports from IHS Energy, World Geophysical News, an extensive bibliographic study through more than 200 articles, abstracts and summaries, a collaboration with CGG. For all market estimations, numbers computed from IFP databases and from interviews of oil companies were extrapolated from 90% to 100%, to quantify the total 4D activity. The estimations obtained were not rounded in order to preserve trends with a consistent computation from one year to another and from one market segment to another, despite uncertainties of about 10%. Quality controls were performed to validate the final estimations: volumes of 4D seismic data, computed from IFP databases, were checked by comparing processed data with acquired data

  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. Nuclear borehole logging techniques for coal quality

    International Nuclear Information System (INIS)

    The progress achieved by nuclear logging in the coal industry has been significant. The 'in-situ' information about coal seams provided by borehole logging can significantly reduce exploration and development costs. Nuclear borehole logging is used routinely in the exploration for coal and is getting more acceptance in the mining stage for quality control. Nuclear borehole logging is used to delineate the coal strata and to determine their thickness, depth, ash content, calorific value and Fe and Si content of ash. Two techniques have been developed in the last 7 years for coal logging in boreholes: (i) The spectrometric gamma-gamma for the determination of ash content in coal; and (ii) the prompt neutron-gamma method for the determination of ash, calorific value, Si and Fe in coal. In this paper both gamma-gamma and neutron-gamma techniques were developed for delineating the coal seams and predicting the ash content in coal. The neutron-gamma technique is superior because it can also determine the Si and Fe content of coal and it can sample a larger volume of coal. The neutron-gamma technique is less affected by the rugosity and condition of the borehole. (author). 6 refs, 5 figs, 2 tabs

  13. Seismic imaging of a convergent continental margin and plateau in the central Andes (Andean Continental Research Project 1996 (ANCORP'96))

    OpenAIRE

    Onno Oncken; Stephan V. Sobolev; Manfred Stiller; Günter Asch; Christian Haberland; James Mechie; Xiaohui Yuan; E. Lüchen; P. Giese; P. Wigger; Stefan Lüth; E. Scheuber; H.-J. Götze; H. Brasse; S. Buske

    2003-01-01

    A 400-km-long seismic reflection profile (Andean Continental Research Project 1996 (ANCORP'96)) and integrated geophysical experiments (wide-angle seismology, passive seismology, gravity, and magnetotelluric depth sounding) across the central Andes (21°S) observed subduction of the Nazca plate under the South American continent. An east dipping reflector (Nazca Reflector) is linked to the down going oceanic crust and shows increasing downdip intensity before gradual breakdown below 80 km. We ...

  14. Observation of the Existing Boreholes, Analysis of the Produced Data, and Modelling of the Long-term Variation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sung Oong; Kim, J. Y.; Sung, I. H.; Shin, H. S.; Cho, B. O.; Syhn, J. H.; Park, C.; Hyun, H. J. [Korea Institute of Geology, Mining and Materials, Taejon (Korea, Republic of)

    1997-11-01

    Long-term observations on the ground water, classification on the rock mass via seismic tomography, and in-situ measurements by the hydraulic fracturing technique were performed to construct KAERI research tunnel for high-level radioactive waste disposal. Water level was checked for 7 boreholes and the quality of the ground water was analyzed for 4 boreholes. Statistical analysis on the discontinuity and the results of the water pressure test were reevaluated through the results of the borehole televiewer prospecting. And with the seismic tomographic prospectings on the BH3-BH5 section and the BH5-BH6 section, the condition of the rock amss was classified very clearly. Furthermore the in-situ stress was measured for BH3 and BH5 boreholes by hydraulic fracturing techniques, and these results were compared to the other data obtained by overcoring method. Also the lugeon test was performed, even through it is some apparent, on the natural crack with the hydraulic fracturing system, and we could obtain the permeability for that joint. 46 refs., 10 tabs., 64figs. (author)

  15. 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.

  16. Migration of seismic data

    International Nuclear Information System (INIS)

    Prospecting for oil and gas resources poses the problem of determining the geological structure of the earth's crust from indirect measurements. Seismic migration is an acoustic image reconstruction technique based on the inversion of the scalar wave equation. Extensive computation is necessary before reliable information can be extracted form large sets of recorded data. In this paper a collection of open-quotes industrialclose quotes migration techniques, each giving rise to a data parallel algorithm, is outlined. Computer simulations on synthetic seismic data illustrate the problem and the approach

  17. Seismic Imaging across the Moroccan Atlas (SIMA): An effort to constrain the crustal thickness of the Atlas Mountains

    Science.gov (United States)

    Carbonell, R.; Ayarza, P.; Harnafi, M.; Teixell, A.; Kchikah, A.; Martí, D.; Palomeras, I.; Levander, A.; Gallart, J.; Arboleya, M.; Charroud, M.; Amrhar, M.

    2011-12-01

    The Atlas Mountains are a young intra-continental Cenozoic orogenic belt located at the southern edge of the diffuse plate boundary zone separating Africa and Europe. The Atlas features a high topography that locally exceeds 4000 m. However, geological and preliminary geophysical studies suggest that it has experienced less than 25% of shortening and moderate crustal thickening. These observations rise the question of the origin of the Atlas high elevation. Potential field geophysical studies and previous low-resolution refraction experiments report a maximum crustal thickness of ~40 km, suggesting that the range is out of isostatic equilibrium at a crustal level and that an asthenospheric upwelling is needed to support the mountain load. These models, however, lack the constraints that would provide the knowledge of the precise Moho depth. In order to fulfill this requirement and to constrain the seismic velocity structure of this mountain system, a 700 km long, seismic wide-angle reflection and refraction transect has been recently acquired by an international team. The north-south transect extends from the Sahara Desert south of Merzouga, to Ceuta at the Gibraltar arc, crossing the High and Middle Atlas and the Rif mountains. Seismic energy released at 6 shot points generated by the detonation of 1 TN of explosives was recorded by ~ 900 Reftek-125a seismic recorders from the IRIS-PASSCAL pool. Seismic stations were deployed with an average spacing of 650-750 m. The 6 shot points were located within the southern part of the transect with a shot spacing of ~60-70 km. Preliminary analysis of data shows an uneven distribution of the energy, providing a poor signal/ratio relation at longest offsets, thus hindering the identification of the deepest phases. However, crustal phases (Pg and PiP) and mantle reflected/refracted phases (PmP and Pn) are present in most of the shot gathers. Preliminary modelling of these phases leads to an estimation of the changes in the

  18. VTT test borehole for bedrock investigations

    International Nuclear Information System (INIS)

    A borehole of depth 150 m and diameter 56 mm has been drilled in the area adjacent to the premises of the Technical Research Centre of Finland (VTT) at Otaniemi, Espoo, for the purposes of calibrating geophysical measurements devices. This report presents the test results obtained so far and illustrates the processing of these, in which the various measurements are plotted as curves and combinations of curves. The interpretations provided so far consists of analyses of lithological variations, bedrock fracturing, the nature and occurrence of fracture zones and groundwater flow patterns. Samples were taken from those parts of the core shown by the borehole measurements to be homogenous and thin sections made from these for mineralogical determinations. The rock mechanical and petrophysical properties of the same points were examined. The core is in the possession of VTT, and the hole itself is available to outsiders for the calibration and testing of borehole measurement equipment. (orig.). (21 refs., 13 figs., 5 tabs.)

  19. Excess plutonium disposition: The deep borehole option

    International Nuclear Information System (INIS)

    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

  20. 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.

  1. VTT test borehole for bedrock investigations

    Science.gov (United States)

    Okko, Olli; Hassinen, Pertti; Front, Kai

    1994-02-01

    A borehole of depth 150 m and diameter 56 mm has been drilled in the area adjacent to the premises of the Technical Research Center of Finland (VTT) at Otaniemi, Espoo, for the purposes of calibrating geophysical measurement devices. The report presents the test results obtained so far and illustrates the processing of these, in which the various measurements are plotted as curves and combinations of curves. The interpretations provided so far consist of analyses of lithological variations, bedrock fracturing, the nature and occurrence of fracture zones and groundwater flow patterns. Samples were taken from those parts of the core shown by the borehole measurements to be homogeneous and thin sections made from these for mineralogical determinations. The rock mechanical and petrophysical properties of the same points were examined. The core is in the possession of VTT, and the hole itself is available to outsiders for the calibration and testing of borehole measurement equipment.

  2. 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.

  3. 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.

  4. 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

  5. Borehole radar and BIPS investigations in boreholes at the Boda area

    International Nuclear Information System (INIS)

    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

  6. Borehole sealing: conceptual design and feasibility study

    International Nuclear Information System (INIS)

    In this report criteria for sealing boreholes are first considered and the requirements for sealing materials are then specified. For the conceptual design use is made of a multiple-zone borehole plug consisting of key zones and intermediate zones in between. The key zones are located in competent, low-fissured rock and act as efficient barriers to prevent a drain effect by the borehole. Highly compacted bentonite in the form of cylinders with a diameter slightly smaller than that of the borehole and also in the form of spheres or pellets is used as plug material in the key zones, while cement is employed for the intermediate zones. A literature review has revealed that in past experiments mostly cement and bentonite were used as plug materials. The corresponding results showed that both materials are potentially successful candidates. For plug emplacement, it is proposed to employ either a specially designed emplacement tool or a perforated pipe. The latter method is easier to use but the pipe has to remain in the borehole. It is recommended to have a dry density of the bentonite after swelling of not less than 1.3 Mg/m3. This implies limiting values for the space between the bentonite cylinder and the borehole wall. By means of a bentonite slurry filled into the borehole at the key zone, the allowable ring space can be slightly enlarged. For the use of bentonite in the form of spheres or pellets experimental data are scarce and emplacement procedures are not sufficiently developed to guarantee the required minimum final dry density. In order to check the quality of the plug, an indirect procedure is recommended. For sealing boreholes penetrating into the repository zone, direct quality control is then limited to checking whether the procedure is adhered to as specified and to recording the quantities of materials emplaced. It is shown that the proposed plug design represents an efficient flow barrier and that it can satisfy the specified requirements. (author) 13

  7. Application of integrated magnetic resonance sounding and resistivity methods for borehole implementation. A case study in Cambodia

    Science.gov (United States)

    Vouillamoz, Jean-Michel; Descloitres, Marc; Bernard, Jean; Fourcassier, Pierre; Romagny, Laurent

    2002-05-01

    A geophysical survey was conducted in Cambodia to measure the contribution of geophysics to a running drilling programme. The geology of the area (the province of Siem Reap) mainly consists of recent heterogeneous sediments of sand, silt and clay. The thickness of this formation ranges from 20 to 100 m and lies on Jurassic to Tertiary rocks. Surveys were done with direct current methods [one-dimensional vertical electrical sounding (1D VES), and two-dimensional (2D) electrical imaging], time domain electromagnetic (TDEM) sounding and proton magnetic resonance sounding (MRS). To validate the geophysical results, boreholes were drilled and tested with electrical logs and pumping tests. We found that: (1) The resistivity methods (VES, 2D electrical imaging and TDEM) are very sensitive to the groundwater electrical conductivity which is highly heterogeneous within the province. A preliminary relationship between measured groundwater conductivity and aquifer resistivity is proposed. (2) The MRS gives accurate information on groundwater occurrence for the 5- to 60-m-deep layers. A preliminary relationship between MRS data (aquifer transmissivity estimated from MRS field measurements) and hydrodynamic parameters (aquifer local transmissivity and borehole relative specific capacity estimated from borehole pumping tests) is proposed. (3) The resistivity methods and MRS are complementary, and a joint use is recommended. (4) At the survey scale, the borehole success rate was improved from 56% to 90% by the use of geophysics. Crossing the technical and cost analyses, we propose a geophysical methodology to implement boreholes in the province of Siem Reap. This methodology could both increase the borehole success rate and save money at the programme scale. It consists of the use of: MRS, TDEM and electrical methods jointly where the borehole success rate is less than 30%. MRS and TDEM jointly where the borehole success rate ranges from 30% to 50%. Electrical methods (VES and 2D

  8. New observations of the magmatic segmentation of the East Pacific Rise from Siquieros to Clipperton from a multi-streamer seismic reflection imaging study

    Science.gov (United States)

    Carbotte, S. M.; Mutter, J. C.; Canales, J. P.; Nedimovic, M. R.; Carton, H.; Xu, M.; Newman, K.; Marjanovic, M.; Aghaei, O.; Stowe, L.

    2008-12-01

    In summer 2008, we collected the first multi-streamer 3D seismic reflection dataset of the new national seismic imaging facility, the R/V Marcus G. Langseth, during cruise MGL0812. Our survey included a primary 3D grid extending from 9°57 to 9°42 centered on the EPR ISS "bulls eye" site at 9°50' and 3 parallel along axis lines extending from ~10°05' N to 9°40N. The central along-axis line was extended to encompass the entire length of the ridge from Clipperton to Siquieros fracture zones to facilitate regional studies of magmatic segmentation along the full length of this first order ridge segment. Multibeam bathymetry data were collected simultaneously with the seismic data using the 1°x1° beam EM120 available on the Langseth providing high quality bathymetry extending 30-40 km to either side of the axis north of 8°50'N. In this presentation we present preliminary results focused on axial segmentation from Siquieros to Clipperton. The data reveal fine-scale segmentation of the axial magma lens coincident with the volcanic segmentation of the ridge axis evident in the seafloor morphology. Each volcanic segment is associated with a discrete melt lens, ~5-10 km long, and, in several cases, defined by diffractions from the lens edges. Adjacent lenses differ in reflection strength, depth, and dip. At the discontinuities, lenses are offset from one another and overlap forming shingled lenses in along-axis view and multiple lenses in cross-axis view. These magma lens discontinuities correspond with offsets in the axial summit trough and changes in the volcanic morphology of the axial high, and point to a similar lifespan for these structures. The segmentation of the axial magma body observed in our new data is also apparent in early seismic reflection data collected with the R/V Conrad over 20 years ago, indicating persistent segmentation through the two volcanic eruptions that have occurred in this region since this time.

  9. Optical seismic sensor systems and methods

    Science.gov (United States)

    Beal, A. Craig; Cummings, Malcolm E.; Zavriyev, Anton; Christensen, Caleb A.; Lee, Keun

    2015-12-08

    Disclosed is an optical seismic sensor system for measuring seismic events in a geological formation, including a surface unit for generating and processing an optical signal, and a sensor device optically connected to the surface unit for receiving the optical signal over an optical conduit. The sensor device includes at least one sensor head for sensing a seismic disturbance from at least one direction during a deployment of the sensor device within a borehole of the geological formation. The sensor head includes a frame and a reference mass attached to the frame via at least one flexure, such that movement of the reference mass relative to the frame is constrained to a single predetermined path.

  10. Constrains on the topography of the Moroccan High Atlas: Contribution of the SIMA (Seismic Imaging across the Moroccan Atlas) project

    Science.gov (United States)

    Ayarza, P.; Carbonell, R.; Teixell, A.; Kchikach, A.; Harnafi, M.; Marti, D.; Palomeras, I.; Levander, A.; Gallart, J.; Arboleya, M. L.; Charroud, M.; Amrahr, M.

    2012-04-01

    The Atlas Mountain Range is a young intra-continental Cenozoic orogenic belt located at the southern edge of the diffuse plate boundary zone separating Africa and Europe. The Moroccan High Atlas, part of this range, features high topographies that locally exceed 4000 m. However, geological studies suggest that it has experienced low to moderate shortening. Furthermore, shortenning and elevation keep an inverse relationship: while shortening decreases to the west, elevation increases in the same direction. Geophysical studies support these interpretations with potential field models where crustal thickness never exceeds 40 km. These observations rise the question about the origin of the Atlas Mountains topography. If topography does not respond to isostatic equilibrium at a crustal level, then the mantle must be involved in this process. Potential field based multidisciplinary models suggest that an astenospheric upwelling place the mantle as shallow as 70 km and that it is this feature that helps to support the mountain load. The only uncertainty related to these models lies in the assumed crustal thickness: if it increased, the LAB would be displaced downwards and conversely. In order to picture the Moho topography and depth, and to constrain the seismic velocity structure of this mountain system, a 700 km long, seismic wide-angle reflection and refraction transect was acquired in 2010 by an international team. The north-south transect extends from the Sahara Desert south of Merzouga, to Ceuta at the Gibraltar arc, crossing the High and Middle Atlas and the Rif mountains. Seismic energy released at 6 shot points was generated by the detonation of 1 TN of explosives and was recorded by ~ 900 Reftek-125a seismic recorders from the IRIS-PASSCAL pool. Even with a low signal/noise ratio, the data allows the identification of crustal phases (Pg and PiP) and mantle reflected/refracted phases (PmP and Pn). Forward modeling pictures the Moho as an asymmetric feature that

  11. Joint seismic, hydrogeological, and geomechanical investigations of a fracture zone in the Grimsel Rock Laboratory, Switzerland

    International Nuclear Information System (INIS)

    This report is one of a series documenting the results of the Nagra-DOE Cooperative (NDC-I) research program in which the cooperating scientists explore the geological, geophysical, hydrological, geochemical, and structural effects anticipated from the use of a rock mass as a geologic repository for nuclear waste. From 1987 to 1989 the United States Department of Energy (DOE) and the Swiss Cooperative for the Storage of Nuclear Waste (Nagra) participated in an agreement to carryout experiments for understanding the effect of fractures in the storage and disposal of nuclear waste. As part of this joint work field and laboratory experiments were conducted at a controlled site in the Nagra underground Grimsel test site in Switzerland. The primary goal of these experiments in this fractured granite was to determine the fundamental nature of the propagation of seismic waves in fractured media, and to relate the seismological parameters to the hydrological parameters. The work is ultimately aimed at the characterization and monitoring of subsurface sites for the storage of nuclear waste. The seismic experiments utilizes high frequency (1000 to 10,000 Hertz) signals in a cross-hole configuration at scales of several tens of meters. Two-, three-, and four-sided tomographic images of the fractures and geologic structure were produced from over 60,000 raypaths through a 10 by 21 meter region bounded by two nearly horizontal boreholes and two tunnels. Intersecting this region was a dominant fracture zone which was the target of the investigations. In addition to these controlled seismic imaging experiments, laboratory work using core from this region were studied for the relation between fracture content, saturation, and seismic velocity and attenuation. In-situ geomechanical and hydrologic tests were carried out to determine the mechanical stiffness and conductivity of the fractures. 20 refs., 90 figs., 6 tabs

  12. Continuous recording of seismic signals in Alpine permafrost

    Science.gov (United States)

    Hausmann, H.; Krainer, K.; Staudinger, M.; Brückl, E.

    2009-04-01

    three different types of applications. It enabled fast and efficient field work and provided excellent seismic data at two permafrost sites. At Krummgampen Valley (Ötztal Alps, Tyrol) 13 seismic profiles were measured at altitudes ranging from 2400 to 2900 m to assess information on the permafrost occurrences. At the crest of Hoher Sonnblick (3106 m, Hohe Tauern, Salzburg) seismic signals were recorded on 15 borehole geophones deployed in three 20 m deep boreholes for the application of seismic tomography and passive monitoring of rock falls.

  13. Seismic Creep

    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 erupture associated with an earthquake. It is a usually slow deformation...

  14. Borehole radar modeling for reservoir monitoring applications

    NARCIS (Netherlands)

    Miorali, M.; Slob, E.C.; Arts, R.J.

    2010-01-01

    The use of down-hole sensors and remotely controlled valves in wells provide enormous benefits to reservoir management and oil production. We suggest borehole radar measurements as a promising technique capable of monitoring the arrival of undesired fluids in the proximity of production wells. The h

  15. Groundwater flow dynamic investigation without drilling boreholes

    Science.gov (United States)

    Moustafa, Mahmoud

    2015-02-01

    The flow net map is a basic tool for groundwater flow dynamics investigation. In areas where there are no boreholes or piezometers are not available, constructing flow net map may be difficult. This work proposes a simple methodology to construct flow net map without drilling boreholes. The flow net map constructed using the proposed approach represents an expected flow net map, which can draw conceptual flow model of the site. The major benefit from constructing the expected flow net map is it gives guidance for locating new boreholes for site investigation, carrying out investigation of the groundwater flow directions and estimating recharge/discharge from the site boundary. An illustrative example for the proposed approach was presented to show how the data required to construct the expected flow net map can be collected. The constructed, expected flow net map using the proposed methodology was compared with actual flow net map constructed from measured water levels. Both maps give consistent hydrological information about the site. The suggested approach represents a simple and cheap way to carry out investigation of groundwater flow dynamics in areas where there are no boreholes are available.

  16. Exploratory borehole Kaisten. Geology - text volume

    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) 6 tabs., 122 refs

  17. Method for orienting a borehole core

    International Nuclear Information System (INIS)

    A method is described for longitudinally orienting a borehold core with respect to the longitudinal axis of the drill string which drilled said borehold core in such a manner that the original longitudinal attitude of said borehold core within the earth may be determined. At least a portion of said borehold core is partialy demagnetized in steps to thereby at least partially remove in steps the artificial remanent magnetism imparted to said borehole core by said drill string. The artifical remanent magnetism is oriented substantially parallel to the longitudinal axis of said drill string. The direction and intensity of the total magnetism of said borehold core is measured at desired intervals during the partial demagnetizing procedure. An artificial remanent magnetism vector is established which extends from the final measurement of the direction and intensity of the total magnetism of said borehole core taken during said partial demagnetizing procedure towards the initial measurement of the direction and intensity of the total magnetism of said borehold core taken during said partial demagnetizing procedure. The borehold core is oriented in such a manner that said artificial remanent magnetism vector points at least substantially downwardly towards the bottom of said borehold core for a borehold in the northern hemisphere and points at least substantailly upwardly towards the top of said borehole core for a borehole in the southern hemisphere

  18. Hydrological and hydrogeochemical investigations in boreholes

    International Nuclear Information System (INIS)

    Underground investigations in boreholes are presumed to be an important investigation technique for the detailed design of a final repository for nuclear waste. The siting of the repository will be based on surface investigations, but for detailed investigations when the access shafts are sunk, investigations in underground boreholes from the initial shafts and tunnels will be of importance. The hydrogeological investigations in boreholes aimed at testing and developing of hydrogeological techniques and instruments for use in an underground environment in order to reflect actual working and testing conditions. This report is the final report from the hydrogeological investigations in boreholes, and it summarizes the different activities carried out during the course of the program. Most of the included activities are reported in separate internal reports, and therefore only the most important results are included, together with the experiences and conclusions gained during the investigations. The hydrogeochemical part of the program is in a separate final report, consequently no hydrogeochemical information is in the current report. (Author)

  19. Borehole data and climate reconstruction in Korea

    Czech Academy of Sciences Publication Activity Database

    Okubo, Y.; Kim, H.CH.; Uchida, Y.; Šafanda, Jan

    Matsuyama, 2003 - (Yamano, M.; Nagao, T.; Sweda, T.), s. 126-135 [ Geothermal /dendrochronological paleoclimate reconstruction across eastern margin of Eurasia. Matsuyama (JP), 28.11.2002-30.11.2002] Institutional research plan: CEZ:AV0Z3012916 Keywords : borehole data * climate change * Korea Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  20. Deep seismic reflection images of the Wharton Basin oceanic crust and uppermost mantle offshore Northern Sumatra: Relation with active and past deformation

    Science.gov (United States)

    Carton, Hélène; Singh, Satish C.; Hananto, Nugroho D.; Martin, James; Djajadihardja, Yusuf S.; Udrekh; Franke, Dieter; Gaedicke, Christoph

    2014-01-01

    present deep seismic reflection images along two profiles collected in 2006 in the Wharton Basin offshore Northern Sumatra. The main profile is located subparallel to the Sumatran trench at a distance of 32-66 km. Faulting of the entire sedimentary section (strike-slip deformation sometimes accompanied by a dip-slip component) is imaged over two fracture zones of the extinct Wharton Spreading Center that prior studies have shown to be reactivated as left-lateral faults. The western fracture zone is associated with a wide region of strong basement topog