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Sample records for sandstone reservoirs characteristics

  1. Characteristics of Chang 21 Low Permeability Sandstone Reservoir in Shunning Oil Field

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-min; YU Liu-ying

    2006-01-01

    Characteristics of Chang 21 low permeability sandstone reservoir of Shunning oil field are analyzed and evaluated based on the data of well logging and experiment. The result shows that 1) the Chang 21 low permeability reservoir belongs to the classification of middle-to-fine sized feldspar sandstone, with its components being low in maturity, deposited in distributary rivers in the front of the delta; 2) the reservoir is obviously dominated by a low or a very low permeability with a linear variation tendency different from that of the ultra-low permeability reservoir; 3) the spatial variation in lithology and physical properties of the reservoir are controlled by the sedimentary facies zones, and 4)the physical property of the reservoir is significantly influenced by clastic constituents and their structure, and the constituent of cement materials and their content. The result also shows that the diagenesis action of the reservoir is quite strong in which dissolution greatly modified the reservoir In addition, the inter-granular dissolved pores are the mainly developed ones and the micro-structure is dominated by the combination of middle-to-large sized pores with fine-to-coarse throats. Finally, the radius of the throats is in good exponential correlation with permeability and the seepage capacity comes from those large sized throats.

  2. Sedimentological reservoir characteristics of the Paleocene fluvial/lacustrine Yabus Sandstone, Melut Basin, Sudan

    Science.gov (United States)

    Mahgoub, M. I.; Padmanabhan, E.; Abdullatif, O. M.

    2016-11-01

    Melut Basin in Sudan is regionally linked to the Mesozoic-Cenozoic Central and Western African Rift System (CWARS). The Paleocene Yabus Formation is the main oil producing reservoir in the basin. It is dominated by channel sandstone and shales deposited in fluvial/lacustrine environment during the third phase of rifting in the basin. Different scales of sedimentological heterogeneities influenced reservoir quality and architecture. The cores and well logs analyses revealed seven lithofacies representing fluvial, deltaic and lacustrine depositional environments. The sandstone is medium to coarse-grained, poorly to moderately-sorted and sub-angular to sub-rounded, arkosic-subarkosic to sublitharenite. On the basin scale, the Yabus Formation showed variation in sandstone bodies, thickness, geometry and architecture. On macro-scale, reservoir quality varies vertically and laterally within Yabus Sandstone where it shows progressive fining upward tendencies with different degrees of connectivity. The lower part of the reservoir showed well-connected and amalgamated sandstone bodies, the middle to the upper parts, however, have moderate to low sandstone bodies' connectivity and amalgamation. On micro-scale, sandstone reservoir quality is directly affected by textures and diagenetic changes such as compaction, cementation, alteration, dissolution and kaolinite clays pore fill and coat all have significantly reduced the reservoir porosity and permeability. The estimated porosity in Yabus Formation ranges from 2 to 20% with an average of 12%; while permeability varies from 200 to 500 mD and up to 1 Darcy. The understanding of different scales of sedimentological reservoir heterogeneities might contribute to better reservoir quality prediction, architecture, consequently enhancing development and productivity.

  3. Characteristics and mechanism of low permeability beach-bar sandstone reservoir of Es4 in Dongying sag

    Institute of Scientific and Technical Information of China (English)

    WANG Hua-ai; ZHONG Jian-hua; ZHONG Fu-ping; NIU Yong-bin; WANG Pei-jun

    2009-01-01

    Core and cast sections observation and description, and logging, scanning electron microscope and core lab analysis data etc. Were applied to the present research of the characteristics and mechanism of low permeability beach-bar sandstone reservoir of Es4 in Dongying sag. The results indicated the reservoir has the characteristics of middle-low pores, low-permeability, low compo-sitional and structural maturity, and thin throat. The low-permeability is mainly due to sedimentation (fine particles and argillaceous inter beds) and diagenesis (compaction, cementation, and dissolution). The cementation reduced the physical property of the reser-voir mainly by carbonate cementation, quartz autogeny and enragement, and autogeny clay. Clay minerals usually jam the pores by filling holes, close-fitting the wall of hole, bridging, wrapping grains, and separate attaching the pores and so on. The dissolution is insufficient so as not to improve the porosity and permeability of the reservoir obviously. So it is also an important factor of form-ing low-permeability reservoir.

  4. Micropore Structure Representation of Sandstone in Petroleum Reservoirs Using an Atomic Force Microscope

    Institute of Scientific and Technical Information of China (English)

    BAI Yong-Qiang; ZHU Xing; WU Jun-Zheng; BAI Wen-Guang

    2011-01-01

    @@ The pore structure of sandstone in an oil reservoir is investigated using atomic force microscopy(AFM).At nanoscale resolution,AFM images of sandstone show us the fine structure.The real height data of images display the three-dimensional space structure of sandstone effectively.The three-dimensional analysis results show that the AFM images of sandstone have unique characteristics that,like fingerprints,can identify different structural properties of sandstones.The results demonstrate that AFM is an effective method used to represent original sandstone in petroleum reservoirs,and may help geologists to appreciate the sandstone in oil reservoirs fully.

  5. Reservoir characterization of Pennsylvanian sandstone reservoirs. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, M.

    1995-02-01

    This final report summarizes the progress during the three years of a project on Reservoir Characterization of Pennsylvanian Sandstone Reservoirs. The report is divided into three sections: (i) reservoir description; (ii) scale-up procedures; (iii) outcrop investigation. The first section describes the methods by which a reservoir can be described in three dimensions. The next step in reservoir description is to scale up reservoir properties for flow simulation. The second section addresses the issue of scale-up of reservoir properties once the spatial descriptions of properties are created. The last section describes the investigation of an outcrop.

  6. Reservoir assessment of the Nubian sandstone reservoir in South Central Gulf of Suez, Egypt

    Science.gov (United States)

    El-Gendy, Nader; Barakat, Moataz; Abdallah, Hamed

    2017-05-01

    The Gulf of Suez is considered as one of the most important petroleum provinces in Egypt and contains the Saqqara and Edfu oil fields located in the South Central portion of the Gulf of Suez. The Nubian sandstone reservoir in the Gulf of Suez basin is well known for its great capability to store and produce large volumes of hydrocarbons. The Nubian sandstone overlies basement rocks throughout most of the Gulf of Suez region. It consists of a sequence of sandstones and shales of Paleozoic to Cretaceous age. The Nubian sandstone intersected in most wells has excellent reservoir characteristics. Its porosity is controlled by sedimentation style and diagenesis. The cementation materials are mainly kaolinite and quartz overgrowths. The permeability of the Nubian sandstone is mainly controlled by grain size, sorting, porosity and clay content especially kaolinite and decreases with increase of kaolinite. The permeability of the Nubian Sandstone is evaluated using the Nuclear Magnetic Resonance (NMR technology) and formation pressure data in addition to the conventional logs and the results were calibrated using core data. In this work, the Nubian sandstone was investigated and evaluated using complete suites of conventional and advanced logging techniques to understand its reservoir characteristics which have impact on economics of oil recovery. The Nubian reservoir has a complicated wettability nature which affects the petrophysical evaluation and reservoir productivity. So, understanding the reservoir wettability is very important for managing well performance, productivity and oil recovery.

  7. Diagenetic characteristics and reservoir quality of the Lower Cretaceous Biyadh sandstones at Kharir oilfield in the western central Masila Basin, Yemen

    Science.gov (United States)

    Hakimi, Mohammed Hail; Shalaby, Mohamed Ragab; Abdullah, Wan Hasiah

    2012-06-01

    The Lower Cretaceous Biyadh Formation in the Masila Basin is an important hydrocarbon reservoir. However, in spite of its importance as a reservoir, published studies on the Biyadh Formation more specifically on the diagenesis and relate with reservoir quality, are limited. Based on core samples from one well in the Kharir oilfield, western central Masila Basin, this study reports the lithologic and diagenetic characteristics of this reservoir. The Biyadh sandstones are very fine to very coarse-grained, moderate to well sorted quartzarenite and quartzwacke. The diagenetic processes recognized include mechanical compaction, cementation (carbonate, clay minerals, quartz overgrowths, and a minor amount of pyrite), and dissolution of the calcite cement and feldspar grains. The widespread occurrences of early calcite cement suggest that the Biyadh sandstones lost a significant amount of primary porosity at a very early stage of its diagenetic history. Based on the framework grain-cement relationships, precipitation of the early calcite cement was either accompanied or followed by the development of part of the pore-lining and pore-filling clay cements. Secondary porosity development occurred due to partial to complete dissolution of early calcite cement and feldspar grains. In addition to calcite, several different clay minerals including kaolinite and chlorite occur as pore-filling and pore-lining cements. Kaolinite largely occurs as vermiform and accelerated the minor porosity loss due to pore-occlusion. Chlorite coating grains helps to retain primary porosity a by retarding the envelopment of quartz overgrowths. Porosity and permeability data exhibit good inverse correlation with cement. Thus, reservoir quality is controlled by pore occluding cement. Diagenetic history of the Biyadh sandstones as established here is expected to help better understanding and exploitation of this reservoir. The relation between diagenesis and reservoir quality is as follows: the

  8. Appalachian Basin Low-Permeability Sandstone Reservoir Characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Ray Boswell; Susan Pool; Skip Pratt; David Matchen

    1993-04-30

    A preliminary assessment of Appalachian basin natural gas reservoirs designated as 'tight sands' by the Federal Energy Regulatory Commission (FERC) suggests that greater than 90% of the 'tight sand' resource occurs within two groups of genetically-related units; (1) the Lower Silurian Medina interval, and (2) the Upper Devonian-Lower Mississippian Acadian clastic wedge. These intervals were targeted for detailed study with the goal of producing geologic reservoir characterization data sets compatible with the Tight Gas Analysis System (TGAS: ICF Resources, Inc.) reservoir simulator. The first phase of the study, completed in September, 1991, addressed the Medina reservoirs. The second phase, concerned with the Acadian clastic wedge, was completed in October, 1992. This report is a combined and updated version of the reports submitted in association with those efforts. The Medina interval consists of numerous interfingering fluvial/deltaic sandstones that produce oil and natural gas along an arcuate belt that stretches from eastern Kentucky to western New York. Geophysical well logs from 433 wells were examined in order to determine the geologic characteristics of six separate reservoir-bearing intervals. The Acadian clastic wedge is a thick, highly-lenticular package of interfingering fluvial-deltaic sandstones, siltstones, and shales. Geologic analyses of more than 800 wells resulted in a geologic/engineering characterization of seven separate stratigraphic intervals. For both study areas, well log and other data were analyzed to determine regional reservoir distribution, reservoir thickness, lithology, porosity, water saturation, pressure and temperature. These data were mapped, evaluated, and compiled into various TGAS data sets that reflect estimates of original gas-in-place, remaining reserves, and 'tight' reserves. The maps and data produced represent the first basin-wide geologic characterization for either interval. This report

  9. Reservoir characterization of Pennsylvanian Sandstone Reservoirs. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, M.

    1992-09-01

    This annual report describes the progress during the second year of a project on Reservoir Characterization of Pennsylvanian Sandstone Reservoirs. The report is divided into three sections: (i) reservoir description and scale-up procedures; (ii) outcrop investigation; (iii) in-fill drilling potential. The first section describes the methods by which a reservoir can be characterized, can be described in three dimensions, and can be scaled up with respect to its properties, appropriate for simulation purposes. The second section describes the progress on investigation of an outcrop. The outcrop is an analog of Bartlesville Sandstone. We have drilled ten wells behind the outcrop and collected extensive log and core data. The cores have been slabbed, photographed and the several plugs have been taken. In addition, minipermeameter is used to measure permeabilities on the core surface at six inch intervals. The plugs have been analyzed for the permeability and porosity values. The variations in property values will be tied to the geological descriptions as well as the subsurface data collected from the Glen Pool field. The third section discusses the application of geostatistical techniques to infer in-fill well locations. The geostatistical technique used is the simulated annealing technique because of its flexibility. One of the important reservoir data is the production data. Use of production data will allow us to define the reservoir continuities, which may in turn, determine the in-fill well locations. The proposed technique allows us to incorporate some of the production data as constraints in the reservoir descriptions. The technique has been validated by comparing the results with numerical simulations.

  10. Brittleness index and seismic rock physics model for anisotropic tight-oil sandstone reservoirs

    Institute of Scientific and Technical Information of China (English)

    Huang Xin-Rui; Huang Jian-Ping; Li Zhen-Chun; Yang Qin-Yong; Sun Qi-Xing; Cui Wei

    2015-01-01

    Brittleness analysis becomes important when looking for sweet spots in tight-oil sandstone reservoirs. Hence, appropriate indices are required as accurate brittleness evaluation criteria. We construct a seismic rock physics model for tight-oil sandstone reservoirs with vertical fractures. Because of the complexities in lithology and pore structure and the anisotropic characteristics of tight-oil sandstone reservoirs, the proposed model is based on the solid components, pore connectivity, pore type, and fractures to better describe the sandstone reservoir microstructure. Using the model, we analyze the brittleness sensitivity of the elastic parameters in an anisotropic medium and establish a new brittleness index. We show the applicability of the proposed brittleness index for tight-oil sandstone reservoirs by considering the brittleness sensitivity, the rock physics response characteristics, and cross-plots. Compared with conventional brittleness indexes, the new brittleness index has high brittleness sensitivity and it is the highest in oil-bearing brittle zones with relatively high porosity. The results also suggest that the new brittleness index is much more sensitive to elastic properties variations, and thus can presumably better predict the brittleness characteristics of sweet spots in tight-oil sandstone reservoirs.

  11. DELAYED POLYMER CROSSLINKING USED FOR PROFILE CONTROL IN SANDSTONE RESERVOIRS

    Institute of Scientific and Technical Information of China (English)

    Wang Zhongmao; Dong Bo; Fu Xiaofeng; Rong Jiashu

    1997-01-01

    @@ Most of the oil reservoirs in Jilin province occur in fractured sandstone with low permeability and heavy heterogeneity. In addition, with fracture development, the artificial fractures around producing wells and water injection wells have been increased, further aggravating the heterogeneity of oil reservoirs.

  12. Diagenetic effect on permeabilities of geothermal sandstone reservoirs

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

    The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting...... and permeability is caused by increased diagenetic changes of the sandstones due to increased burial depth and temperatures. Therefore, the highest water temperatures typically correspond with the lowest porosities and permeabilities. Especially the permeability is crucial for the performance of the geothermal......-line fractures. Continuous thin chlorite coatings results in less porosity- and permeability-reduction with burial than the general reduction with burial, unless carbonate cemented. Therefore, localities of sandstones characterized by these continuous chlorite coatings may represent fine geothermal reservoirs...

  13. Diagenetic effect on permeabilities of geothermal sandstone reservoirs

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

    The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting ...

  14. On the water saturation calculation in hydrocarbon sandstone reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Stalheim, Stein Ottar

    2002-07-01

    The main goal of this work was to identify the most important uncertainty sources in water saturation calculation and examine the possibility for developing new S{sub w} - equations or possibility to develop methods to remove weaknesses and uncertainties in existing S{sub w} - equations. Due to the need for industrial applicability of the equations we aimed for results with the following properties: The accuracy in S{sub w} should increase compared with existing S{sub w} - equations. The equations should be simple to use in petrophysical evaluations. The equations should be based on conventional logs and use as few as possible input parameters. The equations should be numerical stable. This thesis includes an uncertainty and sensitivity analysis of the most common S{sub w} equations. The results are addressed in chapter 3 and were intended to find the most important uncertainty sources in water saturation calculation. To increase the knowledge of the relationship between R{sub t} and S{sub w} in hydrocarbon sandstone reservoirs and to understand how the pore geometry affects the conductivity (n and m) of the rock a theoretical study was done. It was also an aim to examine the possibility for developing new S{sub w} - equations (or investigation an effective medium model) valid inhydrocarbon sandstone reservoirs. The results are presented in paper 1. A new equation for water saturation calculation in clean sandstone oil reservoirs is addressed in paper 2. A recommendation for best practice of water saturation calculation in non water wet formation is addressed in paper 3. Finally a new equation for water saturation calculation in thinly interbedded sandstone/mudstone reservoirs is presented in paper 4. The papers are titled: 1) Is the saturation exponent n a constant. 2) A New Model for Calculating Water Saturation In 3) Influence of wettability on water saturation modeling. 4) Water Saturation Calculations in Thinly Interbedded Sandstone/mudstone Reservoirs. A

  15. Capillarity and wetting of carbon dioxide and brine during drainage in Berea sandstone at reservoir conditions

    Science.gov (United States)

    Al-Menhali, Ali; Niu, Ben; Krevor, Samuel

    2015-10-01

    The wettability of CO2-brine-rock systems will have a major impact on the management of carbon sequestration in subsurface geological formations. Recent contact angle measurement studies have reported sensitivity in wetting behavior of this system to pressure, temperature, and brine salinity. We report observations of the impact of reservoir conditions on the capillary pressure characteristic curve and relative permeability of a single Berea sandstone during drainage—CO2 displacing brine—through effects on the wetting state. Eight reservoir condition drainage capillary pressure characteristic curves were measured using CO2 and brine in a single fired Berea sandstone at pressures (5-20 MPa), temperatures (25-50°C), and ionic strengths (0-5 mol kg-1 NaCl). A ninth measurement using a N2-water system provided a benchmark for capillarity with a strongly water wet system. The capillary pressure curves from each of the tests were found to be similar to the N2-water curve when scaled by the interfacial tension. Reservoir conditions were not found to have a significant impact on the capillary strength of the CO2-brine system during drainage through a variation in the wetting state. Two steady-state relative permeability measurements with CO2 and brine and one with N2 and brine similarly show little variation between conditions, consistent with the observation that the CO2-brine-sandstone system is water wetting and multiphase flow properties invariant across a wide range of reservoir conditions.

  16. Water coning mechanism in Tarim fractured sandstone gas reservoirs

    Institute of Scientific and Technical Information of China (English)

    沈伟军; 刘晓华; 李熙喆; 陆家亮

    2015-01-01

    The problem of water coning into the Tarim fractured sandstone gas reservoirs becomes one of the major concerns in terms of productivity, increased operating costs and environmental effects. Water coning is a phenomenon caused by the imbalance between gravity and viscous forces around the completion interval. There are several controllable and uncontrollable parameters influencing this problem. In order to simulate the key parameters affecting the water coning phenomenon, a model was developed to represent a single well with an underlying aquifer using the fractured sandstone gas reservoir data of the A-Well in Dina gas fields. The parametric study was performed by varying six properties individually over a representative range. The results show that matrix permeability, well penetration (especially fracture permeability), vertical-to-horizontal permeability ratio, aquifer size and gas production rate have considerable effect on water coning in the fractured gas reservoirs. Thus, investigation of the effective parameters is necessary to understand the mechanism of water coning phenomenon. Simulation of the problem helps to optimize the conditions in which the breakthrough of water coning is delayed.

  17. Core-log integration for a Saudi Arabian sandstone reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Saha, S.; Al-Kaabi, A.U.; Amabeoku, M.O.; Al-Fossail, K.

    1995-10-01

    For a detailed characterization of a reservoir, core-log integration is essential. In this paper, data integration from logs and cores of a Saudi Arabian sandstone reservoir is discussed with particular attention to effects of clay on resistivity logs and water saturation. There are four sources of data, namely, core resistivity measurement, clay study from cores (XRD, CEC), spectral core gamma ray, and well logs. In order to generate continuous cation exchange capacity (CEC) with depth, spectral gamma ray measurements (both from core and downhole log) and CEC from cores and correlated. Q{sub v} (CEC per unit pore volume) values are calculated utilizing only well logs by applying Waxman-Smits equation in water bearing zone. Log derived Q{sub v} values from water zone were then correlated with porosity to generate Q{sub v} values in the oil column and compared with core derived Z{sub v}. Finally, data from well logs (porosity, resistivity and Q{sub v}) and cores (resistivity parameters m, n, and Q{sub v}) were integrated for more accurate water saturation calculation. The core-log correlation can be applied to other wells avoiding expensive core analysis, and the technique developed in this project can be used in other sandstone reservoirs.

  18. Study of Displacement Characteristics of CO2 in Tight Sandstone Reservoir by Nuclear Magnetic Resonance%致密砂岩储层CO2驱油特征的核磁共振实验研究

    Institute of Scientific and Technical Information of China (English)

    郎东江; 伦增珉; 吕成远; 王海涛; 潘伟义

    2016-01-01

    The displacement oil characteristics of different pressure of carbon dioxide (CO2) in cores of different permeability and core with fracture of tight sandstone reservoir are studied bynuclear magnetic resonance (NMR) technology. This paper briefly describes the principle of nuclear magnetic resonance (NMR) and the experimental method. The results show that the tight sandstone reservoir, low and ultra-low permeability core in the initial CO2 displacement pressure,core capillary pores rang and micro capillary pores rang of oil is produced different degree, with CO2 displacement pressure increased, oil recovery degree of core capillary pores rang is increase and cumulative recovery degree is different. Tight sandstone reservoir core with fractures,oil of fractures and the part of oil in capillary pores range in the initial CO2 displacement pressure is displacement, with CO2 displacement pressure increased, oil recovery degree and cumulative recovery degree is smaller in core capillary pores rang and micro capillary pores rang. When CO2 displacement pressure increased, the part of oil of core capillary pores range is proportional to the increase into micro capillary pores rang in tight sandstone reservoir, low and ultra-low permeability cores and fracture tight sandstone reservoir core and change the distribution of residual oil. Thus it is concluded that the nuclear magnetic resonance (NMR) technology can further study of oil recovery degree and the distribution of residual oil under different displacement pressure of CO in capillary pores rang and micro capillary pores rang of tight sandstone reservoir, for the tight sandstone reservoir microscopic oil displacement mechanism is of important value.%利用核磁共振技术对致密砂岩储层不同渗透率级别基质岩心和裂缝基质岩心不同驱替压力下CO2驱油特征进行了研究,简述核磁共振原理及实验方法.表明:致密砂岩储层特低、超低渗透基质岩心在初始CO2驱替压力

  19. Diagenesis and porosity evolution of sandstone reservoirs in the East Ⅱ part of Sulige gas field, Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    Yang Renchao; Fan Aiping; Han Zuozhen; Wang Xiuping

    2012-01-01

    It is becoming an important controlling factor of gas exploration and exploitation in the east part of Sulige gas field in the Ordos Basin where the reservoir of main gas formations is tight sandstones.Employing experimental methods of slice identification,casting slice,scan electron microscope,and X-ray diffractions,we studied the characteristics of petrology and diagenesis on reservoirs in Shan1 section of Shanxi formation and He8 section of Shihezi formation of the Permian system in the East Ⅱ part of Sulige gas field.The results include:(1) the main sandstones in these areas are dominated by lithic sandstone and lithic silicarenite with low grade of maturity; (2) the diagenesis of sandstone in these areas mainly include compaction,cementation,corrosion and alteration.Conclusions are as follows:(1) the diagenetic stage reached period B of the middle diagenetic stage; (2) the early diagenetic compaction is one of the main factors to decreasing porosity:(3) the secondary pores formed by corrosion in acidity medium conditions in period A of the middle diagenetic stage can distinctly ameliorate the poor reservoir capability of sandstone and; (4) cementation in period B of the middle diagenetic stage is the most important factor leading to poor physical property of sandstone reservoirs.

  20. RESERVOIR CHARACTERIZATION OF UPPER DEVONIAN GORDON SANDSTONE, JACKSONBURG STRINGTOWN OIL FIELD, NORTHWESTERN WEST VIRGINIA

    Energy Technology Data Exchange (ETDEWEB)

    S. Ameri; K. Aminian; K.L. Avary; H.I. Bilgesu; M.E. Hohn; R.R. McDowell; D.L. Matchen

    2001-07-01

    The Jacksonburg-Stringtown oil field contained an estimated 88,500,000 barrels of oil in place, of which approximately 20,000,000 barrels were produced during primary recovery operations. A gas injection project, initiated in 1934, and a pilot waterflood, begun in 1981, yielded additional production from limited portions of the field. The pilot was successful enough to warrant development of a full-scale waterflood in 1990, involving approximately 8,900 acres in three units, with a target of 1,500 barrels of oil per acre recovery. Historical patterns of drilling and development within the field suggests that the Gordon reservoir is heterogeneous, and that detailed reservoir characterization is necessary for understanding well performance and addressing problems observed by the operators. The purpose of this work is to establish relationships among permeability, geophysical and other data by integrating geologic, geophysical and engineering data into an interdisciplinary quantification of reservoir heterogeneity as it relates to production. Conventional stratigraphic correlation and core description shows that the Gordon sandstone is composed of three parasequences, formed along the Late Devonian shoreline of the Appalachian Basin. The parasequences comprise five lithofacies, of which one includes reservoir sandstones. Pay sandstones were found to have permeabilities in core ranging from 10 to 200 mD, whereas non-pay sandstones have permeabilities ranging from below the level of instrumental detection to 5 mD; Conglomeratic zones could take on the permeability characteristics of enclosing materials, or could exhibit extremely low values in pay sandstone and high values in non-pay or low permeability pay sandstone. Four electrofacies based on a linear combination of density and scaled gamma ray best matched correlations made independently based on visual comparison of geophysical logs. Electrofacies 4 with relatively high permeability (mean value > 45 mD) was

  1. Evaluation and prevention of formation damage in offshore sandstone reservoirs in China

    Institute of Scientific and Technical Information of China (English)

    Yang Shenglai; Sheng Zhichao; Liu Wenhui; Song Zhixue; Wu Ming; Zhang Jianwei

    2008-01-01

    Reduction in water injectivity would be harmful to the waterflood development of offshore sandstone oil reservoirs. In this paper the magnitude of formation damage during water injection was evaluated by analyzing the performance of water injection in the Bohai offshore oilfield, China. Two parameters, permeability reduction and rate of wellhead pressure rise, were proposed to evaluate the formation damage around injection wells. The pressure performance curve could be divided into three stages with different characteristics. Analysis of field data shows that formation damage caused by water injection was severe in some wells in the Bohai offshore oilfield, China. In the laboratory, the content of clay minerals in reservoir rock was analyzed and sensitivity tests (including sensitivity to water,flow rate, alkali, salt and acid) were also conducted. Experimental results show that the reservoir had a strong to medium sensitivity to water (i.e. clay swelling) and a strong to medium sensitivity to flow rate,which may cause formation damage. For formation damage prevention, three injection schemes of clay stabilizer (CS) were studied, i.e. continuous injection of low concentration CS (Ci), slug injection of high concentration CS (SI), and slug injection of high concentration CS followed by continuous injection of low concentration CS (SI-CI). Core flooding experiments show that SI-CI is an effective scheme to prevent formation damage and is recommended for the sandstone oil reservoirs in the Bohai offshore oilfield during water injection.

  2. Reservoir heterogeneity in carboniferous sandstone of the Black Warrior basin. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.

    1994-06-01

    Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

  3. Reservoir heterogeneity in Carboniferous sandstone of the Black Warrior basin. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.

    1994-04-01

    Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

  4. Reservoir characteristics of detrital sandstones in Zhuhai formation of Baiyun sag, Pearl River Mouth Basin%珠江口盆地白云凹陷珠海组碎屑岩储层特征及成因机制

    Institute of Scientific and Technical Information of China (English)

    吕成福; 陈国俊; 张功成; 杜贵超; 王琪; 李超; 李伟; 陈吉

    2011-01-01

    通过岩石铸体薄片、粒度分析和压汞分析等手段,分析白云凹陷珠海组储层的岩石学特征和物性演化特征,研究沉积环境和成岩演化过程对储层特征的影响机制.研究结果表明:储层主要以长石质石英砂岩和长石岩屑质石英砂岩为主,颗粒支撑并以碳酸盐、自生石英和黏土矿物接触式胶结.储层物性总体具有中低孔中低渗特征,以粒间溶蚀扩大孔为主,其次为珠海组底部黏土膜保护的原生孔隙,分选好的中-粗喉型喉道使孔隙连通性良好;在凹陷西斜坡,珠海组上部和底部分别发育钙质砂岩夹层和铁泥质砂岩夹层.三角洲前缘环境是珠海组储层物性良好的先决条件;酸性流体的溶蚀溶解作用和绿泥石黏土膜保护是储层物性较好的根本原因,压实作用是粒间孔隙损失的主要原因,而部分储层渗透率较低是因为自生石英和黏土矿物充填喉道;钙质砂岩夹层物性差是胶结作用所致,而铁泥质砂岩夹层物性差是压实和胶结共同作用的结果.%Based on analyses of casting thin sections and particle size, mercury porosity measurements of the reservoir sandstones from Zhuhai formation of Baiyun sag, the petrography, pore types, pore-throat structure, reservoir quality evolution, diagenetic stage and diagenesis and their effects on reservoir quality were studied. The results show that reservoir sandstones mainly consist of feldspathic quartz sandstone and feldspar lithic quartz sandstone. Detrital grains are grain-supported and cemented by carbonate cements, authigenic quartz and clay minerals. Reservoir properties in general have medium-low porosity and permeability, pores are mainly intergranular dissolved pores and the next is residual primary pores protect by clay film preserved in the bottom Zhuhai formation. Due to pore-throats which are good sorted, pores show good connectivity. In the western slope of the sag, calcareous sandstone and

  5. Fluid identification in tight sandstone reservoirs based on a new rock physics model

    Science.gov (United States)

    Sun, Jianmeng; Wei, Xiaohan; Chen, Xuelian

    2016-08-01

    To identify pore fluids, we establish a new rock physics model named the tight sandstone dual-porosity model based on the Voigt-Reuss-Hill model, approximation for the Xu-White model and Gassmann’s equation to predict elastic wave velocities. The modeling test shows that predicted sonic velocities derived from this rock physics model match well with measured ones from logging data. In this context, elastic moduli can be derived from the model. By numerical study and characteristic analyzation of different elastic properties, a qualitative fluid identification method based on Poisson’s ratio and the S-L dual-factor method based on synthetic moduli is proposed. Case studies of these two new methods show the applicability in distinguishing among different fluids and different layers in tight sandstone reservoirs.

  6. Interaction of oil components and clay minerals in reservoir sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Changchun Pan; Linping Yu; Guoying Sheng; Jiamo Fu [Chinese Academy of Sciences, State Key Lab. of Organic Geochemistry, Wushan, Guangzhou (China); Jianhui Feng; Yuming Tian [Chinese Academy of Sciences, State Key Lab. of Organic Geochemistry, Wushan, Guangzhou (China); Zhongyuan Oil Field Co., Puyang, Henan (China); Xiaoping Luo [Zhongyuan Oil Field Co., Puyang, Henan (China)

    2005-04-15

    The free oil (first Soxhlet extract) and adsorbed oil (Soxhlet extract after the removal of minerals) obtained from the clay minerals in the <2 {mu}m size fraction as separated from eight hydrocarbon reservoir sandstone samples, and oil inclusions obtained from the grains of seven of these eight samples were studied via GC, GC-MS and elemental analyses. The free oil is dominated by saturated hydrocarbons (61.4-87.5%) with a low content of resins and asphaltenes (6.0-22.0% in total) while the adsorbed oil is dominated by resins and asphaltenes (84.8-98.5% in total) with a low content of saturated hydrocarbons (0.6-9.5%). The inclusion oil is similar to the adsorbed oil in gross composition, but contains relatively more saturated hydrocarbons (16.87-31.88%) and less resins and asphaltenes (62.30-78.01% in total) as compared to the latter. Although the amounts of both free and adsorbed oils per gram of clay minerals varies substantially, the residual organic carbon content in the clay minerals of the eight samples, after the free oil extraction, is in a narrow range between 0.537% and 1.614%. From the decrease of the percentage of the extractable to the total of this residual organic matter of the clay minerals with burial depth it can be inferred that polymerization of the adsorbed polar components occurs with the increase of the reservoir temperature. The terpane and sterane compositions indicate that the oil adsorbed onto the clay surfaces appears to be more representative of the initial oil charging the reservoir than do the oil inclusions. This phenomenon could possibly demonstrate that the first oil charge preferentially interacts with the clay minerals occurring in the pores and as coatings around the grains. Although the variation of biomarker parameters between the free and adsorbed oils could be ascribed to the compositional changes of oil charges during the filling process and/or the differential maturation behaviors of these two types of oils after oil

  7. Laboratory study of fluid viscosity induced ultrasonic velocity dispersion in reservoir sandstones

    Science.gov (United States)

    He, Tao; Zou, Chang-Chun; Pei, Fa-Gen; Ren, Ke-Ying; Kong, Fan-Da; Shi, Ge

    2010-06-01

    Ultrasonic velocities of a set of saturated sandstone samples were measured at simulated in-situ pressures in the laboratory. The samples were obtained from the W formation of the WXS Depression and covered low to nearly high porosity and permeability ranges. The brine and four different density oils were used as pore fluids, which provided a good chance to investigate fluid viscosity-induced velocity dispersion. The analysis of experimental observations of velocity dispersion indicates that (1) the Biot model can explain most of the small discrepancy (about 2-3%) between ultrasonic measurements and zero frequency Gassmann predictions for high porosity and permeability samples saturated by all the fluids used in this experiment and is also valid for medium porosity and permeability samples saturated with low viscosity fluids (less than approximately 3 mP·S) and (2) the squirt flow mechanism dominates the low to medium porosity and permeability samples when fluid viscosity increases and produces large velocity dispersions as high as about 8%. The microfracture aspect ratios were also estimated for the reservoir sandstones and applied to calculate the characteristic frequency of the squirt flow model, above which the Gassmann’ s assumptions are violated and the measured high frequency velocities cannot be directly used for Gassmann’s fluid replacement at the exploration seismic frequency band for W formation sandstones.

  8. Factors controlling reservoir quality in tertiary sandstones and their significance to geopressured geothermal production

    Energy Technology Data Exchange (ETDEWEB)

    Loucks, R.G.; Richmann, D.L.; Milliken, K.L.

    1981-01-01

    Variable intensity of diagenesis is the factor primarily responsible for contrasting regional reservoir quality of Tertiary sandstones from the upper and lower Texas coast. Detailed comparison of Frio sandstone from the Chocolate Bayou/Danbury Dome area, Brazoria County, and Vicksburg sandstones from the McAllen Ranch Field area, Hidalgo County, reveals that extent of diagenetic modification is most strongly influenced by (1) detrital mineralogy and (2) regional geothermal gradients. The regional reservoir quality of Frio sandstones from Brazoria County is far better than that characterizing Vicksburg sandstones from Hidalgo County, especially at depths suitable for geopressured geothermal energy production. However, in predicting reservoir quality on a site-specific basis, locally variable factors such as relative proportions for porosity types, pore geometry as related to permeability, and local depositional environment must also be considered. Even in an area of regionally favorable reservoir quality, such local factors can significantly affect reservoir quality and, hence, the geothermal production potential of a specific sandstone unit.

  9. A new biostratigraphical tool for reservoir characterisation and well correlation in permo-carboniferous sandstones

    NARCIS (Netherlands)

    Garming, J.F.L.; Cremer, H.; Verreussel, R.M.C.H.; Guasti, E.; Abbink, O.A.

    2010-01-01

    Permo-Carboniferous sandstones are important reservoir rocks for natural gas in the Southern North Sea basin. This is a mature area which makes tools for reservoir characterization and well to well correlation important for field optimalisation and ongoing exploration activities. Within the Permo-Ca

  10. Improving recovery efficiency of water-drive channel sandstone reservoir by drilling wells laterally

    Energy Technology Data Exchange (ETDEWEB)

    Zhiguo, F.; Quinglong, D.; Pingshi, Z.; Bingyu, J.; Weigang, L. [Research Institute of Exploration and Development, Daqing (China)

    1998-12-31

    Example of drilling a horizontal well in reservoir rock of only four meter thick by using existing casing pipe of low efficiency vertical wells to induce production in the top remaining reservoir is described. The experience shows that drilling horizontal wells laterally in thin bodies of sandstone reservoirs and improve their productivity is a feasible proposition. Productivity will still be low, but it can be improved by well stimulation. 3 refs., 3 figs.

  11. Geological characteristics of the Triassic tight sandstone oil and gas reservoirs in Luoyang-Yichuan area%洛阳-伊川地区三叠系致密砂岩油气藏地质特征

    Institute of Scientific and Technical Information of China (English)

    杜建波; 田景春; 胡俊卿; 曹建康

    2013-01-01

    Research of the petroleum geological conditions indicates that Luoyang-Yichuan area is located in the same large depressed lacustrine basin with Ordos Basin in the Triassic.They have similar source-reservoir-caprock associations,thick and extensive source rocks,tight reservoir and active hydrocarbon shows in the Triassic.Therefore,the Luoyang-Yichuan area has the geological conditions for accumulation of tight sand oil/gas.In combination with the analysis of industrial gas flow from the Upper Triassic Chunshuyao Formation in Well Tun 1,we believe that the Triassic reservoirs of the Luoyang-Yichuan area are pre-existing tight sandstone oil/gas reservoirs with low permeability,abnormal pressure,inverted oil-gas contact with oil in the upper and gas in the lower.The Triassic tight sandstone reservoirs are the main targets of petroleum exploration in Luoyang-Yichuan area in the future.%通过对洛阳-伊川地区三叠系基本石油地质条件的分析,认为三叠纪洛阳-伊川地区与鄂尔多斯盆地处于同一大型坳陷型湖盆,生储盖架构相似,烃源岩发育、厚度大、横向展布稳定、储层致密,且三叠系油气显示丰富,具致密砂岩油气藏形成的地质条件.结合对屯l井上三叠统椿树腰组工业天然气流分析,进一步明确了洛阳-伊川地区三叠系油气藏为具有低孔渗性、地层压力异常、油气呈“上油下气”倒置关系等特征的先成型致密砂岩油气藏,从而指出三叠系为洛阳-伊川地区下一步油气勘探的主攻层系,致密砂岩油气藏是该区勘探的主要方向.

  12. Comparison analysis of fractal characteristics for tight sandstones using different calculation methods

    Science.gov (United States)

    Zhang, Xiaoyang; Wu, Caifang; Li, Teng

    2017-02-01

    The micropore structure of a tight sandstone is the decisive factor in determining its reserve and seepage characteristics. An accurate description of the pore structures and a complete characterization of the gas-water permeability are critical when exploring for tight sandstone gas. One simple and effective way to quantitatively characterize the heterogeneity and complexity of the pore structures in a low permeability reservoir is the fractal dimension. In this study, three different methods, each utilizing mercury intrusion porosimetry (MIP) data, were adopted to analyze the fractal dimensions and the fractal curves of sandstones from the no. 8 layer of the Xiashihezi Formation (He 8 member) in the Linxing block, dated from the Middle Permian. The morphological features of the fractal curves, the characteristics of the fractal dimensions and the theoretical differences between these three methods were also discussed. The results show that the fractal dimensions obtained by method I reflect the characteristics of the remaining pores that are not intruded by mercury, and they show that the involved pore scales are more comprehensive. While in methods II and III, both obtain the fractal dimensions of the pores intruded by mercury, the difference between them is in the selection of a simplified pore shape model, which results in the fractal dimensions differing by a value of 1 between them. No matter which method is adopted, the pore structures of tight sandstone reservoirs in the Linxing block exhibit fractal characteristics. However, the fractal dimensions obtained by method I are more suitable for describing the complexity and petrophysical properties of the tight sandstone pores in the He 8 member of the Linxing block. The fractal curves obtained by different methods are consistent to a certain extent in terms of morphological changes. Small pores (fractal characteristics, while large pores (>r max-point) are the critical factor affecting the seepage

  13. Diagenetic fluids evolution and genetic mechanism of tight sandstone gas reservoirs in Upper Triassic Xujiahe Formation in Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The reservoirs of the Upper Triassic Xujiahe Formation in Sichuan Basin have the characteristics of low compositional maturity, low contents of cements and medium textural maturity. The general physical properties of the reservoirs are poor, with low porosity and low permeability, and there are only a few reservoirs with medium porosity and low permeability in local areas. Based on the diagenetic mineral association, a diagenetic sequence of cements is established: early calcites (or micrite siderites) →first quartz overgrowth→chlorite coatings→dissolution of feldspars and debris→chlorite linings→ second quartz overgrowth (quartz widen or filled in remain intergranular pores and solution pores)→dissolution→third quartz overgrowth (quartz filled in intergranular and intragranular solution pores)→intergrowth (ferro) calcites→dolomites→ferro (calcites) dolomites→later dissolution→veins of quartz and calcites formation. Mechanical compaction is the main factor in making the reservoirs tight in the basin, followed by the second and third quartz overgrowth. In a long-term closed system, only feld-spars and some lithic fragments are dissolved by diagenetic fluids, while intergranular cements such as quartz and calcit are not dissolved and thus have little influence on the porosity of the Xujiahe Formation. This is the third factor that may have kept the sandstones of Xujiahe Formation tight finally. The hydrocarbon was extensively generated from organic materials after the second quartz overgrowth, and selectively entered favorable reservoirs to form tight sandstone gas reservoirs.

  14. Diagenetic fluids evolution and genetic mechanism of tight sandstone gas reservoirs in Upper Triassic Xujiahe Formation in Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)

    ZHU RuKai; ZOU CaiNeng; ZHANG Nai; WANG XueSong; CHENG Rong; LIU LiuHong; ZHOU ChuanMin; SONG LiHong

    2008-01-01

    The reservoirs of the Upper Triassic Xujiahe Formation in Sichuan Basin have the characteristics of low compositional maturity, low contents of cements and medium textural maturity.The general physical properties of the reservoirs are poor, with low porosity and low permeability, and there are only a few reservoirs with medium porosity and low permeability in local areas.Based on the diagenetic mineral association, a diagenetic sequence of cements is established: early calcites (or micrite siderites)→ first quartz overgrowth→chlorite coatings→dissolution of feldspars and debris→chlorite linings→ second quartz overgrowth (quartz widen or filled in remain intergranular pores and solution pores→ dissolution→third quartz overgrowth (quartz filled in intergranular and intragranular solution pores)→ intergrowth (ferro) calcites→dolomites→ferro (calcites) dolomites→later dissolution→veins of quartz and calcites formation.Mechanical compaction is the main factor in making the reservoirs tight in the basin, followed by the second and third quartz overgrowth.In a long-term closed system, only feldspars and some lithic fragments are dissolved by diagenetic fluids, while intergranular cements such as quartz and calcit are not dissolved and thus have little influence on the porosity of the Xujiahe Formation.This is the third factor that may have kept the sandstones of Xujiahe Formation tight finally.The hydrocarbon was extensively generated from organic materials after the second quartz overgrowth, and selectively entered favorable reservoirs to form tight sandstone gas reservoirs.

  15. Types of Sandstone Reservoir Diagenetic Facies and Microscopic Pore Structure Characteristics of Chang 8 1 Reservoir in Huaqing Oilfield%华庆油田长81储层成岩相类型及微观孔隙结构特征

    Institute of Scientific and Technical Information of China (English)

    任大忠; 孙卫; 魏虎; 周树勋; 张一果; 张茜

    2014-01-01

    In order to characterize the diagenetic facies and microscopic pore structure characteristics of low/ul-tra-low permeability sandstone reservoir in Chang 8 1 segments of Huaqing Oilfield,this paper discusses the dia-genetic process,cement type of each diagenetic facies,pore evolution,the effect of pore structure on the physi-cal property and fluid seepage characteristics.On the background of reservoir sedimentary characteristics,the test analysis methods are used and the testing oil exploration results for dynamic data validation is made,such as,physical property,casting lamella,scanning electron microscope (SEM),conventional pressure mercury, image pore,X-ray diffraction,oil-water relative permeability.Establishing the reservoir evolution frame in time and space:deposition (sedimentary facies)-diagenesis (diagenetic facies)-pore evolution are the controls of microscopic pore structure of reservoir physical property and seepage characteristics.Different diagenetic facies type have both constructive and destructive dual effects,specificing in the degrees of differences of compaction, cementation,function,dissolution.The qualitative analysis and quantitative description of indoor experiment of diagenetic facies microscopic pore structure have a consistency with testing for oil exploration results and experi-mental data.It is pointed out that the diagenetic facies and microscopic pore structure characteristics of this kind of reservoir can predict and evaluate favorable space.Chang 81 reservoir underwater distributary channel micro-facies with chlorite lining edge residual pore-dissolution phase combination of intergranular pore development is the most favorable reservoir belt.Pore of forced compaction-carbonate +illite cementation facies association is damaged too seriously to be an invalid reservoir zone.%为探讨华庆油田长81储层成岩相类型及相内微观孔隙结构特征,在储层沉积特征背景上,开展物性、铸体薄片、扫描电镜、

  16. The influence of diagenesis on the reservoir quality of Cambrian and Carboniferous sandstones, southwest Sinai, Egypt

    Science.gov (United States)

    McBride, Earle F.; Abdel-Wahab, Antar; Salem, Alaa M. K.

    1996-04-01

    The diagenetic influence on hydrocarbon reservoir quality was investigated for the Cambrian and Lower Carboniferous sandstones of southwestern Sinai. These quartzose and feldspathic Palaeozoic sandstones were not buried more than 1 to 1.5 km until Late Cretaceous and more recent times, when the most deeply buried rocks may have reached 25 km. Porosity was reduced by compaction from an assumed original 45% to about 26%. In general, both Cambrian and Carboniferous sandstones lost more porosity by compaction (average of 19% for each) than by cementation (average of 17% and 13%, respectively). There is no significant difference in the degree of compaction shown by Cambrian (older, deeper buried) rather than Carboniferous sandstones. Cementation by iron oxide, quartz, calcite and kaolinite reduced porosity to 12-15%, except in silcretes and some ferricretes where porosity was reduced to <5%. Significant secondary porosity was created (5.8 and 5.1 % for Cambrian and Carboniferous sandstones, respectively ) chiefly by dissolution of feldspar. Kaolinite (maximum of 20%) is the most deleterious cement because it has high microporosity, which causes high residual water saturation, and occurs as tiny crystals that have the potential to break loose during rapid fluid flow and block the pore throats. The present-day porosity in these sandstones averages 19% and ranges from 1.5 to 32%. Many sandstone samples (47% of a total of 178 samples) have permeability values higher than 1000 md. The plot of porosity versus the log of permeability has a good correlation indicating that microporosity, even though locally important, does not significantly influence reservoir quality. In spite of their age and the large volumes of groundwater that probably passed through them, these Palaeozoic sandstones retain sufficient porosity and permeability to possess excellent reservoir quality.

  17. The impact of reservoir conditions on the residual trapping of carbon dioxide in Berea sandstone

    Science.gov (United States)

    Niu, Ben; Al-Menhali, Ali; Krevor, Samuel C.

    2015-04-01

    The storage of carbon dioxide in deep brine-filled permeable rocks is an important tool for CO2 emissions mitigation on industrial scales. Residual trapping of CO2 through capillary forces within the pore space of the reservoir is one of the most significant mechanisms for storage security and is also a factor determining the ultimate extent of CO2 migration within the reservoir. In this study we have evaluated the impact of reservoir conditions of pressure, temperature, and brine salinity on the residual trapping characteristic curve of a fired Berea sandstone rock. The observations demonstrate that the initial-residual characteristic trapping curve is invariant across a wide range of pressure, temperature, and brine salinities and is also the same for CO2-brine systems as a N2-water system. The observations were made using a reservoir condition core-flooding laboratory that included high-precision pumps, temperature control, the ability to recirculate fluids for weeks at a time, and an X-ray CT scanner. Experimental conditions covered pressures of 5-20 MPa, temperatures of 25-50°C, and 0-5 mol/kg NaCl brine salinity. A novel coreflooding approach was developed, making use of the capillary end effect to create a large range in initial CO2 saturation (0.15-0.6) in a single coreflood. Upon subsequent flooding with CO2-equilibriated brine, the observation of residual saturation corresponded to the wide range of initial saturations before flooding resulting in a rapid construction of the initial-residual curve. For each condition we report the initial-residual curve and the resulting parameterization of the Land hysteresis models.

  18. Reservoir heterogeneity in Carter Sandstone, North Blowhorn Creek oil unit and vicinity, Black Warrior Basin, Alabama

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, R.L.; Pashin, J.C.

    1992-05-01

    This report presents accomplishments made in completing Task 3 of this project which involves development of criteria for recognizing reservoir heterogeneity in the Black Warrior basin. The report focuses on characterization of the Upper Mississippian Carter sandstone reservoir in North Blowhorn Creek and adjacent oil units in Lamar County, Alabama. This oil unit has produced more than 60 percent of total oil extracted from the Black Warrior basin of Alabama. The Carter sandstone in North Blowhorn Creek oil unit is typical of the most productive Carter oil reservoirs in the Black Warrior basin of Alabama. The first part of the report synthesizes data derived from geophysical well logs and cores from North Blowhorn Creek oil unit to develop a depositional model for the Carter sandstone reservoir. The second part of the report describes the detrital and diagenetic character of Carter sandstone utilizing data from petrographic and scanning electron microscopes and the electron microprobe. The third part synthesizes porosity and pore-throat-size-distribution data determined by high-pressure mercury porosimetry and commercial core analyses with results of the sedimentologic and petrographic studies. The final section of the report discusses reservoir heterogeneity within the context of the five-fold classification of Moore and Kugler (1990).

  19. Predicting cement distribution in geothermal sandstone reservoirs based on estimates of precipitation temperatures

    Science.gov (United States)

    Olivarius, Mette; Weibel, Rikke; Whitehouse, Martin; Kristensen, Lars; Hjuler, Morten L.; Mathiesen, Anders; Boyce, Adrian J.; Nielsen, Lars H.

    2016-04-01

    Exploitation of geothermal sandstone reservoirs is challenged by pore-cementing minerals since they reduce the fluid flow through the sandstones. Geothermal exploration aims at finding sandstone bodies located at depths that are adequate for sufficiently warm water to be extracted, but without being too cemented for warm water production. The amount of cement is highly variable in the Danish geothermal reservoirs which mainly comprise the Bunter Sandstone, Skagerrak and Gassum formations. The present study involves bulk and in situ stable isotope analyses of calcite, dolomite, ankerite, siderite and quartz in order to estimate at what depth they were formed and enable prediction of where they can be found. The δ18O values measured in the carbonate minerals and quartz overgrowths are related to depth since they are a result of the temperatures of the pore fluid. Thus the values indicate the precipitation temperatures and they fit the relative diagenetic timing identified by petrographical observations. The sandstones deposited during arid climatic conditions contain calcite and dolomite cement that formed during early diagenesis. These carbonate minerals precipitated as a response to different processes, and precipitation of macro-quartz took over at deeper burial. Siderite was the first carbonate mineral that formed in the sandstones that were deposited in a humid climate. Calcite began precipitating at increased burial depth and ankerite formed during deep burial and replaced some of the other phases. Ankerite and quartz formed in the same temperature interval so constrains on the isotopic composition of the pore fluid can be achieved. Differences in δ13C values exist between the sandstones that were deposited in arid versus humid environments, which suggest that different kinds of processes were active. The estimated precipitation temperatures of the different cement types are used to predict which of them are present in geothermal sandstone reservoirs in

  20. Imaging pore space in tight gas sandstone reservoir: insights from broad ion beam cross-sectioning

    OpenAIRE

    Konstanty J.; Kukla P.A.; Urai J.L.; Baerle C.; Enzmann F.; Desbois G.

    2010-01-01

    Monetization of tight gas reservoirs, which contain significant gas reserves world-wide, represents a challenge for the entire oil and gas industry. The development of new technologies to enhance tight gas reservoir productivity is strongly dependent on an improved understanding of the rock properties and especially the pore framework. Numerous methods are now available to characterize sandstone cores. However, the pore space characterization at pore scale remains difficult due to the f...

  1. Architecture of an Upper Jurassic barrier island sandstone reservoir, Danish Central Graben:

    DEFF Research Database (Denmark)

    Johannessen, Peter N.; Nielsen, Lars H.; Nielsen, Lars

    2010-01-01

    An unusually thick (c. 88 m), transgressive barrier island and shoreface sandstone succession characterizes the Upper Jurassic Heno Formation reservoir of the Freja oil field situated on the boundary of Denmark and Norway. The development and preservation of such thick transgressive barrier islan...... such that the island aggraded and even prograded seawards and became wider and longer due to the large surplus of sand....

  2. Reservoir condition special core analyses and relative permeability measurements on Almond formation and Fontainebleu sandstone rocks

    Energy Technology Data Exchange (ETDEWEB)

    Maloney, D.

    1993-11-01

    This report describes the results from special core analyses and relative permeability measurements conducted on Almond formation and Fontainebleu sandstone plugs. Almond formation plug tests were performed to evaluate multiphase, steady-state,reservoir-condition relative permeability measurement techniques and to examine the effect of temperature on relative permeability characteristics. Some conclusions from this project are as follows: An increase in temperature appeared to cause an increase in brine relative permeability results for an Almond formation plug compared to room temperature results. The plug was tested using steady-state oil/brine methods. The oil was a low-viscosity, isoparaffinic refined oil. Fontainebleu sandstone rock and fluid flow characteristics were measured and are reported. Most of the relative permeability versus saturation results could be represented by one of two trends -- either a k{sub rx} versus S{sub x} or k{sub rx} versus Sy trend where x and y are fluid phases (gas, oil, or brine). An oil/surfactant-brine steady-state relative permeability test was performed to examine changes in oil/brine relative permeability characteristics from changes in fluid IFTS. It appeared that, while low interfacial tension increased the aqueous phase relative permeability, it had no effect on the oil relative permeability. The BOAST simulator was modified for coreflood simulation. The simulator was useful for examining effects of variations in relative permeability and capillary pressure functions. Coreflood production monitoring and separator interface level measurement techniques were developed using X-ray absorption, weight methods, and RF admittance technologies. The three types of separators should be useful for routine and specialized core analysis applications.

  3. Experimental evaluation on well pattern adaptability of ultra-low permeability reservoir using sandstone flat model

    Institute of Scientific and Technical Information of China (English)

    肖前华; 魏国齐; 杨正明; 徐轩; 田文博; 张亚蒲

    2014-01-01

    As for ultra-low permeability reservoir, the adaptability of common nine-spot well pattern is studied through large-scale flat models made by micro-fractured natural sandstone outcrops. Combined with non-linear porous flow characteristics, the concept of dimensionless pressure sweep efficiency and deliverability index are put forward to evaluate the physical models’ well pattern adaptability. Through experiments, the models’ pressure distribution is measured and on which basis, the pressure gradient fields are drawn and the porous flow regions of these models are divided into dead oil region, non-linear porous flow region, and quasi-linear porous flow region with the help of twin-core non-linear porous flow curve. The results indicate that rectangular well pattern in fracture reservoirs has the best adaptability, while the worst is inverted nine-spot equilateral well pattern. With the increase of drawdown pressure, dead oil region decreases, pressure sweep efficiency and deliverability index increase; meantime, the deliverability index of rectangular well pattern has much more rational increase. Under the same drawdown pressure, the rectangular well pattern has the largest pressure sweep efficiency.

  4. Production of a Porosity Map by Kriging in Sandstone Reservoirs, Case Study from the Sava Depression

    Directory of Open Access Journals (Sweden)

    Tomislav Malvić

    2008-05-01

    Full Text Available Variogram analyses and usages of geostatistical interpolations have been standard analytical tools in Croatian geology in the last five years. Such analyses have especially been applied in the mapping of petroleum geological data. In this paper, spatial modelling of porosity data and, consequently, kriging mapping are described for a relatively large dataset obtained at an oil field located in the Croatian part of Pannonian basin (Sava depression. Analyzed datasets included porosity values measured in a sandstone reservoir of Pannonian age. The original dataset can be considered as a rare extensive porosity set available for Croatian hydrocarbon reservoirs. It made possible very reliable semivariogram modelling and kriging interpolation of porosity. The obtained results point out kriging as the most appropriate interpolation approach for porosity, but also for other geological data in sandstone reservoirs of Miocene age.

  5. Prediction of calcite Cement Distribution in Shallow Marine Sandstone Reservoirs using Seismic Data

    Energy Technology Data Exchange (ETDEWEB)

    Bakke, N.E.

    1996-12-31

    This doctoral thesis investigates how calcite cemented layers can be detected by reflection seismic data and how seismic data combined with other methods can be used to predict lateral variation in calcite cementation in shallow marine sandstone reservoirs. Focus is on the geophysical aspects. Sequence stratigraphy and stochastic modelling aspects are only covered superficially. Possible sources of calcite in shallow marine sandstone are grouped into internal and external sources depending on their location relative to the presently cemented rock. Well data and seismic data from the Troll Field in the Norwegian North Sea have been analysed. Tuning amplitudes from stacks of thin calcite cemented layers are analysed. Tuning effects are constructive or destructive interference of pulses resulting from two or more closely spaced reflectors. The zero-offset tuning amplitude is shown to depend on calcite content in the stack and vertical stack size. The relationship is found by regression analysis based on extensive seismic modelling. The results are used to predict calcite distribution in a synthetic and a real data example. It is found that describing calcite cemented beds in shallow marine sandstone reservoirs is not a deterministic problem. Hence seismic inversion and sequence stratigraphy interpretation of well data have been combined in a probabilistic approach to produce models of calcite cemented barriers constrained by a maximum amount of information. It is concluded that seismic data can provide valuable information on distribution of calcite cemented beds in reservoirs where the background sandstones are relatively homogeneous. 63 refs., 78 figs., 10 tabs.

  6. Integrated geologic and engineering reservoir characterization of the Hutton Sandstone, Jackson region, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, D.S.; Holtz, M.H.; Yeh, J. [Univ. of Texas, Austin, TX (United States)] [and others

    1996-08-01

    An integrated geologic and engineering reservoir characterization study of the Hutton Sandstone was completed for the Jackson region, Eromanga Basin, Australia. Our approach involves four principal steps: (1) determine reservoir architecture within a high-resolution sequence stratigraphic framework, (2) investigate trends in reservoir fluid flow, (3) integrate fluid flow trends with reservoir architecture to identify fundamental reservoir heterogeneities, and (4) identify opportunities for reserve growth. Contrary to the existing perception, the Hutton Sandstone, a continental-scale bed-load fluvial system, does not behave as a large, homogeneous tank in which pistonlike displacement of produced oil occurs unimpeded by vertical migration of the aquifer. The sequence stratigraphic analysis identified numerous thin but widespread shale units, deposited during lacustrine flooding events that periodically interrupted episodes of coarse clastic Hutton deposition. These shales represent chronostratigraphically significant surfaces. More importantly, the trends established in reservoir fluid flow from monitoring aquifer encroachment, production response to water shut-off workovers, and differential depletion in Repeat Formation Tests indicate that these shale units act as efficient barriers to vertical fluid flow. Erosion of the upper part of the Hutton reservoir by the younger Birkhead mixed-load fluvial system caused further stratigraphic complexity and introduced additional barriers to vertical and lateral migration of mobile oil and aquifer encroachment. This integrated characterization targeted strategic infill and step-out drilling and recompletion candidates.

  7. Characterization of the Qishn sandstone reservoir, Masila Basin-Yemen, using an integrated petrophysical and seismic structural approach

    Science.gov (United States)

    Lashin, Aref; Marta, Ebrahim Bin; Khamis, Mohamed

    2016-03-01

    This study presents an integrated petrophysical and seismic structural analysis that is carried out to evaluate the reservoir properties of Qishn sandstone as well as the entrapment style of the hydrocarbons at Sharyoof field, Sayun-Masila Basin that is located at the east central of Yemen. The reservoir rocks are dominated by clean porous and permeable sandstones zones usually intercalated with some clay stone interbeds. As identified from well logs, Qishn sandstone is classified into subunits (S1A, S1B, S1C and S2) with different reservoir characteristics and hydrocarbon potentiality. A number of qualitative and quantitative well logging analyses are used to characterize the different subunits of the Qishn reservoir and identify its hydrocarbon potentiality. Dia-porosity, M-N, Pickett, Buckles plots, petrophysical analogs and lateral distribution maps are used in the analysis. Shale volume, lithology, porosity, and fluid saturation are among the most important deduced parameters. The analysis revealed that S1A and S1C are the main hydrocarbon-bearing units. More specifically, S1A unit is the best, as it attains the most prolific hydrocarbon saturations (oil saturation "SH″ up to 65) and reservoir characteristics. An average petrophysical ranges of 4-21%, 16-23%, 11-19%, 0-65%, are detected for S1A unit, regarding shale volume, total and effective porosity, and hydrocarbon saturation, respectively. Meanwhile, S1B unit exhibits less reservoir characteristics (Vsh>30%, ϕEff<15% and SH< 15%). The lateral distribution maps revealed that most of the hydrocarbons (for S1A and S1C units) are indicated at the middle of the study area as NE-SW oriented closures. The analysis and interpretation of seismic data had clarified that the structure of study area is represented by a big middle horst bounded by a group of step-like normal faults at the extreme boundaries (faulted anticlinal-structure). In conclusion, the entrapment of the encountered hydrocarbon at Sharyoof oil

  8. CHARACTERIZATION OF SANDSTONE RESERVOIRS FOR ENHANCED OIL RECOVERY: THE PERMIAN UPPER MINNELUSA FORMATION, POWDER RIVER BASIN, WYOMING.

    Science.gov (United States)

    Schenk, C.J.; Schmoker, J.W.; Scheffler, J.M.

    1986-01-01

    Upper Minnelusa sandstones form a complex group of reservoirs because of variations in regional setting, sedimentology, and diagenetic alteration. Structural lineaments separate the reservoirs into northern and southern zones. Production in the north is from a single pay sand, and in the south from multi-pay sands due to differential erosion on top of the Upper Minnelusa. The intercalation of eolian dune, interdune, and sabkha sandstones with marine sandstones, carbonates, and anhydrites results in significant reservoir heterogeneity. Diagenetic alterations further enhance heterogeneity, because the degree of cementation and dissolution is partly facies-related.

  9. The effects of impure CO2 on reservoir sandstones: results from mineralogical and geomechanical experiments

    Science.gov (United States)

    Marbler, H.; Erickson, K. P.; Schmidt, M.; Lempp, Ch.; Pöllmann, H.

    2012-04-01

    An experimental study of the behaviour of reservoir sandstones from deep saline aquifers during the injection and geological storage of CO2 with the inherent impurities SOX and NOX is part of the German national project COORAL*. Sample materials were taken from outcrops of possible reservoir formations of Rotliegend and Bunter Sandstones from the North German Basin. A combination of mineralogical alteration experiments and geomechanical tests was carried out on these rocks to study the potential effects of the impurities within the CO2 pore fluid. Altered rock samples after the treatment with CO2 + SOX/NOX in an autoclave system were loaded in a triaxial cell under in-situ pressure and temperature conditions in order to estimate the modifications of the geomechanical rock properties. Mineralogical alterations were observed within the sandstones after the exposure to impure supercritical (sc)CO2 and brine, mainly of the carbonatic, but also of the silicatic cements, as well as of single minerals. Besides the partial solution effects also secondary carbonate and minor silicate mineral precipitates were observed within the pore space of the treated sandstones. These alterations affect the grain structure of the reservoir rock. Results of geomechanical experiments with unaltered sandstones show that the rock strength is influenced by the degree of rock saturation before the experiment and the chemical composition of the pore fluid (scCO2 + SOX + NOX). After long-term autoclave treatment with impure scCO2, the sandstone samples exhibit modified strength parameters and elastic deformation behaviour as well as changes in porosity compared to untreated samples. Furthermore, the injected fluid volume into the pore space of sandstones from the same lithotype varies during triaxial loading depending on the chemistry of the pore fluid. CO2 with NOX and SOX bearing fluid fills a significantly larger proportion of the sandstone pore space than brine with pure scCO2. * The

  10. Diagenesis and Its Effect on Reservoir Quality of Silurian Sandstones, Tabei Area, Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    Zhang Jinliang; Jia Ying; Du Guilin

    2007-01-01

    The diagenetic processes of the Tabei sandstones in the Tarim Basin include compaction, cementation (quartz overgrowths, calcite, clay minerals and a minor amount of pyrite), and dissolution of the feldspar and calcite cement.Porosity was reduced by compaction from an assumed original 40% to about 22.1%. Cementation reduced porosity to 26.6%. The Tabei sandstones lost a little more porosity by compaction than by cementation. Quartz cementation,especially syntaxial quartz overgrowth, is a major cause of porosity-loss in many reservoirs in moderately to deeply buried sandstone. Calcite cementation played a key role in the porosity evolution of sandstones. At the early stage of burial, the early calcite cement occupied most of the pore spaces resulting in significant porosity. On the other hand, some primary porosity has been preserved due to incomplete filling or the presence of scattered patches of calcite cement. In addition to calcite, several clay minerals, including illite and chlorite occurred as pore-filling and pore-lining cements.The pore-lining chlorite may have helped in retaining the porosity by preventing the precipitation of syntaxial quartz overgrowths. Illite, which largely occurred as hair-like rims around the grains and bridges on the pore throats, caused a substantial deterioration of penetrability of the reservoir. Calcite cement dissolution was extensive and contributed significantly to the development of secondary porosity.

  11. Oxfordian-Kimmeridgian (Late Jurassic) reservoir sandstones in the Witch Ground Graben, U. K. North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Harker, S.D. (Occidental Petroleum (Caledonia) Ltd., Aberdeen (United Kingdom)); Mantel, K.A. (Narwhal, London (United Kingdom)); Morton, D.J. (Deminex U.K. Oil and Gas Ltd., London (United Kingdom)); Riley, L.A. (Paleoservices, Watford (United Kingdom))

    1991-03-01

    Oil-bearing Late Jurassic Oxfordian-Kimmeridgian sandstones of the Sgiath and Piper formations are of major economic importance in the Witch Ground Graben. They form the reservoirs in Scott, which in 1993 will be the largest producing North Sea oil field to come on stream for more than a decade. Together with Scott, the Piper, Saltire, Tartan, Highlander, Petronella, Rob Roy, and Ivanhoe fields contained almost 2 Bbbl of recoverable reserves in these formations. The Sgiath and Piper represent two phases of Late Jurassic transgression and regression, initially represented by paralic deposited sand culminating in a wave-dominated delta sequence. The history of the Sgiath and Piper formations is reviewed and lithostratigraphic and biostratigraphic correlations presented to illustrate the distribution of the reservoir sandstones.

  12. A Study of Thin Sandstone Reservoirs by High-resolution Seismic Inversion

    Institute of Scientific and Technical Information of China (English)

    Ning Songhua

    2006-01-01

    In this paper seismic inversion was used as a key technique and the seismic wavelet most suitable to the actual underground situation was extracted with the higher-order statistics algorithm. The wavelets extracted in this way and the wavelets extracted with the seismic statistics techniques were used separately for inverting the seismic data of the southern part of Tahe oilfield, Tarim basin. The results showed that the resolution of the wavelet inversion with the higher-order statistics method was greatly improved, and the wavelet-inverted section could better distinguish the thin sandstone reservoirs of the upper and lower Carboniferous and their lateral distribution, providing a reliable basis of analysis for the study of thin sandstone reservoirs.

  13. Donghe Sandstone Subtle Reservoir Exploration and Development Technology in Hade 4 Oilfield

    Institute of Scientific and Technical Information of China (English)

    SunLongde; ZhouXinyuan; SongWenjie; JiangTongwen; ZhuWeihong; YangPing; NiuYujie; DiHongli

    2004-01-01

    Hade 4 oilfield is located on the Hadexun tectonic belt north of the Manjiaer depression in the Tarim basin, whose main target layer is the Donghe sandstone reservoir, with a burial depth over 5,000m and an amplitude below 34m, at the bottom of the Carboniferous. The Donghe sandstone reservoir consists of littoral facies deposited quartz sandstones of the transgressive system tract, overlapping northward and pinching out. Exploration and development confirms that water-oil contact tilts from the southeast to the northwest with a drop height of nearly 80m. The reservoir, under the control of both the stratigraphic overlap pinch-out and tectonism, is a typical subtle reservoir. The Donghe sandstone reservoir in Hade 4 oilfield also has the feature of a large oil-bearing area (over 130 km2 proved), a small thickness (average efficient thickness below 6m) and a low abundance (below 50)< 104t/km2). Moreover, above the target layer developed a set of igneous rocks with an uneven thickness in the Permian formation, thus causing a great difficulty in research of the velocity field. Considering these features,an combination mode of exploration and development is adopted, namely by way of whole deployment, step-by-step enforcement and rolling development with key problems to be tackled, in order to further deepen the understanding and enlarge the fruits of exploration and development. The paper technically focuses its study on the following four aspects concerning problem tackling. First, to strengthen the collecting, processing and explanation of seismic data, improve the resolution, accurately recognize the pinch-out line of the Donghe sandstone reservoir by combining the drilling materials in order to make sure its distribution law; second, to strengthen the research on velocity field, improve the accuracy of variable speed mapping, make corrections by the data from newlydrilled key wells and, as a result, the precision of tectonic description is greatly improved; third

  14. Diagenesis and reservoir quality of the Lower Cretaceous Quantou Formation tight sandstones in the southern Songliao Basin, China

    Science.gov (United States)

    Xi, Kelai; Cao, Yingchang; Jahren, Jens; Zhu, Rukai; Bjørlykke, Knut; Haile, Beyene Girma; Zheng, Lijing; Hellevang, Helge

    2015-12-01

    The Lower Cretaceous Quantou Formation in the southern Songliao Basin is the typical tight oil sandstone in China. For effective exploration, appraisal and production from such a tight oil sandstone, the diagenesis and reservoir quality must be thoroughly studied first. The tight oil sandstone has been examined by a variety of methods, including core and thin section observation, XRD, SEM, CL, fluorescence, electron probing analysis, fluid inclusion and isotope testing and quantitative determination of reservoir properties. The sandstones are mostly lithic arkoses and feldspathic litharenites with fine to medium grain size and moderate to good sorting. The sandstones are dominated by feldspar, quartz, and volcanic rock fragments showing various stages of disintegration. The reservoir properties are quite poor, with low porosity (average 8.54%) and permeability (average 0.493 mD), small pore-throat radius (average 0.206 μm) and high displacement pressure (mostly higher than 1 MPa). The tight sandstone reservoirs have undergone significant diagenetic alterations such as compaction, feldspar dissolution, quartz cementation, carbonate cementation (mainly ferrocalcite and ankerite) and clay mineral alteration. As to the onset time, the oil emplacement was prior to the carbonate cementation but posterior to the quartz cementation and feldspar dissolution. The smectite to illite reaction and pressure solution at stylolites provide a most important silica sources for quartz cementation. Carbonate cements increase towards interbedded mudstones. Mechanical compaction has played a more important role than cementation in destroying the reservoir quality of the K1q4 sandstone reservoirs. Mixed-layer illite/smectite and illite reduced the porosity and permeability significantly, while chlorite preserved the porosity and permeability since it tends to be oil wet so that later carbonate cementation can be inhibited to some extent. It is likely that the oil emplacement occurred

  15. Reservoir uncertainty, Precambrian topography, and carbon sequestration in the Mt. Simon Sandstone, Illinois Basin

    Science.gov (United States)

    Leetaru, H.E.; McBride, J.H.

    2009-01-01

    Sequestration sites are evaluated by studying the local geological structure and confirming the presence of both a reservoir facies and an impermeable seal not breached by significant faulting. The Cambrian Mt. Simon Sandstone is a blanket sandstone that underlies large parts of Midwest United States and is this region's most significant carbon sequestration reservoir. An assessment of the geological structure of any Mt. Simon sequestration site must also include knowledge of the paleotopography prior to deposition. Understanding Precambrian paleotopography is critical in estimating reservoir thickness and quality. Regional outcrop and borehole mapping of the Mt. Simon in conjunction with mapping seismic reflection data can facilitate the prediction of basement highs. Any potential site must, at the minimum, have seismic reflection data, calibrated with drill-hole information, to evaluate the presence of Precambrian topography and alleviate some of the uncertainty surrounding the thickness or possible absence of the Mt. Simon at a particular sequestration site. The Mt. Simon is thought to commonly overlie Precambrian basement granitic or rhyolitic rocks. In places, at least about 549 m (1800 ft) of topographic relief on the top of the basement surface prior to Mt. Simon deposition was observed. The Mt. Simon reservoir sandstone is thin or not present where basement is topographically high, whereas the low areas can have thick Mt. Simon. The paleotopography on the basement and its correlation to Mt. Simon thickness have been observed at both outcrops and in the subsurface from the states of Illinois, Ohio, Wisconsin, and Missouri. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

  16. The impact of reservoir conditions and rock heterogeneity on multiphase flow in CO2-brine-sandstone systems

    Science.gov (United States)

    Krevor, S. C.; Reynolds, C. A.; Al-Menhali, A.; Niu, B.

    2015-12-01

    Capillary strength and multiphase flow are key for modeling CO2 injection for CO2 storage. Past observations of multiphase flow in this system have raised important questions about the impact of reservoir conditions on flow through effects on wettability, interfacial tension and fluid-fluid mass transfer. In this work we report the results of an investigation aimed at resolving many of these outstanding questions for flow in sandstone rocks. The drainage capillary pressure, drainage and imbibition relative permeability, and residual trapping [1] characteristic curves have been characterized in Bentheimer and Berea sandstone rocks across a pressure range 5 - 20 MPa, temperatures 25 - 90 C and brine salinities 0-5M NaCl. Over 30 reservoir condition core flood tests were performed using techniques including the steady state relative permeability test, the semi-dynamic capillary pressure test, and a new test for the construction of the residual trapping initial-residual curve. Test conditions were designed to isolate effects of interfacial tension, viscosity ratio, density ratio, and salinity. The results of the tests show that, in the absence of rock heterogeneity, reservoir conditions have little impact on flow properties, consistent with continuum scale multiphase flow theory for water wet systems. The invariance of the properties is observed, including transitions of the CO2 from a gas to a liquid to a supercritical fluid, and in comparison with N2-brine systems. Variations in capillary pressure curves are well explained by corresponding changes in IFT although some variation may reflect small changes in wetting properties. The low viscosity of CO2at certain conditions results in sensitivity to rock heterogeneity. We show that (1) heterogeneity is the likely source of uncertainty around past relative permeability observations and (2) that appropriate scaling of the flow potential by a quantification of capillary heterogeneity allows for the selection of core flood

  17. Relations between seismic signals and reservoir properties of tight gas reservoirs in North Germany (Permian Rotliegend sandstones)

    Energy Technology Data Exchange (ETDEWEB)

    Abram, P.; Gaupp, R. [Friedrich-Schiller-Univ., Inst. of Geosciences, Jena (Germany)

    2006-07-01

    Tight gas reservoirs in North Germany consist of sandstones of eolian, fluvial and lacustrine origin in 3,5-5 km (11500-16500 ft) depth. Different mechanical compaction, mineral authigenesis and cement dissolution resulted in proximate zones with good and poor reservoir qualities. Some regions with moderate porosities provide very low permeabilities whereas regions with low porosities can offer profitable permeabilities within comparable depositional lithologies. Therefore deep gas exploration is very dependent on predictive reservoir information from 3D seismic signals due to the locally varying reservoir qualities. A recent study succeeded in subdividing a tight gas reservoir into parts with good, moderate and poor qualities and to predict reservoir properties for parts without well information. For this purpose 3D seismic signals had been classified with Neural Network techniques based on amplitude, shape and lateral coherency of seismic traces. The unsupervised classification (Kohonen map) with a single layer of neurons generated classes, which are representative for seismic wave and rock properties at the reservoir level. The geographical distribution of these seismic facies classes correlates to locations of wells with either good or poor reservoir qualities and to zones of specific petrophysical, petrological and sedimentological data. Wells with mean permeabilities between 9-50 mD are located within the red areas (seismic classes 6 and 7), while wells with mean permeabilities below 0,5 mD are all found in blue and green areas (seismic classes 1 till 4). Furthermore, the red zone in the East corresponds to the eastern part of a production field of high transmissivity. The main reason for the strong reduction in mean permeability was found to be a specific morphotype of authigenic illite which occurs almost only in the blue and green zones. This paper outlines SOME theories and results of the doctoral thesis.

  18. Distribution characteristics and petroleum geological significance of the Silurian asphaltic sandstones in Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Jun; PANG; Xiongqi; LIU; Luofu; JIANG; Zhenxue; LIU

    2004-01-01

    The Tarim Basin is a typical superimposed basin in which there have occurred multiphase adjustment and destruction of the reservoirs. The widely distributed asphaltic sandstones of the Silurian are the very product after destruction of the reservoirs. Studies show that the Silurian asphaltic sandstones distributed in both the middle and western parts on the basin are controlled chiefly by the Caledonian oil source area and by the Tazhong, Tabei and Bachu uplifts, whereas the distribution of the asphaltic sandstones on local structural belts is controlled by the reservoir's sedimentary system. Vertically, most of the asphaltic sandstones are under the regional caprock of red mudstones and the upper sandstone section of compact lithology. Due to the difference of hydrocarbon destruction in the early stage and the influence of hydrocarbon recharge in the late stage, the asphaltic sandstones and oil-bearing sandstones in the Tazhong area can be vertically divided into the upper and lower sections and they have an interactive distribution relationship as well. Asphaltic sandstones exist not only in intergranular pores but also inside the grains of sand and between the crevices, proving the destruction of early reservoirs due to uplifting. The existence of asphaltic sandstones over a large area reveals that the large-scale migration and accumulation and the subsequent destruction of hydrocarbons in the Craton area. The destruction caused a loss of the reserve resources of the Palaeozoic amounting to nearly 13.3 billion tons. Asphaltic sandstones formed after the destruction of oil and gas may serve as an effective caprock which is beneficial to accumulation of hydrocarbons and formation of the pool sealed by asphaltic sandstones in the later stage. The destruction of the early Silurian hydrocarbons depends on the stratigraphic burial depth. The deep part under the northern slope of Tazhong is an area favorable to search of undestroyed Silurian oil reservoirs.

  19. Facies architecture of the Bluejacket Sandstone in the Eufaula Lake area, Oklahoma: Implications for the reservoir characterization of the Bartlesville Sandstone

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Liangmiao; Yang, Kexian [Univ. of Tulsa, OK (United States)

    1997-08-01

    Outcrop studies of the Bluejacket Sandstone (Middle Pennsylvanian) provide significant insights to reservoir architecture of the subsurface equivalent Bartlesville Sandstone. Quarry walls and road cuts in the Lake Eufaula area offer excellent exposures for detailed facies architectural investigations using high-precision surveying, photo mosaics. Directional minipermeameter measurements are being conducted. Subsurface studies include conventional logs, borehole image log, and core data. Reservoir architectures are reconstructed in four hierarchical levels: multi-storey sandstone, i.e. discrete genetic intervals; individual discrete genetic interval; facies within a discrete genetic interval; and lateral accretion bar deposits. In both outcrop and subsurface, the Bluejacket (Bartlesville) Sandstone comprises two distinctive architectures: a lower braided fluvial and an upper meandering fluvial. Braided fluvial deposits are typically 30 to 80 ft thick, and are laterally persistent filling an incised valley wider than the largest producing fields. The lower contact is irregular with local relief of 50 ft. The braided-fluvial deposits consist of 100-400-ft wide, 5-15-ft thick channel-fill elements. Each channel-fill interval is limited laterally by an erosional contact or overbank deposits, and is separated vertically by discontinuous mudstones or highly concentrated mudstone interclast lag conglomerates. Low-angle parallel-stratified or trough cross-stratified medium- to coarse-grained sandstones volumetrically dominate. This section has a blocky well log profile. Meandering fluvial deposits are typically 100 to 150 ft thick and comprise multiple discrete genetic intervals.

  20. Understanding creep in sandstone reservoirs - theoretical deformation mechanism maps for pressure solution in granular materials

    Science.gov (United States)

    Hangx, Suzanne; Spiers, Christopher

    2014-05-01

    Subsurface exploitation of the Earth's natural resources removes the natural system from its chemical and physical equilibrium. As such, groundwater extraction and hydrocarbon production from subsurface reservoirs frequently causes surface subsidence and induces (micro)seismicity. These effects are not only a problem in onshore (e.g. Groningen, the Netherlands) and offshore hydrocarbon fields (e.g. Ekofisk, Norway), but also in urban areas with extensive groundwater pumping (e.g. Venice, Italy). It is known that fluid extraction inevitably leads to (poro)elastic compaction of reservoirs, hence subsidence and occasional fault reactivation, and causes significant technical, economic and ecological impact. However, such effects often exceed what is expected from purely elastic reservoir behaviour and may continue long after exploitation has ceased. This is most likely due to time-dependent compaction, or 'creep deformation', of such reservoirs, driven by the reduction in pore fluid pressure compared with the rock overburden. Given the societal and ecological impact of surface subsidence, as well as the current interest in developing geothermal energy and unconventional gas resources in densely populated areas, there is much need for obtaining better quantitative understanding of creep in sediments to improve the predictability of the impact of geo-energy and groundwater production. The key problem in developing a reliable, quantitative description of the creep behaviour of sediments, such as sands and sandstones, is that the operative deformation mechanisms are poorly known and poorly quantified. While grain-scale brittle fracturing plus intergranular sliding play an important role in the early stages of compaction, these time-independent, brittle-frictional processes give way to compaction creep on longer time-scales. Thermally-activated mass transfer processes, like pressure solution, can cause creep via dissolution of material at stressed grain contacts, grain

  1. Genesis Analysis of High-Gamma Ray Sandstone Reservoir and Its Log Evaluation Techniques: A Case Study from the Junggar Basin, Northwest China

    Directory of Open Access Journals (Sweden)

    Liang Wang

    2013-01-01

    Full Text Available In the Junggar basin, northwest China, many high gamma-ray (GR sandstone reservoirs are found and routinely interpreted as mudstone non-reservoirs, with negative implications for the exploration and exploitation of oil and gas. Then, the high GR sandstone reservoirs’ recognition principles, genesis, and log evaluation techniques are systematically studied. Studies show that the sandstone reservoirs with apparent shale content greater than 50% and GR value higher than 110API can be regarded as high GR sandstone reservoir. The high GR sandstone reservoir is mainly and directly caused by abnormally high uranium enrichment, but not the tuff, feldspar or clay mineral. Affected by formation’s high water sensitivity and poor borehole quality, the conventional logs can not recognize reservoir and evaluate the physical property of reservoirs. Then, the nuclear magnetic resonance (NMR logs is proposed and proved to be useful in reservoir recognition and physical property evaluation.

  2. Kinetic Modeling of Diagenesis of Eogene Lacustrine Sandstone Reservoirs in the Jianghan Basin, Southeastern China

    Institute of Scientific and Technical Information of China (English)

    倪师军; 卿海若; 唐建武; 周美夫; 李泽琴

    2002-01-01

    In the Tuoshi oilfield, located in the Cenozoic Jianghan Basin of southeastern China, there have been found hydrocarbon reservoirs hosted in lacustrine sandstones of the Eogene Xingouzui Formation. The main diagenetic features identified in these sandstones include the dissolution of detrital K-feldspar and albite grains, the precipitation of quartz as overgrowths and/or cements, and the precipitation and/or transformation of clay minerals. These diagenetic features were interpreted to have occurred in early, intermediate and late stages, based on the burial depth. The kinetics of fluid-mineral reactions and the concentrations of aqueous species at each stage of diagenesis were simulated numerically for these lacustrine sandstones, using a quasi-stationary state approximation that incorporates simultaneous chemical reactions in a time-space continuum. During the early diagenetic stage, pore fluid was weakly acidic, which resulted in dissolution of K-feldspar and albite and, therefore, led to the release of K + , Na + , Al3 + and SiO2(aq) into the diagenetic fluid. The increased K+ , Na + , Al3+ and SiO2(aq) concentrations in the diagenetic fluid caused the precipitation of quartz, kaolinite and illite. At the beginning of the intermediate diagenetic stage the concentration of H + was built up due to the decomposition of organic matter, which was responsible for further dissolution of K-feldspar and albite and precipitation of quartz, kaolinite, and illite. During the late diagenetic stage, the pore fluid was weakly alkaline, K-feldspar became stable and was precipitated with quartz and clay minerals.When the burial depth was greater than 3000 m, the pore fluids became supersaturated with respect to albite, but undersaturated with respect to quartz, resulting in the precipitation of albite and the dissolution of quartz. The diagenetic reactions forecasted in the numerical modeling closely matched the diagenetic features identified by petrographic examination, and

  3. A New Multichelating Acid System for High-Temperature Sandstone Reservoirs

    Directory of Open Access Journals (Sweden)

    Nianyin Li

    2015-01-01

    Full Text Available Sandstone reservoir acidizing is a complex and heterogeneous acid-rock reaction process. If improper acid treatment is implemented, further damage can be induced instead of removing the initial plug, particularly in high-temperature sandstone reservoirs. An efficient acid system is the key to successful acid treatment. High-temperature sandstone treatment with conventional mud acid system faces problems including high acid-rock reaction rate, short acid effective distance, susceptibility to secondary damage, and serious corrosion to pipelines. In this paper, a new multichelating acid system has been developed to overcome these shortcomings. The acid system is composed of ternary weak acid, organic phosphonic chelating agent, anionic polycarboxylic acid chelating dispersant, fluoride, and other assisted additives. Hydrogen ion slowly released by multistage ionization in ternary weak acid and organic phosphonic within the system decreases the concentration of HF to achieve retardation. Chelating agent and chelating dispersant within the system inhibited anodic and cathodic reaction, respectively, to protect the metal from corrosion, while chelating dispersant has great chelating ability on iron ions, restricting the depolarization reaction of ferric ion and metal. The synergic effect of chelating agent and chelating dispersant removes sulfate scale precipitation and inhibits or decreases potential precipitation such as CaF2, silica gel, and fluosilicate. Mechanisms of retardation, corrosion-inhibition, and scale-removing features have been discussed and evaluated with laboratory tests. Test results indicate that this novel acid system has good overall performance, addressing the technical problems and improving the acidizing effect as well for high-temperature sandstone.

  4. Study of the Effect of Clay Particles on Low Salinity Water Injection in Sandstone Reservoirs

    Directory of Open Access Journals (Sweden)

    Sina Rezaei Gomari

    2017-03-01

    Full Text Available The need for optimal recovery of crude oil from sandstone and carbonate reservoirs around the world has never been greater for the petroleum industry. Water-flooding has been applied to the supplement primary depletion process or as a separate secondary recovery method. Low salinity water injection is a relatively new method that involves injecting low salinity brines at high pressure similar to conventional water-flooding techniques, in order to recover crude oil. The effectiveness of low salinity water injection in sandstone reservoirs depends on a number of parameters such as reservoir temperature, pressure, type of clay particle and salinity of injected brine. Clay particles present on reservoir rock surfaces adsorb polar components of oil and modify wettability of sandstone rocks to the oil-wet state, which is accountable for the reduced recovery rates by conventional water-flooding. The extent of wettability alteration caused by three low salinity brines on oil-wet sandstone samples containing varying clay content (15% or 30% and type of clay (kaolinite/montmorillonite were analyzed in the laboratory experiment. Contact angles of mica powder and clay mixture (kaolinite/montmorillonite modified with crude oil were measured before and after injection with three low salinity sodium chloride brines. The effect of temperature was also analyzed for each sample. The results of the experiment indicate that samples with kaolinite clay tend to produce higher contact angles than samples with montmorillonite clay when modified with crude oil. The highest degree or extent of wettability alteration from oil-wet to intermediate-wet state upon injection with low salinity brines was observed for samples injected with brine having salinity concentration of 2000 ppm. The increase in temperature tends to produce contact angles values lying in the higher end of the intermediate-wet range (75°–115° for samples treated at 50 °C, while their corresponding

  5. Characteristics and their controlling factors of Cretaceous Kezilesu Group sandstone reservoirs in Akmomu gas field, northwestern Tarim Basin%塔西南阿克莫木气田白垩系克孜勒苏群砂岩储层特征及其控制因素

    Institute of Scientific and Technical Information of China (English)

    石石; 常志强; 徐艳梅; 阳建平; 初广震

    2012-01-01

    Characteristics of Kezilesu Group sandstone reservoirs and factors controlling their development are investigated based on the analysis of routine thin-sections,cast thin-sections,physical property and grain sizes. The results show that the reservoir rocks are dominanted by feldspathic litharemte and lithic sandstones with low porosity and permeability,and the pore types are mainly secondary pores including intragranular dissolved pores, intergranular dissolved pores and micropores. The mercury intrusion curve has high displacement pressure, indicating that the sorting of pore throats is poor and the pore structure feature in small pores and fine throats. The development of Kezilesu Group sandstone reservoirs in Akemomu gas field has strong correlation with grain sizes, debris content and diagenetic compaction, cementation and dissolution. For reservoir rocks were deposited under the control of braided rivers, their quality improves with grain size enlarging, debns content increasing and enhancing of dissolution. On the contrary, compaction and cementation of carbonate, clay and siliceous mineral formed during the post-diagenesis have adverse effects on reservoir rocks.%根据常规薄片、铸体薄片、常规物性和粒度分析,研究了塔西南阿克莫木气田克孜勒苏群砂岩储层的地质特征及其主控因素.结果表明,该套储层岩石类型以长石岩屑砂岩及岩屑砂岩为主;储层物性较差,为低孔、低渗储层;孔隙类型以次生孔隙为主,主要有粒内溶孔、粒间溶孔及微孔隙等;压汞曲线排驱压力较高,一般孔喉分选较差,总体具有小孔细喉的孔隙结构特征.阿克莫木气田克孜勒苏群砂岩储层发育程度与碎屑颗粒的粒度粗细,岩屑含量以及成岩阶段的压实、胶结和溶蚀作用具有较强的相关性.辫状水道控制下的碎屑颗粒越粗,岩屑含量相对越高,溶蚀作用越强,储层就越发育;压实作用及成岩后期的碳酸盐岩、

  6. Integrated reservoir characterization of a heterogeneous channel sandstone : the Duchess Lower Manville X pool

    Energy Technology Data Exchange (ETDEWEB)

    Potocki, D.; Raychaudhuri, I.; Thorburn, L. [PanCanadian Petroleum Ltd. (Canada); Galas, C.; King, H.

    1999-01-01

    The Basal Quartz formation of the Duchess Lower Mannville X pool located in southern Alberta was characterized to determine if the reservoir was a good candidate for waterflooding. Twenty performance predictions were run. The Basal Quartz reservoir sandstones have large unanticipated intrawell and interwell variations in log derived porosity and resistivity. An extensive gas cap was also found in most of the wells. Most wells were producing with a high GOR despite the thick oil zone. It was concluded that conversion of selected wells to injection and horizontal infill wells would increase the oil recovery, but due to geological heterogeneity, the gas cap and a high in situ oil viscosity, the pool could not be considered to be a good candidate for waterflooding. 3 refs., 12 figs.

  7. Use of nanoparticles to improve the performance of sodium dodecyl sulfate flooding in a sandstone reservoir

    Science.gov (United States)

    Ahmadi, Mohammad Ali

    2016-12-01

    One of the prominent enhanced oil recovery (EOR) methods in oil reservoirs is surfactant flooding. The purpose of this research is to study the effect of nanoparticles on the surfactant adsorption. Real reservoir sandstone rock samples were implemented in adsorption tests. The ranges of the initial surfactant and nano silica concentrations were from 500 to 5000 ppm and 500 ppm to 2000 ppm, respectively. The commercial surfactant used is sodium dodecyl sulfate (SDS) as an ionic surfactant and two different types of nano silica were employed. The rate of surfactant losses extremely depends on the concentration of surfactant in the system, and it was found that the adsorption of surfactant decreased with increasing the concentration of nano silica. Also, it was found that hydrophobic nano silica is more effective than hydrophilic nanoparticles.

  8. A geological overview of the Panuke field reservoir sandstones, offshore Nova Scotia

    Energy Technology Data Exchange (ETDEWEB)

    Hogg, J.R.; DeLong, I.D. [PanCanadian Petroleum Ltd., Calgary, AB (Canada)

    1998-09-01

    The Panuke oil field, discovered in 1986, was one of the first producing fields in the Canadian offshore with first oil in 1992. The field is associated with the Scotian Basin, an early Cretaceous reservoir with porosity ranging from 20 to 26 per cent and permeability from 500 to 2000 md. The Cohasset and Panuke fields combined, produce an average of 4500 m{sup 3}/d of high gravity oil with a gas-oil ratio of 17 m{sup 3}/m{sup 3}. Migration of the hydrocarbons into the structure is believed to be through a listric normal fault formed by differential subsidence of the Cretaceous sediments over the Jurassic bank edge. Details of the sedimentology and the stratigraphic relationship of the reservoir sandstones of the Panuke field are provided. 4 figs.

  9. Study on fine geological modelling of the fluvial sandstone reservoir in Daqing oilfield

    Energy Technology Data Exchange (ETDEWEB)

    Zhoa Han-Qing [Daqing Research Institute, Helongjiang (China)

    1997-08-01

    These paper aims at developing a method for fine reservoir description in maturing oilfields by using close spaced well logging data. The main productive reservoirs in Daqing oilfield is a set of large fluvial-deltaic deposits in the Songliao Lake Basin, characterized by multi-layers and serious heterogeneities. Various fluvial channel sandstone reservoirs cover a fairly important proportion of reserves. After a long period of water flooding, most of them have turned into high water cut layers, but there are considerable residual reserves within them, which are difficult to find and tap. Making fine reservoir description and developing sound a geological model is essential for tapping residual oil and enhancing oil recovery. The principal reason for relative lower precision of predicting model developed by using geostatistics is incomplete recognition of complex distribution of fluvial reservoirs and their internal architecture`s. Tasking advantage of limited outcrop data from other regions (suppose no outcrop data available in oilfield) can only provide the knowledge of subtle changing of reservoir parameters and internal architecture. For the specific geometry distribution and internal architecture of subsurface reservoirs (such as in produced regions) can be gained only from continuous infilling logging well data available from studied areas. For developing a geological model, we think the first important thing is to characterize sandbodies geometries and their general architecture`s, which are the framework of models, and then the slight changing of interwell parameters and internal architecture`s, which are the contents and cells of the model. An excellent model should possess both of them, but the geometry is the key to model, because it controls the contents and cells distribution within a model.

  10. Performance of Surfactant Methyl Ester Sulphonate solution for Oil Well Stimulation in reservoir sandstone TJ Field

    Science.gov (United States)

    Eris, F. R.; Hambali, E.; Suryani, A.; Permadi, P.

    2017-05-01

    Asphaltene, paraffin, wax and sludge deposition, emulsion and water blocking are kinds ofprocess that results in a reduction of the fluid flow from the reservoir into formation which causes a decrease of oil wells productivity. Oil well Stimulation can be used as an alternative to solve oil well problems. Oil well stimulation technique requires applying of surfactant. Sodium Methyl Ester Sulphonate (SMES) of palm oil is an anionic surfactant derived from renewable natural resource that environmental friendly is one of potential surfactant types that can be used in oil well stimulation. This study was aimed at formulation SMES as well stimulation agent that can identify phase transitions to phase behavior in a brine-surfactant-oil system and altered the wettability of rock sandstone and limestone. Performance of SMES solution tested by thermal stability test, phase behavioral examination and rocks wettability test. The results showed that SMES solution (SMES 5% + xylene 5% in the diesel with addition of 1% NaCl at TJformation water and SMES 5% + xylene 5% in methyl ester with the addition of NaCl 1% in the TJ formation water) are surfactant that can maintain thermal stability, can mostly altered the wettability toward water-wet in sandstone reservoir, TJ Field.

  11. Imaging pore space in tight gas sandstone reservoir: insights from broad ion beam cross-sectioning

    Science.gov (United States)

    Desbois, G.; Enzmann, F.; Urai, J. L.; Baerle, C.; Kukla, P. A.; Konstanty, J.

    2010-06-01

    Monetization of tight gas reservoirs, which contain significant gas reserves world-wide, represents a challenge for the entire oil and gas industry. The development of new technologies to enhance tight gas reservoir productivity is strongly dependent on an improved understanding of the rock properties and especially the pore framework. Numerous methods are now available to characterize sandstone cores. However, the pore space characterization at pore scale remains difficult due to the fine pore size and delicate sample preparation, and has thus been mostly indirectly inferred until now. Here we propose a new method of ultra high-resolution petrography combining high resolution SEM and argon ion beam cross sectioning (BIB, Broad Ion Beam) which prepares smooth and damage free surfaces. We demonstrate this method using the example of Permian (Rotliegend) age tight gas sandstone core samples. The combination of Ar-beam cross-sectioning facility and high-resolution SEM imaging has the potential to result in a step change in the understanding of pore geometries, in terms of its morphology, spatial distribution and evolution based on the generation of unprecedented image quality and resolution enhancing the predictive reliability of image analysis.

  12. Imaging pore space in tight gas sandstone reservoir: insights from broad ion beam cross-sectioning

    Directory of Open Access Journals (Sweden)

    Konstanty J.

    2010-06-01

    Full Text Available Monetization of tight gas reservoirs, which contain significant gas reserves world-wide, represents a challenge for the entire oil and gas industry. The development of new technologies to enhance tight gas reservoir productivity is strongly dependent on an improved understanding of the rock properties and especially the pore framework. Numerous methods are now available to characterize sandstone cores. However, the pore space characterization at pore scale remains difficult due to the fine pore size and delicate sample preparation, and has thus been mostly indirectly inferred until now. Here we propose a new method of ultra high-resolution petrography combining high resolution SEM and argon ion beam cross sectioning (BIB, Broad Ion Beam which prepares smooth and damage free surfaces. We demonstrate this method using the example of Permian (Rotliegend age tight gas sandstone core samples. The combination of Ar-beam cross-sectioning facility and high-resolution SEM imaging has the potential to result in a step change in the understanding of pore geometries, in terms of its morphology, spatial distribution and evolution based on the generation of unprecedented image quality and resolution enhancing the predictive reliability of image analysis.

  13. Geology and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Annual report, October 1, 1996--September 30, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Chidsey, T.C. Jr.; Anderson, P.B.; Morris, T.H.; Dewey, J.A. Jr.; Mattson, A.; Foster, C.B.; Snelgrove, S.H.; Ryer, T.A.

    1998-05-01

    The objective of the Ferron Sandstone (Utah) project is to develop a comprehensive, interdisciplinary, quantitative characterization of a fluvial-deltaic reservoir to allow realistic interwell and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Both new and existing data is being integrated into a 3-D model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. The project is divided into four tasks: (1) regional stratigraphic analysis, (2) case studies, (3) reservoirs models, and (4) field-scale evaluation of exploration strategies. The primary objective of the regional stratigraphic analysis is to provide a more detailed interpretation of the stratigraphy and gross reservoir characteristics of the Ferron Sandstone as exposed in outcrop. The primary objective of the case-studies work is to develop a detailed geological and petrophysical characterization, at well-sweep scale or smaller, of the primary reservoir lithofacies typically found in a fluvial-dominated deltaic reservoir. Work on tasks 3 and 4 consisted of developing two- and three-dimensional reservoir models at various scales. The bulk of the work on these tasks is being completed primarily during the last year of the project, and is incorporating the data and results of the regional stratigraphic analysis and case-studies tasks.

  14. Geological and Petrophysical Characterization of the Ferron Sandstone for 3-D Simulation of a Fluvial-Deltaic Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Chidsey, Jr, Thomas C.

    2001-10-31

    The objective of the Ferron Sandstone project was to develop a comprehensive, interdisciplinary, quantitative characterization f fluvial-deltaic reservoir to allow realistic interwell and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Quantitative geological and petrophysical information on the Cretaceous Ferron Sandstone in east-central Utah was collected. Both new and existing data was integrated into a three-dimensional model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations.

  15. Reservoir Characterization of Bridgeport and Cypress Sandstones in Lawrence Field Illinois to Improve Petroleum Recovery by Alkaline-Surfactant-Polymer Flood

    Energy Technology Data Exchange (ETDEWEB)

    Seyler, Beverly; Grube, John; Huff, Bryan; Webb, Nathan; Damico, James; Blakley, Curt; Madhavan, Vineeth; Johanek, Philip; Frailey, Scott

    2012-12-21

    Within the Illinois Basin, most of the oilfields are mature and have been extensively waterflooded with water cuts that range up to 99% in many of the larger fields. In order to maximize production of significant remaining mobile oil from these fields, new recovery techniques need to be researched and applied. The purpose of this project was to conduct reservoir characterization studies supporting Alkaline-Surfactant-Polymer Floods in two distinct sandstone reservoirs in Lawrence Field, Lawrence County, Illinois. A project using alkaline-surfactantpolymer (ASP) has been established in the century old Lawrence Field in southeastern Illinois where original oil in place (OOIP) is estimated at over a billion barrels and 400 million barrels have been recovered leaving more than 600 million barrels as an EOR target. Radial core flood analysis using core from the field demonstrated recoveries greater than 20% of OOIP. While the lab results are likely optimistic to actual field performance, the ASP tests indicate that substantial reserves could be recovered even if the field results are 5 to 10% of OOIP. Reservoir characterization is a key factor in the success of any EOR application. Reservoirs within the Illinois Basin are frequently characterized as being highly compartmentalized resulting in multiple flow unit configurations. The research conducted on Lawrence Field focused on characteristics that define reservoir compartmentalization in order to delineate preferred target areas so that the chemical flood can be designed and implemented for the greatest recovery potential. Along with traditional facies mapping, core analyses and petrographic analyses, conceptual geological models were constructed and used to develop 3D geocellular models, a valuable tool for visualizing reservoir architecture and also a prerequisite for reservoir simulation modeling. Cores were described and potential permeability barriers were correlated using geophysical logs. Petrographic analyses

  16. Reservoir zonation based on statistical analyses: A case study of the Nubian sandstone, Gulf of Suez, Egypt

    Science.gov (United States)

    El Sharawy, Mohamed S.; Gaafar, Gamal R.

    2016-12-01

    Both reservoir engineers and petrophysicists have been concerned about dividing a reservoir into zones for engineering and petrophysics purposes. Through decades, several techniques and approaches were introduced. Out of them, statistical reservoir zonation, stratigraphic modified Lorenz (SML) plot and the principal component and clustering analyses techniques were chosen to apply on the Nubian sandstone reservoir of Palaeozoic - Lower Cretaceous age, Gulf of Suez, Egypt, by using five adjacent wells. The studied reservoir consists mainly of sandstone with some intercalation of shale layers with varying thickness from one well to another. The permeability ranged from less than 1 md to more than 1000 md. The statistical reservoir zonation technique, depending on core permeability, indicated that the cored interval of the studied reservoir can be divided into two zones. Using reservoir properties such as porosity, bulk density, acoustic impedance and interval transit time indicated also two zones with an obvious variation in separation depth and zones continuity. The stratigraphic modified Lorenz (SML) plot indicated the presence of more than 9 flow units in the cored interval as well as a high degree of microscopic heterogeneity. On the other hand, principal component and cluster analyses, depending on well logging data (gamma ray, sonic, density and neutron), indicated that the whole reservoir can be divided at least into four electrofacies having a noticeable variation in reservoir quality, as correlated with the measured permeability. Furthermore, continuity or discontinuity of the reservoir zones can be determined using this analysis.

  17. Factors controlling reservoir quality in tertiary sandstones and their significance to geopressured geothermal production. Annual report, May 1, 1979-May 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Loucks, R.G.; Richmann, D.L.; Milliken, K.L.

    1980-07-01

    Differing extents of diagenetic modification is the factor primarily responsible for contrasting regional reservoir quality of Tertiary sandstones from the Upper and Lower Texas Gulf Coast. Detailed comparison of Frio sandstones from the Chocolate Bayou/Danbury Dome area, Brazoria County, and Vicksburg sandstones from the McAllen Ranch Field area, Hidalgo County, reveals that extent of diagenetic modification is most strongly influenced by (1) detrital mineralogy and (2) regional geothermal gradients. Vicksburg sandstones from the McAllen Ranch Field area are less stable, chemically and mechanically, than Frio sandstones from the Chocolate Bayou/Danbury dome area. Vicksburg sandstones are mineralogically immature and contain greater proportions of feldspars and rock fragments than do Frio sandstones. Thr reactive detrital assemblage of Vicksubrg sandstones is highly susceptible to diagenetic modification. Susceptibility is enhanced by higher than normal geothermal gradients in the McAllen Ranch Field area. Thus, consolidation of Vicksburg sandstones began at shallower depth of burial and precipitation of authigenic phases (especially calcite) was more pervasive than in Frio sandstones. Moreover, the late-stage episode of ferroan calcite precipitation that occluded most secondary porosity in Vicksburg sandstones did not occur significantly in Frio sandstones. Therefore, regional reservoir quality of Frio sandstones from Brazoria County is far better than that characterizing Vicksburg sandstones from Hidalgo County, especially at depths suitable for geopressured geothermal energy production.

  18. Continuity and internal properties of Gulf Coast sandstones and their implications for geopressured fluid production

    Energy Technology Data Exchange (ETDEWEB)

    Morton, R.A.; Ewing, T.E.; Tyler, N.

    1983-01-01

    The intrinsic properties of the genetic sandstone units that typify many geopressured geothermal aquifers and hydrocarbon reservoirs in the Gulf Coast region were systematically investigated classified, and differentiated. The following topics are coverd: structural and stratigraphic limits of sandstone reservoirs, characteristics and dimensions of Gulf Coast sandstones; fault-compartment areas; comparison of production and geologic estimates of aquifer fluid volume; geologic setting and reservoir characteristics, Wells of Opportunity; internal properties of sandstones; and implications for geopressured fluid production. (MHR)

  19. Petroacoustic Modelling of Heterolithic Sandstone Reservoirs: A Novel Approach to Gassmann Modelling Incorporating Sedimentological Constraints and NMR Porosity data

    Science.gov (United States)

    Matthews, S.; Lovell, M.; Davies, S. J.; Pritchard, T.; Sirju, C.; Abdelkarim, A.

    2012-12-01

    Heterolithic or 'shaly' sandstone reservoirs constitute a significant proportion of hydrocarbon resources. Petroacoustic models (a combination of petrophysics and rock physics) enhance the ability to extract reservoir properties from seismic data, providing a connection between seismic and fine-scale rock properties. By incorporating sedimentological observations these models can be better constrained and improved. Petroacoustic modelling is complicated by the unpredictable effects of clay minerals and clay-sized particles on geophysical properties. Such effects are responsible for erroneous results when models developed for "clean" reservoirs - such as Gassmann's equation (Gassmann, 1951) - are applied to heterolithic sandstone reservoirs. Gassmann's equation is arguably the most popular petroacoustic modelling technique in the hydrocarbon industry and is used to model elastic effects of changing reservoir fluid saturations. Successful implementation of Gassmann's equation requires well-constrained drained rock frame properties, which in heterolithic sandstones are heavily influenced by reservoir sedimentology, particularly clay distribution. The prevalent approach to categorising clay distribution is based on the Thomas - Stieber model (Thomas & Stieber, 1975), this approach is inconsistent with current understanding of 'shaly sand' sedimentology and omits properties such as sorting and grain size. The novel approach presented here demonstrates that characterising reservoir sedimentology constitutes an important modelling phase. As well as incorporating sedimentological constraints, this novel approach also aims to improve drained frame moduli estimates through more careful consideration of Gassmann's model assumptions and limitations. A key assumption of Gassmann's equation is a pore space in total communication with movable fluids. This assumption is often violated by conventional applications in heterolithic sandstone reservoirs where effective porosity, which

  20. Relationships between stylolites and cementation in sandstone reservoirs: Examples from the North Sea, U.K. and East Greenland

    Science.gov (United States)

    Baron, Martin; Parnell, John

    2007-01-01

    The reservoir potential of hydrocarbon sandstone reservoirs may be significantly reduced by compartmentation as a result of the development of stylolites. A petrographic and fluid inclusion microthermometric study was performed on sandstones containing abundant stylolites from the Buchan, Galley and Scott Fields in the Outer Moray Firth, offshore Scotland, and from a palaeo-oil bearing sequence in East Greenland. The main objective of this study was to further constrain the temperatures and burial depths at which stylolitization occurs in sandstone reservoirs. The sandstones containing abundant stylolites are also characterized by their highly cemented nature. Numerous occurrences of quartz overgrowths clearly truncated by sutured stylolites are evident in all of the samples. Fluid inclusion microthermometry reveals that quartz cementation, which is interpreted to be coeval with stylolitization, occurred at minimum temperatures of between 86 and 136 °C. Basin modelling of the Scott and Galley Fields indicates that quartz cementation and stylolite development formed at depths greater than 2.5 km which were attained during rapid Tertiary burial. The occurrence of hydrocarbon fluid inclusions within healed microfractures orientated at high angles to the stylolites suggests that these microfractures provided pathways for hydrocarbon migration in the highly cemented, low permeability zones associated with highly stylolitized sandstones.

  1. Predictive modeling of CO2 sequestration in deep saline sandstone reservoirs: Impacts of geochemical kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Balashov, Victor N.; Guthrie, George D.; Hakala, J. Alexandra; Lopano, Christina L.; Rimstidt, J. Donald; Brantley, Susan L.

    2013-03-01

    One idea for mitigating the increase in fossil-fuel generated CO{sub 2} in the atmosphere is to inject CO{sub 2} into subsurface saline sandstone reservoirs. To decide whether to try such sequestration at a globally significant scale will require the ability to predict the fate of injected CO{sub 2}. Thus, models are needed to predict the rates and extents of subsurface rock-water-gas interactions. Several reactive transport models for CO{sub 2} sequestration created in the last decade predicted sequestration in sandstone reservoirs of ~17 to ~90 kg CO{sub 2} m{sup -3|. To build confidence in such models, a baseline problem including rock + water chemistry is proposed as the basis for future modeling so that both the models and the parameterizations can be compared systematically. In addition, a reactive diffusion model is used to investigate the fate of injected supercritical CO{sub 2} fluid in the proposed baseline reservoir + brine system. In the baseline problem, injected CO{sub 2} is redistributed from the supercritical (SC) free phase by dissolution into pore brine and by formation of carbonates in the sandstone. The numerical transport model incorporates a full kinetic description of mineral-water reactions under the assumption that transport is by diffusion only. Sensitivity tests were also run to understand which mineral kinetics reactions are important for CO{sub 2} trapping. The diffusion transport model shows that for the first ~20 years after CO{sub 2} diffusion initiates, CO{sub 2} is mostly consumed by dissolution into the brine to form CO{sub 2,aq} (solubility trapping). From 20-200 years, both solubility and mineral trapping are important as calcite precipitation is driven by dissolution of oligoclase. From 200 to 1000 years, mineral trapping is the most important sequestration mechanism, as smectite dissolves and calcite precipitates. Beyond 2000 years, most trapping is due to formation of aqueous HCO{sub 3}{sup -}. Ninety-seven percent of the

  2. Diagenesis, provenance and reservoir quality of Triassic TAGI sandstones from Ourhoud field, Berkine (Ghadames) Basin, Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, C.; Arribas, J.; Tortosa, A. [Universidad Complutense de Madrid, (Spain). Departamento de Petrologia y Geoquimica; Kalin, O. [Universidad Complutense, Madrid (Spain). Departamento de Paleontologia

    2002-02-01

    The Triassic TAGI (Trias Argilo-Greseux Inferieur) fluvial sandstones are the main oil reservoirs in the Berkine Basin, Algeria. Nonetheless, their provenance and diagenesis, and their impact on reservoir quality, are virtually unknown. Samples from the Ourhoud field, representing the Lower, Middle and Upper TAGI subunits, were studied using a combination of petrographic, mineralogical and geochemical techniques. The Lower TAGI sandstones have an average framework composition of Q{sub 98.3}F{sub 0.6}R{sub 1.1} and 95% of the quartz grains are monocrystalline. By contrast, the Middle-Upper TAGI sandstones have an average framework composition of Q{sub 88.3}F{sub 9.8}R{sub 1.9} and 79% of the quartz grains are monocrystalline. The Lower TAGI quartz arenites derived from Paleozoic siliclastic rocks, whereas the Middle-Upper TAGI subarkoses originated mainly from metamorphic terrains. This change in provenance is a potential criterion for correlation within the TAGI. Also, this change has contributed to the significantly different diagenetic paths followed by the Lower TAGI quartz arenites and the Middle-Upper TAGI subarkoses. Grain-coating illitic clays are abundant in the Lower TAGI, where they exert a critical control on reservoir quality. These clays are interpreted as pedogenic and/or infiltrated in origin and to have had, in part, smectitic precursors. Shallow burial Fe-dolomite cementation was favored in the downthrown block of the field-bounding fault, where it contributed to the poor reservoir quality. Magnesite-siderite cements are multiphase. The earliest generation is composed of Fe-rich magnesite that precipitated during shallow burial from hypersaline fluids with high Mg/Ca ratios, probably refluxed residual brines associated with the Liassic evaporites. Later magnesite-siderite generations precipitated during deeper burial from waters with progressively higher Fe/Mg ratios. Authigenic vermicular kaolin largely consists of dickite that replaced previously

  3. An integrated approach to remove and mitigate carbonate scale in a low temperature sandstone reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Al-Saiari, H.A.; Nasr-El-Din, H.A.

    2006-03-15

    Calcium carbonate and iron sulfide scales were detected in several wells in a low temperature sandstone reservoir. These scales were detected downhole; covering perforations and in-take of submersible pumps. The presence of scale has adversely affected well performance. The paper will present the results of detailed studies conducted to design and field test acid treatment to remove the scale and a new scale squeeze treatment to mitigate scale formation. The treatment has been successfully applied to more than 35 wells. Some of these wells were de scaled before the squeeze, while other wells were squeeze before scale detection. Field data indicated that the acid treatment resorted well productivity. The scale squeeze treatment which utilized a newly developed inhibitor was successfully applied in the field and has a life time that exceeded two years in most of the treated wells. (Author)

  4. Reservoir Characterization of Bridgeport and Cypress Sandstones in Lawrence Field Illinois to Improve Petroleum Recovery by Alkaline-Surfactant-Polymer Flood

    Energy Technology Data Exchange (ETDEWEB)

    Seyler, Beverly; Grube, John; Huff, Bryan; Webb, Nathan; Damico, James; Blakley, Curt; Madhavan, Vineeth; Johanek, Philip; Frailey, Scott

    2012-12-21

    Within the Illinois Basin, most of the oilfields are mature and have been extensively waterflooded with water cuts that range up to 99% in many of the larger fields. In order to maximize production of significant remaining mobile oil from these fields, new recovery techniques need to be researched and applied. The purpose of this project was to conduct reservoir characterization studies supporting Alkaline-Surfactant-Polymer Floods in two distinct sandstone reservoirs in Lawrence Field, Lawrence County, Illinois. A project using alkaline-surfactantpolymer (ASP) has been established in the century old Lawrence Field in southeastern Illinois where original oil in place (OOIP) is estimated at over a billion barrels and 400 million barrels have been recovered leaving more than 600 million barrels as an EOR target. Radial core flood analysis using core from the field demonstrated recoveries greater than 20% of OOIP. While the lab results are likely optimistic to actual field performance, the ASP tests indicate that substantial reserves could be recovered even if the field results are 5 to 10% of OOIP. Reservoir characterization is a key factor in the success of any EOR application. Reservoirs within the Illinois Basin are frequently characterized as being highly compartmentalized resulting in multiple flow unit configurations. The research conducted on Lawrence Field focused on characteristics that define reservoir compartmentalization in order to delineate preferred target areas so that the chemical flood can be designed and implemented for the greatest recovery potential. Along with traditional facies mapping, core analyses and petrographic analyses, conceptual geological models were constructed and used to develop 3D geocellular models, a valuable tool for visualizing reservoir architecture and also a prerequisite for reservoir simulation modeling. Cores were described and potential permeability barriers were correlated using geophysical logs. Petrographic analyses

  5. Characterizing gas shaly sandstone reservoirs using the magnetic resonance technology in the Anaco area, East Venezuela

    Energy Technology Data Exchange (ETDEWEB)

    Fam, Maged; August, Howard [Halliburton, Houston, TX (United States); Zambrano, Carlos; Rivero, Fidel [PDVSA Gas (Venezuela)

    2008-07-01

    With demand for natural gas on the rise every day, accounting for and booking every cubic foot of gas is becoming very important to operators exploiting natural gas reservoirs. The initial estimates of gas reserves are usually established through the use of petrophysical parameters normally based on wireline and/or LWD logs. Conventional logs, such as gamma ray, density, neutron, resistivity and sonic, are traditionally used to calculate these parameters. Sometimes, however, the use of such conventional logs may not be enough to provide a high degree of accuracy in determining these petrophysical parameters, which are critical to reserve estimates. Insufficient accuracy can be due to high complexities in the rock properties and/or a formation fluid distribution within the reservoir layers that is very difficult to characterize with conventional logs alone. The high degree of heterogeneity in the shaly sandstone rock properties of the Anaco area, East Venezuela, can be characterized by clean, high porosity, high permeability sands to very shaly, highly laminated, and low porosity rock. This wide variation in the reservoir properties may pose difficulties in identifying gas bearing zones which may affect the final gas reserves estimates in the area. The application of the magnetic resonance imaging (MRI) logging technology in the area, combined with the application of its latest acquisition and interpretation methods, has proven to be very adequate in detecting and quantifying gas zones as well as providing more realistic petrophysical parameters for better reserve estimates. This article demonstrates the effectiveness of applying the MRI logging technology to obtain improved petrophysical parameters that will help better characterize the shaly-sands of Anaco area gas reservoirs. This article also demonstrates the value of MRI in determining fluid types, including distinguishing between bound water and free water, as well as differentiating between gas and liquid

  6. Geochemical modeling of diagenetic reactions in Snorre Field reservoir sandstones: a comparative study of computer codes

    Directory of Open Access Journals (Sweden)

    Marcos Antonio Klunk

    Full Text Available ABSTRACTDiagenetic reactions, characterized by the dissolution and precipitation of minerals at low temperatures, control the quality of sedimentary rocks as hydrocarbon reservoirs. Geochemical modeling, a tool used to understand diagenetic processes, is performed through computer codes based on thermodynamic and kinetic parameters. In a comparative study, we reproduced the diagenetic reactions observed in Snorre Field reservoir sandstones, Norwegian North Sea. These reactions had been previously modeled in the literature using DISSOL-THERMAL code. In this study, we modeled the diagenetic reactions in the reservoirs using Geochemist's Workbench (GWB and TOUGHREACT software, based on a convective-diffusive-reactive model and on the thermodynamic and kinetic parameters compiled for each reaction. TOUGHREACT and DISSOL-THERMAL modeling showed dissolution of quartz, K-feldspar and plagioclase in a similar temperature range from 25 to 80°C. In contrast, GWB modeling showed dissolution of albite, plagioclase and illite, as well as precipitation of quartz, K-feldspar and kaolinite in the same temperature range. The modeling generated by the different software for temperatures of 100, 120 and 140°C showed similarly the dissolution of quartz, K-feldspar, plagioclase and kaolinite, but differed in the precipitation of albite and illite. At temperatures of 150 and 160°C, GWB and TOUGHREACT produced different results from the DISSOL-THERMAL, except for the dissolution of quartz, plagioclase and kaolinite. The comparative study allows choosing the numerical modeling software whose results are closer to the diagenetic reactions observed in the petrographic analysis of the modeled reservoirs.

  7. Electrofacies vs. lithofacies sandstone reservoir characterization Campanian sequence, Arshad gas/oil field, Central Sirt Basin, Libya

    Science.gov (United States)

    Burki, Milad; Darwish, Mohamed

    2017-06-01

    The present study focuses on the vertically stacked sandstones of the Arshad Sandstone in Arshad gas/oil field, Central Sirt Basin, Libya, and is based on the conventional cores analysis and wireline log interpretation. Six lithofacies types (F1 to F6) were identified based on the lithology, sedimentary structures and biogenic features, and are supported by wireline log calibration. From which four types (F1-F4) represent the main Campanian sandstone reservoirs in the Arshad gas/oil field. Lithofacies F5 is the basal conglomerates at the lower part of the Arshad sandstones. The Paleozoic Gargaf Formation is represented by lithofacies F6 which is the source provenance for the above lithofacies types. Arshad sediments are interpreted to be deposited in shallow marginal and nearshore marine environment influenced by waves and storms representing interactive shelf to fluvio-marine conditions. The main seal rocks are the Campanian Sirte shale deposited in a major flooding events during sea level rise. It is contended that the syn-depositional tectonics controlled the distribution of the reservoir facies in time and space. In addition, the post-depositional changes controlled the reservoir quality and performance. Petrophysical interpretation from the porosity log values were confirmed by the conventional core measurements of the different sandstone lithofacies types. Porosity ranges from 5 to 20% and permeability is between 0 and 20 mD. Petrophysical cut-off summary of the lower part of the clastic dominated sequence (i. e. Arshad Sandstone) calculated from six wells includes net pay sand ranging from 19.5‧ to 202.05‧, average porosity from 7.7 to 15% and water saturation from 19 to 58%.

  8. Revitalizing a mature oil play: Strategies for finding and producing oil in Frio Fluvial-Deltaic Sandstone reservoirs of South Texas

    Energy Technology Data Exchange (ETDEWEB)

    Knox, P.R.; Holtz, M.H.; McRae, L.E. [and others

    1996-09-01

    Domestic fluvial-dominated deltaic (FDD) reservoirs contain more than 30 Billion barrels (Bbbl) of remaining oil, more than any other type of reservoir, approximately one-third of which is in danger of permanent loss through premature field abandonments. The U.S. Department of Energy has placed its highest priority on increasing near-term recovery from FDD reservoirs in order to prevent abandonment of this important strategic resource. To aid in this effort, the Bureau of Economic Geology, The University of Texas at Austin, began a 46-month project in October, 1992, to develop and demonstrate advanced methods of reservoir characterization that would more accurately locate remaining volumes of mobile oil that could then be recovered by recompleting existing wells or drilling geologically targeted infill. wells. Reservoirs in two fields within the Frio Fluvial-Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas, a mature play which still contains 1.6 Bbbl of mobile oil after producing 1 Bbbl over four decades, were selected as laboratories for developing and testing reservoir characterization techniques. Advanced methods in geology, geophysics, petrophysics, and engineering were integrated to (1) identify probable reservoir architecture and heterogeneity, (2) determine past fluid-flow history, (3) integrate fluid-flow history with reservoir architecture to identify untapped, incompletely drained, and new pool compartments, and (4) identify specific opportunities for near-term reserve growth. To facilitate the success of operators in applying these methods in the Frio play, geologic and reservoir engineering characteristics of all major reservoirs in the play were documented and statistically analyzed. A quantitative quick-look methodology was developed to prioritize reservoirs in terms of reserve-growth potential.

  9. The equilibrium between diagenetic calcites and dolomites and its impact on reservoir quality in the sandstone reservoir of Kela 2 gas field

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the equilibrium theory of chemical reactions between water and rocks, this paper establishes a thermodynamic phase relationship diagram among calcites, dolomites and water solution under the condition of diagenesis based on the thermodynamic database of related minerals and fluids and dolomite's degree of order parameters. It has been discovered that the equilibrium between calcites and dolomites in the diagenetic environment is strongly impacted by temperature and the Ca/Mg ratios in groundwater, and that the dolomite's degree of order in the diagenetic environment is a function of crystallization temperature and time, not controlled by water solution. Hereby, the authors make a further analysis of the close relationship of chemical reaction between carbonate cements and pore water in the sandstone reservoirs of Kala 2 gas field in Kuche sag. It can be seen that there are different impacts on sandstone reservoir quality among the equilibrium system of calcites, dolomites and pore water at different depths of reservoirs.

  10. Geothermal energy from the Main Karoo Basin (South Africa): An outcrop analogue study of Permian sandstone reservoir formations

    Science.gov (United States)

    Campbell, Stuart A.; Lenhardt, Nils; Dippenaar, Matthys A.; Götz, Annette E.

    2016-04-01

    The geothermal potential of the South African Main Karoo Basin has not been addressed in the past, although thick siliciclastic successions in geothermal prone depths are promising target reservoir formations. A first assessment of the geothermal potential of the Karoo Basin is based on petro- and thermophysical data gained from an outcrop analogue study of Permian sandstones in the Eastern Cape Province, and evaluation of groundwater temperature and heat flow values from literature. A volumetric approach of the sandstones' reservoir potential leads to a first estimation of 2240 TWh (8.0 EJ) of power generation within the central and southern part of the basin. Comparison with data from other sedimentary basins where deep geothermal reservoirs are identified shows the high potential of the Karoo for future geothermal resource exploration, development and production. The mainly low permeability lithotypes may be operated as stimulated systems, depending on the fracture porosity in the deeper subsurface. In some areas auto-convective thermal water circulation might be expected and direct heat use becomes reasonable. The data presented here serve to identify exploration areas and are valuable attributes for reservoir modeling, contributing to (1) a reliable reservoir prognosis, (2) the decision of potential reservoir stimulation, and (3) the planning of long-term efficient reservoir utilization.

  11. Effective Wettability Measurements of CO2-Brine-Sandstone System at Different Reservoir Conditions

    Science.gov (United States)

    Al-Menhali, Ali; Krevor, Samuel

    2014-05-01

    , core-scale effective contact angle can be determined. In addition to providing a quantitative measure of the core-averaged wetting properties, the technique allows for the observation of shifts in contact angle with changing conditions. We examine the wettability changes of the CO2-brine system in Berea sandstone with variations in reservoir conditions including supercritical, gaseous and liquid CO2injection. We evaluate wettability variation within a single rock with temperature, pressure, and salinity across a range of conditions relevant to subsurface CO2 storage. This study will include results of measurements in a Berea sandstone sample across a wide range of conditions representative of subsurface reservoirs suitable for CO2 storage (5-20 MPa, 25-90 oC, 0-5 mol kg-1). The measurement uses X-ray CT imaging in a state of the art core flooding laboratory designed to operate at high temperature, pressure, and concentrated brines.

  12. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in frio fluvial-deltaic sandstone reservoirs at South Texas. Annual report, October 1994--October 1995

    Energy Technology Data Exchange (ETDEWEB)

    Holtz, M.; Knox, P.; McRae, L. [and others

    1996-02-01

    The Frio Fluvial-Deltaic Sandstone oil play of South Texas has produced nearly 1 billion barrels of oil, yet it still contains about 1.6 billion barrels of unrecovered mobile oil and nearly the same amount of residual oil resources. Interwell-scale geologic facise models of Frio Fluvial-deltaic reservoirs are being combined with engineering assessments and geophysical evaluations in order to determine the controls that these characteristics exert on the location and volume or unrecovered mobile and residual oil. Progress in the third year centered on technology transfer. An overview of project tasks is presented.

  13. Research on the Log Interpretation Method of Tuffaceous Sandstone Reservoirs of X Depression in Hailar-Tamtsag Basin

    Science.gov (United States)

    Liu, S.; Pan, B.

    2015-12-01

    The logging evaluation of tuffaceous sandstone reservoirs is always a difficult problem. Experiments show that the tuff and shale have different logging responses. Since the tuff content exerts an influence on the computation of shale content and the parameters of the reservoir, and the accuracy of saturation evaluation is reduced. Therefore, the effect of tuff on the calculation of saturation cannot be ignored. This study takes the tuffaceous sandstone reservoirs in the X depression of Hailar-Tamtsag basin as an example to analyze. And the electric conduction model of tuffaceous sandstone reservoirs is established. The method which combines bacterial foraging algorithm and particle swarm optimization algorithm is used to calculate the content of reservoir components in well logging for the first time, and the calculated content of tuff and shale corresponds to the results analysis of thin sections. The experiment on cation exchange capacity (CEC) proves that tuff has conductivity, and the conversion relationship between CEC and resistivity proposed by Toshinobu Iton has been improved. According to the rock electric experiment under simulated reservoir conditions, the rock-electro parameters (a, b, m and n) are determined. The improved relationship between CEC and resistivity and the rock-electro parameters are used in the calculation of saturation. Formula (1) shows the saturation equation of the tuffaceous reservoirs:According to the comparative analysis between irreducible water saturation and the calculated saturation, we find that the saturation equation used CEC data and rock-electro parameters has a better application effect at oil layer than Archie's formulas.

  14. The stratigraphy of Oxfordian-Kimmeridgian (Late Jurassic) reservoir sandstones in the Witch Ground Graben, United Kingdom North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Harker, S.D. (Elf Enterprise Caledonia Ltd., Aberdeen (United Kingdom)); Mantel, K.A. (Narwhal, London (United Kingdom)); Morton, D.J. (Deminex UK Oil Gas Ltd., London (United Kingdom)); Riley, L.A. (Paleo Services, Hertfordshire (United Kingdom))

    1993-10-01

    Oil-bearing Upper Jurassic Oxfordian-Kimmeridgian sandstones of the Sgiath and Piper formations are of major economic importance in the Witch Ground Gaben, United Kingdom North Sea. They form the reservoirs in 14 fields that originally contained 2 billion bbl of oil reserves, including Scott Field, which in 1993 will be the largest producing United Kingdom North Sea oil field to come on stream in more than a decade. The Sgiath and Piper formations represent Late Jurassic transgressive and regressive phases that began with paralic deposition and culminated in a wave-dominated delta system. These phases preceded the major grabel rifting episode (late Kimmeridgian to early Ryazanian) and deposition of the Kimmeridge Clay Formation, the principal source rock of the Witch Ground Graben oil fields. A threefold subdivision of the middle to upper Oxfordian Sgiath Formation is formally proposed, with Scott field well 15/21a-15 as the designated reference well. The basal Skene Member consists of thinly interbedded paralic carbonaceous shales, coals, and sandstones. This is overlain by transgressive marine shales of the Saltire Member. The upper-most Oxfordian Scott Member consists of shallow marine sandstones that prograded to the southwest. The contact of the Sgiath and Piper formations is a basinwide transgressive marine shale (I shale), which can act as an effective barrier to fluid communication between the Sgiath and Piper reservoir sandstones.

  15. Effect of temperature on ultrasonic velocities of unconsolidated sandstones reservoirs during the SAGD recovery process

    Directory of Open Access Journals (Sweden)

    Delage P.

    2010-06-01

    Full Text Available The steam assisted gravity drainage (SAGD is a thermal in-situ technology that has been successfully used to enhance the recovery of heavy oil and bitumen in the Western Canada and in the Eastern Venezuela basins. Pressure and temperature variations during SAGD operations induce complex changes in the mechanical and acoustic properties of the reservoir rocks as well as of the caprock. To study these changes, measurements of ultrasonic wave velocities Vp, Vs were performed on both reconstituted samples and natural samples from oil sands reservoir. Reconstituted samples were made of Fontainebleau sands with a slight cementation formed by a silicate solution. They have a high porosity (about 30 % to 40 % and a high permeability (up to 10 D. Natural oil sands samples are unconsolidated sandstones extracted from the fluvio-estuarine McMurray Formation in Alberta (Canada. The saturating fluids were bitumen and glycerol with a strongly temperature dependent viscosity. The tests were carried out at different temperatures (in the range 40° and +86°C and at different effective pressures (from 12 bars up to 120 bars. Experimental results firstly showed that the elastic wave propagation velocities measured are strongly dependent on temperature and pore fluid viscosity whereas little effect of effective pressure was observed. Velocities decreased with increasing temperature and increased with increasing effective pressure. These effects are mainly due to the variations of the saturating fluids properties. Finally, the tests were modelled by using Ciz and Shapiro (2007 approach and satisfactory velocities values were obtained with highly viscous fluids, a case that cannot be easily explained by using the poro-elastic theory of Biot-Gassmann.

  16. Effect of temperature on ultrasonic velocities of unconsolidated sandstones reservoirs during the SAGD recovery process

    Science.gov (United States)

    Doan, D.-H.; Nauroy, J.-F.; Delage, P.; Mainguy, M.

    2010-06-01

    The steam assisted gravity drainage (SAGD) is a thermal in-situ technology that has been successfully used to enhance the recovery of heavy oil and bitumen in the Western Canada and in the Eastern Venezuela basins. Pressure and temperature variations during SAGD operations induce complex changes in the mechanical and acoustic properties of the reservoir rocks as well as of the caprock. To study these changes, measurements of ultrasonic wave velocities Vp, Vs were performed on both reconstituted samples and natural samples from oil sands reservoir. Reconstituted samples were made of Fontainebleau sands with a slight cementation formed by a silicate solution. They have a high porosity (about 30 % to 40 %) and a high permeability (up to 10 D). Natural oil sands samples are unconsolidated sandstones extracted from the fluvio-estuarine McMurray Formation in Alberta (Canada). The saturating fluids were bitumen and glycerol with a strongly temperature dependent viscosity. The tests were carried out at different temperatures (in the range 40° and +86°C) and at different effective pressures (from 12 bars up to 120 bars). Experimental results firstly showed that the elastic wave propagation velocities measured are strongly dependent on temperature and pore fluid viscosity whereas little effect of effective pressure was observed. Velocities decreased with increasing temperature and increased with increasing effective pressure. These effects are mainly due to the variations of the saturating fluids properties. Finally, the tests were modelled by using Ciz and Shapiro (2007) approach and satisfactory velocities values were obtained with highly viscous fluids, a case that cannot be easily explained by using the poro-elastic theory of Biot-Gassmann.

  17. Reservoir permeability prediction based on sandstone texture classification%基于砂岩组构分类评价的储层渗透率预测

    Institute of Scientific and Technical Information of China (English)

    孟万斌; 吕正祥; 唐宇; 冯明石

    2013-01-01

    By using different permeability prediction models based on petrologic analysis of the sandstone, the permeability prediction of sandstone was studied for the Upper Shaximiao formation in Xinchang area of Western Sichuan Basin. The results show that the sandstones are secondary porosity dominated with poor porosity-permeability relationships and consequently have a disparity between gas production and reservoir evaluation using porosity data. The reservoirs were classified on the basis of component, texture and pore space types of sandstones, and the corresponding permeability prediction models of porosity-permeability relationship were developed, which can increase the correlation between porosity and permeability. The reservoir types can be differentiated by analyzing the relationships between reservoir characteristics and well log parameters. Based on enhanced well logging porosity interpretation, more accurate permeability values are obtained by using well-log-calculated porosities and permeability prediction models, which is helpful for improving reservoir evaluation.%依据以砂岩岩石学特征为基础的不同类型储层孔渗定量关系渗透率预测模型,对川西新场地区上沙溪庙组Js2气藏储层渗透率进行研究.结果表明:研究区储层砂岩以次生孔隙为主,孔渗相关性差,以孔隙度参数进行的储层评价结果与产出状况匹配性差;根据岩石成份、结构和储集空间发育情况对储层进行分类,建立不同类型储层的孔渗定量关系渗透率预测模型,可明显提高孔隙度和渗透率之间的相关性;根据不同类型储层与测井特征的匹配关系,可实现储层类型的测井判别;在提高孔隙度测井解释精度的基础上,利用测井解释孔隙度,分别用不同类型储层的孔渗定量关系渗透率预测模型计算渗透率,可提高渗透率求取精度,从而提高致密砂岩储层渗透率预测水平.

  18. Palaeozoic sandstone reservoirs of the Hamada Basin, NW Libya: effects of synsedimentary processes on porosity

    Energy Technology Data Exchange (ETDEWEB)

    Shah, S.H.A.; Mansouri, A.; El Ghoul, M. (Arabian Gulf Oil Co., Benghazi (Libyan Arab Jamahiriya). Exploration Div.)

    1993-07-01

    The Hamada Basin of NW Libya is an intracratonic basin in which a thick sequence of clastic rocks was deposited during the Palaeozoic. These sediments were derived from a PreCambrian basement of felsic igneous and metamorphic rocks, and include both sands and clays; almost all the clays in formations of Palaeozoic age were produced from the alteration of feldspar. Structures were developed as these sediments were draped over the surface of the basement. Reservoirs in the Lower Palaeozoic (Lower Devonian, Lower Silurian and Cambro-Ordovician Sandstones) appear to have developed as a result of synsedimentary processes, such as winnowing and washing-out of clayey material from the sand by percolating waters, and sliding and slumping on the steep depositional surface during or soon after deposition. Oil traps are independent of structural elevation, but appear to have developed on those surfaces which were sufficiently steep to have initiated the above synsedimentary processes. This theory has been successfully tested in many places in the basin, and may provide a lead for exploration in other basins in Libya that have similar geological settings. (Author)

  19. Silurian "Clinton" Sandstone Reservoir Characterization for Evaluation of CO2-EOR Potential in the East Canton Oil Field, Ohio

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Ronald; Wicks, John; Perry, Christopher

    2009-12-30

    The purpose of this study was to evaluate the efficacy of using CO2-enhanced oil recovery (EOR) in the East Canton oil field (ECOF). Discovered in 1947, the ECOF in northeastern Ohio has produced approximately 95 million barrels (MMbbl) of oil from the Silurian “Clinton” sandstone. The original oil-in-place (OOIP) for this field was approximately 1.5 billion bbl and this study estimates by modeling known reservoir parameters, that between 76 and 279 MMbbl of additional oil could be produced through secondary recovery in this field, depending on the fluid and formation response to CO2 injection. A CO2 cyclic test (“Huff-n-Puff”) was conducted on a well in Stark County to test the injectivity in a “Clinton”-producing oil well in the ECOF and estimate the dispersion or potential breakthrough of the CO2 to surrounding wells. Eighty-one tons of CO2 (1.39 MMCF) were injected over a 20-hour period, after which the well was shut in for a 32-day “soak” period before production was resumed. Results demonstrated injection rates of 1.67 MMCF of gas per day, which was much higher than anticipated and no CO2 was detected in gas samples taken from eight immediately offsetting observation wells. All data collected during this test was analyzed, interpreted, and incorporated into the reservoir characterization study and used to develop the geologic model. The geologic model was used as input into a reservoir simulation performed by Fekete Associates, Inc., to estimate the behavior of reservoir fluids when large quantities of CO2 are injected into the “Clinton” sandstone. Results strongly suggest that the majority of the injected CO2 entered the matrix porosity of the reservoir pay zones, where it diffused into the oil. Evidence includes: (A) the volume of injected CO2 greatly exceeded the estimated capacity of the hydraulic fracture and natural fractures; (B) there was a gradual injection and pressure rate build-up during the test; (C) there was a subsequent

  20. Silurian "Clinton" Sandstone Reservoir Characterization for Evaluation of CO2-EOR Potential in the East Canton Oil Field, Ohio

    Energy Technology Data Exchange (ETDEWEB)

    Ronald Riley; John Wicks; Christopher Perry

    2009-12-30

    The purpose of this study was to evaluate the efficacy of using CO2-enhanced oil recovery (EOR) in the East Canton oil field (ECOF). Discovered in 1947, the ECOF in northeastern Ohio has produced approximately 95 million barrels (MMbbl) of oil from the Silurian 'Clinton' sandstone. The original oil-in-place (OOIP) for this field was approximately 1.5 billion bbl and this study estimates by modeling known reservoir parameters, that between 76 and 279 MMbbl of additional oil could be produced through secondary recovery in this field, depending on the fluid and formation response to CO2 injection. A CO2 cyclic test ('Huff-n-Puff') was conducted on a well in Stark County to test the injectivity in a 'Clinton'-producing oil well in the ECOF and estimate the dispersion or potential breakthrough of the CO2 to surrounding wells. Eighty-one tons of CO2 (1.39 MMCF) were injected over a 20-hour period, after which the well was shut in for a 32-day 'soak' period before production was resumed. Results demonstrated injection rates of 1.67 MMCF of gas per day, which was much higher than anticipated and no CO2 was detected in gas samples taken from eight immediately offsetting observation wells. All data collected during this test was analyzed, interpreted, and incorporated into the reservoir characterization study and used to develop the geologic model. The geologic model was used as input into a reservoir simulation performed by Fekete Associates, Inc., to estimate the behavior of reservoir fluids when large quantities of CO2 are injected into the 'Clinton' sandstone. Results strongly suggest that the majority of the injected CO2 entered the matrix porosity of the reservoir pay zones, where it diffused into the oil. Evidence includes: (A) the volume of injected CO2 greatly exceeded the estimated capacity of the hydraulic fracture and natural fractures; (B) there was a gradual injection and pressure rate build-up during the test

  1. Erosion characteristic of slope sandstone soaking in acid mine drainage

    Institute of Scientific and Technical Information of China (English)

    JIANG Li-chun; CHEN Jia-sheng; WU Ai-xiang

    2007-01-01

    Acid mine drainage(AMD) is one of the main reasons of slope instability in chemical mines with high sulfide. The pH values of the solution inside the mining pit decrease with the increasing of distance from ore body and vary from 1.2 to 4.6,according to the results of the water environmental investigation and the composition test of the slope sandstone in Xinqiao Pyrite Mine. Comparative experiments between original sandstone and AMD eroded sandstone samples show that after AMD erosion the uniaxial compressive strength and elastic modulus decrease by 30%-50% and 25%-45%, respectively, the cohesion and internal friction angle decrease obviously, and the Poisson ratio fluctuates between 0.20-0.29. The greater joints development, the higher residual stress after peak value, and the longer time to damage. Besides above, the reaction mechanism analysis of AMD eroded sandstone shows that the fillings in joints and fissures of sandstone are frequently decomposed and polyreacted, resulting in changes of interior molecule structure and framework composition, and decreases of cohesion and angle of internal friction between rock structure interfaces.

  2. Reservoir attributes of a hydrocarbon-prone sandstone complex: case of the Pab Formation (Late Cretaceous) of Southwest Pakistan

    DEFF Research Database (Denmark)

    Umar, Muhammad; Khan, Abdul Salam; Kelling, Gilbert;

    2016-01-01

    Links between the architectural elements of major sand bodies and reservoir attributes have been explored in a field study of the hydrocarbon-yielding Late Cretaceous Pab Formation of southwest Pakistan. The lithofacies and facies associations represented in the Pab Formation are the main...... porosity values than more shale-rich successions. Diagenetic studies of Pab sandstones reveal that intense mechanical compaction and cementation have reduced primary porosity and reservoir quality. Conversely, dissolution of detrital feldspar grains and volcanic fragments during burial and later uplift...

  3. Model building for Chang-8 low permeability sandstone reservoir in the Yanchang formation of the Xifeng oil field

    Institute of Scientific and Technical Information of China (English)

    SONG Fan; HOU Jia-gen; SU Ni-na

    2009-01-01

    In order to build a model for the Chang-8 low permeability sandstone reservoir in the Yanchang formation of the Xifeng oil field, we studied sedlimentation and diagenesis of sandstone and analyzed major factors controlling this low permeability reser-voir. By doing so, we have made clear that the spatial distribution of reservoir attribute parameters is controlled by the spatial dis-tribution of various kinds of sandstone bodies. By taking advantage of many coring wells and high quality logging data, we used regression analysis for a single well with geological conditions as constraints, to build the interpretation model for logging data and to calculate attribute parameters for a single well, which ensured accuracy of the 1-D vertical model. On this basis, we built a litho-facies model to replace the sedimentary facies model. In addition, we also built a porosity model by using a sequential Gaussian simulation with the lithofacies model as the constraint. In the end, we built a permeability model by using Markov-Bayes simula-tion, with the porosity attribute as the covariate. The results show that the permeability model reflects very well the relative differ-ences between low permeability values, which is of great importance for locating high permeability zones and forecasting zones favorable for exploration and exploitation.

  4. Control factors and porosity evolution of high-quality sandstone reservoirs of Kela-2gas field in Kuqa Depression

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By using the integrated methods including sandbodies modelling of the outcrops, sedimentary facies of the cores and well logs of the drilled wells, and the reservoir correlation of interwells, it is thought that the sandstone reservoirs of Kela-2 gas field are a suit of high-quality natural gas reservoirs with great thickness, extensive and continuous distribution, high porosity and permeability, and a few barrier beds. Sedimentary facies and microfacies are the main factors controlling the reservoir distribution and interior heterogeneity. Based on a great deal of data of rock's thin sections, porosity, permeability, and the parameters of capillary pressure, the reservoir diagenesis, controls, mechanism and evolution of pores have been studied. It is considered that compaction in the early stage and diagenetic dolomite and calcite cements have effect on the decline of reservoirs property. Now compaction is chiefly middle to weak. The better reservoirs have no or a few calcite cements. In the early of deep buried stage, there are still mainly remainder primary intergranular pores. The authigenic kaolinite of reservoirs is the production of the dissolution of feldspars and lithic fragments. The dissolution results in the partly modified and broadened secondary intergranular pores. In the late of deep buried stage, structure fissures and overpressure were in favor of improving and preservation of these pores.

  5. Measuring and predicting reservoir heterogeneity in complex deposystems: The fluvial-deltaic Big Injun sandstone in West Virginia

    Energy Technology Data Exchange (ETDEWEB)

    Patchen, D.G.; Hohn, M.E.; Aminian, K.; Donaldson, A.; Shumaker, R.; Wilson, T.

    1993-04-01

    The purpose of this research is to develop techniques to measure and predict heterogeneities in oil reservoirs that are the products of complex deposystems. The unit chosen for study is the Lower Mississippian Big Injun sandstone, a prolific oil producer (nearly 60 fields) in West Virginia. This research effort has been designed and is being implemented as an integrated effort involving stratigraphy, structural geology, petrology, seismic study, petroleum engineering, modeling and geostatistics. Sandstone bodies are being mapped within their regional depositional systems, and then sandstone bodies are being classified in a scheme of relative heterogeneity to determine heterogeneity across depositional systems. Facies changes are being mapped within given reservoirs, and the environments of deposition responsible for each facies are being interpreted to predict the inherent relative heterogeneity of each facies. Structural variations will be correlated both with production, where the availability of production data will permit, and with variations in geologic and engineering parameters that affect production. A reliable seismic model of the Big Injun reservoirs in Granny Creek field is being developed to help interpret physical heterogeneity in that field. Pore types are being described and related to permeability, fluid flow and diagenesis, and petrographic data are being integrated with facies and depositional environments to develop a technique to use diagenesis as a predictive tool in future reservoir development. Another objective in the Big Injun study is to determine the effect of heterogeneity on fluid flow and efficient hydrocarbon recovery in order to improve reservoir management. Graphical methods will be applied to Big Injun production data and new geostatistical methods will be developed to detect regional trends in heterogeneity.

  6. Multilayer stress field interference in sandstone and mudstone thin interbed reservoir

    Science.gov (United States)

    Guo, Jian-Chun; Luo, Bo; Zhu, Hai-Yan; Yuan, Shu-Hang; Deng, Yan; Duan, You-Jing; Duan, Wei-Gang; Chen, Li

    2016-10-01

    General fracturing and separate layer fracturing play an important role in sandstone and mudstone thin interbed (SMTI) reservoirs, where one of the main issues is to control the excessive height growth of fracturing. The fracture propagation at the interface depends on the induced stress produced by the hydraulic fracturing construction. This paper employed a poroelastic coupled damage element with the cohesive zone method (CZM) to establish a 2D fracture quasi-static propagation model. A parametric study was performed under different fracture height, fracture width, pumping rate, fluid viscosity, in situ stress, elastic modulus and tensile strength with this model. General fracturing and separate layer fracturing are compared with each other through fracture morphology and induced stress. The simulation results show that the absolute value of induced stress increases with the decrease in matrix stress near the fracture tip. As a result, the propagation of the fractures is much easier due to the weakened degree of compression. The growth of fracture height and width, the increase in pumping rate and the excessively large or small value of fluid viscosity lead to larger induced stress on the interface. Higher in situ stress, lower elastic modulus, and higher tensile strength of the interlayers can control the excessive height growth of fracturing. The simulated results also show that the fractures are more likely to be overlapped with each other in general fracturing compared to that in separate-layer fracturing. Results of the simulations suggest that lower pumping rates, the proper value of fluid viscosity, separate layer fracturing and interlayers with higher in situ stress, lower elastic modulus and higher tensile strength tend to limit fracture height. Finally, the proposed model was applied to a practical oil field case to verify its effectiveness.

  7. Continuity and internal properties of Gulf Coast sandstones and their implications for geopressured energy development. Annual report, November 1, 1980-October 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Morton, R.A.; Ewing, T.E.; Tyler, N.

    1982-06-01

    Systematic investigation, classification, and differentiation of the intrinsic properties of genetic sandstone units that typify many geopressured geothermal aquifers and hydrocarbon reservoirs of the Gulf Coast region are provided. The following are included: structural and stratigraphic limits of sandstone reservoirs; characteristics and dimensions of Gulf Coast Sandstones; fault compartment areas; comparison of production and geologic estimates of aquifer volume; geologic setting and reservoir characteristics, wells of opportunity; internal properties of sandstones and implications for geopressured energy development. (MHR)

  8. Long-Term CO2 Exposure Experiments - Geochemical Effects on Brine-Saturated Reservoir Sandstone

    Science.gov (United States)

    Fischer, Sebastian; Zemke, Kornelia; Liebscher, Axel; Wandrey, Maren

    2010-05-01

    The injection of CO2 into deep saline aquifers is the most promising strategy for the reduction of CO2 emissions to the atmosphere via long-term geological storage. The study is part of the CO2SINK project conducted at Ketzin, situated 40 km west of Berlin. There, food grade CO2 has been pumped into the Upper Triassic Stuttgart Formation since June 2008. The main objective of the experimental program is to investigate the effects of long-term CO2 exposure on the physico-chemical properties of the reservoir rock. To achieve this goal, core samples from observation well Ktzi 202 have been saturated with synthetic brine and exposed to CO2 in high quality steel autoclaves at simulated reservoir P-T-conditions of 5.5 MPa and 40 ° C. The synthetic brine had a composition representative of the formation fluid (Förster et al., 2006) of 172.8 g/l NaCl, 8.0 g/l MgCl2×2H2O, 4.8 g/l CaCl2×2H2O and 0.6 g/l KCl. After 15 months, the first set of CO2-exposed samples was removed from the pressure vessels. Thin sections, XRD, SEM as well as EMP data were used to determine the mineralogical features of the reservoir rocks before and after the experiments. Additionally, NMR relaxation and MP was performed to measure poroperm and pore size distribution values of the twin samples. The analyzed samples are fine- to medium grained, moderately well- to well sorted and weakly consolidated sandstones. Quartz and plagioclase are the major components, while K-feldspar, hematite, white & dark mica, chlorite and illite are present in minor and varying amounts. Cements are composed of analcime, dolomite and anhydrite. Some samples show mm- to cm-scale cross-beddings. The laminae comprise lighter, quartz- and feldspar-dominated layers and dark-brownish layers with notably less quartz and feldspars. The results are consistent with those of Blaschke et al. (2008). The plagioclase composition indicates preferred dissolution of the Ca-component and a trend toward albite-rich phases or even pure

  9. Reconstruction of the diagenesis of the fluvial-lacustrine- deltaic sandstones and its influence on the reservoir quality evolution-- Evidence from Jurassic and Triassic sandstones, Yanchang Oil Field, Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The reservoir quality of Jurassic and Triassic fluvial and lacustrine-deltaic sandstones of the Yanchang Oil Field in the Ordos Basin is strongly influenced by the burial history and facies-related diagenetic events. The fluvial sandstones have a higher average porosity (14.8%) and a higher permeability (12.7×10?3 ?m2) than those of the deltaic sandstones (9.8% and 5.8 ×10?3 ?m2, respectively). The burial compaction, which resulted in 15% and 20% porosity loss for Jurassic and Triassic sandstones, respectively, is the main factor causing the loss of porosity both for the Jurassic and Triassic sandstones. Among the cements, carbonate is the main one that reduced the reservoir quality of the sandstones. The organic acidic fluid derived from organic matter in the source rocks, the inorganic fluid from rock-water reaction during the late diagenesis, and meteoric waters during the epidiagenesis resulted in the formation of dissolution porosity, which is the main reason for the enhancement of reservoir-quality.

  10. Acoustic emission signals frequency-amplitude characteristics of sandstone after thermal treated under uniaxial compression

    Science.gov (United States)

    Kong, Biao; Wang, Enyuan; Li, Zenghua; Wang, Xiaoran; Niu, Yue; Kong, Xiangguo

    2017-01-01

    Thermally treated sandstone deformation and fracture produced abundant acoustic emission (AE) signals. The AE signals waveform contained plentiful precursor information of sandstone deformation and fracture behavior. In this paper, uniaxial compression tests of sandstone after different temperature treatments were conducted, the frequency-amplitude characteristics of AE signals were studied, and the main frequency distribution at different stress level was analyzed. The AE signals frequency-amplitude characteristics had great difference after different high temperature treatment. Significant differences existed of the main frequency distribution of AE signals during thermal treated sandstone deformation and fracture. The main frequency band of the largest waveforms proportion was not unchanged after different high temperature treatments. High temperature caused thermal damage to the sandstone, and sandstone deformation and fracture was obvious than the room temperature. The number of AE signals was larger than the room temperature during the initial loading stage. The low frequency AE signals had bigger proportion when the stress was 0.1, and the maximum value of the low frequency amplitude was larger than high frequency signals. With the increase of stress, the low and high frequency AE signals were gradually increase, which indicated that different scales ruptures were broken in sandstone. After high temperature treatment, the number of high frequency AE signals was significantly bigger than the low frequency AE signals during the latter loading stage, this indicates that the small scale rupture rate of recurrence and frequency were more than large scale rupture. The AE ratio reached the maximum during the sandstone instability failure period, and large scale rupture was dominated in the failure process. AE amplitude increase as the loading increases, the deformation and fracture of sandstone was increased gradually. By comparison, the value of the low frequency

  11. Study on pore characteristics and microstructure of sandstones with different grain sizes

    Science.gov (United States)

    Li, Huigui; Li, Huamin; Gao, Baobin; Wang, Wen; Liu, Chuang

    2017-01-01

    The grain sizes have a pronounced influence on the pore characteristics and microstructure of sandstone. This work examined the pore structure and characteristics of three kinds of sandstones with different grain sizes using the scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) methods and analyzed their grain size distributions, pore size distributions, T2-distributions, and porosity variations. The experimental results showed that sandstones with different grain sizes have significant differences in the microstructures grain size distribution, pore size distribution, T2-distribution, and porosity variation. The results show that coarse, medium and fine sandstones have two peaks in T2-distributions, mean grain size of 398.5, 145.1 and 25.1 μm, respectively, mean pore size of 46.3, 25.9, and 8.4 μm, respectively, porosity of 7.52%, 5.88% and 1.55%, respectively, indicating that both coarse and medium sandstones contain big pores, while fine sandstone contains small pores. This study is of significance for understanding of water migration characteristics in aquifers and gas in coal seams after the working face exploitation.

  12. Quantifying the Texture, Composition, and Coupled Chemical-Mechanical Diagenesis of Deformation Bands within Sandstone Reservoir Outcrop Analogs of Assorted Detrital Compositions, Southwestern USA

    Science.gov (United States)

    Elliott, S. J.; Eichhubl, P.

    2015-12-01

    In porous sandstones many factors including grain size, sorting, stress-state, and composition influence deformation mechanisms and resulting deformation band properties, especially those related to fluid flow. Using high resolution SEM-CL, EDS, and BSE images we quantitatively point counted various band types and their associated host rocks at the sub-micron scale, performed comprehensive grain size analyses on the undeformed host rocks, and calculated the total porosity lost through coupled chemical-mechanical means for each host rock and band. Our goals were to 1) determine the influence of detrital composition and texture [Cedar Mesa, Navajo, and Entrada sandstones] both on bands formed by different mechanisms and on bands formed by the same deformation mechanism at various stages of development, and to 2) assess the effects of coupled chemical-mechanical processes leading to deformation localization within these sandstone reservoir outcrop analogs. Analyzed samples include a non-cataclastic disaggregation band, a non-cataclastic pressure solution band, and single, multistrand, and clustered cataclastic bands, all of which formed through combinations of grain reorganization, brittle processes, pressure solution, and cementation. The textural, compositional, and diagenetic properties of the older burial-related bands (pressure solution and disaggregation) are more comparable to the detrital host rocks than the later, faulting-related cataclastic bands, regardless of the host rock characteristics. Furthermore, the relative influence of the detrital sandstone properties varies throughout the evolutionary stages of cataclastic band development. For example, multistrand bands across formations have undergone similar chemical-mechanical deformation, yet their remnant porosities and compositions vary drastically. Cluster bands, on the other hand, represent a later developmental stage than multistrand bands, and yet their porosities and compositions are similar across

  13. Reservoir quality and petrophysical properties of Cambrian sandstones and their changes during the experimental modelling of CO2 storage in the Baltic Basin

    Directory of Open Access Journals (Sweden)

    Kazbulat Shogenov

    2015-08-01

    Full Text Available The objectives of this study were (1 to review current recommendations on storage reservoirs and classify their quality using experimental data of sandstones of the Deimena Formation of Cambrian Series 3, (2 to determine how the possible CO2 geological storage (CGS in the Deimena Formation sandstones affects their properties and reservoir quality and (3 to apply the proposed classification to the storage reservoirs and their changes during CGS in the Baltic Basin. The new classification of the reservoir quality of rocks for CGS in terms of gas permeability and porosity was proposed for the sandstones of the Deimena Formation covered by Lower Ordovician clayey and carbonate cap rocks in the Baltic sedimentary basin. Based on permeability the sandstones were divided into four groups showing their practical usability for CGS (‘very appropriate’, ‘appropriate’, ‘cautionary’ and ‘not appropriate’. According to porosity, eight reservoir quality classes were distinguished within these groups. The petrophysical, geochemical and mineralogical parameters of the sandstones from the onshore South Kandava and offshore E6 structures in Latvia and the E7 structure in Lithuania were studied before and after the CO2 injection-like alteration experiment. The greatest changes in the composition and properties were determined in the carbonate-cemented sandstones from the uppermost part of the South Kandava onshore structure. Partial dissolution of pore-filling carbonate cement (ankerite and calcite and displacement of clay cement blocking pores caused significant increase in the effective porosity of the samples, drastic increase in their permeability and decrease in grain and bulk density, P- and S-wave velocity, and weight of the dry samples. As a result of these alterations, carbonate-cemented sandstones of initially ‘very low’ reservoir quality (class VIII, ‘not appropriate’ for CGS, acquired an ‘appropriate’ for CGS

  14. Sequential Extraction on Oil Sandstones from TZ401 Well——A Case Study on Filling History of Hydrocarbon Reservoir

    Institute of Scientific and Technical Information of China (English)

    Pan Changchun; Liu Dayong

    2008-01-01

    Sequential extraction was performed on two oil sandstones from the Upper Carboniferous oil columns of TZ401 well.The free oils of these two oil sandstones and a crude oil from the Lower Carboniferous oil column of this well have low ratios of C28/C27+C28+ C29) steranes and gammacerane/C31 hopanes,ranging of 0.11-0.16 and 0.09-0.15,respectively,similar to those from the Middle-Upper Ordovician source rock.However,these two ratios for the adsorbed and inclusion oils of these two oil sandstones are relatively high,ranging of 0.29-0.31 and 0.26-0.40,respectively,similar to those of the Cambrian-Lower Ordovician source rock.This result demonstrates that the initial oil charging the reservoirs was derived from the Cambrian-Lower Ordovician source rock,whereas the later charging oil was derived from the Middle--Upper Ordovician source rock.

  15. Halomonas sulfidaeris-dominated microbial community inhabits a 1.8 km-deep subsurface Cambrian Sandstone reservoir.

    Science.gov (United States)

    Dong, Yiran; Kumar, Charu Gupta; Chia, Nicholas; Kim, Pan-Jun; Miller, Philip A; Price, Nathan D; Cann, Isaac K O; Flynn, Theodore M; Sanford, Robert A; Krapac, Ivan G; Locke, Randall A; Hong, Pei-Ying; Tamaki, Hideyuki; Liu, Wen-Tso; Mackie, Roderick I; Hernandez, Alvaro G; Wright, Chris L; Mikel, Mark A; Walker, Jared L; Sivaguru, Mayandi; Fried, Glenn; Yannarell, Anthony C; Fouke, Bruce W

    2014-06-01

    A low-diversity microbial community, dominated by the γ-proteobacterium Halomonas sulfidaeris, was detected in samples of warm saline formation porewater collected from the Cambrian Mt. Simon Sandstone in the Illinois Basin of the North American Midcontinent (1.8 km/5872 ft burial depth, 50°C, pH 8, 181 bars pressure). These highly porous and permeable quartz arenite sandstones are directly analogous to reservoirs around the world targeted for large-scale hydrocarbon extraction, as well as subsurface gas and carbon storage. A new downhole low-contamination subsurface sampling probe was used to collect in situ formation water samples for microbial environmental metagenomic analyses. Multiple lines of evidence suggest that this H. sulfidaeris-dominated subsurface microbial community is indigenous and not derived from drilling mud microbial contamination. Data to support this includes V1-V3 pyrosequencing of formation water and drilling mud, as well as comparison with previously published microbial analyses of drilling muds in other sites. Metabolic pathway reconstruction, constrained by the geology, geochemistry and present-day environmental conditions of the Mt. Simon Sandstone, implies that H. sulfidaeris-dominated subsurface microbial community may utilize iron and nitrogen metabolisms and extensively recycle indigenous nutrients and substrates. The presence of aromatic compound metabolic pathways suggests this microbial community can readily adapt to and survive subsurface hydrocarbon migration.

  16. Correlative multiple porosimetries for reservoir sandstones with adoption of a new reference-sample-guided computed-tomographic method

    Science.gov (United States)

    Jin, Jae Hwa; Kim, Junho; Lee, Jeong-Yil; Oh, Young Min

    2016-07-01

    One of the main interests in petroleum geology and reservoir engineering is to quantify the porosity of reservoir beds as accurately as possible. A variety of direct measurements, including methods of mercury intrusion, helium injection and petrographic image analysis, have been developed; however, their application frequently yields equivocal results because these methods are different in theoretical bases, means of measurement, and causes of measurement errors. Here, we present a set of porosities measured in Berea Sandstone samples by the multiple methods, in particular with adoption of a new method using computed tomography and reference samples. The multiple porosimetric data show a marked correlativeness among different methods, suggesting that these methods are compatible with each other. The new method of reference-sample-guided computed tomography is more effective than the previous methods when the accompanied merits such as experimental conveniences are taken into account.

  17. Correlative multiple porosimetries for reservoir sandstones with adoption of a new reference-sample-guided computed-tomographic method.

    Science.gov (United States)

    Jin, Jae Hwa; Kim, Junho; Lee, Jeong-Yil; Oh, Young Min

    2016-07-22

    One of the main interests in petroleum geology and reservoir engineering is to quantify the porosity of reservoir beds as accurately as possible. A variety of direct measurements, including methods of mercury intrusion, helium injection and petrographic image analysis, have been developed; however, their application frequently yields equivocal results because these methods are different in theoretical bases, means of measurement, and causes of measurement errors. Here, we present a set of porosities measured in Berea Sandstone samples by the multiple methods, in particular with adoption of a new method using computed tomography and reference samples. The multiple porosimetric data show a marked correlativeness among different methods, suggesting that these methods are compatible with each other. The new method of reference-sample-guided computed tomography is more effective than the previous methods when the accompanied merits such as experimental conveniences are taken into account.

  18. Researches on Nitrogen Foam Flooding Technology in the Tahe Triassic Sandstone Reservoir%塔河底水砂岩油藏氮气泡沫驱技术研究

    Institute of Scientific and Technical Information of China (English)

    刘学利; 胡文革; 谭涛; 张林艳; 刘蕊

    2016-01-01

    塔河三叠系砂岩油藏为块状底水油藏,与中国其他砂岩油藏相比,其埋藏深、底水能量强,具有油藏温度高、矿化度高和钙镁离子含量高的特点,进入开发中后期以后油井水淹现象严重,低产低效井多,由于高温高盐的特征,一般的化学驱提高采收率方法很难适用。在调研砂岩油藏提高采收率技术的基础上,结合塔河底水砂岩油藏实际特点,开展了氮气泡沫驱室内实验研究,确定了氮气泡沫驱的可行性,并在现场进行了先导试验。实践表明,氮气泡沫驱技术是底水砂岩油藏有效的提高采收率手段。%Compared with other sandstone reservoirs in China, the Tahe triassic sandstone reservoir is a block bottom water reservoir, which is characteristic of deeply buried reservoir, active bottom water, high formation temperature and high salini-ty(excessive calcium and magnesian ion). Therefore the number of low production and low effectiveness wells is increasing when the oil wells are flooded in the middle-later developed period. In addition, the chemical flooding to improve oil recovery does not apply due to high temperature and high salinity. Based on the researches on enhanced oil recovery technology in sandstone reservoir and the practical characteristics of bottom water sandstone reservoir of Tahe Oilfield, nitrogen foam flood-ing experiments were made and the feasibility was proved. Then the pilot test on field was conducted, and it showed that the nitrogen foam flooding technology is an effective method of improving oil recovery in bottom water sandstone reservoir.

  19. Combined rock-physical modelling and seismic inversion techniques for characterisation of stacked sandstone reservoir

    NARCIS (Netherlands)

    Justiniano, A.; Jaya, Y.; Diephuis, G.; Veenhof, R.; Pringle, T.

    2015-01-01

    The objective of the study is to characterise the Triassic massive stacked sandstone deposits of the Main Buntsandstein Subgroup at Block Q16 located in the West Netherlands Basin. The characterisation was carried out through combining rock-physics modelling and seismic inversion techniques. The app

  20. Combined rock-physical modelling and seismic inversion techniques for characterisation of stacked sandstone reservoir

    NARCIS (Netherlands)

    Justiniano, A.; Jaya, Y.; Diephuis, G.; Veenhof, R.; Pringle, T.

    2015-01-01

    The objective of the study is to characterise the Triassic massive stacked sandstone deposits of the Main Buntsandstein Subgroup at Block Q16 located in the West Netherlands Basin. The characterisation was carried out through combining rock-physics modelling and seismic inversion techniques. The app

  1. 二连盆地阿南低渗透火山碎屑砂岩油藏储层特征及其对开发的影响%Reservoir characteristics of low-permeability pyroclastic sandstones and their influences on petroleum development in A'nan oilfield of Erlian Basin

    Institute of Scientific and Technical Information of China (English)

    梁官忠; 姜振学; 刘忠; 尹志军; 申保华; 马俊恒

    2013-01-01

    The reservoir rocks of A' nan sandstone oilfield are dominated by feldspar lithic sandstone, and are proximal subaqueous fan deposits with prominent influences of volcanic activity.They feature in high content of pyroclastic debris and tufaceous cements,low composition maturity and structure maturity.Although their burial depth is shallow, epidiagenesis such as compaction and cementation are intense, leading to the poor development of primary porosity.As the major secondary pores,the dissolution pores feature in micro-pore throat and poor sorting of pore throat, resulting in poor storage capacity and permeability.Therefore, A' nan oil reservoir is typical low permeable pyroclastic sandstone reservoir.The pore structure deteriorates during water flooding due to various factors such as water sensitivity and velocity sensitivity.As a result,the displacement-pressure increases, while water-free oil recovery and ultimate oil displacement efficiency decrease.During waterflooding, water injection pressure increases continuously, and pressure buildup is significant, but well deliverability is commonly low.Several measures such as layer-subdivision and infill drilling are carried out to improve oilfield development.%阿南砂岩油藏储集岩以长石岩屑砂岩为主,属近源快速沉积的水下扇砂体,且沉积时受火山活动影响明显.岩石中火山成因岩屑及凝灰质胶结物含量高,岩石成分成熟度和结构成熟度均较低,储集体具有埋藏浅但压实作用、胶结作用等成岩后生作用强烈的特点,导致油层原生孔隙不发育,主要发育次生溶孔.孔喉以微喉为主,吼道分选差、储渗能力较弱,油藏具有典型的低渗火山碎屑砂岩油藏特征.油藏注水开发后,由于水敏和速敏等因素的影响,孔隙结构进一步变差,油层驱替压力上升,无水采收率和最终驱油效率下降,油藏注水开发表现出注水压力不断上升、地层憋压现象明显但油井供液能力普

  2. Diagenesis and reservoir quality evolution of palaeocene deep-water, marine sandstones, the Shetland-Faroes Basin, British continental shelf

    Energy Technology Data Exchange (ETDEWEB)

    Mansurbeg, H. [Department of Earth Sciences, Uppsala University, Villavaegen 16, SE 752 36 Uppsala (Sweden); Morad, S. [Department of Earth Sciences, Uppsala University, Villavaegen 16, SE 752 36 Uppsala (Sweden); Department of Petroleum Geosciences, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Salem, A. [Faculty of Education at Kafr El-Sheikh, Tanta University, Kafr El-Sheikh (Egypt); Marfil, R.; Caja, M.A. [Departmento Petrologia y Geoquimica, Facultad de Geologia, UCM, 28040 Madrid (Spain); El-ghali, M.A.K. (Geology Department, Al-Fateh University, P.O. Box 13696, Libya); Nystuen, J.P. [Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, NO-0316 Oslo (Norway); Amorosi, A. [Department of Earth Sciences, University of Bologna, Via Zamboni 67, 40127 Bologna (Italy); Garcia, D. [Centre SPIN, Department GENERIC, Ecole Nationale Superieure des Mines de Saint Etienne 158, Cours Fauriel 42023, Saint-Etienne (France); La Iglesia, A. [Instituto de Geologia Economica (CSIC-UCM), Facultad de Geologia, UCM, 28040 Madrid (Spain)

    2008-06-15

    The Palaeocene, deep-water marine sandstones recovered from six wells in the Shetland-Faroes Basin represent lowstand, transgressive and highstand systems tract turbiditic sediments. Mineralogic, petrographic, and geochemical analyses of these siliciclastics are used to decipher and discuss the diagenetic alterations and subsequent reservoir quality evolution. The Middle-Upper Palaeocene sandstones (subarkoses to arkoses) from the Shetland-Faroes Basin, British continental shelf are submarine turbiditic deposits that are cemented predominantly by carbonates, quartz and clay minerals. Carbonate cements (intergranular and grain replacive calcite, siderite, ferroan dolomite and ankerite) are of eogenetic and mesogenetic origins. The eogenetic alterations have been mediated by marine, meteoric and mixed marine/meteoric porewaters and resulted mainly in the precipitation of calcite ({delta}{sup 18}O{sub V-PDB}=-10.9 permille and -3.8 permille), trace amounts of non-ferroan dolomite, siderite ({delta}{sup 18}O{sub V-PDB}=-14.4 permille to -0.6 permille), as well as smectite and kaolinite in the lowstand systems tract (LST) and highstand systems tract (HST) turbiditic sandstone below the sequence boundary. Minor eogenetic siderite has precipitated between expanded and kaolinitized micas, primarily biotite. The mesogenetic alterations are interpreted to have been mediated by evolved marine porewaters and resulted in the precipitation of calcite ({delta}{sup 18}O{sub V-PDB}=-12.9 permille to -7.8 permille) and Fe-dolomite/ankerite ({delta}{sup 18}O{sub V-PDB}=-12.1 permille to -6.3 permille) at temperatures of 50-140 and 60-140 C, respectively. Quartz overgrowths and outgrowth, which post- and pre-date the mesogenetic carbonate cements is more common in the LST and TST of distal turbiditic sandstone. Discrete quartz cement, which is closely associated with illite and chlorite, is the final diagenetic phase. The clay minerals include intergranular and grain replacive

  3. Measuring and predicting reservoir heterogeneity in complex deposystems. The fluvial-deltaic Big Injun Sandstone in West Virginia. Final report, September 20, 1991--October 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Hohn, M.E.; Patchen, D.G.; Heald, M.; Aminian, K.; Donaldson, A.; Shumaker, R.; Wilson, T.

    1994-05-01

    Non-uniform composition and permeability of a reservoir, commonly referred to as reservoir heterogeneity, is recognized as a major factor in the efficient recovery of oil during primary production and enhanced recovery operations. Heterogeneities are present at various scales and are caused by various factors, including folding and faulting, fractures, diagenesis and depositional environments. Thus, a reservoir consists of a complex flow system, or series of flow systems, dependent on lithology, sandstone genesis, and structural and thermal history. Ultimately, however, fundamental flow units are controlled by the distribution and type of depositional environments. Reservoir heterogeneity is difficult to measure and predict, especially in more complex reservoirs such as fluvial-deltaic sandstones. The Appalachian Oil and Natural Gas Research Consortium (AONGRC), a partnership of Appalachian basin state geological surveys in Kentucky, Ohio, Pennsylvania, and West Virginia, and West Virginia University, studied the Lower Mississippian Big Injun sandstone in West Virginia. The Big Injun research was multidisciplinary and designed to measure and map heterogeneity in existing fields and undrilled areas. The main goal was to develop an understanding of the reservoir sufficient to predict, in a given reservoir, optimum drilling locations versus high-risk locations for infill, outpost, or deeper-pool tests.

  4. Predictive modeling of CO{sub 2} sequestration in deep saline sandstone reservoirs: Impacts of geochemical kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Balashov, Victor N; Guthrie, George D; Hakala, J Alexandra; Lopano, Christina L. J.; Rimstidt, Donald; Brantley, Susan L

    2013-03-01

    One idea for mitigating the increase in fossil-fuel generated CO{sub 2} in the atmosphere is to inject CO{sub 2} into subsurface saline sandstone reservoirs. To decide whether to try such sequestration at a globally significant scale will require the ability to predict the fate of injected CO{sub 2}. Thus, models are needed to predict the rates and extents of subsurface rock-water-gas interactions. Several reactive transport models for CO{sub 2} sequestration created in the last decade predicted sequestration in sandstone reservoirs of ~17 to ~90 kg CO{sub 2} m{sup -3|. To build confidence in such models, a baseline problem including rock + water chemistry is proposed as the basis for future modeling so that both the models and the parameterizations can be compared systematically. In addition, a reactive diffusion model is used to investigate the fate of injected supercritical CO{sub 2} fluid in the proposed baseline reservoir + brine system. In the baseline problem, injected CO{sub 2} is redistributed from the supercritical (SC) free phase by dissolution into pore brine and by formation of carbonates in the sandstone. The numerical transport model incorporates a full kinetic description of mineral-water reactions under the assumption that transport is by diffusion only. Sensitivity tests were also run to understand which mineral kinetics reactions are important for CO{sub 2} trapping. The diffusion transport model shows that for the first ~20 years after CO{sub 2} diffusion initiates, CO{sub 2} is mostly consumed by dissolution into the brine to form CO{sub 2,aq} (solubility trapping). From 20-200 years, both solubility and mineral trapping are important as calcite precipitation is driven by dissolution of oligoclase. From 200 to 1000 years, mineral trapping is the most important sequestration mechanism, as smectite dissolves and calcite precipitates. Beyond 2000 years, most trapping is due to formation of aqueous HCO{sub 3}{sup -}. Ninety-seven percent of the

  5. An Experimental and Modeling Study on the Response to Varying Pore Pressure and Reservoir Fluids in the Morrow A Sandstone

    Directory of Open Access Journals (Sweden)

    Aaron V. Wandler

    2012-01-01

    Full Text Available In mature oil fields undergoing enhanced oil recovery methods, such as CO2 injection, monitoring the reservoir changes becomes important. To understand how reservoir changes influence compressional wave (P and shear wave (S velocities, we conducted laboratory core experiments on five core samples taken from the Morrow A sandstone at Postle Field, Oklahoma. The laboratory experiments measured P- and S-wave velocities as a function of confining pressure, pore pressure, and fluid type (which included CO2 in the gas and supercritical phase. P-wave velocity shows a response that is sensitive to both pore pressure and fluid saturation. However, S-wave velocity is primarily sensitive to changes in pore pressure. We use the fluid and pore pressure response measured from the core samples to modify velocity well logs through a log facies model correlation. The modified well logs simulate the brine- and CO2-saturated cases at minimum and maximum reservoir pressure and are inputs for full waveform seismic modeling. Modeling shows how P- and S-waves have a different time-lapse amplitude response with offset. The results from the laboratory experiments and modeling show the advantages of combining P- and S-wave attributes in recognizing the mechanism responsible for time-lapse changes due to CO2 injection.

  6. Effect of Water Washing on Hydrocarbon Compositions of Petropleum Sandstone Reservoir Rocks in Tarim Basin,NW China

    Institute of Scientific and Technical Information of China (English)

    张敏; 张俊

    2000-01-01

    Gross compositions and distribution of saturated and aromatic hydrocarbons in Carboniferous sandstone reservoire rocks in oil and water zones for Tzhong-10 well of the Zhongyang Uplift in the Tarim Basin were studied in dteail by means of Rock-Eval Pyrolysis,thin-chromatograph-flame ionization detection(TLC-FID),gas chromatography,gas chromatography-mass spectrometry.The results suggest that the gross composition of reservoir hydrocarbons between the oil zone and the water zone show significant differences,Water wahing has a dramatic effect on saturated hydrocarbon blomarkers,especially drimane series compounds,Drimane series compounds in the water zone have been depleted completely.However,the contents of tricyclic iterpanes and pentacyclic triterpanes tend to decrease slightly,but the water-zone reservoir hydrocarbons contian a large amount of gammacerane.This suggests that gammacerane be more resistant to water washing than diterpanes and homohopanes.The contents of pregnane,homopregrane,diasteranes relastively decrease as a result of water washing.Water washing has a noticeable effect on polycyclic aromatic hydrocarbon compounds,especially aromatic sulfur compounds,and the contents of dibenzothiophene series compounds and benzonaplyiothipophene decrease significantly as a result of water washing.However,the conterts of bicyclic and tricyclic aromatic hydrocarbons decrase slightly and those of tetracyclic and pentacyclic aromatic hydrocarbons,especially benzofluoranthene and benzopyrenes,increase markedly owing to adecrease in light aromatie hydrocarbons as a result of water washing.

  7. Spatial Persistence of Macropores and Authigenic Clays in a Reservoir Sandstone: Implications for Enhanced Oil Recovery and CO2 Storage

    Science.gov (United States)

    Dewers, T. A.

    2015-12-01

    Multiphase flow in clay-rich sandstone reservoirs is important to enhanced oil recovery (EOR) and the geologic storage of CO2. Understanding geologic controls on pore structure allows for better identification of lithofacies that can contain, storage, and/or transmit hydrocarbons and CO2, and may result in better designs for EOR-CO2 storage. We examine three-dimensional pore structure and connectivity of sandstone samples from the Farnsworth Unit, Texas, the site of a combined EOR-CO2 storage project by the Southwest Regional Partnership on Carbon Sequestration (SWP). We employ a unique set of methods, including: robotic serial polishing and reflected-light imaging for digital pore-structure reconstruction; electron microscopy; laser scanning confocal microscopy; mercury intrusion-extrusion porosimetry; and relative permeability and capillary pressure measurements using CO2 and synthetic formation fluid. Our results link pore size distributions, topology of porosity and clay-rich phases, and spatial persistence of connected flow paths to multiphase flow behavior. The authors gratefully acknowledge the U.S. Department of Energy's National Energy Technology Laboratory for sponsoring this project through the SWP under Award No. DE-FC26-05NT42591. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  8. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio Fluvial-Deltaic Sandstone Reservoirs of South Texas

    Energy Technology Data Exchange (ETDEWEB)

    McRae, L.E.; Holtz, M.H.; Knox, P.R.

    1995-07-01

    The Frio Fluvial-Deltaic Sandstone Play of South Texas is one example of a mature play where reservoirs are being abandoned at high rates, potentially leaving behind significant unrecovered resources in untapped and incompletely drained reservoirs. Nearly 1 billion barrels of oil have been produced from Frio reservoirs since the 1940`s, yet more than 1.6 BSTB of unrecovered mobile oil is estimated to remain in the play. Frio reservoirs of the South Texas Gulf Coast are being studied to better characterize interwell stratigraphic heterogeneity in fluvial-deltaic depositional systems and determine controls on locations and volumes of unrecovered oil. Engineering data from fields throughout the play trend were evaluated to characterize variability exhibited by these heterogeneous reservoirs and were used as the basis for resource calculations to demonstrate a large additional oil potential remaining within the play. Study areas within two separate fields have been selected in which to apply advanced reservoir characterization techniques. Stratigraphic log correlations, reservoir mapping, core analyses, and evaluation of production data from each field study area have been used to characterize reservoir variability present within a single field. Differences in sandstone depositional styles and production behavior were assessed to identify zones with significant stratigraphic heterogeneity and a high potential for containing unproduced oil. Detailed studies of selected reservoir zones within these two fields are currently in progress.

  9. Well logging evaluation of water-flooded layers and distribution rule of remaining oil in marine sandstone reservoirs of the M oilfield in the Pearl River Mouth basin

    Science.gov (United States)

    Li, Xiongyan; Qin, Ruibao; Gao, Yunfeng; Fan, Hongjun

    2017-03-01

    In the marine sandstone reservoirs of the M oilfield the water cut is up to 98%, while the recovery factor is only 35%. Additionally, the distribution of the remaining oil is very scattered. In order to effectively assess the potential of the remaining oil, the logging evaluation of the water-flooded layers and the distribution rule of the remaining oil are studied. Based on the log response characteristics, the water-flooded layers can be qualitatively identified. On the basis of the mercury injection experimental data of the evaluation wells, the calculation model of the initial oil saturation is built. Based on conventional logging data, the evaluation model of oil saturation is established. The difference between the initial oil saturation and the residual oil saturation can be used to quantitatively evaluate the water-flooded layers. The evaluation result of the water-flooded layers is combined with the ratio of the water-flooded wells in the marine sandstone reservoirs. As a result, the degree of water flooding in the marine sandstone reservoirs can be assessed. On the basis of structural characteristics and sedimentary environments, the horizontal and vertical water-flooding rules of the different types of reservoirs are elaborated upon, and the distribution rule of the remaining oil is disclosed. The remaining oil is mainly distributed in the high parts of the structure. The remaining oil exists in the top of the reservoirs with good physical properties while the thickness of the remaining oil ranges from 2–5 m. However, the thickness of the remaining oil of the reservoirs with poor physical properties ranges from 5–8 m. The high production of some of the drilled horizontal wells shows that the above distribution rule of the remaining oil is accurate. In the marine sandstone reservoirs of the M oilfield, the research on the well logging evaluation of the water-flooded layers and the distribution rule of the remaining oil has great practical significance

  10. Reservoir Characterization of Upper Devonian Gordon Sandstone, Jacksonburg, Stringtown Oil Field, Northwestern West Virginia

    Energy Technology Data Exchange (ETDEWEB)

    Ameri, S.; Aminian, K.; Avary, K.L.; Bilgesu, H.I.; Hohn, M.E.; McDowell, R.R.; Patchen, D.L.

    2002-05-21

    The purpose of this work was to establish relationships among permeability, geophysical and other data by integrating geologic, geophysical and engineering data into an interdisciplinary quantification of reservoir heterogeneity as it relates to production.

  11. Effect of specimen size on energy dissipation characteristics of red sandstone under high strain rate

    Institute of Scientific and Technical Information of China (English)

    Li Ming; Mao Xianbiao; Lu Aihong; Tao Jing; Zhang Guanghui; Zhang Lianying; Li Chong

    2014-01-01

    In this experiment, red sandstone specimens, having slenderness ratios of 0.5, 0.7, 0.9 and 1.1 respec-tively, were subjected to blow tests using a Split Hopkinson Pressure Bar (SHPB) system at a pressure of 0.4 atmospheres. In this paper, we have analyzed the effect of slenderness ratio on the mechanical properties and energy dissipation characteristics of red sandstone under high strain rates. The processes of compaction, elastic deformation and stress softening deformation of specimens contract with an increase in slenderness ratio, whilst the nonlinear deformation process extends correspondingly. In addi-tion, degrees of damage of specimens reduced gradually and the type of destruction showed a transfor-mation trend from stretching failure towards shear failure when the slenderness ratio increased. A model of dynamic damage evolution in red sandstone was established and the parameters of the constitutive model at different ratios of length to diameter were determined. By comparison with the experimental curve, the accuracy of the model, which could reflect the stress-strain dynamic characteristics of red sandstone, was verified. From the view of energy dissipation, an increase in slenderness ratio of a specimen decreased the proportion of energy dissipation and caused a gradual fall in the capability of energy dissipation during the specimen failure process. To some extent, the study indicated the effects of slenderness ratios on the mechanical properties and energy dissipation characteristics of red sandstone under the high strain rate, which provides valuable references to related engineering designs and academic researches.

  12. Grain-scale deformation in granular materials: time-lapse XCT-imaging of a deforming reservoir sandstone

    Science.gov (United States)

    Hangx, Suzanne; Cordonnier, Benoît; Pijnenburg, Ronald; Renard, François; Spiers, Christopher

    2017-04-01

    Relating macroscopic deformation of granular media to grain-scale processes, such as grain fracturing, has been a focus of many studies. Understanding these processes is key for predicting surface subsidence and induced seismicity caused by hydrocarbon depletion, the hydraulic fracturing response of geothermal reservoirs, and post-seismic crustal deformation. With the development of state-of-the-art techniques, such as time-lapse X-ray tomography imaging during triaxial deformation, new avenues to investigate the operating mechanisms have opened up. As a first step to understanding grain-scale deformation processes, we performed a deformation experiment on highly porous sandstone, obtained from a depleting gas reservoir, using a novel small-scale triaxial deformation apparatus coupled to high-resolution 4D X-ray tomography, available at the European Synchrotron Radiation Facility (ESRF, Grenoble) and Université Grenoble Alpes. This state-of-the-art apparatus allows for 3D time-lapse imaging of samples, while deforming at pressure, temperature and fluid flow conditions relevant for geological reservoirs. We performed our experiment at relevant in-situ reservoir conditions (T = 100˚ C, 10 MPa pore pressure, 40 MPa effective confining pressure). Axial stress was increased step-wise until failure occurred, while continuously imaging deformation. This enables us to monitor progressive grain failure, and strain localisation, during deformation in real-time. Though the vast amount of data obtained from even a single test poses challenges for data analysis, this presentation will address the first results obtained from this experiment.

  13. Diagenesis characteristics and their influence on Porosity and Permeability of sandstone from Yingcheng Formation in Jinshan field

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ruiyao,GAO Fuhong; ZHANG Zhongyue

    2014-01-01

    In order to understand the diagenesis and its influence on Porosity and Permeability of sandstones from Yingcheng Formation in Jinshan field,aPPlying thin sections,casting and scanning electron microscoPe, the authors studied PetrograPhy,diagenesis,Porosity and Permeability of Yingcheng Formation sandstone reser-voir. The results show that the reservoir of Yingcheng Formation is mainly comPosed of lithic arkoses. Sand-stones exPerienced comPaction,Pressolution,cementation,metasomatism and dissolution. The Primary Pores of the sandstones are undeveloPed;most of Pores are the secondary Pores,which are mainly intragranular dissolu-tion Pores in feldsPar and debris. The comPaction and cementation reduced the Primary Pores in sandstones,the Porosity and Permeability decreased;while the dissolution formed the secondary Pores,resulting in the Porosity and Permeability increase. Due to comPaction and cementation,the Porosity and Permeability are reduced with increasing of dePth. There exists an abnormal enlargement of Porosity and Permeability within a dePth range 2 310-2 450 m. In combination with analysis of Petrology,the dissolution of feldsPar and debris is most deve-loPed in the dePth range. Therefore,comPaction,cementation and dissolution are the imPortant factors which affect the Porosity and Permeability of sandstones.

  14. Study on the Mechanism of Acidification of Unconsolidated Sandstone Reservoir in Jinjia Oil Filed%金家油田疏松砂岩油藏酸化机理室内研究

    Institute of Scientific and Technical Information of China (English)

    白云云

    2011-01-01

    Jinjia oilfield is the Sandstone reservoir with high clay content, there is easy to sand conventional acidification, leading to acidification of the problem of poor results. On the basis of the injury characteristics in the reservoir, through the corrosion experiment, the suitable acid type of jinjia unconsolidated sandstone oil reservoir can be to option, At the same time, through the core flow experiments and environmental scanning electron microscope , ion concentration of residual acid acidification of its mechanism of evaluation techniques are discussed. The results show that the acidification of liquid formula for the effect of acidification of unconsolidated sandstone reservoir, and can effectively prevent the migration of clay particles to reduce the reservoir of secondary injury.%金家油田砂岩储层泥质含量高,存在常规酸化易出砂,导致酸化效果不佳的问题.在储层伤害特征研究的基础上,利用溶蚀实验优选出适合金家油田疏松砂岩油藏的酸液类型,同时通过岩心流动实验及环境扫描电镜、残酸离子浓度评价技术对其酸化机理进行了讨论.结果表明该酸化液配方对于疏松砂岩油藏酸化效果好,可有效防止黏土微粒运移,减少储层二次伤害.

  15. Classification and quantification of pore shapes in sandstone reservoir rocks with 3-D X-ray micro-computed tomography

    Directory of Open Access Journals (Sweden)

    M. Schmitt

    2015-12-01

    Full Text Available Recent years have seen a growing interest in the characterization of the pore morphologies of reservoir rocks and how the spatial organization of pore traits affects the macro behaviour of rock-fluid systems. With the availability of 3-D high-resolution imaging (e.g. μ-CT, the detailed quantification of particle shapes has been facilitated by progress in computer science. Here, we show how the shapes of irregular rock particles (pores can be classified and quantified based on binary 3-D images. The methodology requires the measurement of basic 3-D particle descriptors and a shape classification that involves the similarity of artificial objects, which is based on main pore network detachments and 3-D sample sizes. The results were validated for three sandstones (S1, S2 and S3 from distinct reservoirs, and most of the pore shapes were found to be plate- and cube-like. Furthermore, this study generalizes a practical way to correlate specific particle shapes, such as rods, blades, cuboids, plates and cubes, to characterize asymmetric particles of any material type with 3-D image analysis.

  16. Diagenesis and reservoir properties of Cretaceous-Lower Tertiary sandstones: the GANT-1 well, western Nuussuaq, central West Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Kierkegaard, Thomas

    1998-08-01

    The main purpose of this study is to describe the diagenetic alterations occurring in the Cretaceous to Lower Paleocene sedimentary succession of the GANT-1 well, and to determine the diagenetic and detrital factors which control present porosity and permeability. The GANT-1 well is located on north-western Nuussuaq, central West Greenland. The West Greenland margin is a continental margin subdivided into linked basins where Cretaceous to Lower Tertiary and probably older sediments have been deposited. In the Nuussuaq area these sediments are overlain by a succession of Early Tertiary basaltic volcanic rocks which reaches a combined thickness of around 2-2.5 km. Although the reservoir properties of the sandstone intervals in the GANT-1 and GANE-1 wells are generally relatively poor, it is suggested that moderate to good properties may be found in certain intervals within the Maastrichtian-Paleocene succession. However, the reason for the locally enhanced reservoir properties in GANT-1 was not clarified by this study due to the lack of regional petrographical data. (EG) EFP-96. 41 refs., 3 maps

  17. Study on detailed geological modelling for fluvial sandstone reservoir in Daqing oil field

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Hanqing; Fu Zhiguo; Lu Xiaoguang [Institute of Petroleum Exploration and Development, Daqing (China)

    1997-08-01

    Guided by the sedimentation theory and knowledge of modern and ancient fluvial deposition and utilizing the abundant information of sedimentary series, microfacies type and petrophysical parameters from well logging curves of close spaced thousands of wells located in a large area. A new method for establishing detailed sedimentation and permeability distribution models for fluvial reservoirs have been developed successfully. This study aimed at the geometry and internal architecture of sandbodies, in accordance to their hierarchical levels of heterogeneity and building up sedimentation and permeability distribution models of fluvial reservoirs, describing the reservoir heterogeneity on the light of the river sedimentary rules. The results and methods obtained in outcrop and modem sedimentation studies have successfully supported the study. Taking advantage of this method, the major producing layers (PI{sub 1-2}), which have been considered as heterogeneous and thick fluvial reservoirs extending widely in lateral are researched in detail. These layers are subdivided into single sedimentary units vertically and the microfacies are identified horizontally. Furthermore, a complex system is recognized according to their hierarchical levels from large to small, meander belt, single channel sandbody, meander scroll, point bar, and lateral accretion bodies of point bar. The achieved results improved the description of areal distribution of point bar sandbodies, provide an accurate and detailed framework model for establishing high resolution predicting model. By using geostatistic technique, it also plays an important role in searching for enriched zone of residual oil distribution.

  18. What's shaking?: Understanding creep and induced seismicity in depleting sandstone reservoirs

    Science.gov (United States)

    Hangx, Suzanne; Spiers, Christopher

    2015-04-01

    Subsurface exploitation of the Earth's natural resources, such as oil, gas and groundwater, removes the natural system from its chemical and physical equilibrium. With global energy and water demand increasing rapidly, while availability diminishes, densely populated areas are becoming increasingly targeted for exploitation. Indeed, the impact of our geo-resources needs on the environment has already become noticeable. Deep groundwater pumping has led to significant surface subsidence in urban areas such as Venice and Bangkok. Hydrocarbons production has also led to subsidence and seismicity in offshore (e.g. Ekofisk, Norway) and onshore hydrocarbon fields (e.g. Groningen, the Netherlands). Fluid extraction inevitably leads to (poro)elastic compaction of reservoirs, hence subsidence and occasional fault reactivation. However, such effects often exceed what is expected from purely elastic reservoir behaviour and may continue long after exploitation has ceased or show other time-lag effects in relation to changes in production rates. One of the main hypotheses advanced to explain this is time-dependent compaction, or 'creep deformation', of such reservoirs, driven by the reduction in pore fluid pressure compared with the vertical rock overburden pressure. The operative deformation mechanisms may include grain-scale brittle fracturing and thermally-activated mass transfer processes (e.g. pressure solution). Unfortunately, these mechanisms are poorly known and poorly quantified. As a first step to better describe creep in sedimentary granular aggregates, we have derived a universal, simple model for intergranular pressure solution (IPS) within an ordered pack of spherical grains. This universal model is able to predict the conditions under which each of the respective pressure solution serial processes, i.e. diffusion, precipitation or dissolution, is dominant. In essence, this creates a generic deformation mechanism map for IPS in any granular material. We have used

  19. Modelling of Seismic and Resistivity Responses during the Injection of CO2 in Sandstone Reservoir

    Science.gov (United States)

    Omar, Muhamad Nizarul Idhafi Bin; Almanna Lubis, Luluan; Nur Arif Zanuri, Muhammad; Ghosh, Deva P.; Irawan, Sonny; Regassa Jufar, Shiferaw

    2016-07-01

    Enhanced oil recovery plays vital role in production phase in a producing oil field. Initially, in many cases hydrocarbon will naturally flow to the well as respect to the reservoir pressure. But over time, hydrocarbon flow to the well will decrease as the pressure decrease and require recovery method so called enhanced oil recovery (EOR) to recover the hydrocarbon flow. Generally, EOR works by injecting substances, such as carbon dioxide (CO2) to form a pressure difference to establish a constant productive flow of hydrocarbon to production well. Monitoring CO2 performance is crucial in ensuring the right trajectory and pressure differences are established to make sure the technique works in recovering hydrocarbon flow. In this paper, we work on computer simulation method in monitoring CO2 performance by seismic and resistivity model, enabling geoscientists and reservoir engineers to monitor production behaviour as respect to CO2 injection.

  20. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Technical progress report, January 1, 1995--March 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Allison, M.L.

    1995-05-02

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be developed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project.

  1. Sandstone consolidation analysis to delineate areas of high-quality reservoirs suitable for production of geopressured geothermal energy along the Texas Gulf Coast

    Energy Technology Data Exchange (ETDEWEB)

    Loucks, R.G.; Dodge, M.M.; Galloway, W.E.

    1979-01-01

    Analysis of reservoir quality of lower Tertiary sandstones along the Texas Gulf Coast delineates areas most favorable for geopressured geothermal exploration. Reservoir quality is determined by whole core, acoustic log, and petrographic analyses. The Wilcox Group has good reservoir potential for geopressured geothermal energy in the Middle Texas Gulf Coast and possibly in adjacent areas, but other Wilcox areas are marginal. The Vicksburg Formation in the Lower Texas Gulf Coast is not prospective. Reservoir quality in the Frio Formation increases from very poor in lowermost Texas, to marginal into the Middle Texas Gulf Coast and to good through the Upper Texas Gulf Coast. The Frio Formation in the Upper Texas Gulf Coast has the best deep-reservoir quality of any unit along the Texas Gulf Coast. (MHR)

  2. A Novel Method for Improving Water Injectivity in Tight Sandstone Reservoirs

    Directory of Open Access Journals (Sweden)

    Mohamad Yousef Alklih

    2014-01-01

    Full Text Available Applicability of electrokinetic effect in improving water injectivity in tight sandstone is studied. DC potential and injection rate are varied for optimization and determination of their individual impact on clay discharge and movement. The liberated clays were characterized through size exclusion microfiltration and ICP-MS analysis. Real time temperature and pH monitoring were also informative. Results showed that severalfold (up to 152% apparent increase of core permeability could be achieved. Some of the experiments were more efficient in terms of dislodgement of clays and enhanced stimulation which is supported by produced brines analysis with higher concentration of clay element. The results also showed larger quantity of clays in the produced brine in the initial periods of water injection followed by stabilization of differential pressure and electrical current, implying that the stimulation effect stops when the higher voltage gradient and flow rates are no more able to dislodge remaining clays. Additionally, fluid temperature measurement showed an increasing trend with the injection time and direct proportionality with the applied voltage. The basic theory behind this stimulation effect is predicted to be the colloidal movement of pore lining clays that results in widening of pore throats and/or opening new flow paths.

  3. Geological and petrophysical characterization of the ferron sandstone for 3-D simulation of a fluvial-deltaic reservoir. Annual report, October 1, 1994--September 30, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Chidsey, T.C. Jr.; Allison, M.L.

    1996-05-01

    The objective of the Ferron Sandstone project is to develop a comprehensive, interdisciplinary, quantitative characterization of a fluvial-deltaic reservoir to allow realistic interwell and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Quantitative geological and petrophysical information on the Cretaceous Ferron Sandstone in east-central Utah was collected. Both new and existing data is being integrated into a three-dimensional model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project. This report covers research activities for fiscal year 1994-95, the second year of the project. Most work consisted of developing field methods and collecting large quantities of existing and new data. We also continued to develop preliminary regional and case-study area interpretations. The project is divided into four tasks: (1) regional stratigraphic analysis, (2) case studies, (3) reservoirs models, and (4) field-scale evaluation of exploration strategies.

  4. Muddy and dolomitic rip-up clasts in Triassic fluvial sandstones: Origin and impact on potential reservoir properties (Argana Basin, Morocco)

    Science.gov (United States)

    Henares, Saturnina; Arribas, Jose; Cultrone, Giuseppe; Viseras, Cesar

    2016-06-01

    The significance of rip-up clasts as sandstone framework grains is frequently neglected in the literature being considered as accessory components in bulk sandstone composition. However, this study highlights the great value of muddy and dolomitic rip-up clast occurrence as: (a) information source about low preservation potential from floodplain deposits and (b) key element controlling host sandstone diagenetic evolution and thus ultimate reservoir quality. High-resolution petrographic analysis on Triassic fluvial sandstones from Argana Basin (T6 and T7/T8 units) highlights the significance of different types of rip-up clasts as intrabasinal framework components of continental sediments from arid climates. On the basis of their composition and ductility, three main types are distinguished: (a) muddy rip-up clasts, (b) dolomitic muddy rip-up clasts and (c) dolomite crystalline rip-up clasts. Spatial distribution of different types is strongly facies-related according to grain size. Origin of rip-up clasts is related to erosion of coeval phreatic dolocretes, in different development stages, and associated muddy floodplain sediments. Cloudy cores with abundant inclusions and clear outer rims of dolomite crystals suggest a first replacive and a subsequent displacive growth, respectively. Dolomite crystals are almost stoichiometric. This composition is very similar to that of early sandstone dolomite cement, supporting phreatic dolocretes as dolomite origin in both situations. Sandstone diagenesis is dominated by mechanical compaction and dolomite cementation. A direct correlation exists between: (1) muddy rip-up clast abundance and early reduction of primary porosity by compaction with irreversible loss of intergranular volume (IGV); and (2) occurrence of dolomitic rip-up clasts and dolomite cement nucleation in host sandstone, occluding adjacent pores but preserving IGV. Both processes affect reservoir quality by generation of vertical and 3D fluid flow baffles and

  5. Sedimentology and reservoir heterogeneity of a valley-fill deposit-A field guide to the Dakota Sandstone of the San Rafael Swell, Utah

    Science.gov (United States)

    Kirschbaum, Mark A.; Schenk, Christopher J.

    2010-01-01

    Valley-fill deposits form a significant class of hydrocarbon reservoirs in many basins of the world. Maximizing recovery of fluids from these reservoirs requires an understanding of the scales of fluid-flow heterogeneity present within the valley-fill system. The Upper Cretaceous Dakota Sandstone in the San Rafael Swell, Utah contains well exposed, relatively accessible outcrops that allow a unique view of the external geometry and internal complexity of a set of rocks interpreted to be deposits of an incised valley fill. These units can be traced on outcrop for tens of miles, and individual sandstone bodies are exposed in three dimensions because of modern erosion in side canyons in a semiarid setting and by exhumation of the overlying, easily erodible Mancos Shale. The Dakota consists of two major units: (1) a lower amalgamated sandstone facies dominated by large-scale cross stratification with several individual sandstone bodies ranging in thickness from 8 to 28 feet, ranging in width from 115 to 150 feet, and having lengths as much as 5,000 feet, and (2) an upper facies composed of numerous mud-encased lenticular sandstones, dominated by ripple-scale lamination, in bedsets ranging in thickness from 5 to 12 feet. The lower facies is interpreted to be fluvial, probably of mainly braided stream origin that exhibits multiple incisions amalgamated into a complex sandstone body. The upper facies has lower energy, probably anastomosed channels encased within alluvial and coastal-plain floodplain sediments. The Dakota valley-fill complex has multiple scales of heterogeneity that could affect fluid flow in similar oil and gas subsurface reservoirs. The largest scale heterogeneity is at the formation level, where the valley-fill complex is sealed within overlying and underlying units. Within the valley-fill complex, there are heterogeneities between individual sandstone bodies, and at the smallest scale, internal heterogeneities within the bodies themselves. These

  6. Characteristics and controlling factors of movable fluid in deep-buried high-pressure and low-permeability sandstone reservoirs:A case study of middle section of 3rd member of Shahejie Formation in Wendong Oil Field, Dongpu Sag%深层高压低渗砂岩储层可动流体赋存特征及控制因素--以东濮凹陷文东沙三中油藏为例

    Institute of Scientific and Technical Information of China (English)

    王瑞飞; 齐宏新; 吕新华; 国殿斌

    2014-01-01

    利用核磁共振技术,对东濮凹陷文东沙三中深层高压低渗砂岩储层样品进行测试分析,通过可动流体百分数、可动流体孔隙度参数分析了可动流体的赋存特征及控制因素。研究结果表明,不同离心力的T2谱形态表现为4种类型,T2截止值与物性呈正相关关系。可动流体含量低且其分布具有较强的非均质性,渗透率越高,主流喉道半径越大,可动流体参数值越大,可动流体参数与渗透率的相关关系越好;渗透率越低,可动流体参数衰减越快。储层微观孔隙结构是可动流体赋存的主要控制因素。应用喉道半径区间分布表征微观孔隙结构对可动流体分布的控制,效果较好。物性越好,大喉道控制的可动流体量越高。%The samples of the deep-buried high-pressure and low-permeability sandstone reservoirs in the middle section of the 3rd member of the Shahejie Formation in the Wendong Oil Field of the Dongpu Sag were tested with nuclear magnetic resonance technique. The characteristics and controlling factors of movable fluid were analyzed with movable fluid percentage and porosity. The results have shown that the T2 pattern of the samples displays 4 modes, and the T2 cutoff value is positively correlated with porosity. The movable fluid content is relatively low and the heterogeneity is intense. The higher the permeability is, the wider is the main throat radius. The relation between the movable fluid parameter and the permeability gets better with the increase of permeability. The mova-ble fluid parameter gets higher attenuation velocity with the decrease of permeability and has more sensitivity to the changes of permeability. The micro-pore structure determines the existing state of fluid in deep-buried high-pressure and low-permeability sandstone reservoir. Applying main throat radius, the micro-pore structure control-ling movable fluid was token, which has achieved good results

  7. Geochemical characteristics of Dongsheng sandstone-type uranium deposit, Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    SUN Yuzhuang; LIU Chiyang; DAI Shifeng; QIN Peng

    2007-01-01

    Generally, sandstone-type uranium deposits can be divided into three zones according to their redox conditions: oxidized zone, ore zone and reduced zone. The Dongsheng uranium deposit belongs to this type. In order to study its geochemical characteristics, 11 samples were taken from the three zones of the Dongsheng uranium deposit. Five samples of them were collected from the oxidized zone, four samples from the ore zone and two samples from the reduced zone. These samples were analyzed using organic and inorganic geochemical methods. The results of GC traces and ICP-MASS indicate that the three zones show different organic and inorganic geochemical characteristics.

  8. Characteristics of bleaching of sandstone in northeast of Ordos Basin and its relationship with natural gas leakage

    Institute of Scientific and Technical Information of China (English)

    MA; YanPing; LIU; ChiYang; ZHAO; JunFeng; HUANG; Lei; YU; Lin; WANG; JianQiang

    2007-01-01

    Bleaching of sandstone has significant applications to tracing hydrocarbon pathways and evaluating the scale of natural gas seepage. Bleaching of sandstones in the northeast of Ordos Basin is mainly distributed in the Mesozoic Yan'an Formation. Studying on petrology, major elements, REEs and trace elements of bleached sandstones and comparing with adjacent sandstones, combining with geologic-geochemical evidences of gas seepage in the northeast of the basin, the bleached sandstones are formed in the acid environment and reducing fluids. Characteristics of petrology show that the contents of kaolinite are high and the color of margin of ferric oxide minerals is lighter than that of the center. Major elements of sandstone samples show high contents of Al2O3 and low ratio of Fe3+/Fe2+. The TFe2O3 content of the bleached sandstone is lower than that of red rock. REE data show that bleached sandstones have low ∑REE contents and Eu-depleted and slightly Ce-enriched. Trace elements show that the bleached sandstones enrich in Co, deplete in Sr, and slightly enrich in Zr and Hf which are close to the values for the green alteration sandstones, and slightly lower than ore-bearing sandstones. Geochemical characteristics of oil-bearing sandstone in the northern basin suggest that the oil-shows are formed by matured Carboniferous-Permian coal bed methane escaping to the surface, and natural gas in field could migrate to the north margin of the basin. The δ13C (PDB) andδ18O(PDB) values of calcite cement in the study area range from -11.729‰ to -10.210‰ and -14.104‰ to -12.481‰, respectively. Theδ13C (PDB) values less than -10‰ imply the carbon sources part from organic carbon. Comprehensive study suggests that the gas leakage has occurred in the northeastern basin, which is responsible for bleaching of the sandstone on top of the Yan'an Formation.

  9. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly report, July 1--September 30, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Allison, M.L.

    1997-11-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Two activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone: (1) evaluation of the Ivie Creek and Willow Springs Wash case-study areas and (2) technology transfer.

  10. The experimental modeling of gas percolation mechanisms in a coal-measure tight sandstone reservoir: A case study on the coal-measure tight sandstone gas in the Upper Triassic Xujiahe Formation, Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Shizhen Tao

    2016-12-01

    Full Text Available Tight sandstone gas from coal-measure source rock is widespread in China, and it is represented by the Xujiahe Formation of the Sichuan Basin and the Upper Paleozoic of the Ordos Basin. It is affected by planar evaporative hydrocarbon expulsion of coal-measure source rock and the gentle structural background; hydrodynamics and buoyancy play a limited role in the gas migration-accumulation in tight sandstone. Under the conditions of low permeability and speed, non-Darcy flow is quite apparent, it gives rise to gas-water mixed gas zone. In the gas displacing water experiment, the shape of percolation flow curve is mainly influenced by core permeability. The lower the permeability, the higher the starting pressure gradient as well as the more evident the non-Darcy phenomenon will be. In the gas displacing water experiment of tight sandstone, the maximum gas saturation of the core is generally less than 50% (ranging from 30% to 40% and averaging at 38%; it is similar to the actual gas saturation of the gas zone in the subsurface core. The gas saturation and permeability of the core have a logarithm correlation with a correlation coefficient of 0.8915. In the single-phase flow of tight sandstone gas, low-velocity non-Darcy percolation is apparent; the initial flow velocity (Vd exists due to the slippage effect of gas flow. The shape of percolation flow curve of a single-phase gas is primarily controlled by core permeability and confining pressure; the lower the permeability or the higher the confining pressure, the higher the starting pressure (0.02–0.08 MPa/cm, whereas, the higher the quasi-initial flow speed, the longer the nonlinear section and the more obvious the non-Darcy flow will be. The tight sandstone gas seepage mechanism study shows that the lower the reservoir permeability, the higher the starting pressure and the slower the flow velocity will be, this results in the low efficiency of natural gas migration and accumulation as well as

  11. Lack of inhibiting effect of oil emplacement on quartz cementation: Evidence from Cambrian reservoir sandstones, Paleozoic Baltic Basin

    DEFF Research Database (Denmark)

    Molenaar, Nicolaas; Cyziene, Jolanta; Sliaupa, Saulius;

    2008-01-01

    Currently, the question of whether or not the presence of oil in sandstone inhibits quartz cementation and preserves porosity is still debated. Data from a number of Cambrian sandstone oil fields and dry fields have been studied to determine the effects of oil emplacement on quartz cementation...... cementation is derived from internal sources. Rather, in spite of large variation in porosity and quartz cement content, a regular pattern of porosity decrease is related to increasing temperature or depth. The observed heterogeneity is due to local factors that influence the precipitation of quartz cement......, including sandstone architecture, i.e., distribution of shales within the sandstone bodies, and sandstone thickness. Heterogeneity is inherent to sandstone architecture and to the fact that silica for quartz cementation is derived from heterogeneously distributed local pressure solution. Models predicting...

  12. Effect of hydrocarbon to nuclear magnetic resonance (NMR) logging in tight sandstone reservoirs and method for hydrocarbon correction

    Science.gov (United States)

    Xiao, Liang; Mao, Zhi-qiang; Xie, Xiu-hong

    2017-04-01

    It is crucial to understand the behavior of the T2 distribution in the presence of hydrocarbon to properly interpret pore size distribution from NMR logging. The NMR T2 spectrum is associated with pore throat radius distribution under fully brine saturated. However, when the pore space occupied by hydrocarbon, the shape of NMR spectrum is changed due to the bulk relaxation of hydrocarbon. In this study, to understand the effect of hydrocarbon to NMR logging, the kerosene and transformer oil are used to simulate borehole crude oils with different viscosity. 20 core samples, which were separately drilled from conventional, medium porosity and permeability and tight sands are saturated with four conditions of irreducible water saturation, fully saturated with brine, hydrocarbon-bearing condition and residual oil saturation, and the corresponding NMR experiments are applied to acquire NMR measurements. The residual oil saturation is used to simulate field NMR logging due to the shallow investigation depth of NMR logging. The NMR spectra with these conditions are compared, the results illustrate that for core samples drilled from tight sandstone reservoirs, the shape of NMR spectra have much change once they pore space occupied by hydrocarbon. The T2 distributions are wide, and they are bimodal due to the effect of bulk relaxation of hydrocarbon, even though the NMR spectra are unimodal under fully brine saturated. The location of the first peaks are similar with those of the irreducible water, and the second peaks are close to the bulk relaxation of viscosity oils. While for core samples drilled from conventional formations, the shape of T2 spectra have little changes. The T2 distributions overlap with each other under these three conditions of fully brine saturated, hydrocarbon-bearing and residual oil. Hence, in tight sandstone reservoirs, the shape of NMR logging should be corrected. In this study, based on the lab experiments, seven T2 times of 1ms, 3ms, 10ms, 33ms

  13. Fragmentation characteristics analysis of sandstone fragments based on impact rockburst test

    Directory of Open Access Journals (Sweden)

    Dongqiao Liu

    2014-06-01

    Full Text Available Impact rockburst test on sandstone samples with a central hole is carried out under true triaxial static loads and vertical dynamic load conditions, and rock fragments after the test are collected. The fragments of sandstone generated from strain rockburst test and uniaxial compression test are also collected. The fragments are weighed and the length, width and thickness of each piece of fragments are measured respectively. The fragment quantities with coarse, medium, fine and micro grains in different size ranges, mass and particles distributions are also analyzed. Then, the fractal dimension of fragments is calculated by the methods of size-frequency, mass-frequency and length-to-thickness ratio-frequency. It is found that the crushing degree of impact rockburst fragments is higher, accompanied with blocky characteristics observably. The mass percentage of small grains, including fine and micro grains, in impact rockburst test is higher than those in strain rockburst test and uniaxial compression test. Energy dissipation from rockburst tests is more than that from uniaxial compression test, as the quantity of micro grains generated does.

  14. NMR Pore Structure and Dynamic Characteristics of Sandstone Caused by Ambient Freeze-Thaw Action

    Directory of Open Access Journals (Sweden)

    Bo Ke

    2017-01-01

    Full Text Available For a deeper understanding of the freeze-thaw weathering effects on the microstructure evolution and deterioration of dynamic mechanical properties of rock, the present paper conducted the nuclear magnetic resonance (NMR tests and impact loading experiments on sandstone under different freeze-thaw cycles. The results of NMR test show that, with the increase of freeze-thaw cycles, the pores expand and pores size tends to be uniform. The experimental results show that the stress-strain curves all go through four stages, namely, densification, elasticity, yielding, and failure. The densification curve is shorter, and the slope of elasticity curve decreases as the freeze-thaw cycles increase. With increasing freeze-thaw cycles, the dynamic peak stress decreases and energy absorption of sandstone increases. The dynamic failure form is an axial splitting failure, and the fragments increase and the size diminishes with increasing freeze-thaw cycles. The higher the porosity is, the more severe the degradation of dynamic characteristics is. An increase model for the relationships between the porosity or energy absorption and freeze-thaw cycles number was built to reveal the increasing trend with the freeze-thaw cycles increase; meanwhile, a decay model was built to predict the dynamic compressive strength degradation of rock after repeated freeze-thaw cycles.

  15. Experimental Study on the Softening Characteristics of Sandstone and Mudstone in Relation to Moisture Content

    Directory of Open Access Journals (Sweden)

    Gui-chen Li

    2017-01-01

    Full Text Available The kinetics of fluid-solid coupling during immersion is an important topic of investigation in rock engineering. Two rock types, sandstone and mudstone, are selected in this work to study the correlation between the softening characteristics of the rocks and moisture content. This is achieved through detailed studies using scanning electron microscopy, shear tests, and evaluation of rock index properties during exposure to different moisture contents. An underground roadway excavation is simulated by dynamic finite element modeling to analyze the effect of moisture content on the stability of the roadway. The results show that moisture content has a significant effect on shear properties reduction of both sandstone and mudstone, which must thus be considered in mining or excavation processes. Specifically, it is found that the number, area, and diameter of micropores, as well as surface porosity, increase with increasing moisture content. Additionally, stress concentration is negatively correlated with moisture content, while the influenced area and vertical displacement are positively correlated with moisture content. These findings may provide useful input for the design of underground roadways.

  16. Fragmentation characteristics analysis of sandstone fragments based on impact rockburst test

    Institute of Scientific and Technical Information of China (English)

    Dongqiao Liu; Dejian Li; Fei Zhao; Chengchao Wang

    2014-01-01

    Impact rockburst test on sandstone samples with a central hole is carried out under true triaxial static loads and vertical dynamic load conditions, and rock fragments after the test are collected. The fragments of sandstone generated from strain rockburst test and uniaxial compression test are also collected. The fragments are weighed and the length, width and thickness of each piece of fragments are measured respectively. The fragment quantities with coarse, medium, fine and micro grains in different size ranges, mass and particles distributions are also analyzed. Then, the fractal dimension of fragments is calculated by the methods of size-frequency, mass-frequency and length-to-thickness ratio-frequency. It is found that the crushing degree of impact rockburst fragments is higher, accompanied with blocky character-istics observably. The mass percentage of small grains, including fine and micro grains, in impact rock-burst test is higher than those in strain rockburst test and uniaxial compression test. Energy dissipation from rockburst tests is more than that from uniaxial compression test, as the quantity of micro grains generated does.

  17. Radon-222 content of natural gas samples from Upper and Middle Devonian sandstone and shale reservoirs in Pennsylvania—preliminary data

    Science.gov (United States)

    Rowan, E.L.; Kraemer, T.F.

    2012-01-01

    Samples of natural gas were collected as part of a study of formation water chemistry in oil and gas reservoirs in the Appalachian Basin. Nineteen samples (plus two duplicates) were collected from 11 wells producing gas from Upper Devonian sandstones and the Middle Devonian Marcellus Shale in Pennsylvania. The samples were collected from valves located between the wellhead and the gas-water separator. Analyses of the radon content of the gas indicated 222Rn (radon-222) activities ranging from 1 to 79 picocuries per liter (pCi/L) with an overall median of 37 pCi/L. The radon activities of the Upper Devonian sandstone samples overlap to a large degree with the activities of the Marcellus Shale samples.

  18. The characteristics of gravity and magnetic fields and the distribution of tight sandstone gas in the eastern Ordos Basin, China

    Science.gov (United States)

    Yuan, Bingqiang; Zhang, Huaan; Zhang, Chunguan; Xu, Haihong; Yan, Yunkui

    2016-04-01

    In order to perform gas exploration and determine the distribution pattern of gas in the Yanchang Oil Field in the eastern part of the North Shaanxi Slope, Ordos Basin, China, gravity and magnetic survey data were systemically collated, processed and interpreted in combination with the drilling data and recent seismic data. The genesis of gravity and magnetic anomalies and the relationship between the characteristics of the gravity and magnetic fields and known gas distribution were explored in order to predict the favourable exploration targets for gas. Gravity anomalies resulted both from the lateral variation in density of the basement rock and lateral lithologic transformation in the sedimentary cover. The regional magnetic anomalies were mainly caused by the basement metamorphic rocks and the residual magnetic anomalies may reflect the amount and general location of the volcanic materials in the overlying strata. The residual gravity and magnetic anomalies generated by high-density sandstone and high content of volcanics in the gas reservoir of the upper Paleozoic distorted and deformed the anomaly curves when they were stacked onto the primary background anomaly. The gas wells were generally found to be located in the anomaly gradient zones, or the distorted part of contour lines, and the flanks of high and low anomalies, or the transitional zones between anomaly highs and lows. The characteristics of gravity and magnetic fields provide significant information that can be used for guidance when exploring the distribution of gas. Based on these characteristics, five favourable areas for gas exploration were identified; these are quasi-equally spaced like a strip extending from the southeast to the northwest.

  19. Physical mechanisms of permeability evolution of sandstone under simulating reservoir depletion; Mecanismes physiques de l'evolution de la permeabilite d'un gres sous chargements simulant la depletion d'un gisement

    Energy Technology Data Exchange (ETDEWEB)

    Ferfera, F.M.R. [Sonatrach, Centre de Recherche et Developpement, Boumerdes (Algeria)

    2001-07-01

    During the early years of a reservoir life, production is done by depletion (decrease of pore pressure) which results in an increase of the effective stresses in the reservoir. In situ measurements show that the stress increase seems to follow two loading pathways, odometric or proportional, depending on parameters such as the rock petrophysical characteristics, the reservoir shape, boundary conditions, etc. All these changes induce variations of petrophysical characteristics of in situ rocks and particularly permeability variations, which depend on pore geometry, mineral composition of the rock and the loading type conditions. The modelling of permeability evolution during the primary production is then a complex problem which can be translated into the following question: Should we link permeability variations to the change of stresses or to strains? At first, a strain-permeability relationship seems to be more logical because permeability is a geometrical value. However, the analysis of the physical phenomenon (either mechanical or hydraulic) induced by the increase of the effective stress shows that a similar approach cannot be applied systematically to all rocks. That is what we want to illustrate, by an experimental work, on Vosges sandstone of good petrophysical characteristics (average porosity{phi}{sub avr} = 20 % and average permeability {kappa}{sub avr}{approx} 500 mD) where simultaneous measurements of strains and monophasic permeabilities were conducted. (author)

  20. Determining between-well reservoir architecture in deltaic sandstones using only well data: Oligocene Frio formation, Tijerina-Canales-Blucher field, South Texas

    Energy Technology Data Exchange (ETDEWEB)

    Knox, P.R. [Univ. of Texas, Austin, TX (United States)

    1996-09-01

    Accurate prediction of compartment architecture and intra-compartment heterogeneity is necessary to locate and recover the estimated 15 billion barrels of mobile oil remaining in U.S. fluvial-dominated deltaic reservoirs. Complex architecture and rapid lateral variability in such reservoirs complicate subsurface prediction, particularly in mature fields where well logs are the only available subsurface data. A genetic-stratigraphy-based methodology has been developed that improves between-well prediction of deltaic reservoir architecture and, thus, reduces risks associated with infill-drilling. In the area of Tijerina-Canales-Blucher (T-C-B) field, the productive 3rd-order Lower Frio unit was subdivided into eight 4th-order genetic units. Delta-front positions were identified on the basis of regional and subregional cross sections. The 4th-order units (30 to 80 ft thick) were subdivided into two five 5th-order units (10 to 30 ft thick). Log patterns and n sandstone maps were used to identify facies, which include (1) distributary channels (up to 25 ft thick, <1,000 to >8,000 ft wide, and commonly narrower than 40-acre well spacing), (2) mouth bars (up to 15 ft thick, ranging in size from 40 to 640 acres in area, commonly <320 acres), (3) bayfill splays (up to 10 ft thick, 20 to 700 acres in area, and commonly <160 acres), (4) wave-reworked delta fronts (up to 35 ft thick, and >5,000 ft wide), and (5) washover fans (up to 10 ft thick, and 7,000 ft wide). Many reservoir compartments, including the prolific 21-B interval, contain a significant degree of stratigraphic trapping caused by updip pinchout of delta front or washover sandstones or convex-updip segments of meandering distributary channel sandstones. The methodology and results of this study are directly applicable to other Gulf Coast fluvial-deltaic reservoirs in the Frio Formation and Wilcox Group, as well as to deltaic reservoirs throughout the U.S.

  1. [Species Determination and Spectral Characteristics of Swelling Clay Minerals in the Pliocene Sandstones in Xinghai, Qinghai].

    Science.gov (United States)

    Wang, Chao-wen; Chen, Jiang-jun; Fang, Qian; Yin, Ke; Hong, Han-lie

    2015-10-01

    X-ray diffraction (XRD) and Fourier infrared absorption spectroscopy (FTIR) were conducted to deepen our research on specific species and spectral characteristics of swelling clay minerals in the Pliocene sandstones in Xinghai, Qinghai province. XRD results show that swelling clay minerals are dominant clay minerals in the sandstones, which can be up to 97% in percentage. XRD patterns show 060 reflections of the samples occur both remarkably at 1.534 Å and 1.498 Å, indicating the samples contain physical mixtures of trioctahedral and dioctahedral swelling clay minerals, respectively. Further treatment of Li-300 degrees C heat and glycerol saturation shows the swelling clay minerals collapse to 9.3-9.9 Å with a partial expansion to -18 Å. This indicates the swelling clay minerals dominate montmorillonite and contain minor saponite. The montmorillonite shows no swelling after Li-300 degrees C heat and glycerol saturation because of Li+ inserting into the octahedral layers, which balances the layer charge caused by the substitution of Mg to Al. FTIR results show the samples are composed of a kind of phyllosilicate with absorbed and structural water, which is in agreement with the results of XRD. Absorbed peaks at 913, 842, 880 cm(-1), corresponding to OH associated with Al-Al, Al-Mg, and Al-Fe pairs, further indicates the minerals are dominant dioctahedron in structure. Meanwhile, absorbed peaks at 625 and 519 cm(-1), corresponding to coupled Si-O and Al-O-Si deformation, indicates parts of Si is replaced by Al in tetrahedron. The spectral characteristics of the samples are against the presence of beidellite and nontronite based on the results of XRD and FTIR, while demonstrating an,existence of montmorillonite. This study, to distinguish the specific species of swelling clay species in clay minerals, would be of great importance when using clay mineralogy to interpret provenance and climatic information.

  2. Outcrop analogue study of Permocarboniferous geothermal sandstone reservoir formations (northern Upper Rhine Graben, Germany): impact of mineral content, depositional environment and diagenesis on petrophysical properties

    Science.gov (United States)

    Aretz, Achim; Bär, Kristian; Götz, Annette E.; Sass, Ingo

    2016-07-01

    oil and acidic waters led to the dissolution of haematite cements in the lower Permocarboniferous formations. During the Eocene, subsidence of the Upper Rhine Graben porosities and permeabilities of the sandstones of these formations were strongly reduced to 2.5 % and 3.2 × 10-18 m2. The second important influence on reservoir quality is the distinct depositional environment and its influence on early diagenetic processes. In early stage diagenesis, the best influence on reservoir properties exhibits a haematite cementation. It typically occurs in eolian sandstones of the Kreuznach Formation (Upper Permocarboniferous) and is characterized by grain covering haematite coatings, which are interpreted to inhibit cementation, compaction and illitization of pore space during burial. Eolian sandstones taken from outcrops and reservoir depths exhibit the highest porosities (16.4; 12.3 %) and permeabilities (2.0 × 10-15; 8.4 × 10-16 m2). A third important influence on reservoir quality is the general mineral composition and the quartz content which is the highest in the Kreuznach Formation with 73.8 %. Based on the integrated study of depositional environments and diagenetic processes, reservoir properties of the different Permocarboniferous formations within the northern Upper Rhine Graben and their changes with burial depth can be predicted with satisfactory accuracy. This leads to a better understanding of the reservoir quality and enables an appropriate well design for exploration and exploitation of these geothermal resources.

  3. Anisotropy and spatial variation of relative permeability and lithologic character of Tensleep Sandstone reservoirs in the Bighorn and Wind River basins, Wyoming. Final technical report, September 15, 1993--October 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, T.L.

    1996-10-01

    This multidisciplinary study was designed to provide improvements in advanced reservoir characterization techniques. This goal was accomplished through: (1) an examination of the spatial variation and anisotropy of relative permeability in the Tensleep Sandstone reservoirs of Wyoming; (2) the placement of that variation and anisotropy into paleogeographic, and depositional regional frameworks; (3) the development of pore-system imagery techniques for the calculation of relative permeability; and (4) reservoir simulations testing the impact of relative permeability anisotropy and spatial variation on Tensleep Sandstone reservoir enhanced oil recovery. Concurrent efforts were aimed at understanding the spatial and dynamic alteration in sandstone reservoirs that is caused by rock-fluid interaction during CO{sub 2} enhanced oil recovery processes. The work focused on quantifying the interrelationship of fluid-rock interaction with lithologic characterization and with fluid characterization in terms of changes in chemical composition and fluid properties. This work establishes new criteria for the susceptibility of Tensleep Sandstone reservoirs to formation alteration that results in wellbore scale damage. This task was accomplished by flow experiments using core material; examination of regional trends in water chemistry; examination of local water chemistry trends the at field scale; and chemical modeling of both the experimental and reservoir systems.

  4. Mechanical properties and failure characteristics of fractured sandstone with grouting and anchorage

    Institute of Scientific and Technical Information of China (English)

    Zong Yijiang; Han Lijun; Qu Tao; Yang Shengqi

    2014-01-01

    Based on uniaxial compression experimental results on fractured sandstone with grouting and anchorage, we studied the strength and deformation properties, the failure model, crack formation and evolution laws of fractured sandstone under different conditions of anchorage. The experimental results show that the strength and elastic modulus of fractured sandstone with different fracture angles are sig-nificantly lower than those of intact sandstone. Compared with the fractured samples without anchorage, the peak strength, residual strength, peak and ultimate axial strain of fractured sandstone under different anchorage increase by 64.5-320.0%, 62.8-493.0%, and 31.6-181.4%, respectively. The number of bolts and degree of pre-stress has certain effects on the peak strength and failure model of fractured sandstone. The peak strength of fractured sandstone under different anchorage increases to some extent, and the failure model of fractured sandstone also transforms from tensile failure to tensile-shear mixed failure with the number of bolts. The pre-stress can restrain the formation and evolution process of tensile cracks, delay the failure process of fractured sandstone under anchorage and impel the transformation of failure model from brittle failure to plastic failure.

  5. Study on Mechanism of Low Permeability Sandstone Gas Reservoir in Fourth Member of Xujiahe in Guang An Gas Field%广安气田须四段低渗砂岩气藏渗流机理研究

    Institute of Scientific and Technical Information of China (English)

    李辉; 王燕; 欧剑; 许涛; 汪娟

    2013-01-01

    On the basis of a detailed analysis of the reservoir characteristics, from the capillary pressure, reservoir structure characteristics, percolation characteristics of the two-phase, gas single -phase low-speed and water lock, oil lock damage, etc. develop detailed study on the mechanism of low permeability sandstone gas reservoir in Fourth Member of Xujiahe in Guangan Gas Field seepage. Results show that: low permeability sandstone gas reservoir porosity is concentrated in the range of 3% to 7% , penetration concentrated between 0.001 × 10-3 μm ~ 16. 2 × 10-3μm2, it belongs to a typical low porosity and low permeability gas reservoirs; capillary pressure curve has a bimodal characteristics, it' s a moderate deviation reservoir, the pore throats value radius 0. 1 μm as a division of the reservoir and non- reservoir boundaries; coexistence of gas and water permeability reservoir , gas seepage by the slippage effect and capillary forces affect the slow seepage stage , the capillary force of the impact is more obvious, and gas seepage produce low velocity non-Darcy flow phenomena. Reservoir initial water saturation , with movable water can be taken out , water blocking damage will be improved , but the increase in the amount of precipitation of condensate , easy to form at the throat " Jamin effect" increase the gas flow resistance , impact gas well production capacity , resulting in damage to the oil lock.%在对储层特征进行详细分析的基础上,从毛管压力、储层结构特征、两相渗流特征、气体单相低速渗流特征和水锁、油锁损害等方面,深入研究了广安气田须四段低渗砂岩气藏渗流机理.研究结表明:须四段低渗砂岩气藏孔隙度集中在3%~7%之间,渗透率集中在0.001×10-3 μm2 ~ 16.2×10-3 μm2之间,属典型的低孔、低渗气藏.毛管压力曲线具有双峰态特征,属于中等偏差储层,孔喉中值半径0.1 μm可作为划分储层与非储层的界限.低渗储层气水

  6. Petroleum system and production characteristics of the Muddy (J) Sandstone (Lower Cretaceous) Wattenberg continuous gas field, Denver basin, Colorado

    Science.gov (United States)

    Higley, D.K.; Cox, D.O.; Weimer, R.J.

    2003-01-01

    Wattenberg field is a continuous-type gas accumulation. Estimated ultimate recovery from current wells is 1.27 tcf of gas from the Lower Cretaceous Muddy (J) Sandstone. Mean gas resources that have the potential to be added to these reserves in the next 30 yr are 1.09 tcf; this will be primarily through infill drilling to recover a greater percentage of gas in place and to drain areas that are isolated because of geologic compartmentalization. Greatest gas production from the Muddy (J) Sandstone in Wattenberg field occurs (1) from within the most permeable and thickest intervals of Fort Collins Member delta-front and nearshore-marine sandstones, (2) to a lesser extent from the Horsetooth Member valley-fill channel sandstones, (3) in association with a large thermal anomaly that is delineated by measured temperatures in wells and by vitrinite reflectance contours of 0.9% and greater, (4) in proximity to the bounding Mowry, Graneros, and Skull Creek shales that are the hydrocarbon source rocks and reservoir seals, and (5) between the Lafayette and Longmont right-lateral wrench fault zones (WFZs) with secondary faults that act as conduits in areas of the field. The axis of greatest gas production is north 25 to 35?? northeast, which parallels the basin axis. Recurrent movement along five right-lateral WFZs that crosscut Wattenberg field shifted the Denver basin axis to the northeast and influenced depositional and erosional patterns of the reservoir and seal intervals. Levels of thermal maturity within the Wattenberg field are anomalously high compared to other areas of the Denver basin. The Wattenberg field thermal anomaly may be due to upward movement of fluids along faults associated with probable igneous intrusions. Areas of anomalous high heat flow within the field correlate with an increased and variable gas-oil ratio.

  7. The distribution rule and seepage effect of the fractures in the ultra-low permeability sandstone reservoir in east Gansu Province,Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To study the impact of the fractures on development in the ultra-low permeability sandstone reservoir of the Yangchang Formation of the Upper Triassic in the Ordos Basin,data on outcrops,cores,slices,well logging and experiments are utilized to analyze the cause of the formation of the fractures,their distribution rules and the control factors and discuss the seepage flow effect of the fractures. In the studied area developed chiefly high-angle tectonic fractures and horizontal bedding fractures,inter-granular fractures and grain boundary fractures as well. Grain boundary fractures and intragranular fractures serve as vital channels linking intragranular pores and intergranular solution pores in the reservoir matrix,thus providing a good connectivity between the pores in the ultra-low perme-ability sandstone reservoir. The formation of fractures and their distribution are influenced by such external and internal factors as the palaeo-tectonic stress field,the reservoir lithological character,the thickness of the rock layer and the anisotropy of a layer. The present-day stress field influences the preservative state of fractures and their seepage flow effect. Under the tec-tonic effect of both the Yanshan and Himalayan periods,in this region four sets of fractures are distributed,respectively assuming the NE-SW,NW-SE,nearly E-W and nearly S-N orientations,but,due to the effect of the rock anisotropy of the rock formation,in some part of it two groups of nearly orthogonal fractures are chiefly distributed. Under the effect of the present-day stress field,the fractures that assume the NE-SW direction have a good connectivity,big apertures,a high permeability and a minimum starting pressure,all of which are main advantages of the seepage fractures in this region. With the development of oilfields,the permeability of the fractures of dif-ferent directions will have a dynamic change.

  8. Reservoir

    Directory of Open Access Journals (Sweden)

    M. Mokhtar

    2016-12-01

    Full Text Available Scarab field is an analog for the deep marine slope channels in Nile Delta of Egypt. It is one of the Pliocene reservoirs in West delta deep marine concession. Channel-1 and channel-2 are considered as main channels of Scarab field. FMI log is used for facies classification and description of the channel subsequences. Core data analysis is integrated with FMI to confirm the lithologic response and used as well for describing the reservoir with high resolution. A detailed description of four wells penetrated through both channels lead to define channel sequences. Some of these sequences are widely extended within the field under study exhibiting a good correlation between the wells. Other sequences were of local distribution. Lithologic sequences are characterized mainly by fining upward in Vshale logs. The repetition of these sequences reflects the stacking pattern and high heterogeneity of the sandstone reservoir. It also refers to the sea level fluctuation which has a direct influence to the facies change. In terms of integration of the previously described sequences with a high resolution seismic data a depositional model has been established. The model defines different stages of the channel using Scarab-2 well as an ideal analog.

  9. Seismic modeling, rock physics, avo and seismic attribute analysis for illuminating sandstone facies of the Late Ordovic Ian Mamuniyat Reservoir, R-Field, Murzuq Basin-Libya

    Science.gov (United States)

    Abushalah, Yousf Milad

    The Late Ordovician Mamuniyat Formation is the main hydrocarbon reservoir in the R-Field in Murzuq Basin, SW Libya. The Lower Mamuniyat, which is the only unit that was encountered in the study area, is composed of sandstone facies called Clean Mamuniyat and shaly sandstone facies called Dirty Mamuniyat. One major problem with the development of the R-Field is the difficulty of distinguishing the two units so this project was aimed to develop better methods for distinguishing between the two units of the Lower Mamuniyat. The other problem is to distinguish the transgressive shaly facies of the Bir Tlacsin, which has an impact on the hydrocarbon accumulation. Those issues manifested in limit of seismic resolution and interference that resulted from the converted shear mode waves. The dissertation was divided into three chapters. In the first chapter, seismic modeling using a deterministic and a Ricker wavelet were used to investigate the interference effects on the poststack seismic data and a bandpass filter was used to remove those effects. Instantaneous frequency, spectral-based colored inversion and rock physics were, then applied to determine the distributions of the sandstone facies of the Lower Mamuniyat Formation and to interpret the depositional setting of it. In the second chapter, spectral decomposition and inverted density were utilized to determine the distribution of the shaly facies of Bir Tlacsin, and its temporal thickness and to remap the top reservoir. In the last chapter, amplitude variation with offset (AVO) modeling, ray tracing, and spectral analysis were used to investigate the mode conversion and its effect on AVO signature, the amplitude of the near-mid and far offsets and frequency contents. Data enhancement then was performed using partial stacks and a bandpass filter.

  10. Reservoir Characterization, Production Characteristics, and Research Needs for Fluvial/Alluvial Reservoirs in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Cole, E.L.; Fowler, M.L.; Jackson, S.R.; Madden, M.P.; Raw-Schatzinger, V.; Salamy, S.P.; Sarathi, P.; Young, M.A.

    1999-04-28

    The Department of Energy's (DOE's) Oil Recovery Field Demonstration Program was initiated in 1992 to maximize the economically and environmentally sound recovery of oil from known domestic reservoirs and to preserve access to this resource. Cost-shared field demonstration projects are being initiated in geology defined reservoir classes which have been prioritized by their potential for incremental recovery and their risk of abandonment. This document defines the characteristics of the fifth geological reservoir class in the series, fluvial/alluvial reservoirs. The reservoirs of Class 5 include deposits of alluvial fans, braided streams, and meandering streams. Deposit morphologies vary as a complex function of climate and tectonics and are characterized by a high degree of heterogeneity to fluid flow as a result of extreme variations in water energy as the deposits formed.

  11. Reservoir sandstones and their physical properties of the Chang-6 oil measures in the Yanchang Formation, Huaqing region, Ordos Basin%华庆地区延长组长6油层组储集砂岩特征及对储层物性的影响

    Institute of Scientific and Technical Information of China (English)

    苏楠; 隆昊; 田景春; 王卫红; 张锦泉

    2011-01-01

    长6油层组储集砂岩主要为岩屑长石砂岩,粒度较细,分选中等偏差,填隙物主要为碳酸盐矿物和粘土矿物.砂岩的物质组成影响着其储层性能,储层物性随着石英含量的增加而变好,而随着岩屑含量的增加而变差.砂岩中长石的溶蚀作用是改善储层物性的关键因素.填隙物的含量越大,则孔隙喉道堵塞和充填的程度增加,导致储层物性变差.%The emphasis of this study is placed on the types and characteristics of the reservoir sandstones and their bearings on physical properties of the Chang-6 oil measures in the Yanchang Formation, Huaqing region, Ordos Basin. The reservoir sandstones are represented by lithic feldspathic sandstone with finer grain sizes and moderate to poor sorting. The interstitial materials contain carbonate minerals and clay minerals. The physical properties of the reservoir sandstones are progressively getting better in response to the increase of quartz contents, while worse with the increase of lithoclastic contents. The dissolution of feldspar from the sandstones is believed to be a key factor for the improvement of the physical properties. The higher contents of the interstitial material give rise to the plugging and filling of pore throats, and thus result in the deterioration of the physical properties.

  12. Reservoir Characteristic of Famennian Deposits of the Solikamsk Depression

    Directory of Open Access Journals (Sweden)

    A. V. Plyusnin

    2015-06-01

    Full Text Available The article describes the reservoir rock properties of Famennian (Late Devonian reef carbonate strata obtained by core study at boreholes № 1-4 of the Sukharev oil field. Based on the results of detailed study of lithological features of productive strata, authors defined the structural types and composed their description. The characteristics of the porosity and permeability of oil-bearing beds were shown. In a result of studies, the structure and main lithotypes of Famennian portion of reservoir were determined that allowed predicting the spatial distribution of reservoir properties within oilfield area.

  13. Sequence Stratigraphy of the Dakota Sandstone, Eastern San Juan Basin, New Mexico, and its Relationship to Reservoir Compartmentalization

    Energy Technology Data Exchange (ETDEWEB)

    Varney, Peter J.

    2002-04-23

    This research established the Dakota-outcrop sequence stratigraphy in part of the eastern San Juan Basin, New Mexico, and relates reservoir quality lithologies in depositional sequences to structure and reservoir compartmentalization in the South Lindrith Field area. The result was a predictive tool that will help guide further exploration and development.

  14. Reservoir characteristics and genesis of high-porosity and high-permeability reservoirs in Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on detailed studies, this paper proposes that in the Tarim Basin, hydrocarbon reservoirs widespread either in vertical sequences or in plane and high-porosity and high-permeability reservoirs are developed all over the basin. However, obvious difference and heterogeneity exist among different kinds of reservoirs. The lithologic characteristics, reservoir space types and reservoir properties in various strata have been probed. The result indicates that although the Paleozoic carbonates have been deeply buried for a long period, high-quality reservoirs with the porosity of up to 5%-8% (12% as the maximum) and the permeability of 10×10?3-100×10?3 ?m2 (1000×10?3 ?m2 as the maximum) can be found in certain areas. These include the area with the development of reefs and carbonate beaches, the weathered-crust buried-hill belts that have undergone the long-term exposure, weathering and leaching, the area with the development of dolomitization, and those areas that have experienced the resolution of carbonic acid and organic acid generated by the maturity of the organic matter. Finally, the genesis of the high-porosity and high-permeability reservoirs in deep-buried conditions (with the depth more than 3500 m) have been investigated thoroughly.

  15. Development characteristics of interlayer oxidation zone type of sandstone uranium deposits in the southwestern Turfan-Hami basin

    Institute of Scientific and Technical Information of China (English)

    YANG; Dianzhong; XIA; Bin; WU; Guogan

    2004-01-01

    The Turfan-Hami basin is the key area for the exploration of sandstone uranium deposits of the leachable interlayered oxidation zone type. The aim of this study is to shed light on the development characteristics of this type of uranium deposits and provide new clues to further exploration. Detailed study led to the following conclusions: (1) uranium orebodies are hosted mainly in the lower Middle Jurassic Xishanyao Formation and the lower Lower Jurassic Badaowan Formation; (2) the formation of uranium orebodies is closely related to organic matter; (3) the front of the interlayered oxidation zone is snake-shaped in plane and imbricated in the section; the more the interlayered oxidation zone and zonation are developed, the better the uranium mineralization will be; according to lithological and geochemical characteristics, the oxidation zone, the oxidation-reduction transitional zone and the reduction zone can be distinguished; (4) the development of interlayered oxidation zone is controlled by geological structure, underground water, sandstone permeability and other factors; (5) sandstone uranium orebodies hosted in the interlayered oxidation zone are very complicated in spatial distribution, of which some are rolled and plated in shape and some are highly variable in shape.

  16. Geologic Characteristics of Gas Reservoirs in West Sichuan Foreland Basin

    Institute of Scientific and Technical Information of China (English)

    YANG Keming

    2008-01-01

    The foreland basin in West Sichuan is a tectonic unit that has undergone multi-periods tectonic movements of Indosinian-Yanshanian-Himalayan. Since late Triassic, it has been in a passive subsidence environment controlled by basin margin mountain systems and by the compression with abundant sediment sources. With the complex geologic setting, the main geologic characteristics of natural gas reservoir are listed as following:(1)Source rocks are coal-bearing mud and shale series with high to over maturity, and long and progressive hydrocarbon generation-displacement period. The key accumulation period is middle-late Yanshanian epoch.(2)There are three gas-bearing systems vertically, each of which has different reservoir mechanism, main-controlled factors and distribution law, so the exploration thoughts and techniques are also different.(3)Undergoing multi-period generation-migration-accumulation, oil and gas have encountered multi-period modification or destruction, and gas accumulation overpass multiple tectonic periods. So the trap type is complicated and dominated by combination traps. Because the main accumulation period of natural gas is early and the reservoir encountered the modification of strong Himalayan movement, there is great difference in the fullness degree of gas reservoirs and complicated gas-water relation. (4) Reservoir is tight to very tight, but reservoirs of relatively high quality developed under the super tight setting. (5) The key techniques for oil and gas exploration in west Sichuan foreland basin are the prediction of relatively favorable reservoirs, fractures and gas bearing; and the key techniques for oil and gas development are how to improve the penetration rate, reservoir protection and modification.

  17. Thermal-mechanical coupled effect on fracture mechanism and plastic characteristics of sandstone

    Institute of Scientific and Technical Information of China (English)

    ZUO; JianPing; XIE; HePing; ZHOU; HongWei; PENG; SuPing

    2007-01-01

    Scanning electronic microscopy (SEM) was employed to investigate fractographs of sandstone in mine roof strata under thermal-mechanical coupled effect. Based on the evolution of sandstone surface morphology in the failure process and fractography, the fracture mechanism was studied and classified under meso and micro scales, respectively. The differences between fractographs under different temperatures were examined in detail. Under high temperature, fatigue fracture and plastic deformation occurred in the fracture surface. Therefore, the temperature was manifested by these phenomena to influence strongly on micro failure mechanism of sandstone. In addition, the failure mechanism would transit from brittle failure mechanism at low temperature to coupled brittle-ductile failure mechanism at high temperature. The variation of sandstone strength under different temperature can be attributed to the occurrence of plastic deformation, fatigue fracture, and microcracking. The fatigue striations in the fracture surfaces under high temperature may be interpreted as micro fold. And the coupled effect of temperature and tensile stress may be another formation mechanism of micro fold in geology.

  18. Neutron and density logging responses to gas reservoir for well-balanced and under-balanced logging:Gas reservoirs of sandstone in a western China field

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Studying the response differences between neutron and density logging of gas reservoir for well-balanced and under-balanced logging will be of significance in evaluation of gas reservoir under the under-balanced condition and application of logging data. With Monte Carlo simulation technique,the paper obtains the relationship between neutron and density logging measurement and borehole di-ameter,porosity or gas saturation for well-balanced and under-balanced logging. The conclusions show that the response trend of under-balanced logging to gas reservoirs agrees with that of well-balanced logging with small borehole,and under-balanced logging data can be used usually as well-balanced logging data. When borehole diameter is large,under-balanced logging data should be corrected for the influences of borehole.

  19. Rate type isotach compaction of consolidated sandstone

    NARCIS (Netherlands)

    Waal, J.A. de; Thienen-Visser, K. van; Pruiksma, J.P.

    2015-01-01

    Laboratory experiments on samples from a consolidated sandstone reservoir are presented that demonstrate rate type compaction behaviour similar to that observed on unconsolidated sands and soils. Such rate type behaviour can have large consequences for reservoir compaction, surface subsidence and

  20. A Method to Recover Useful Geothermal-Reservoir Parameters from Production Characteristic Curves (1) Steam Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias, E.; Arellano, V.; Garfias, A.; Miranda, C.; Hernandez, J.; Gonzalez, J.

    1983-12-15

    In this paper we develop and demonstrate a method to estimate the reservoir pressure and a productivity index for vertical steam wells, from its production characteristic (also called output) curves. In addition, the method allows to estimate the radius of influence of the well, provided that a value of the reservoir transmisivity is available. The basic structure of the present method is: first, the measured well head mass flowrates and pressures are transformed to downhole conditions by means of a numerical simulator; then, the computed downhole variables are fitted to a simple radial model that predicts the sandface flowrate in terms of the flowing pressure. For demonstration, the method was applied to several steam wells from the Los Azufres Geothermal field. We found excellent agreement of the model with this ample set of field data. As a bonus, the processed data allowed several inferences about the steam producing zone of the reservoir: that the wells considered produce from relatively isolated pockets of steam, which are probably fed by near-by inmobile water; and that these feed zones are in poor hydraulic communication with the field surface waters. our method are that it provides a way to retrieve important reservoir information from usually available production characteristic curves, and that the method works from easily and accurately taken wellhead measurements.

  1. REE/trace element characteristics of sandstone-type uranium deposits in the Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    LING Mingxing; YANG Xiaoyong; SUN Wei; MIAO Jianyu; LIU Chiyang

    2006-01-01

    The major elements, trace elements and REEs were analyzed on the samples collected from the sandstone-type uranium deposits in the Ordos Basin to constrain the mechanism of uranium enrichment. The total REE amount ranges from 36.7 to 701.8 μg/g and the REE distribution patterns of the sandstone-type uranium samples are characterized by LREE enrichment and high REE depletion. The results also indicated a high Y abundance and Eu anomalies between 0.77-1.81. High-precision ICP-MS results showed that U abundances are within the range of 0.73-150 μg/g, showing some strong correlation between U enrichment and related elements such as Ti, V, Zr, Mo, and Au. In addition, Th abundance is correlated with ΣREE.

  2. Investigation of gas hydrate-bearing sandstone reservoirs at the "Mount Elbert" stratigraphic test well, Milne Point, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Boswell, R.M.; Hunter, R. (ASRC Energy Services, Anchorage, AK); Collett, T. (USGS, Denver, CO); Digert, S. (BP Exploration (Alaska) Inc., Anchorage, AK); Hancock, S. (RPS Energy Canada, Calgary, Alberta, Canada); Weeks, M. (BP Exploration (Alaska) Inc., Anchorage, AK); Mt. Elbert Science Team

    2008-01-01

    In February 2007, the U.S. Department of Energy, BP Exploration (Alaska), Inc., and the U.S. Geological Survey conducted an extensive data collection effort at the "Mount Elbert #1" gas hydrates stratigraphic test well on the Alaska North Slope (ANS). The 22-day field program acquired significant gas hydrate-bearing reservoir data, including a full suite of open-hole well logs, over 500 feet of continuous core, and open-hole formation pressure response tests. Hole conditions, and therefore log data quality, were excellent due largely to the use of chilled oil-based drilling fluids. The logging program confirmed the existence of approximately 30 m of gashydrate saturated, fine-grained sand reservoir. Gas hydrate saturations were observed to range from 60% to 75% largely as a function of reservoir quality. Continuous wire-line coring operations (the first conducted on the ANS) achieved 85% recovery through 153 meters of section, providing more than 250 subsamples for analysis. The "Mount Elbert" data collection program culminated with open-hole tests of reservoir flow and pressure responses, as well as gas and water sample collection, using Schlumberger's Modular Formation Dynamics Tester (MDT) wireline tool. Four such tests, ranging from six to twelve hours duration, were conducted. This field program demonstrated the ability to safely and efficiently conduct a research-level openhole data acquisition program in shallow, sub-permafrost sediments. The program also demonstrated the soundness of the program's pre-drill gas hydrate characterization methods and increased confidence in gas hydrate resource assessment methodologies for the ANS.

  3. Carbon and oxygen isotopic composition of carbonate cements of different phases in terrigenous siliciclastic reservoirs and significance for their origin: A case study from sandstones of the Triassic Yanchang Formation, southwestern Ordos Basin,China

    Institute of Scientific and Technical Information of China (English)

    WANG Qi; ZHUO Xizhun; CHEN Guojun; LI Xiaoyan

    2008-01-01

    Early carbonate cements in the Yanchang Formation sandstones are composed mainly of calcite with relatively heavier carbon isotope (their δ18O values range from -0.3‰-0.1‰) and lighter oxygen isotope (their ‰18O values range from -22.1‰--19.5‰). Generally, they are closely related to the direct precipitation of oversaturated calcium carbonate from alkaline lake water. This kind of cementation plays an important role in enhancing the anti-compaction ability of sandstones, preserving intragranular volume and providing the mass basis for later dissolution caused by acidic fluid flow to produce secondary porosity. Ferriferous calcites are characterized by relatively light carbon isotope with δ13C values ranging from -8.02‰ to -3.23‰, and lighter oxygen isotope with δ18O values ranging from -22.9‰ to -19.7‰, which is obviously related to the decarboxylation of organic matter during the late period of early diagenesis to the early period of late diagenesis. As the mid-late diagenetic products, ferriferous calcites in the study area are considered as the characteristic authigenic minerals for indicating large-scaled hydrocarbon influx and migration within the clastic reservoir. The late ankerite is relatively heavy in carbon isotope with δ13C values ranging from -1.92‰ to -0.84‰, and shows a wide range of variations in oxygen isotopic composition, with δ18O values ranging from -20.5‰ to -12.6‰. They are believed to have nothing to do with decarboxylation, but the previously formed marine carbonate rock fragments may serve as the chief carbon source for their precipitation, and the alkaline diagenetic environment at the mid-late stage would promote this process.

  4. Sequence stratigraphic and sedimentologic significance of biogenic structures from a late Paleozoic marginal- to open-marine reservoir, Morrow Sandstone, subsurface of southwest Kansas, USA

    Science.gov (United States)

    Buatois, L.A.; Mangano, M.G.; Alissa, A.; Carr, T.R.

    2002-01-01

    Integrated ichnologic, sedimentologic, and stratigraphic studies of cores and well logs from Lower Pennsylvanian oil and gas reservoirs (lower Morrow Sandstone, southwest Kansas) allow distinction between fluvio-estuarine and open marine deposits in the Gentzler and Arroyo fields. The fluvio-estuarine facies assemblage is composed of both interfluve and valley-fill deposits, encompassing a variety of depositional environments such as fluvial channel, interfluve paleosol, bay head delta, estuary bay, restricted tidal flat, intertidal channel, and estuary mouth. Deposition in a brackish-water estuarine valley is supported by the presence of a low diversity, opportunistic, impoverished marine ichnofaunal assemblage dominated by infaunal structures, representing an example of a mixed, depauperate Cruziana and Skolithos ichnofacies. Overall distribution of ichnofossils along the estuarine valley was mainly controlled by the salinity gradient, with other parameters, such as oxygenation, substrate and energy, acting at a more local scale. The lower Morrow estuarine system displays the classical tripartite division of wave-dominated estuaries (i.e. seaward-marine sand plug, fine-grained central bay, and sandy landward zone), but tidal action is also recorded. The estuarine valley displays a northwest-southeast trend, draining to the open sea in the southeast. Recognition of valley-fill sandstones in the lower Morrow has implications for reservoir characterization. While the open marine model predicts a "layer-cake" style of facies distribution as a consequence of strandline shoreline progradation, identification of valley-fill sequences points to more compartmentalized reservoirs, due to the heterogeneity created by valley incision and subsequent infill. The open-marine facies assemblage comprises upper, middle, and lower shoreface; offshore transition; offshore; and shelf deposits. In contrast to the estuarine assemblage, open marine ichnofaunas are characterized by a

  5. Sequence stratigraphic and sedimentologic significance of biogenic structures from a late Paleozoic marginal- to open-marine reservoir, Morrow Sandstone, subsurface of southwest Kansas, USA

    Science.gov (United States)

    Buatois, Luis A.; Mángano, M. Gabriela; Alissa, Abdulrahman; Carr, Timothy R.

    2002-09-01

    Integrated ichnologic, sedimentologic, and stratigraphic studies of cores and well logs from Lower Pennsylvanian oil and gas reservoirs (lower Morrow Sandstone, southwest Kansas) allow distinction between fluvio-estuarine and open marine deposits in the Gentzler and Arroyo fields. The fluvio-estuarine facies assemblage is composed of both interfluve and valley-fill deposits, encompassing a variety of depositional environments such as fluvial channel, interfluve paleosol, bay head delta, estuary bay, restricted tidal flat, intertidal channel, and estuary mouth. Deposition in a brackish-water estuarine valley is supported by the presence of a low diversity, opportunistic, impoverished marine ichnofaunal assemblage dominated by infaunal structures, representing an example of a mixed, depauperate Cruziana and Skolithos ichnofacies. Overall distribution of ichnofossils along the estuarine valley was mainly controlled by the salinity gradient, with other parameters, such as oxygenation, substrate and energy, acting at a more local scale. The lower Morrow estuarine system displays the classical tripartite division of wave-dominated estuaries (i.e. seaward-marine sand plug, fine-grained central bay, and sandy landward zone), but tidal action is also recorded. The estuarine valley displays a northwest-southeast trend, draining to the open sea in the southeast. Recognition of valley-fill sandstones in the lower Morrow has implications for reservoir characterization. While the open marine model predicts a "layer-cake" style of facies distribution as a consequence of strandline shoreline progradation, identification of valley-fill sequences points to more compartmentalized reservoirs, due to the heterogeneity created by valley incision and subsequent infill. The open-marine facies assemblage comprises upper, middle, and lower shoreface; offshore transition; offshore; and shelf deposits. In contrast to the estuarine assemblage, open marine ichnofaunas are characterized by a

  6. Investigation of gas hydrate-bearing sandstone reservoirs at the Mount Elbert stratigraphic test well, Milne Point, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Boswell, R. [United States Dept. of Energy, Morgantown, WV (United States). National Energy Technology Lab; Hunter, R. [ASRC Energy Services, Anchorage, AK (United States); Collett, T. [United States Geological Survey, Denver, CO (United States); Digert, S.; Weeks, M. [BP Exploration Alaska Inc., Anchorage, AK (United States); Hancock, S. [RPS Energy Canada, Calgary, AB (Canada)

    2008-07-01

    Gas hydrates occur within the shallow sand reservoirs on the Alaska North Slope (ANS). The mean estimate for gas hydrate in-place resources on the ANS is 16.7 trillion cubic metres. In the past, they were viewed primarily as a drilling hazard to be managed during the development of deeper oil resources. In 2002, a cooperative research program was launched to help determine the potential for environmentally-sound and economically-viable production of methane from gas hydrates. Additional objectives were to refine ANS gas hydrate resource potential, improve the geologic and geophysical methods used to locate and asses gas hydrate resources, and develop numerical modeling capabilities that are essential in both planning and evaluating gas hydrate field programs. This paper reviewed the results of the an extensive data collection effort conducted at the Mount Elbert number 1 gas hydrates stratigraphic test well on the ANS. The 22-day field program acquired significant gas hydrate-bearing reservoir data, including a suite of open-hole well logs, over 500 feet of continuous core, and open-hole formation pressure response tests. The logging program confirmed the existence of approximately 30 m of gas hydrate saturated, fine-grained sand reservoir. Gas hydrate saturations were observed to range from 60 to 75 per cent. Continuous wire-line coring operations achieved 85 per cent recovery. The Mount Elbert field program also involved gas and water sample collection. It demonstrated the ability to safely and efficiently conduct a research-level open-hole data acquisition program in shallow, sub-permafrost sediments and increased confidence in gas hydrate resource assessment methodologies for the ANS. 10 refs., 9 figs.

  7. Seismic amplitude variation with offset: Its effects on weighted stacking, and its uses in characterization of sandstone and carbonate reservoirs

    Science.gov (United States)

    Madiba, Gislain Bolouvi

    An algorithm for weighted stacking, which is not particularly expensive in terms of computer time or memory and can be easily incorporated into routine processing is proposed. A comprehensive comparison of the proposed weighted stacking algorithm and the conventional stacking algorithm is conducted through testing on synthetics and a real data set from New Mexico, USA. This weighted stacking algorithm achieves the primary goal of signal-to-noise ratio improvement while at the same time providing better resolution, wider bandwidth, and a higher signal-to-noise ratio than the conventional stack. A novel hydrocarbon indicator [the water-filled porosity (S wv)], which is estimated from the ratio of P-velocity to S-velocity (Vp/Vs), is proposed and applied to characterize clastic hydrocarbon reservoirs in the North Sea. The separation between pore fluids and lithologies is enhanced by mapping from V p/Vs to Swv using an empirical crossplot-derived relationship. The Swv-V p/Vs plane still does not produce unique interpretations in many situations. However, the critical distinction, which is between hydrocarbon-bearing sands and all other geologic/reservoir configurations, is defined. Porosity is the dominant factor controlling reservoir signature for carbonate rocks. Acoustic impedance and seismic amplitudes are porosity and lithology indicators. Angle-dependent reflectivity effects are introduced for determination of fluid charactersitics by simultaneous elastic impedance inversion of three non-overlapping migrated common-angle stacked sections for P- and S-impedance (Ip and Is). Deviations of points from a water-filled baseline in the Ip-I s plane define a gas potential section that is used for direct identification of gas zones in the dolomitized limestone reservoirs of the Turner Valley Formation in southern Alberta, Canada. There is consistency with the known gas production at a well and agreement with gas index sections obtained through the use of Lame parameter

  8. Microbial water diversion technique-designed for near well treatment in low temperature sandstone reservoirs in the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Paulsen, J.E.; Vatland, A. [RF-Rogaland Research, Stavanger (Norway); Sorheim, R. [SINTEF, Oslo (Norway)] [and others

    1995-12-31

    A Norwegian Research Program on Improved Oil Recovery (IOR) in North Sea reservoirs was launched in 1992. Microbial methods, applied in this context, is a part of this program. The scope, the methodological approach, and results from the three first years are presented. Water profile control, using biomass to block high permeable zones of a reservoir, has been investigated using nitrate-reducing bacteria in the injected sea water as plugging agents. Emphasis has been put on developing a process that does not have disadvantages secondary to the process itself, such as souring and impairment of the overall injectivity of the field. Data from continuous culture studies indicate that souring may successfully be mitigated by adding nitrite to the injected seawater. The morphology and size of generic-nitrate-reducing seawater bacteria have been investigated. Screening of growth-promoting nutrients has been carried out, and some sources were detected as favorable. Transport and penetration of bacteria in porous media have been given special attention. Investigations with sand packs, core models, and pore micromodels have been carried out. The inherent problems connected with permeability contrasts and flow patterns, versus bacterial behavior, are believed to be critical for the success of this technology. Data from the transport and blocking experiments with the porous matrices confirm this concern. The technology is primarily being developed for temperatures less than 40{degrees}C.

  9. Infrastructure and mechanical properties of a fault zone in sandstone as an outcrop analogue of a potential geothermal reservoir

    Science.gov (United States)

    Bauer, J. F.; Meier, S.; Philipp, S. L.

    2013-12-01

    Due to high drilling costs of geothermal projects, it is economically sensible to assess the potential suitability of a reservoir prior to drilling. Fault zones are of particular importance, because they may enhance fluid flow, or be flow barriers, respectively, depending on their particular infrastructure. Outcrop analogue studies are useful to analyze the fault zone infrastructure and thereby increase the predictability of fluid flow behavior across fault zones in the corresponding deep reservoir. The main aims of the present study are to 1) analyze the infrastructure and the differences of fracture system parameters in fault zones and 2) determine the mechanical properties of the faulted rocks. We measure fracture frequencies as well as orientations, lengths and apertures and take representative rock samples for each facies to obtain Young's modulus, compressive and tensile strengths in the laboratory. Since fractures reduce the stiffnesses of in situ rock masses we use an inverse correlation of the number of discontinuities to calculate effective (in situ) Young's moduli to investigate the variation of mechanical properties in fault zones. In addition we determine the rebound hardness, which correlates with the compressive strength measured in the laboratory, with a 'Schmidt-Hammer' in the field because this allows detailed maps of mechanical property variations within fault zones. Here we present the first results for a fault zone in the Triassic Lower Bunter of the Upper Rhine Graben in France. The outcrop at Cleebourg exposes the damage zone of the footwall and a clear developed fault core of a NNW-SSE-striking normal fault. The approximately 15 m wide fault core consists of fault gouge, slip zones, deformation bands and host rock lenses. Intensive deformation close to the core led to the formation of a distal fault core, a 5 m wide zone with disturbed layering and high fracture frequency. The damage zone also contains more fractures than the host rock

  10. Diagenesis of low-permeability and tight sandstone gas reservoir and its effect on reservoir quality: taking the eighth member of Shihezi formation in Su 48 block, Sulige gas field, as an example%低渗透致密气藏成岩作用及对储层物性的影响——以苏里格气田苏48区块盒8段储层为例

    Institute of Scientific and Technical Information of China (English)

    庞振宇; 孙卫; 赵春龙; 马永平

    2012-01-01

    利用普通薄片、铸体薄片、X射线衍射、扫描电镜等资料,分析苏里格气田苏48区块盒8段低渗透储层岩石学特征、成岩作用和孔隙演化过程.研究表明:储集层砂岩类型以岩屑石英砂岩和石英砂岩为主,颗粒分选性中等-好,磨圆度较差,胶结类型以次生加大-孔隙式为主,少量孔隙式胶结.在成岩过程中,强烈的压实作用造成了初始孔隙度的大量丧失,损失率为69.09%,其次为胶结作用,损失率为25.16%.溶蚀作用则形成大量次生孔隙,增加了5.82%的孔隙度,大大改善了储层物性,为该区气藏的聚集提供了主要储集空间.%The characteristics of petrology, the diagenesis and porosity evolution in the eighth member of Shihezi formation in Su 48 block in Sulige gasfield were analyzed, using thin-sections, casting thin-sections, X-ray diffractions, scanning electron micrograph observations, etc. The results showed that both lithic quartz-sandstone and quartz sandstone are the essential components of reservoir sandstones. The sandstone is lithic quartz with middle to perfect sorting and poor psephicity. Cementation is mainly of secondary enlargement-pore and a less proportion of pore cementation. The impact of strong compaction during the early diagenesis was greatest and its porosity loss-rate was 69.09%, and the porosity loss-rate of of cementation was 25.16%. The dissolution of the reservoir sandstone improved the porosity by about 5.82%, which provided the main space for the accumulation of gas reservoirs.

  11. 塔里木盆地典型砂岩油气储层自生伊利石K-Ar同位素测年研究与成藏年代探讨%K-Ar Dating of Authigenic Illites and Its Applications to the Study of Hydrocarbon Charging Histories of Typical Sandstone Reservoirs in Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The Tarim Basin in China comprises eight sets of sandstone reservoirs, five of which are investigated in detail in this study. The main purpose of this study is to investigate the hydrocarbon charging histories of reservoirs by applying K-Ar dating of authigenic illites. The ages of authigenic illites from the Lower Silurian bituminous sandstones in the Central Uplift area range from 383.5 to 235.2 Ma, suggesting that the Silurian oil accumulations were formed from the late Caledonian till the late Hercynian. The ages of authigenic illites from the Upper Devonian Donghe Sandstone reservoirs range from 263.8 to 231.3 Ma, indicating that hydrocarbon accumulations within the Donghe sandstone were formed mainly in the late Hercynian. The authigenic illites ages from the Lower Jurassic Yangxia Group sandstones in the Yinan-2 gas reservoir (Yinan-2, Kuqa Depression) range from 28.1 to 23.9 Ma, suggesting that the initial hydrocarbon charging occurred in the Miocene. The ages of the authigenic illites from the Lower Cretaceous sandstones in the Akemomu gas field (Ake-1, Kashi Sag, Southwest Depression) range from 22.6 to 18.8 Ma, indicating a probable early oil accumulation or early migration of hydrocarbon within this area. The illites from the Paleogene sandstones in the Dina-2 gas reservoir (Dina-201, Kuqa Depression) have a detrital origin; they cannot be used to study the hydrocarbon charging histories. The ages of authigenic illites in the underlying Cretaceous sandstones in the same well (Dina-201)range from 25.5 to 15.5 Ma, indicating that hydrocarbon charging in this reservoir probably occurred within the Miocene.This study highlights the potential of applying K-Ar dating of authigenic illites to investigate the timing of hydrocarbon charging histories of the Tarim Basin reservoir sandstones.

  12. Characteristics of volcanic reservoirs and distribution rules of effective reservoirs in the Changling fault depression, Songliao Basin

    Directory of Open Access Journals (Sweden)

    Pujun Wang

    2015-11-01

    Full Text Available In the Songliao Basin, volcanic oil and gas reservoirs are important exploration domains. Based on drilling, logging, and 3D seismic (1495 km2 data, 546 sets of measured physical properties and gas testing productivity of 66 wells in the Changling fault depression, Songliao Basin, eruptive cycles and sub-lithofacies were distinguished after lithologic correction of the 19,384 m volcanic well intervals, so that a quantitative analysis was conducted on the relation between the eruptive cycles, lithologies and lithofacies and the distribution of effective reservoirs. After the relationship was established between lithologies, lithofacies & cycles and reservoir physical properties & oil and gas bearing situations, an analysis was conducted on the characteristics of volcanic reservoirs and the distribution rules of effective reservoirs. It is indicated that 10 eruptive cycles of 3 sections are totally developed in this area, and the effective reservoirs are mainly distributed at the top cycles of eruptive sequences, with those of the 1st and 3rd Members of Yingcheng Formation presenting the best reservoir properties. In this area, there are mainly 11 types of volcanic rocks, among which rhyolite, rhyolitic tuff, rhyolitic tuffo lava and rhyolitic volcanic breccia are the dominant lithologies of effective reservoirs. In the target area are mainly developed 4 volcanic lithofacies (11 sub-lithofacies, among which upper sub-lithofacies of effusive facies and thermal clastic sub-lithofacies of explosion lithofacies are predominant in effective reservoirs. There is an obvious corresponding relationship between the physical properties of volcanic reservoirs and the development degree of effective reservoirs. The distribution of effective reservoirs is controlled by reservoir physical properties, and the formation of effective reservoirs is influenced more by porosity than by permeability. It is concluded that deep volcanic gas exploration presents a good

  13. 塔里木盆地库车坳陷致密砂岩气藏成因类型%Genetic Types of the Tight Sandstone Gas Reservoirs in the Kuqa Depression, Tarim Basin, NW China

    Institute of Scientific and Technical Information of China (English)

    李卓; 姜振学; 庞雄奇; 李峰; 张宝收

    2013-01-01

    To further understand the genetic types of the tight sandstone gas reservoirs in Kuqa depression, the core from tight sandstone gas reservoirs is sampled to carry out the analysis on hydrocarbon charge history and porosity evolutioa The hydrocarbon charge history is investigated by analyzing the fluid inclusion petrography, and microther mometry and the porosity evolution is restored by using the model of deposition-structure -diagenesis. Combining with gas-water relationship and distribution of tight sandstone gas reservoirs. There are two charge events in the YN2 Jurassic tight sandstone reservoir, with the one of oil charge during 23-12 Ma, and the other gas charge during 5-0 Ma. The reservoir porosity dropped to less than 12% and became tight during the period of 12-8 Ma Two charge events have been recorded in the DN2 Paleogene tight sandstone reservoir; the former is oil charge during 23-12 Ma, and the latter is the gas charge during 5 - 0 Ma. The reservoir porosity dropped to less than 12% during the period of 2-0 Ma and became tight later. Two genetic types of tight sandstone gas reservoirs have been confirmed. The YN2 Jurassic tight sandstone reservoir is of the genetic type of "tight deep basin gas reservoir" with the accumulation process of gas charge after the reservoir tightened and the DN2 Paleogene tight sandstone reservoir is defined as "tight conventional gas reservoir" with the accumulation process of gas charge before the reservoir tightened. This study is of significance for further exploration and exploitation of tight sandstone gas in Kuqa depressioa.%为深化对库车坳陷致密砂岩气藏成因类型的认识,采集致密砂岩储层岩样,开展了油气充注史和孔隙度演化史研究.通过流体包裹体岩相学和显微测温厘定了油气充注史,利用沉积-构造-成岩一体化模型恢复了储层孔隙度演化史,根据两者的先后关系,划分了致密砂岩气藏的成因类型.结果表明,依南2侏罗系气藏

  14. The Relationship between Fractures and Tectonic Stress Field in the Extra Low-Permeability Sandstone Reservoir at the South of Western Sichuan Depression

    Institute of Scientific and Technical Information of China (English)

    Zeng Lianbo; Qi Jiafu; Li Yuegang

    2007-01-01

    The formation and distribution of fractures are controlled by paleotectonic stress field, and their preservative status and effects on development are dominated by the modern stress field. Since Triassic, it has experienced four tectonic movements and developed four sets of tectonic fractures in the extra low-permeability sandstone reservoir at the south of western Sichuan depression. The strikes of fractures are in the S-N, NE-SW, E-W, and NW-SE directions respectively. At the end of Triassic, under the horizontal compression tectonic stress field, for which the maximum principal stress direction was NW-SE,the fractures were well developed near the S-N faults and at the end of NE-SW faults, because of their stress concentration. At the end of Cretaceous, in the horizontal compression stress fields of the NE-SW direction,the stress was obviously lower near the NE-SW faults, thus, fractures mainly developed near the S-N faults.At the end of Neogene-Early Pleistocene, under the horizontal compression tectonic stress fields of E-W direction, stress concentrated near the NE-SW faults and fractures developed at these places, especially at the end of the NE-SE faults, the cross positions of NE-SW, and S-N faults. Therefore, fractures developed mostly near S-N faults and NE-SW faults. At the cross positions of the above two sets of faults, the degree of development of the fractures was the highest. Under the modern stress field of the NW-SE direction, the NW-SE fractures were mainly the seepage ones with tensional state, the best connectivity, the widest aperture, the highest permeability, and the minimum opening pressure.

  15. Basical characteristics of fluid geologic process of interlayer oxidation zone sandstone-typeuranium deposit

    Institute of Scientific and Technical Information of China (English)

    WU; BoLin; LIU; ChiYang; WANG; JianQiang

    2007-01-01

    This paper reveals the physicochemical properties such as component, formulation, genesis, tem- perature, pH, Eh, salinity and pressure of all main alteration fluid of interlayer oxidation zone sand- stone-type uranium deposits after studying the geologic process and geochemistry of internal typical sandstone-type uranium deposits such as Shihongtan deposit in the Turpan-Hami basin, 512 deposit in the Yili basin, Dongsheng deposit in the Ordos basin. The composition of fluid can be divided into two parts based on the analysis of inclusion: one can be affirmed as atmospheric water with ordinary temperature epigenesist according to the character of hydrogen and oxygen isotope of inclusion, the other is natural gas containing gaseous hydrocarbon like CH4, and CO2 as well as a little H2S, CO, H2, N2 and so on, it always contains a small quantity of hydrocarbon liquid in petroliferous basins. The fluid property of oxidation alteration zone is always oxidation alkaline, and neutrality or weak acid-weak alkaline and reducibility during the metallizing process, but at secondary reduction or deoxidization zone it becomes strong reduction alkaline. Oxygenic groundwater in the fluid is the activate and mig- ratory medium of uranium element, but the gaseous hydrocarbon like CH4 as well as H2, H2S, CO from natural gas is the important sedimentary reducer of uranium mineral; the transformation of pH,Eh in fluid environment is the main reason for the formation of uranium metallization.

  16. Effective Thermal Conductivity Modeling of Sandstones: SVM Framework Analysis

    Science.gov (United States)

    Rostami, Alireza; Masoudi, Mohammad; Ghaderi-Ardakani, Alireza; Arabloo, Milad; Amani, Mahmood

    2016-06-01

    Among the most significant physical characteristics of porous media, the effective thermal conductivity (ETC) is used for estimating the thermal enhanced oil recovery process efficiency, hydrocarbon reservoir thermal design, and numerical simulation. This paper reports the implementation of an innovative least square support vector machine (LS-SVM) algorithm for the development of enhanced model capable of predicting the ETCs of dry sandstones. By means of several statistical parameters, the validity of the presented model was evaluated. The prediction of the developed model for determining the ETCs of dry sandstones was in excellent agreement with the reported data with a coefficient of determination value ({R}2) of 0.983 and an average absolute relative deviation of 0.35 %. Results from present research show that the proposed LS-SVM model is robust, reliable, and efficient in calculating the ETCs of sandstones.

  17. Tidal dunes versus tidal bars: The sedimentological and architectural characteristics of compound dunes in a tidal seaway, the lower Baronia Sandstone (Lower Eocene), Ager Basin, Spain

    Science.gov (United States)

    Olariu, Cornel; Steel, Ronald J.; Dalrymple, Robert W.; Gingras, Murray K.

    2012-11-01

    dunes, separated by 10-30 cm of bioturbated muddy sandstone, which migrated over each other in an offlapping, progradational fashion. Each compound-dune complex (the best reservoir rock) thins as it downlaps, at average rates of 3-4 m/km in a dip direction. These reservoir units can be comprised of discrete compartments, each formed by a single compound dune, that extend for 500-1000 m in the direction of the current, and are at least 350-600 m wide in a flow-transverse direction. Distinguishing between tidal bars and tidal dunes in an ancient tidal succession can be difficult because both can contain similar cross-bedded facies and have overlapping thicknesses; however, the internal architecture and sandbody orientations are different. Tidal bars have their long axis almost parallel both to the tidal current direction and to the strike of the lateral-accretion master surfaces. In inshore areas, they are bounded by channels and fine upward. Large compound tidal dunes, in contrast, have their crest oriented approximately normal to the tidal currents and contain a forward-accretion architecture. Coeval channels are uncommon within large, sub-tidal dune fields. The above distinctions are very important to reservoir description and modeling, because the long axis of the intra-reservoir compartments in the two cases will be 90° apart.

  18. Reservoir characteristics and control factors of Carboniferous volcanic gas reservoirs in the Dixi area of Junggar Basin, China

    Directory of Open Access Journals (Sweden)

    Ji'an Shi

    2017-02-01

    Full Text Available Field outcrop observation, drilling core description, thin-section analysis, SEM analysis, and geochemistry, indicate that Dixi area of Carboniferous volcanic rock gas reservoir belongs to the volcanic rock oil reservoir of the authigenic gas reservoir. The source rocks make contact with volcanic rock reservoir directly or by fault, and having the characteristics of near source accumulation. The volcanic rock reservoir rocks mainly consist of acidic rhyolite and dacite, intermediate andesite, basic basalt and volcanic breccia: (1 Acidic rhyolite and dacite reservoirs are developed in the middle-lower part of the structure, have suffered strong denudation effect, and the secondary pores have formed in the weathering and tectonic burial stages, but primary pores are not developed within the early diagenesis stage. Average porosity is only at 8%, and the maximum porosity is at 13.5%, with oil and gas accumulation showing poor performance. (2 Intermediate andesite and basic basalt reservoirs are mainly distributed near the crater, which resembles the size of and suggests a volcanic eruption. Primary pores are formed in the early diagenetic stage, secondary pores developed in weathering and erosion transformation stage, and secondary fractures formed in the tectonic burial stage. The average porosity is at 9.2%, and the maximum porosity is at 21.9%: it is of the high-quality reservoir types in Dixi area. (3 The volcanic breccia reservoir has the same diagenetic features with sedimentary rocks, but also has the same mineral composition with volcanic rock; rigid components can keep the primary porosity without being affected by compaction during the burial process. At the same time, the brittleness of volcanic breccia reservoir makes it easily fracture under the stress; internal fracture was developmental. Volcanic breccia developed in the structural high part and suffered a long-term leaching effect. The original pore-fracture combination also made

  19. Acoustic emission characteristics of sandstone after high temperature under uniaxial compression%单轴压缩下高温后砂岩的声发射特征

    Institute of Scientific and Technical Information of China (English)

    吴刚; 王德咏; 翟松韬

    2012-01-01

    The acoustic emission evolution process of Jiaozuo sandstone with 20 ℃-1 200 ℃ temperatures is studied using acoustic emission (AE) test under uniaxial compression. By analyzing AE parameters and the mechanical properties of sandstone after high temperature, the AE characteristics of sandstone under different temperatures and different loading stages are explored. The results show that temperature has little effect on the acoustic emission of sandstone when temperature is less than 400 ℃. The AE ring-down accumulation counts change rapidly both at about 100 °C and 600 ℃ temperatures. It is shown that 100 ℃ is the threshold of crack growth for sandstone; and the internal structure composition of sandstone changes after 600 ℃; and acoustic emission phenomenon is very obvious. From 600 ℃ to 1 200 ℃, obvious brittle-plastic transition appears in sandstone. At the same time, the emergence of acoustic emission signals is delayed and the growth rate of acoustic emission signals rises because of high temperature. Sandstone releases intensive acoustic emission signals and presents plastic failure characteristics after 1 200 ℃.%通过在单轴压缩下实施的声发射测试,研究焦作砂岩受20~1200℃温度作用后的声发射演变过程;结合不同温度下砂岩的力学性质,通过声发射参数分析研究砂岩在不同受力阶段的声发射特点.研究表明:400℃以内温度对砂岩的声发射影响不太明显,在100℃后和600℃后声发射振铃累计数均发生急剧变化,100℃是砂岩裂纹扩展发育的门槛值,600℃后砂岩内部结构成分发生了变化,声发射现象较为明显.600~1200℃时,砂岩呈现出明显的脆塑性转变现象,高温导致声发射信号的时间有所推迟,声发射信号增长率不断上升.1200℃后,砂岩释放密集的声发射信号,呈现出塑性破坏特征.

  20. A SEMI-ANALYTICAL SOLUTION FOR CHARACTERISTICS OF A DAM-RESERVOIR SYSTEM WITH ABSORPTIVE RESERVOIR BOTTOM

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this study, a semi-analytical formulation based on the Scaled Boundary Finite Element Method (SBFEM) was proposed and used to obtain the solution for the characteristics of a two-dimensional dam-reservoir system with absorptive reservoir bottom in the frequency domain. For simplicity, the dam with arbitrary upstream faces was assumed to be rigid and was subjected to a horizontal ground acceleration, while the reservoir with absorptive bottom was assumed to be semi-infinite. The reservoir was divided into two sub-domains: a near-field sub-domain and a far-field sub-domain. The near-field sub-domain with arbitrary geometry was modelled by the Finite Element Method (FEM), while the effects of the far-field sub-domain which was assumed to be horizontal were described by a semi-analytical formation. The semi-analytical formulation involved the effect of absorptive reservoir bottom, as well as the radiation damping effect of a semi-infinite reservoir. A FEM/SBFEM coupling formulation was presented to solve dam-reservoir coupled problems. The accuracy and efficiency of the coupling formulation were demonstrated by computing some benchmark examples. Highly accurate results are produced even if the near-field sub-domain is very small.

  1. Engineering geological characteristics and the hydraulic fracture propagation mechanism of the sand-shale interbedded formation in the Xu5 reservoir

    Science.gov (United States)

    Lu, Cong; Li, Mei; Guo, Jian-Chun; Tang, Xu-Hai; Zhu, Hai-Yan; Yong-Hui, Wang; Liang, Hao

    2015-06-01

    In the Xu5 formation the sandstone reservoir and the shale reservoir are interbedded with each other. The average thickness of each formation is about 8 m, which increases the difficulty of the hydraulic fracturing treatment. The shale thickness ratio (the ratio of shale thickness to formation thickness) is 55-62.5%. The reservoir is characterized by ultra-low porosity and permeability. The brittleness index of sandstone is 0.5-0.8, and the brittleness index of shale is 0.3-0.8. Natural fractures are poorly developed and are mainly horizontal and at a low angle. The formation strength is medium and the reservoir is of the hybrid strike-slip fault and reverse fault stress regime. The difference between the minimum principal stress and the vertical stress is small, and the maximum horizontal principal stress is 20 MPa higher than the minimum horizontal principal stress and vertical stress. A mechanical model of a hydraulic fracture encountering natural fractures is built according to geological characteristics. Fracture mechanics theory is then used to establish a hydraulic fracturing model coupling the seepage-stress-damage model to simulate the initiation and propagation of a fracture. The hydraulic fracture geometry is mainly I-shaped and T-shaped, horizontal propagation dominates the extension, and vertical propagation is limited. There is a two to three meter stress diversion area around a single hydraulic fracture. The stress diversion between a hydraulic fracture and a natural fracture is advantageous in forming a complex fracture. The research results can provide theoretical guidance for tight reservoir fracturing design.

  2. Terrestrial tight oil reservoir characteristics and Graded Resource Assessment in China

    Science.gov (United States)

    Wang, Shejiao; Wu, Xiaozhi; Guo, Giulin

    2016-04-01

    The success of shale/tight plays and the advanced exploitation technology applied in North America have triggered interest in exploring and exploiting tight oil in China. Due to the increased support of exploration and exploitation,great progress has been made in Erdos basin, Songliao basin, Junggar basin, Santanghu basin, Bohai Bay basin, Qaidam Basin, and Sichuan basin currently. China's first tight oil field has been found in Erdos basin in 2015, called xinanbian oil field, with over one hundred million tons oil reserves and one million tons of production scale. Several hundred million tons of tight oil reserve has been found in other basins, showing a great potential in China. Tight oil in China mainly developed in terrestrial sedimentary environment. According to the relations of source rock and reservoir, the source-reservoir combination of tight oil can be divided into three types, which are bottom generating and top storing tight oil,self- generating and self-storing tight oil,top generating and bottom storing tight oil. The self- generating and self-storing tight oil is the main type discovered at present. This type of tight oil has following characteristics:(1) The formation and distribution of tight oil are controlled by high quality source rocks. Terrestrial tight oil source rocks in China are mainly formed in the deep to half deep lacustrine facies. The lithology includes dark mudstone, shale, argillaceous limestone and dolomite. These source rocks with thickness between 20m-150m, kerogen type mostly I-II, and peak oil generation thermal maturity(Ro 0.6-1.4%), have great hydrocarbon generating potential. Most discovered tight oil is distributed in the area of TOC greater than 2 %.( 2) the reservoir with strong heterogeneity is very tight. In these low porosity and permeability reservoir,the resources distribution is controlled by the physical property. Tight sandstone, carbonate and hybrid sedimentary rocks are three main tight reservoir types in

  3. Experimental Studies on the Effects of Cyclic Freezing-Thawing, Salt Crystallization, and Thermal Shock on the Physical and Mechanical Characteristics of Selected Sandstones

    Science.gov (United States)

    Ghobadi, M. H.; Babazadeh, R.

    2015-05-01

    Rocks are used in engineering works as monuments, building stones, and architectural covering stones. Their weathering behaviors and physical and mechanical properties are the most important factors controlling their suitability as building stones. The aim of this study is to evaluate the weathering behaviors of sandstones from the Qazvin area (western Iran). In total, nine sandstones (A, B, C, CG, S, S1, Min, Tr, and Sh) were analyzed. Accelerated weathering processes, namely freezing-thawing (F-T), salt crystallization (SC), heating-cooling (H-C), and heating-cooling-wetting (H-C-W), were used. Sandstones were subjected to 60 cycles of F-T, H-C, and H-C-W and 20 cycles of SC, and changes in characteristics including weight loss (%), P-wave velocity loss (%), and changes in uniaxial compressive strength (UCS) and point load strength were recorded after different numbers of cycles. The results from our laboratory studies indicate that rocks from the same stratigraphic layer can show major differences in weathering properties, and their sensitivity to these processes are different. Also, it was found that the thermal behavior of sandstones under wet and dry conditions were different. In the next stage of this study, a decay function model was used to statistically evaluate the disintegration rate. This model showed that the disintegration rate was higher for salt recrystallization compared with F-T, H-C, and H-C-W processes.

  4. Fe-oxide grain coatings support bacterial Fe-reducing metabolisms in 1.7-2.0 km-deep subsurface quartz arenite sandstone reservoirs of the Illinois Basin (USA

    Directory of Open Access Journals (Sweden)

    Yiran eDong

    2014-09-01

    Full Text Available The Cambrian-age Mt. Simon Sandstone, deeply buried within the Illinois Basin of the midcontinent of North America, contains quartz sand grains ubiquitously encrusted with iron-oxide cements and dissolved ferrous iron in pore-water. Although microbial iron reduction has previously been documented in the deep terrestrial subsurface, the potential for diagenetic mineral cementation to drive microbial activity has not been well studied. In this study, two subsurface formation water samples were collected at 1.72 and 2.02 km, respectively, from the Mt. Simon Sandstone in Decatur, Illinois. Low-diversity microbial communities were detected from both horizons and were dominated by Halanaerobiales of Phylum Firmicutes. Iron-reducing enrichment cultures fed with ferric citrate were successfully established using the formation water. Phylogenetic classification identified the enriched species to be related to Vulcanibacillus from the 1.72 km depth sample, while Orenia dominated the communities at 2.02 km of burial depth. Species-specific quantitative analyses of the enriched organisms in the microbial communities suggest that they are indigenous to the Mt. Simon Sandstone. Optimal iron reduction by the 1.72 km enrichment culture occurred at a temperature of 40oC (range 20 to 60oC and a salinity of 25 parts per thousand (range 25-75 ppt. This culture also mediated fermentation and nitrate reduction. In contrast, the 2.02 km enrichment culture exclusively utilized hydrogen and pyruvate as the electron donors for iron reduction, tolerated a wider range of salinities (25-200 ppt, and exhibited only minimal nitrate- and sulfate-reduction. In addition, the 2.02 km depth community actively reduces the more crystalline ferric iron minerals goethite and hematite. The results suggest evolutionary adaptation of the autochthonous microbial communities to the Mt. Simon Sandstone and carries potentially important implications for future utilization of this reservoir

  5. Wilcox sandstone reservoirs in the deep subsurface along the Texas Gulf Coast: their potential for production of geopressured geothermal energy. Report of Investigations No. 117

    Energy Technology Data Exchange (ETDEWEB)

    Debout, D.G.; Weise, B.R.; Gregory, A.R.; Edwards, M.B.

    1982-01-01

    Regional studies of the lower Eocene Wilcox Group in Texas were conducted to assess the potential for producing heat energy and solution methane from geopressured fluids in the deep-subsurface growth-faulted zone. However, in addition to assembling the necessary data for the geopressured geothermal project, this study has provided regional information of significance to exploration for other resources such as lignite, uranium, oil, and gas. Because the focus of this study was on the geopressured section, emphasis was placed on correlating and mapping those sandstones and shales occurring deeper than about 10,000 ft. The Wilcox and Midway Groups comprise the oldest thick sandstone/shale sequence of the Tertiary of the Gulf Coast. The Wilcox crops out in a band 10 to 20 mi wide located 100 to 200 mi inland from the present-day coastline. The Wilcox sandstones and shales in the outcrop and updip shallow subsurface were deposited primarily in fluvial environments; downdip in the deep subsurface, on the other hand, the Wilcox sediments were deposited in large deltaic systems, some of which were reworked into barrier-bar and strandplain systems. Growth faults developed within the deltaic systems, where they prograded basinward beyond the older, stable Lower Cretaceous shelf margin onto the less stable basinal muds. Continued displacement along these faults during burial resulted in: (1) entrapment of pore fluids within isolated sandstone and shale sequences, and (2) buildup of pore pressure greater than hydrostatic pressure and development of geopressure.

  6. Provenance of the Lower Triassic Bunter Sandstone Formation: implications for distribution and architecture of aeolian vs. fluvial reservoirs in the North German Basin

    DEFF Research Database (Denmark)

    Olivarius, Mette; Weibel, Rikke; Friis, Henrik

    2017-01-01

    Zircon U–Pb geochronometry, heavy mineral analyses and conventional seismic reflection data were used to interpret the provenance of the Lower Triassic Bunter Sandstone Formation. The succession was sampled in five Danish wells in the northern part of the North German Basin. The results show that s...

  7. Albitization and hydrothermal diagenesis of Yanchang oil sandstone reservoir,Ordos Basin%鄂尔多斯盆地三叠系延长组砂岩钠长石化与热液成岩作用研究

    Institute of Scientific and Technical Information of China (English)

    李荣西; 段立志; 陈宝赟; 夏冰; 李靖波

    2012-01-01

    鄂尔多斯盆地延长组储层砂岩发育大量自生钠长石矿物,其成因和产出与浊沸石有关,含量和分布比浊沸石多而广泛,但没有引起人们的注意.大量详细岩相学观察发现延长组储层砂岩发育丰富的自生钠长石,其主要为由斜长石碎屑蚀变形成或呈胶结物充填分布在砂岩碎屑颗粒之间.钠长石中含有大量原生的发亮黄色荧光的油气包裹体,表明其形成与油气注入同时.电子探针成分分析表明,钠长石Na2O含量较高,几乎为斜长石的纯钠长石端员(NaAlSi3O8),没有钙长石端员(CaAl2Si2O8).激光拉曼光谱特征反映出钠长石为沉积成岩期形成的低温钠长石,而非来源于岩浆岩或者变质岩区的碎屑钠长石.应用LA-MC-ICP/MS原位微分析技术对钠长石进行的稀土元素分析表明,延长组砂岩钠长石具有热水成岩作用地球化学特征,属于热液成岩作用产物.认为大量钠长石形成与石油充注的同时进行导致了储层致密过程中岩性油藏的形成.延长组储层砂岩中热液成岩作用对油藏形成和分布意义重大,值得重视和研究.%The Triassic low permeability reservoir sandstone of Yanchang Formation in Ordos Basin is composed of fine-grained arkose and feldspathic litharenite. Lots of research work has been devoted to the diagenesis of reservoir sandstone of Yanchang Formation. It is considered that the formation of secondary pore through dissolution of laumontite improved the reservoir property of sandstone, and the dissolution of laumontite was closely related to alteration of plagioclase. According to the equilibrium theory of mineral reaction, the laumontite formed by the alteration of plagioclase accompanied by the formation of albite is two times as many as the laumontite in quantity. Therefore, if laumontite of sandstone in Yanchang Formation was dissolved to form dissolution pores, the content of albite with more stability should be higher in theory

  8. Deep Geothermal Energy for Lower Saxony (North Germany) - Combined Investigations of Geothermal Reservoir Characteristics

    Science.gov (United States)

    Hahne, Barbara; Thomas, Rüdiger

    2014-05-01

    In Germany, successful deep geothermal projects are mainly situated in Southern Germany in the Molassebecken, furthermore in the Upper Rhine Graben and, to a minor extend, in the North German Basin. Mostly they are hydrothermal projects with the aim of heat production. In a few cases, they are also constructed for the generation of electricity. In the North German Basin temperature gradients are moderate. Therefore, deep drilling of several thousand meters is necessary to reach temperatures high enough for electricity production. However, the porosity of the sedimentary rocks is not sufficient for hydrothermal projects, so that natural fracture zones have to be used or the rocks must be hydraulically stimulated. In order to make deep geothermal projects in Lower Saxony (Northern Germany) economically more attractive, the interdisciplinary research program "Geothermal Energy and High-Performance Drilling" (gebo) was initiated in 2009. It comprises four focus areas: Geosystem, Drilling Technology, Materials and Technical System and aims at improving exploration of the geothermal reservoir, reducing costs of drilling and optimizing exploitation. Here we want to give an overview of results of the focus area "Geosystem" which investigates geological, geophysical, geochemical and modeling aspects of the geothermal reservoir. Geological and rock mechanical investigations in quarrys and core samples give a comprehensive overview on rock properties and fracture zone characteristics in sandstones and carbonates. We also show that it is possible to transfer results of rock property measurements from quarry samples to core samples or to in situ conditions by use of empirical relations. Geophysical prospecting methods were tested near the surface in a North German Graben system. We aim at transferring the results to the prospection of deep situated fracture zones. The comparison of P- and S-wave measurements shows that we can get hints on a possible fluid content of the

  9. Failure characteristics of two porous sandstones subjected to true triaxial stresses: Applied through a novel loading path

    Science.gov (United States)

    Ma, Xiaodong; Rudnicki, John W.; Haimson, Bezalel C.

    2017-04-01

    We performed an extensive suite of true triaxial experiments in two porous sandstones, Bentheim (porosity ≈ 24%) and Coconino (17%). The experiments were conducted using a novel loading path, which maintains constant Lode angle (Θ) throughout the test. This path enabled the examination of the effects of Lode angle and mean stress on failure (σoct,f). Our tests covered σ3 magnitudes between 0 and 150 MPa and of Θ at -30° (axisymmetric extension), -16°, 0°, +11°, +21°, and +30° (axisymmetric compression). Test results revealed the respective contribution of each of the two stress invariants to failure stress, failure plane angle, and failure mode. In both sandstones, the shear stress required for failure increases with mean stress but decreases with Θ when shear failure mode dominates. However, the dependence of failure stress on mean stress and Θ is reversed when the compactive failure mode is in control. The compactive failure mode was evident in Bentheim sandstone when compaction bands were observed under high mean stress. The Coconino sandstone did not reach the compactive failure regime within the maximum confinement applied. The failure plane angle monotonically decreases with increasing mean stress and Θ. For Coconino sandstone, failure plane angle varies between 80° and 50° for σoct,f between 50 and 450 MPa whereas it drops to 0° as σoct,f, approaches 250 MPa in Bentheim sandstone. We employed the bifurcation theory to relate the stress conditions at failure to the development of failure planes. The theory is in qualitative agreement with the experimental data.

  10. Characteristics of deltaic deposits in the Cretaceous Pierre Shale, Trinidad Sandstone, and Vermejo Formation, Raton Basin, Colorado.

    Science.gov (United States)

    Flores, R.M.; Tur, S.M.

    1982-01-01

    Detailed facies analyses of closely spaced measured surface sections in the Trinidad and adjacent areas of Colorado reflect deposition in the river-influenced delta. That this deltaic system was accompanied by abandonment of subdeltas is indicated by a destructional-deltaic facies of heavily bioturbated, carbonaceous sandstones, siltstones, and shales best recorded in the delta front deposits of the Trinidad Sandstone. Coal accumulation of the Vermejo deposits nevertheless remained primarily controlled by persistent organic sedimentation in interdistributary backswamps. These backswamps, which accumulated thick, lenticular coals, were formed during the normal constructional phase of the delta plain. -from Authors

  11. Chemical and isotopic characteristics of brines from three oil- and gas-producing sandstones in eastern Ohio, with applications to the geochemical tracing of brine sources

    Science.gov (United States)

    Breen, K.J.; Angelo, Clifford G.; Masters, Robert W.; Sedam, Alan C.

    1985-01-01

    Chemical and isotopic characteristics of selected inorganic constituents are reported for brines from the Berea Sandstone of Mississippian age, the Clinton sandstone, Albion Sandstone of Silurian age, and the Rose Run formation of Cambrian and Ordovician age in 24 counties in eastern Ohio. Ionic concentrations of dissolved constituents in brines from these formations generally fall in the following ranges (in millimoles per kilogram of brine): Na, Cl > 1,000; 100 Al, I, HCO3, SiO2 Mg, Na, Cl, K, SO4 and Br, and mean values of density and dissolved solids are significantly different at the 95-percent confidence level in each formation. Only potassium has a unique concentration range in each formation. Selected concentration ratios are identified as potential indicators for geochemical tracing of brines having some history of dilution. The k:Na ratios work best for identifying the source formation of an unidentified brine. Isotopic characteristics of hydrogen and oxygen indicate a meteoric origin for the water matrix of the brines. Sulfur isotopes may have utility for differentiating brines from oxidizing ground water.

  12. Wilcox sandstone reservoirs in the deep subsurface along the Texas Gulf Coast - their potential for production of geopressured geothermal energy. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Debout, D.G.; Weise, B.R.; Gregory, A.R.; Edwards, M.B.

    1979-10-01

    The following subjects are included: regional setting, stratigraphic sections, Lower Wilcox sandstone distribution, formation pressure, formation temperature used to delineate geothermal fairways, Zapata Fairway, Duval Fairway, Live Oak Fairway, De Witt Fairway, Colorado Fairway, and Harris Fairway. Depositional and structural style, formation pressures and temperatures, porosity and permeability, formation water salinity, and Cuero Prospect are covered for De Witt Fairway. Depositional and structural style, formation and fluid properties, and Eagle Lake Prospect are covered for Colorado Fairway. (MHR)

  13. Diagenetic evolution and its effect on reservoir-quality of fan delta sandstones during progressive burial:Evidence from the upper part of the fourth member of Shahejie formation, Bonan sag, Jiyang depression

    Institute of Scientific and Technical Information of China (English)

    马奔奔; 张少敏; 操应长; 贾艳聪; 王艳忠

    2015-01-01

    Petrographic analysis combined with various techniques, such as thin section identification, fluid inclusions, isotopic data, petro-physical property testing and oil testing results, was used to study diagenetic evolution and its effect on reservoir-quality of fan delta reservoirs of Es4s in the Bonan sag. The diagenesis is principally characterized by strong compaction, undercompaction, multi-phase of dissolution and cementation. Compaction played a more important role than cementation in destroying the primary porosity of the sandstones. The reservoirs have experienced complicated diagenetic environment evolution of “weak alkaline− acid−alkalinity−acid−weak alkalinity” and two-stage of hydrocarbon filling. The diagenetic sequences are summarized as “early compaction/early pyrite/gypsum/calcite/dolomite cementation→feldspar dissolution/the first stage of quartz overgrowth→ early hydrocarbon filling→quartz dissolution/anhydrite/Fe-carbonate cementation→Fe-carbonate dissolution/feldspar dissolution/ the second stage of quartz overgrowth→later hydrocarbon filling→later pyrite cementation. In the same diagenetic context, the diagenetic evolution processes that occurred in different sub/micro-facies during progressive burial have resulted in heterogeneous reservoir properties and oiliness. The braided channel reservoirs in fan delta plain are poorly sorted with high matrix contents. The physical properties decrease continually due to the principally strong compaction and weak dissolution. The present properties of braided channel reservoirs are extremely poor, which is evidenced by few oil layers developed in relatively shallow strata while dry layers entirely in deep. The reservoirs both in the underwater distributary channels and mouth bars are well sorted and have a strong ability to resist compaction. Abundant pores are developed in medium-deep strata because of modifications by two-stage of acidic dissolution and hydrocarbon filling. The

  14. Distribution and characteristics of volcanic reservoirs in China

    Institute of Scientific and Technical Information of China (English)

    HUANG Yulong; WANG Pujun; CHEN Shuming

    2009-01-01

    About forty productive oil/gas fields hosted in volcanic reservoirs have been found since 1957 in fourteen basins of China. They can be simply subdivided into two groups, the east and the west. Reservoir volcanic rocks of the east group are predominantly composed of Late Jurassic to Early Cretaceous rhyolite and Tertiary basalt, preferred being considered as rift type volcanics developed in the circum-Pacific tectonic regime. Those of the west are Permo-Carboniferous intermediate/basic volcanic rocks, being island-arc type ones developed in paleo-Asian Ocean tectonic regime.

  15. Variation Characteristics of Water Environmental Capacity in Poyang Lake under the Scheduling of Three Gorges Reservoir

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the variation characteristics of water environmental capacity in Poyang Lake under the scheduling of Three Gorges Reservoir.[Method] Choosing chemical oxygen demand (COD),total nitrogen (TN) and total phosphorus (TP) as the control indexes of pollutants in Poyang Lake,the variation characteristics of water environmental capacity in Poyang Lake under the scheduling of Three Gorges Reservoir were analyzed based on the water environment mathematical models of organic compounds ...

  16. Upper Jurassic - Lower Cretaceous turbidite sandstones in the Central Graben, North Sea; with special focus on the Danish Gertrud Graben

    Energy Technology Data Exchange (ETDEWEB)

    Johannessen, P.

    1998-10-01

    Thick Late Jurassic - Early cretaceous turbidite sandstone successions in the Central Graben are uncommon except from the Moray Firth and Viking Graven north of the Central Graben, where several important hydrocarbon producing turbidite sandstone fields are known. The only hydrocarbon producing turbidite reservoir sandstones in the Central Graben is the up to 55 m thick Ribble Sandstone Member located in the British South-west Central Graben, where it is lying above thick shoreface reservoir sandstones of the Fulmar Formation, separated by offshore claystones of the Kimmeridge Clay Formation. The turbidite sandstones of the Ribble Sandstone Member derived from the more proximal thick reservoir sandstones of the Fulmar Formation located near the Mid North Sea High. It has not yet been possible to correlate thick shoreface sandstones of the Norwegian Ula Formation or the Danish Heno Formation to more distal thick turbidite sandstones derived from the shoreface sandstones. (au) 60 fig., 85 refs.

  17. 疏松砂岩稠油油藏水平井临界出砂量数值模拟%NUMERICAL SIMULATION FOR THE CRITICAL SAND PRODUCTION RATE IN THE HORIZONTAL WELLBORE OF UNCONSOLIDATED SANDSTONE HEAVY OIL RESERVOIR

    Institute of Scientific and Technical Information of China (English)

    张建; 汪志明; 李帮民

    2012-01-01

    In the exploitation process of the moderate sand production from the unconsolidated sandstone heavy-oil reservoirs, the sand particles which are produced in the horizontal reservoirs easily flow into the horizontal boreholes, deposit, and form sand bed. Finally the many damages such as the buried oil reservoirs and blocked oil string by the sand etc. Are resulted in. By means of FLUENT hydrodynamic software, the studies of numerical simulation for the critical sand production rates taken under the different conditions of horizontal-borehole flow velocity are conducted in the exploitation process of the moderate sand production. The results show that there all exist a critical sand production in different flow rates. At this time, the fixed sand bed in the horizontal intervals does not occur, the height of moving sand bed is less then 5 mm and furthermore the critical sand production rates are quantitatively presented under the conditions of different borehole velocities. The research achievements stated above can provide evidences for the technological design of the moderate sand production in the unconsolidated sandstone oil reservoirs in Bohai area.%疏松砂岩稠油油藏适度出砂开采过程中,在水平段储层产出砂粒随稠油进入水平井筒后容易沉积形成砂床,造成油层砂埋、油管砂堵等危害.利用FLUENT流体力学软件对适度出砂开采过程中水平井筒不同井筒流速下可携带的临界出砂量开展了数值模拟研究.结果表明,针对不同井筒流速条件下,均存在一个临界出砂量,此时水平井段未出现固定砂床,移动砂床平均高度小于5 mm,并定量给出了不同井筒流速时的临界出砂量.研究结果可为渤海疏松砂岩油藏适度出砂开采工艺设计提供依据.

  18. 胶结物对东营凹陷储层砂岩弹性特征的影响%Influence of Cements on the Elastic Properties of Reservoir Sandstone in Dongying Depression

    Institute of Scientific and Technical Information of China (English)

    邓继新; 冯佐海

    2009-01-01

    The seismic properties of reservoir rock provide the basis for hydrocarbon exploration and dynamic monitoring.More than 250 sandstone samples are selected from Shahejie Formation of Paleogene age in Dongying drepression,and compressional-and shear-wave velocities are measured by pulse transmission technique.Two dominate variation trends are distinguished in the data plots of compressional-wave velocity versus Possion ratio,indicating the effects of mud content and calcite cement on the elastic properties of sandstone samples.In each change trend,with the rock texture transfering gradually from grain-supporting to matrix-supporting with increasing mud and calcite cement content,the propagation of elastic wave also changed from grain-to-grain contacts to rock matrix,which resulted in the measured data illustrating extremely different tendency.It helps utilize the physics properties of reservoir sandstone to extract rock texture and diagenesis properties in the research area.%储层岩石的地震弹性属性是进行油气储层勘探及动态监测的基础.系统选取东营凹陷古近系各层段砂岩样品250块(以沙河街组为主),在模拟储层条件下利用脉冲穿透法测试样品的纵、横波速度.样品在纵波速度-泊松比交汇图中表现出两种主要变化趋势,分别对应泥质与钙质胶结物的影响;在每个变化趋势中随泥质含量与钙质胶结物含量的增加,岩石结构从颗粒所构成的骨架支撑逐渐表现为基质支撑,弹性波能量的传播也从通过颗粒接触边界转变为通过岩石基质传播,这是使砂岩样品测试结果表现出两种截然不同变化趋势的主要原因,为利用岩石物理特性从地震资料中提取岩石结构、沉积与成岩特征的信息提供了依据.

  19. Geochemical characteristics of sandstones from Cretaceous Garudamangalam area of Ariyalur, Tamilnadu, India: Implications of provenance and tectonic setting

    Indian Academy of Sciences (India)

    Babu K

    2017-04-01

    The Trichinopoly Group (later redesignated as Garudamangalam) has unconformable relationship with underlying Uttatur Group and is divided into lower Kulakanattam Formation and upper Anaipadi Formation. These calcareous sandstones are analysed major, trace and rare earth elements (REEs) to find out CIA, CIW, provenance and tectonic setting. The silica content of fossiliferous calcareous sandstone show wide variation ranging from 12.93 to 42.56%. Alumina content ranged from 3.49 to 8.47%. Higher values of Fe2O3 (2.29–22.02%) and low MgO content (0.75–2.44%) are observed in the Garudamangalam Formation. CaO (23.53–45.90) is high in these sandstones due to the presence of calcite as cementing material. Major element geochemistry of clastic rocks (Al2O3 vs. Na2O) plot and trace elemental ratio (Th/U) reveal the moderate to intense weathering of the source rocks. The Cr/Zr ratio of clastic rocks reveal with an average of 1.74 suggesting of felsic provenance. In clastic rocks, high ratios of ΣLREE/ΣHREE, La/Sc, Th/Sc, Th/Co, La/Co and low ratios of Cr/Zr, and positive Eu anomaly ranges from (Eu/Eu* = 1.87–5.30) reveal felsic nature of the source rocks.

  20. Prediction of Sand Production from a Saudi Sandstone Reservoir Prévision de la production de sable pour un réservoir gréseux d'Arabie Saoudite

    Directory of Open Access Journals (Sweden)

    Al-Awad M. N.

    2006-12-01

    Full Text Available Sand production is encountered in some Saudi oil fields. Six sand samples produced from different wells in a Saudi oil reservoir were obtained. Sandstone samples obtained from the same reservoir were subjected to uniaxial and triaxial failure tests. The debris produced from the sandstone samples and the six sand samples were characterized for their mineralogy using X-ray diffractometer and grain size distribution using standard sieves. Statistical analyses were employed to check whether a statistical difference between the sand samples produced from oil wells and debris collected from the failed sandstone specimens is significant or not. The critical oil rates of the Saudi oil reservoir were also calculated for different well inclination angles. Results show that, no significant statistical difference between the sand samples and debris exists at a confidence level of 95%. Two obvious failure mechanisms, splitting and shear failure, are responsible for sand production from the studied Saudi oil reservoir. The maximum sand-free production for the studied oil reservoir range from 960 to 4080 barrels per day. La production de sable est un phénomène rencontré dans certains gisements pétroliers saoudiens. L'étude a porté sur six échantillons de sable provenant de différents puits d'exploitation d'un réservoir gréseux. Des échantillons de grès issus de ce même réservoir ont été soumis à des essais de compression uniaxiale et triaxiale. Les débris des échantillons de grès et les échantillons de sable ont fait l'objet d'un examen minéralogique par diffractométrie aux rayons X et granulométrie sur tamis standards. Les méthodes d'analyse statistique ont été employées pour vérifier si la différence statistique entre les échantillons de sable provenant des puits et les débris des échantillons de grès est significative ou non. On a également calculé les taux critiques de production du gisement saoudien pour diff

  1. Environmental Characteristics of Reservoir Systems in the Czech Republic

    Science.gov (United States)

    2003-07-01

    highest parts, at the watershed border, there are also granitic rocks (mostly Cadomian). The geological age is Lower Paleozoic – Proterozoic . Fifteen...are included. Stratification of temperature, dissolved oxygen , pH, and alkalinity has been measured at the dam station (St. 16) in three-week...because of relatively imprecise measurement of water surface level of the reservoir pool. Stratification of temperature, dissolved oxygen , pH, and

  2. CO2 Storage Potential of the Eocene Tay Sandstone, Central North Sea, UK

    Science.gov (United States)

    Gent, Christopher; Williams, John

    2017-04-01

    Carbon Capture and Storage (CCS) is crucial for low-carbon industry, climate mitigation and a sustainable energy future. The offshore capacity of the UK is substantial and has been estimated at 78 Gt of CO2 in saline aquifers and hydrocarbon fields. The early-mid Eocene Tay Sandstone Member of the Central North Sea (CNS) is a submarine-fan system and potential storage reservoir with a theoretical capacity of 123 Mt of CO2. The Tay Sandstone comprises of 4 sequences, amalgamating into a fan complex 125km long and 40 km at a minimum of 1500 m depth striking NW-SE, hosting several hydrocarbon fields including Gannett A, B, D and Pict. In order to better understand the storage potential and characteristics, the Tay Sandstone over Quadrant 21 has been interpreted using log correlation and 3D seismic. Understanding the internal and external geometry of the sandstone as well as the lateral extent of the unit is essential when considering CO2 vertical and horizontal fluid flow pathways and storage security. 3D seismic mapping of a clear mounded feature has revealed the youngest sequence of the Tay complex; a homogenous sand-rich channel 12 km long, 1.5 km wide and on average 100 m thick. The sandstone has porosity >35%, permeability >5 D and a net to gross of 0.8, giving a total pore volume of 927x106 m3. The remaining three sequences are a series of stacked channels and interbedded mudstones which are more quiescent on the seismic, however, well logs indicate each subsequent sequence reduce in net to gross with age as mud has a greater influence in the early fan system. Nevertheless, the sandstone properties remain relatively consistent and are far more laterally extensive than the youngest sequence. The Tay Sandstone spatially overlaps several other potential storage sites including the older Tertiary sandstones of the Cromarty, Forties and Mey Members and deeper Jurassic reservoirs. This favours the Tay Sandstone to be considered in a secondary or multiple stacked

  3. Geological and production characteristics of strandplain/barrier island reservoirs in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Cole, E.L.; Fowler, M.; Jackson, S.; Madden, M.P.; Reeves, T.K.; Salamy, S.P.; Young, M.A.

    1994-12-01

    The Department of Energy`s (DOE`s) primary mission in the oil research program is to maximize the economically and environmentally sound recovery of oil from domestic reservoirs and to preserve access to this resource. The Oil Recovery Field Demonstration Program supports DOE`s mission through cost-shared demonstrations of improved Oil Recovery (IOR) processes and reservoir characterization methods. In the past 3 years, the DOE has issued Program Opportunity Notices (PONs) seeking cost-shared proposals for the three highest priority, geologically defined reservoir classes. The classes have been prioritized based on resource size and risk of abandonment. This document defines the geologic, reservoir, and production characteristics of the fourth reservoir class, strandplain/barrier islands. Knowledge of the geological factors and processes that control formation and preservation of reservoir deposits, external and internal reservoir heterogeneities, reservoir characterization methodology, and IOR process application can be used to increase production of the remaining oil-in-place (IOR) in Class 4 reservoirs. Knowledge of heterogeneities that inhibit or block fluid flow is particularly critical. Using the TORIS database of 330 of the largest strandplain/barrier island reservoirs and its predictive and economic models, the recovery potential which could result from future application of IOR technologies to Class 4 reservoirs was estimated to be between 1.0 and 4.3 billion barrels, depending on oil price and the level of technology advancement. The analysis indicated that this potential could be realized through (1) infill drilling alone and in combination with polymer flooding and profile modification, (2) chemical flooding (sufactant), and (3) thermal processes. Most of this future potential is in Texas, Oklahoma, and the Rocky Mountain region. Approximately two-thirds of the potentially recoverable resource is at risk of abandonment by the year 2000.

  4. The Analysis on the Reservoir Characteristics and Reservoir Performance Analysis in Chunfeng Oilfield%春风油田沙湾组储层特征及储集性能分析

    Institute of Scientific and Technical Information of China (English)

    张瑞香; 杨少春; 宋璠; 王杰

    2016-01-01

    春风油田位于准噶尔盆地西部车排子凸起的东北部,主要发育扇三角洲前缘水下分流河道与辫状河三角洲前缘水下分流河道微相。在地层精细划分对比及沉积微相研究基础之上,通过岩心、薄片观察,结合扫描电镜、X-衍射分析、压汞曲线等实验数据,对春风油田沙湾组一段1砂组展开储层特征及主控因素研究。研究结果表明:沙湾组一段1砂组N1 s11层主要为棕褐色含砾不等粒砂岩,经鉴定认为属于岩屑质长石砂岩,目的层自下而上呈现出底砾岩→粗砂岩+含砾砂岩→细砂岩+泥质粉砂岩三层结构;储集空间主要为原生粒间孔,大孔粗喉型及大孔中喉型为目的层油气主要富集型孔隙结构;常见碳酸盐胶结,不同井区不同相带下碳酸盐含量差异较大,为影响储层物性的主控因素。%The Chunfeng Oilfield is locates in the northeast of the Chepaizi Uplift , the western margin of the Junggar Basin , the main Sedimentary microfacies are fan detla front underwater distributary channel and braided river delta front underwater distributary channel .Base on the contrast of stratigraphic subdivision and the research of sedimentary microfacies , through observing the core , thin sections , combineing with the experimental datas of scanning electron microscopy , X-difraction analysis and mercury curve , the reservoir characteristics and the main controlling factors of N 1 s11 layer in Chunfeng Oilfield were researched .The results show that N 1 s11 brown conglomerat-ic sandstone reservoirs are mainly identified lithic arkose , the layer from bottom to top presents three layers struc-ture:the basal conglomerate grit , conglomeratic sandstone and fine sandstone , fine sandstone and argillaceous silt-stone .Reservoir spaces are mainly primary intergranular pore , large pore coarse throat type and large pore medium throat type are the main pore structures for storing oil

  5. Longitudinal heterogeneity of sediment characteristics during southwest monsoon season in hyper-eutrophic Krishnagiri reservoir, India.

    Science.gov (United States)

    Sudha, Velu; Ambujam, Neelakantapillai Kanniperumal

    2012-03-01

    Krishnagiri reservoir is a hyper-eutrophicated reservoir located in Krishnagiri district which is one of the drought-prone districts in Tamil Nadu, India. The reservoir water is being used for various purposes such as irrigation, drinking, fish rearing, livestock rearing, and recreation. Since there is no an evidence of investigation on bottom sediments in Krishnagiri reservoir, the present study was carried out during southwest monsoon season in 2008. This study examined the physical and chemical characteristics of the bottom sediments such as composition, redox potential, moisture content, organic carbon, organic matter, total phosphorus, and total iron at 15 locations in the reservoir. Phosphorus fractionation study was carried out to find out different fractions such as loosely adsorbed phosphorous, iron and aluminium-bound phosphorus, calcium-bound phosphorous, and organic phosphorous. Results indicated that there was spatial variation in the composition of sediments and low values of redox potential. The significant positive correlation exists between the organic carbon and organic phosphorus concentration. The lacustrine zone of the reservoir showed high accumulation of total phosphorus and total iron when compared to riverine and transition zones. This study concludes an allogenic origin of majority of inorganic phosphorus in the reservoir during the study period and this might have been derived from the catchment during the erosion process. The high concentration of surface sediment phosphorus clearly indicates a greater threat of eutrophication in Krishnagiri reservoir.

  6. New scale of turbulent flow characteristics and its use in aspects of reservoir and production engineering

    Energy Technology Data Exchange (ETDEWEB)

    Deghmoum, A.H.; Hamaz, H. [Sonatrach/AMT/CRD, Alger (Algeria)

    2004-07-01

    Fluid flow through a porous medium in turbulent flow regime was examined through laboratory experiments and numerical analysis. The study presented production and core data from thousands of core samples from six reservoirs in Algeria. The core samples were analyzed under unsteady state flow conditions. New concepts of non-Darcian flow characteristics for reservoir characterization and well performance were presented. A universal scale of turbulent factor versus permeability was developed to classify reservoirs in terms of homogeneity and heterogeneity. The new scale also established an isoturbulence map for enhancing reservoir development in terms of localization of good zones to drill new wells and to improve well productivity. This paper also presented a methodology for choosing the best perforation characteristics. 9 refs., 11 figs.

  7. Limnological characteristics and trophic state of a newly created site: the Pareja Limno-reservoir

    Science.gov (United States)

    Molina-Navarro, E.; Martínez-Pérez, S.; Sastre-Merlín, A.

    2012-04-01

    The creation of dams in the riverine zone of large reservoirs is an innovative action whose primary goal is to generate water bodies that ensure a stable level of water there. We have termed these bodies of water "limno-reservoirs" because their water level becomes constant and independent of the fluctuations occurring in the main reservoir. In addition, limno-reservoirs represent environmental initiatives with corrective and/or compensatory effects. Pareja Limno-reservoir, located near the left side of Entrepeñas Reservoir (Guadalajara province, central Spain), is one of the first initiatives of this type in Spain. We are investigating the hydrology, limnology, microbiology, siltation risk and other aspects of this site. This research has a special interest since the building of limno-reservoirs is rising in Spain. To acquire knowledge about their behavior may be helpful for further constructions. In fact, every new reservoir building project usually includes a limno-reservoir. Moreover, there are many initiatives related with the construction of this kind of hydraulic infrastructures in the reservoirs under exploitation. This work focuses on the limnological study of the Pareja Limno-reservoir. To conduct this research, twelve seasonal sample collections at two sampling points (the dam and inflow zones) have been made in Pareja Limno-reservoir, from spring 2008 to winter 2011. The primary goal of this study is to describe the limnological characteristics of the limno-reservoir. Special interest is placed in the study of the trophic state through different indicators (nutrients, transparency, phytoplankton and zooplankton populations), as the European Water Framework Directive objective is to achieve a "good ecological status" in every aquatic ecosystem by 2015. The results of the study show that the Pareja Limno-reservoir follows a warm monomictic water stratification pattern. Water was slightly alkaline and conductivity values were mostly over 1000 μS cm-1 due

  8. Key Elements Controlling Oil Accumulation within the Tight Sandstones

    Institute of Scientific and Technical Information of China (English)

    Haiyan Hu; Zhiping Zeng; Jianzhang Liu

    2015-01-01

    Tight oil sandstone reservoirs with low porosity and permeability, which are an uncon-ventional petroleum resource, have been discovered in the Jurassic intervals of the central Junggar Ba-sin, the northwestern China. To reveal the accumulation mechanism, a relatively comprehensive re-search was conducted, including oil-source correlation, porosity evolution, and hydrocarbon charging history. The results show that crude oil of these tight sandstone reservoirs were mainly from Permian source rocks with some contribution from Jurassic source rocks. The reservoirs were buried at shallow depth (5%). In contrast, the sandstone reservoir had already become tight and did not provide available space to ac-cumulate oil due to severe compaction and cementation when hydrocarbon from Jurassic source rock filled, evidenced by low GOI values (<5%). Therefore, reservoir porosity controls the oil accumulation within tight sandstone. Whether tight sandstone reservoirs accumulate oil depends on the reservoir quality when hydrocarbons charge. Before the exploration of tight oil sandstone reservoirs, it should be required to investigate the relationship between oil charging history and porosity evolution to reduce the exploration risk and figure out the available targets.

  9. Estimates of geothermal reservoir fluid characteristics: GeoSys.Chem and WATCH

    OpenAIRE

    Ignacio Salvador Torres-Alvarado; Mahendra P. Verma; Kizito Opondo; David Nieva; Füsun Tut Haklidir; Edgar Santoyo; Rosa María Barragán; Víctor Arellano

    2012-01-01

    A comparative study of the reservoir fluid characteristics calculation of ten production wells of Los Azufres, Los Humeros and Cerro Prieto geothermal fields using two computer codes GeoChem (GeoSys.Chem) and WATCH is presented. GeoSys.Chem estimates the reservoir temperature and vapor fraction through quartz geothermometry and assuming enthalpy conservation, while the average temperature of quartz and Na/K geothermometers is employed in WATCH and vapor fraction is also calculated through ent...

  10. Pore and Pore-Throat Size Distributions of Low Permeability Sandstone Reservoir and Their Differential Origin%低渗砂岩储层孔喉的分布特征及其差异性成因

    Institute of Scientific and Technical Information of China (English)

    张创; 孙卫; 杨建鹏; 高辉; 侯海林; 齐瑞; 罗江云; 魏希望

    2012-01-01

    Pore and pore-throat size types and distributions of two low permeability sandstone reservoirs (E1f3 reservoir in the Shanian area of North Jiangsu basin and J2x reservoir in the Niujuanhu area of Santanghu basin) were analyzed to understand their origins using a series of methods such as grain size analysis, thin slices, pore images, SEM, mercury-injection data. The results show that pore type in the E1 f3 reservoir is predominantly carbonate cement and feldspar dissolved pores and that in the J2x is mainly tuffaceous and feldspar dissolved pores, with the former containing more large dissolved pores and the latter containing more small intercrystal pores. The pore-throat size distributions in E1 f3 reservoir are wide unimodal for dissolution-origin pore-throats, thin unimodal for those with compaction or compaction- cementation, no peak for tube-shaped ore-throats, as well as bimodal for those with dissolution and compaction or cementation origins. The pore-throat size distributions of J2x reservoir are wide unimodal for that resulting from dissolution, thin unimodal for tube-shaped pore-throat, and bimodal for that resulting from compaction and cementation. No bimodal distribution pattern was observed in dissolution pore-throat or other pore-throats. Pore size and pore-throat radii in the two reservoirs tend to decrease with mean sizes decreasing, and mean pore radii are less than detritus radii. Under the condition of the same grain sizes, the pore and pore-throat sizes of J2 x reservoir are all less than those in the E1f3 reservoir. The higher maturity of E1f3 reservoir composition and structure, along with early carbonate cementation, preserves primary large intergranular pore-space during its compaction, which is enlarged during late-stage dissolution. The J2 x3 reservoir in the Niujuanhu area contains higher plastic detritus content and syn-sedimentary tuffaceous material, greatly decreasing primary intergranular pore-space during the compaction, and late

  11. Coalbed Methane-bearing Characteristics and Reservoir Physical Properties of Principal Target Areas in North China

    Institute of Scientific and Technical Information of China (English)

    TANG Shuheng; SUN Shenglin; HAO Duohu; TANG Dazhen

    2004-01-01

    The coalbed methane (CBM) resources in North China amounts up to 60% of total resources in China.North China is the most important CBM accumulation area in China, The coal beds of the Upper Paleozoic Taiyuan and Shanxi formations have a stable distribution. The coal reservoir of target areas such as Jincheng, Yanquan-Shouyang,Hancheng, Liulin, etc. have good CBM-bearing characteristics, high permeability and appropriate reservoir pressure, and these areas are the preferred target areas of CBM developing in China. The coal reservoirs of Wupu, Sanjiaobei, Lu'an,Xinmi, Anyang-Hebi, Jiaozuo, Xinggong and Huainan also have as good CBM-bearing characteristics, but the physical properties of coal reservoirs vary observably. So, further work should be taken to search for districts with high pressure,high permeability and good CBM-bearing characteristics. Crustal stresses have severe influence on the permeability of coal reservoirs in North China. From west to east, the crustal stress gradient increases, while the coal reservoirs permeability decreases.

  12. 低渗透致密砂岩气层产能预测方法研究%Capacity Prediction Methods of Tight Gas Sandstone Reservoir with Low permeability

    Institute of Scientific and Technical Information of China (English)

    范宜仁; 宋岩; 张海涛; 张鹏; 李思

    2016-01-01

    T he gas reservoir property is poor and the percolation mechanism is complex in the eastern part of Upper Paleozoic in the Ordos Basin . It is difficult to determine the gas productivity index . And the relationship between gas abundance and porosity‐permeability is ambiguity . T herefore conventional productivity prediction method is not effective . Based on petrophysical experiments and wireline log data ,analyzed are the differences of different fluids in acoustic and elastic parameters .Then the sensitive parameters of the gas reservoir is optimized and gets the parameters with the Xu‐White model and Gassmann function .Lastly the prediction model is established on the basis of sensitive parameters . T he research concludes that bulk modulus is highly sensitive to the capacity of gas reservoir .And obtaining elastic parameters does not rely on the physical properties of gas reservoir .This method facilitates the capacity prediction of tight gas sandstone reservoir .%鄂尔多斯盆地东部上古生界含气储层物性差,渗流规律复杂,孔隙流体对测井响应特征贡献小,储层参数计算精度低,导致产能预测困难。针对这一问题,在对不同孔隙结构储层进行分类后,研究了常规产能预测方法,在此基础上从岩石物理实验出发,结合Biot‐Gassmann理论和Xu‐White模型,分析储层含气性与声学特征的关系,提取产能敏感因子,建立基于阵列声波测井的产能预测模型。研究表明,体积模量对储层含气性较为敏感,据此建立的气层产能预测模型克服了储层物性参数计算精度低的问题,与基于常规测井资料的产能预测模型相比,在致密砂岩气层具有更好的应用效果。

  13. Permeability reduction by pyrobitumen, mineralization, and stress along large natural fractures in sandstones at 18,300 ft. depth: Destruction of a reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, J.C. [SPE, Richardson, TX (United States)]|[Sandia National Lab., Albuquerque, NM (United States); Billingsley, R.L.; Evans, L.W.

    1996-11-01

    Production of gas from the Frontier Formation at 18,300 R depth in the Frewen No. 4 Deep well, eastern Green River basin (Wyoming), was uneconomic despite the presence of numerous open natural fractures. Initial production tested at 500 MCFD, but dropped from 360 MCFD to 140 MCFD during a 10-day production test, and the well was abandoned. Examination of the fractures in the core suggests several probable reasons for this poor production. One factor is the presence of a hydrocarbon residue (carbon) which filled much of the porosity left in the smaller fractures after mineralization. An equally important factor is probably the reorientation of the in situ horizontal compressive stress to a trend normal to the main fractures, and which now acts to close fracture apertures rapidly during reservoir drawdown. This data set has unpleasant implications for the search for similar, deep fractured reservoirs.

  14. Micro pore and throat characteristics and moveable fluid variation of tight sandstone in 4th member of Xujiahe Formation, Xinchang Gas Field, western Sichuan Basin%川西新场须四段致密砂岩储层微观孔喉与可动流体变化特征

    Institute of Scientific and Technical Information of China (English)

    肖开华; 冯动军; 李秀鹏

    2014-01-01

    In order to evaluate the tight sandstone reservoirs in the 4th member of the Xujiahe Formation in the Xinchang area of the western Sichuan Basin, nuclear magnetic resonance and constant-rate mercury intrusion ex-periments have been carried out to quantitatively analyze micro pore and throat and moveable fluid variation char-acteristics. Studies have indicated that the moveable fluid parameters, throat parameters and pore parameters of tight sandstones vary largely. In micro-fractured tight sandstones, pores have an advantage over throats affecting the moveable fluid parameters, and the moveable fluid parameters are mainly controlled by pores. Low moveable fluid content and low producing degree of tight sandstones are mainly caused by the relatively long radius and wide distribution of pores and throats. In micro-fractured tight sandstones, the mercury saturation in throats is higher than that in pores, indicating that the dominant type of reservoir space is pore-fracture type in the 4th member of the Xujiahe Formation, the Xinchang Gas Field.%为了评价川西新场须四段致密砂岩储层,应用恒速压汞及核磁共振实验方法对储层微观孔喉与可动流体变化特征进行定量分析。结果表明,须四段致密砂岩储层可动流体参数、喉道特征参数及孔隙参数变化幅度大。微裂隙发育的致密砂岩储层孔隙对可动流体参数的影响较喉道要更大一些,在微观上可动流体参数主要受孔隙控制。孔喉半径比较大、分布范围宽是致密砂岩储层可动流体含量低、可动用程度差的主要原因之一。微裂隙发育的致密砂岩储层具有喉道进汞饱和度较孔隙进汞饱和度高的特点,说明新场须四段致密砂岩储层的储集空间类型主要为孔隙-裂缝型。

  15. Nonassociated gas resources in low-permeability sandstone reservoirs, lower tertiary Wasatch Formation, and upper Cretaceous Mesaverde Group, Uinta Basin, Utah

    Energy Technology Data Exchange (ETDEWEB)

    Fouch, T.D.; Schmoker, J.W.; Boone, L.E.; Wandrey, C.J.; Crovelli, R.A.; Butler, W.C.

    1994-08-01

    The US Geological Survey recognizes six major plays for nonassociated gas in Tertiary and Upper Cretaceous low-permeability strata of the Uinta Basin, Utah. For purposes of this study, plays without gas/water contacts are separated from those with such contacts. Continuous-saturation accumulations are essentially single fields, so large in areal extent and so heterogeneous that their development cannot be properly modeled as field growth. Fields developed in gas-saturated plays are not restricted to structural or stratigraphic traps and they are developed in any structural position where permeability conduits occur such as that provided by natural open fractures. Other fields in the basin have gas/water contacts and the rocks are water-bearing away from structural culmination`s. The plays can be assigned to two groups. Group 1 plays are those in which gas/water contacts are rare to absent and the strata are gas saturated. Group 2 plays contain reservoirs in which both gas-saturated strata and rocks with gas/water contacts seem to coexist. Most units in the basin that have received a Federal Energy Regulatory Commission (FERC) designation as tight are in the main producing areas and are within Group 1 plays. Some rocks in Group 2 plays may not meet FERC requirements as tight reservoirs. However, we suggest that in the Uinta Basin that the extent of low-permeability rocks, and therefore resources, extends well beyond the limits of current FERC designated boundaries for tight reservoirs. Potential additions to gas reserves from gas-saturated tight reservoirs in the Tertiary Wasatch Formation and Cretaceous Mesaverde Group in the Uinta Basin, Utah is 10 TCF. If the potential additions to reserves in strata in which both gas-saturated and free water-bearing rocks exist are added to those of Group 1 plays, the volume is 13 TCF.

  16. Sediment pollution characteristics and in situ control in a deep drinking water reservoir.

    Science.gov (United States)

    Zhou, Zizhen; Huang, Tinglin; Li, Yang; Ma, Weixing; Zhou, Shilei; Long, Shenghai

    2017-02-01

    Sediment pollution characteristics, in situ sediment release potential, and in situ inhibition of sediment release were investigated in a drinking water reservoir. Results showed that organic carbon (OC), total nitrogen (TN), and total phosphorus (TP) in sediments increased from the reservoir mouth to the main reservoir. Fraction analysis indicated that nitrogen in ion exchangeable form and NaOH-extractable P (Fe/Al-P) accounted for 43% and 26% of TN and TP in sediments of the main reservoir. The Risk Assessment Code for metal elements showed that Fe and Mn posed high to very high risk. The results of the in situ reactor experiment in the main reservoir showed the same trends as those observed in the natural state of the reservoir in 2011 and 2012; the maximum concentrations of total OC, TN, TP, Fe, and Mn reached 4.42mg/L, 3.33mg/L, 0.22mg/L, 2.56mg/L, and 0.61mg/L, respectively. An in situ sediment release inhibition technology, the water-lifting aerator, was utilized in the reservoir. The results of operating the water-lifting aerator indicated that sediment release was successfully inhibited and that OC, TN, TP, Fe, and Mn in surface sediment could be reduced by 13.25%, 15.23%, 14.10%, 5.32%, and 3.94%, respectively.

  17. 南堡3号构造带古近系储层特征与四性关系研究%Reservoir Characteristics and Four-Property Relationship of Paleogene Reservoir in Nanpu 3rd Structure Belt

    Institute of Scientific and Technical Information of China (English)

    牛海瑞; 杨少春; 赵晓东; 陈潇; 何妮茜

    2015-01-01

    The third structure belt in Nanpu oilfield is located in the beach area where most of the wells are brine mud wells. The complex geological conditions and the characterization of high salinity and potassium lead to the difficulty of lithology identification. Based on the logging data standardization ,this paper makes full use of well logging data,mud logging data,rock thin section,core analytical data and so on to study on the reservoir characteristics and four-property relationship of Paleogene reservoir. and set up the four-property relationship model of lithology , poroperm characteristics,petroliferous properties and electric properties. The results show that Paleogene reservoir has middle to low porosity and middle permeability. The lithology is mainly medium sandstone,inequigranular sandstone and conglomerate. Along with the lithology change from fine to coarse,the reservoir poroperm characteristics are getting better,and Oil-bearing grade getting higher. Porosity and permeability are exponential correlation while the porosity and acoustic time are simple linear relationship. The study of reservoir four-property relationship is the foundation of well logging interpretation and reservoir evaluation which will provide references for the continue development of oil field.%南堡油田3号构造带地处滩海,具有高盐富钾的地质特点且基本为盐水泥浆基液钻井,增加了储层评价的难度。在测井资料标准化的基础上,综合利用测井、录井、薄片和岩心分析化验等资料,对古近系储层开展储层特征和四性关系研究,建立了储层岩性、物性、电性及含油气性之间的关系模型。研究表明,古近系属于中低孔中渗储层,岩性以中砂岩、不等粒砂岩和砂砾岩为主。随岩性由细变粗,储层物性变好,含油级别变高。孔隙度与渗透率呈指数相关,与声波时差呈较简单线性关系。储层四性关系研究是研究区开展测井解

  18. Investigation of Optimum Polymerization Conditions for Synthesis of Cross-Linked Polyacrylamide-Amphoteric Surfmer Nanocomposites for Polymer Flooding in Sandstone Reservoirs

    Directory of Open Access Journals (Sweden)

    A. N. El-hoshoudy

    2015-01-01

    Full Text Available Currently enhanced oil recovery (EOR technology is getting more attention by many countries since energy crises are getting worse and frightening. Polymer flooding by hydrophobically associated polyacrylamides (HAPAM and its modified silica nanocomposite are a widely implemented technique through enhanced oil recovery (EOR technology. This polymers class can be synthesized by copolymerization of acrylamide (AM, reactive surfmer, functionalized silica nanoparticles, and a hydrophobic cross-linker moiety in the presence of water soluble initiator via heterogeneous emulsion polymerization technique, to form latexes that can be applied during polymer flooding. Chemical structure of the prepared copolymers was proven through different techniques such as Fourier transform infrared spectroscopy (FTIR, and nuclear magnetic spectroscopy (1H&13C-NMR, and molecular weight was measured by gel permeation chromatography. Study of the effects of monomer, surfmer, cross-linker, silica, and initiator concentrations as well as reaction temperature was investigated to determine optimum polymerization conditions through single factor and orthogonal experiments. Evaluation of the prepared copolymers for enhancing recovered oil amount was evaluated by carrying out flooding experiments on one-dimensional sandstone model to determine recovery factor.

  19. Occurrence and Characteristics of Microplastic Pollution in Xiangxi Bay of Three Gorges Reservoir, China.

    Science.gov (United States)

    Zhang, Kai; Xiong, Xiong; Hu, Hongjuan; Wu, Chenxi; Bi, Yonghong; Wu, Yonghong; Zhou, Bingsheng; Lam, Paul K S; Liu, Jiantong

    2017-04-04

    Microplastic pollution in inland waters is receiving growing attentions. Reservoirs are suspected to be particularly vulnerable to microplastic pollution. However, very limited information is currently available on pollution characteristics of microplastics in reservoir ecosystems. This work studied the distribution and characteristics of microplastics in the backwater area of Xiangxi River, a typical tributary of the Three Gorges Reservoir. Microplastics were detected in both surface water and sediment with concentrations ranging from 0.55 × 10(5) to 342 × 10(5) items km(-2) and 80 to 864 items m(-2), respectively. Polyethylene, polypropylene, and polystyrene were identified in surface water, whereas polyethylene, polypropylene, and polyethylene terephthalate, and pigments were observed in sediment. In addition, microplastics were also detected in the digestion tracts of 25.7% of fish samples, and polyethylene and nylon were identified. Redundancy analysis indicates a weak correlation between microplastics and water quality variables but a negative correlation with water level of the reservoir and Secchi depth. Results from this study confirm the presence of high abundance microplastics in reservoir impacted tributaries, and suggest that water level regulated hydrodynamic condition and input of nonpoint sources are important regulators for microplastic accumulation and distribution in the backwater area of reservoir tributaries.

  20. Hydrocarbon accumulation characteristics and enrichment laws of multi-layered reservoirs in the Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Guang Yang

    2017-03-01

    Full Text Available The Sichuan Basin represents the earliest area where natural gas is explored, developed and comprehensively utilized in China. After over 50 years of oil and gas exploration, oil and gas reservoirs have been discovered in 24 gas-dominant layers in this basin. For the purpose of predicting natural gas exploration direction and target of each layer in the Sichuan Basin, the sedimentary characteristics of marine and continental strata in this basin were summarized and the forms of multi-cycled tectonic movement and their controlling effect on sedimentation, diagenesis and hydrocarbon accumulation were analyzed. Based on the analysis, the following characteristics were identified. First, the Sichuan Basin has experienced the transformation from marine sedimentation to continental sedimentation since the Sinian with the former being dominant. Second, multiple source–reservoir assemblages are formed based on multi-rhythmed deposition, and multi-layered reservoir hydrocarbon accumulation characteristics are vertically presented. And third, multi-cycled tectonic movement appears in many forms and has a significant controlling effect on sedimentation, diagenesis and hydrocarbon accumulation. Then, oil and gas reservoir characteristics and enrichment laws were investigated. It is indicated that the Sichuan Basin is characterized by coexistence of conventional and unconventional oil and gas reservoirs, multi-layered reservoir hydrocarbon supply, multiple reservoir types, multiple trap types, multi-staged hydrocarbon accumulation and multiple hydrocarbon accumulation models. Besides, its natural gas enrichment is affected by hydrocarbon source intensity, large paleo-uplift, favorable sedimentary facies belt, sedimentary–structural discontinuity plane and structural fracture development. Finally, the natural gas exploration and research targets of each layer in the Sichuan Basin were predicted according to the basic petroleum geologic conditions

  1. Distribution Characteristics of the Seismicity of Zipingpu Reservoir Region after the Wenchuan Earthquake

    Institute of Scientific and Technical Information of China (English)

    Li Hai'ou; Ma Wentao; Xu Xiwei; Xie Ronghua; Yuan Jingli; Xu Changpeng

    2011-01-01

    815 earthquakes recorded by 12 seismic stations of the Zipingpu reservoir seismic network in 2009 were relocated using the double difference algorithm to analyze the seismic activity of the Zipingpu reservoir. Relocation results show that the earthquakes are concentrated relatively in three zones. The distribution characteristics of focal depth are obviously different among different concentration zones. This means earthquakes in different concentration zones may have different causes. Compared to relocation of earthquakes taking place before the Wenchuan earthquake done by other researchers, the seismic concentration zones in the reservoir area shifted obviously after the Wenchuan earthquake. These variations are related to local stress adjustment in the reservoir area and may also be related to the diffusion depth and range of increased pore pressure caused by rock failure in the course of Wenchuan earthquake.

  2. Multivariate analysis of ground water characteristics of Ajali sandstone formation: A case study of Udi and Nsukka LGAs of Enugu State of Nigeria

    Science.gov (United States)

    Orakwe, L. C.; Chukwuma, E. C.

    2017-05-01

    Multivariate statistical techniques were applied for the evaluation and interpretation of borehole characteristics of the Ajali sandstone geological formation of Enugu state of Nigeria to determine the latent structure of the borehole characteristics and to classify 9 borehole parameters from 33 locations into borehole groups of similar characteristics. Two chemometric data mining techniques used were, Cluster Analysis (CA) and Principal Component Analysis (PCA). PCA identified the borehole parameters responsible for variation in the borehole characteristic of the study area. Out of the nine parameters examined, the PCA identified borehole depth, borehole casing, static water level and dynamic water level as the most significant parameters responsible for variation in borehole characteristics. Hierarchical Cluster Analysis also grouped the 33 borehole locations into three clusters. The CA grouping of the borehole parameters showed similar trend with PCA hence validating the grouping of variations in the borehole characteristics in the geological zone. The results of the study indicate that PCA and CA are useful in offering reliable classification of the borehole characteristic of the study area.

  3. Sedimentology and Reservoir Characteristics of Early Cretaceous Fluvio-Deltaic and Lacustrine Deposits, Upper Abu Gabra Formation, Sufyan Sub-basin, Muglad Rift Basin, Sudan

    Science.gov (United States)

    Yassin, Mohamed; Abdullatif, Osman; Hariri, Mustafa

    2017-04-01

    Sufyan Sub-basin is an East-West trending Sub-basin located in the northwestern part of the Muglad Basin (Sudan), in the eastern extension of the West and Central Africa Rift System (WCARS). The Early Cretaceous Abu Gabra Formation considered as the main source rock in the Muglad Basin. In Sufyan Sub-basin the Early Cretaceous Upper Abu Gabra Formation is the main oil-producing reservoir. It is dominated by sandstone and shales deposited in fluvio-deltaic and lacustrine environment during the first rift cycle in the basin. Depositional and post-depositional processes highly influenced the reservoir quality and architecture. This study investigates different scales of reservoir heterogeneities from macro to micro scale. Subsurface facies analysis was analyzed based on the description of six conventional cores from two wells. Approaches include well log analysis, thin sections and scanning electron microscope (SEM) investigations, grain-size, and X-ray diffraction (XRD) analysis of the Abu Gabra sandstone. The cores and well logs analyses revealed six lithofacies representing fluvio-deltaic and lacustrine depositional environment. The sandstone is medium to coarse-grained, poorly to moderately sorted and sub-angular to subrounded, Sub-feldspathic arenite to quartz arenite. On macro-scale, reservoir quality varies within Abu Gabra reservoir where it shows progressive coarsening upward tendencies with different degrees of connectivity. The upper part of the reservoir showed well connected and amalgamated sandstone bodies, the middle to lower parts, however, have moderate to low sandstone bodies' connectivity and amalgamation. On micro-scale, sandstone reservoir quality is directly affected by textures and diagenesis.The XRD and SEM analyses show that kaolinite and chlorite clay are the common clay minerals in the studied samples. Clay matrix and quartz overgrowth have significantly reduced the reservoir porosity and permeability, while the dissolution of feldspars

  4. Computer-based technology for elaboration of morphometric characteristics of Volga reservoirs

    Science.gov (United States)

    Shikunova, E.

    2009-04-01

    There are nine biggest Russian reservoirs in Volga basin. Total capacity is about 168 km3, effective capacity - 80 km3, total square is equal 24 000 km2 and total length - 3 500 km. Water resources are used in hydroenergetic, navigation, water supply, fishing industry, etc. It is important to know current morphometric characteristics of all reservoirs. For getting all morphometric characteristics we need bottom and coastal zone digital elevation model (DEM) for each reservoir. In 2008 in State Oceanographic Institute methodology and computer-based technology of creating DEM were developed and evaluated on Uglichsky reservoir. The information base includes field survey data, remote sensing data and large-scale maps. Bathymetric survey was made by crosslines with intervals 500 m or 250 m. Expedition team of State Oceanographic Institute made survey using special complex of echo sounder, GPS and specialized computer. This complex allows to determine X, Y, Z coordinates in a moment and display this information. 370 crosslines were measured and they included 416 000 survey data. Large-scale maps were used for vectorization of coastline and relief data. For elaboration coastline in the most difficult zones were used remote sensing data. All received polygonal and line objects were transformed into point's data type with point's frequency 2.5-3 m. The total amount of points was 1 400 000. Water area was breaked up on small zones including 4 crosslines. For each zone grid was created (cell 5x5m) using method Natural Neighbor. Anisotropy depends on channel orientation. Further middle part of grid was clipped. DEM is the result of mosaic of small grids. This technology allows to create bottom and coastline DEM for evaluation of actual morphometric characteristics of reservoirs that is useful for effective water management. Next year State Oceanographic Institute plans to continue works on Gorkovsky, Volgogradsky reservoirs and several reservoirs of Moscow region.

  5. 致密砂岩气藏润湿性对液相圈闭损害的影响%Effect of tight sandstone gas reservoir wettability on liquid traps damage

    Institute of Scientific and Technical Information of China (English)

    蒋官澄; 张弘; 吴晓波; 李颖颖; 张志行

    2014-01-01

    致密砂岩储层易因外来工作液入侵造成严重的液相圈闭损害,岩石表面润湿性对于液相圈闭损害程度具有重要影响。使用氟碳表面活性剂Zonyl8740处理岩心,降低岩心表面能,制得不同润湿程度的岩心。通过岩心驱替和毛管自发渗吸实验分别研究了气湿岩心和液湿岩心的束缚水饱和度、自吸油水动态;建立初始含水饱和度岩心流动实验,对比了钻井液加入气湿反转剂前后液相圈闭损害率。实验表明,致密砂岩表面由液湿反转为优先气湿可大幅度减弱毛管自吸效应、降低自吸液量和最终滞留饱和度。气湿反转剂可有效减少钻井液对储层液相圈闭损害。对预防致密砂岩储层液相圈闭损害具有一定指导意义。%In tight sandstone reservoirs, the liquid traps may be readily damaged by invasion of external work lfuid. The wettabiity of rock surface has a signiifcant impact on the damage degree to liquid traps. The lfuorocarbon surfactant Zonyl8740 was used to treat the cores, reduce the surface energy of the cores and obtain cores with different wetting degree. Through experiment on core displacement and capillary spontaneous imbibition, the irreducible water saturation and spontaneous imbibition oil/water dynamic of gas wet cores and liquid wet cores were studied respectively. The core lfow test with initial water saturation was built, and the damage degrees to liquid trap were compared, before and after gas-wet reversing agent was added to the drilling lfuid. Experiments show that inversion of liquid wetting on tight sandstone surface to preferential gas wetting can signiifcantly weaken the spontaneous imbibition effective of capillary, and reduce the spontaneous imbibition amount and the ifnal retained saturation. Gas wet reverse agent can effectively reduce the damage to liquid traps by drilling lfuid and has a guiding signiifcance to preventing damage to liquid traps in tight

  6. Physical and chemical characteristics of Terrace Reservoir, Conejos County, Colorado, May 1994 through May 1995

    Science.gov (United States)

    Stogner, Sr., Robert W.; Edelmann, Patrick; Walton-Day, Katherine

    1997-01-01

    Terrace Reservoir receives drainage of low-pH, metal-enriched water from mineralized areas, including the Summitville Mine, within the AlamosaRiver Basin. Drainage from the Summitville Mine has contributed a substantial part of the metal load to Terrace Reservoir. From May 1994 through May 1995, a study was done by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to evaluate the physical and chemical characteristics of Terrace Reservoir.Terrace Reservoir was thermally stratified from about mid-May through August 1994. Thermal stratification was absent from September\\x111994through March 1995. During periods of stratification, underflow of the Alamosa River was predominant, and residence times of the underflow were shortened by 40 to 75\\x11percent of the theoretical residence times for a well-mixed reservoir. Transport and deposition of suspended solids in Terrace Reservoir varied spatially and temporally. Most of the suspended solids were deposited in Terrace Reservoir. The concentration of dissolved oxygen in the reservoir varied little spatially or temporally and generally was within a few tenths of the dissolved-oxygen concentration of the inflow. The pH of water in the reservoir generally ranged from about 4.0 to about 7.0, depending on date, depth, and location. The largest pH values were measured during May. A markeddecrease of about 1.5\\x11pH units occurred at site T5 in the reservoir about mid-June. The pH of the reservoir remained at or below 5.5 from mid-June through November. Dissolved-metal concentrations varied spatially and temporally in response to several factors, which included inflow characteristics, reservoir stratification and mixing, inflow-routing and flow-through patterns, residence times, sedimentation, dissolved oxygen, and pH.Inflow chemistry is the dominant controlling factor of metal chemistry within Terrace Reservoir.During periods of stratification, large vertical variations in metal

  7. Investigation on Operational Unsteady Characteristics of CPL:The Effects of Evaporator and Reservoir

    Institute of Scientific and Technical Information of China (English)

    QuWei; HouZengqi; 等

    1999-01-01

    Capillary Pumped Loop(CPL) is a two phase closed system.The two main components of CPL,both evaporator and reservoir are generally believed to play significant roles in its unsteady operation.In this paper,experimental and theoretical investigations are carried out on the influences of unsteady characteristics of both of them,The previous analytical results show that there is a pressure oscillation source in the evaporator and the internal oscillation frequency can be obtained .The reservoir also has an unsteady characteristics,when the reservoir line has a smaller damping value,there will be a self-oscillation of pressure in the reservoir ,and its analytical frequencies are normally one or two quantities bigger than the inherent frequencies of the evaporator.In order to keep CPL operate steadily,on one hand,the structure of evaporator must be increased to make the coninuous generated vapor flow out the wick easily,on the other hand,the return liquid ought to be subcooled enough to the reservoir temperature set value.

  8. 30 CFR 250.407 - What tests must I conduct to determine reservoir characteristics?

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false What tests must I conduct to determine reservoir characteristics? 250.407 Section 250.407 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil...

  9. Fault features and enrichment laws of narrow-channel distal tight sandstone gas reservoirs: A case study of the Jurassic Shaximiao Fm gas reservoir in the Zhongjiang Gas Field, Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Zhongping Li

    2016-11-01

    Full Text Available The Jurassic Shaximiao Fm gas reservoir in the Zhongjiang Gas Field, Sichuan Basin, is the main base of Sinopec Southwest Oil & Gas Company for gas reserves and production increase during the 12th Five-Year Plan. However, its natural gas exploration and development process was restricted severely, since the exploration wells cannot be deployed effectively in this area based on the previous gas accumulation and enrichment pattern of “hydrocarbon source fault + channel sand body + local structure”. In this paper, the regional fault features and the gas accumulation and enrichment laws were discussed by analyzing the factors like fault evolution, fault elements, fault-sand body configuration (the configuration relationship between hydrocarbon source faults and channel sand bodies, trap types, and reservoir anatomy. It is concluded that the accumulation and enrichment of the Shaximiao Fm gas reservoir in this area is controlled by three factors, i.e., hydrocarbon source, sedimentary facies and structural position. It follows the accumulation laws of source controlling region, facies controlling zone and position controlling reservoir, which means deep source and shallow accumulation, fault-sand body conductivity, multiphase channel, differential accumulation, adjusted enrichment and gas enrichment at sweet spots. A good configuration relationship between hydrocarbon source faults and channel sand bodies is the basic condition for the formation of gas reservoirs. Natural gas accumulated preferentially in the structures or positions with good fault-sand body configuration. Gas reservoirs can also be formed in the monoclinal structures which were formed after the late structural adjustment. In the zones supported by multiple faults or near the crush zones, no gas accumulation occurs, but water is dominantly produced. The gas-bearing potential is low in the area with undeveloped faults or being 30 km away from the hydrocarbon source faults. So

  10. Modeling of the permeability of a sandstone reservoir of the North Sea using a combination of image processing data and capillary pressure curves; Modelisation de la permeabilite d'un reservoir greseux de Mer du Nord par combinaison de donnees d'analyse d'images et de courbes de pression capillaire

    Energy Technology Data Exchange (ETDEWEB)

    Belin, S.; Fritz, B. [Centre de Geochimie de la Surface, UMR 7517, 67 - Strasbourg (France); Anguy, Y.; Bernard, D. [Lab. Energetique et Phenomenes de transfert, UMR 8508, 33 - Talence (France)

    1999-07-01

    This study deals with the relation between the micro-geometry and the permeability in a series of samples from a sandstone reservoir of the Alwyn area (North Sea). The samples have various petro-physical properties with porosities comprised between 13 and 26% and permeabilities ranging from 0.1 to 3000 mD. Five different types of pores were identified using micro-graphic images of the porosity. The spatial organization of pores and the 3-D connectivity between adjacent pores is deduced from the image processing data and the petrophysical data combined using multi-linear regression models. This approach has permitted to demonstrate a relation between the type of pores and size of the access radius. (J.S.)

  11. Research on Microscopic Characteristics of Carbonate Reservoir Fracture fillings Based on Microscopic Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Li Jing

    2016-01-01

    Full Text Available The characteristics of hole and seepage of carbonate rocks depend on the structural components of carbonate rocks and the combination relationship with these structural components under multi-scale. The quality of filling in reservoir fracture is an important part of fracture description. In this paper, the method of microscopic infrared spectral imaging was used, and the spectra cubic database was established by means of spectral imaging experiment. Each single band image which characterizes the related substances was extracted and the microcosmic characters of the filling in carbonate reservoirs fracture from Wumishan formation in Renqiu oilfield were studied. The spatial distribution maps of different chemical composition and groups in the core sample were obtained. The distribution of different hydrocarbon in the fracture of the reservoir and the connectivity of the pores etc. were better revealed

  12. Biological characteristics of silver bream (Blicca bjoerkna in commercial fishery in the Kyiv reservoir

    Directory of Open Access Journals (Sweden)

    I. Zakharchenko

    2016-12-01

    Full Text Available Purpose. The determination and analysis of main biological characteristics of silver bream from the point of view of the formation and exploitation of its commercial stock in the Kyiv reservoir. Methodology. The work is based the results of monitoring field studies carried out on the Kyiv reservoir during 2012–2014. Ichthyological materials were collected from standard commercial gill nets with mesh sizes of 30–80 mm, which were set in different habitats and depths of the reservoir. Collection and processing of samples was carried out using conventional ichthyological methods adapted for the Dnieper reservoirs. Findings. According to the data of monitoring gill nets, silver bream population in 2014 was composed of 10 age groups. The majority of their population (70.8% in catches was composed of age-5 to age-7 fish, i.e. the number of modal classes increased due to the right wing of the older age groups. The frequency distribution of silver bream had a shape of a curve with wide, however broken (due to the reduction in age-5 fish peak and gradual decrease. Age-length properties, fatness parameters and condition factor of silver bream in the Kiev reservoir during last years remained on the stable high level indicating on favorable fattening conditions and forming the ichthyomass of this species. At the present time, silver bream of the Kyiv reservoir formed a commercial stock with such qualitative and quantitative characteristics, which allow exploiting it in the mode of traditional commercial harvest and specialized harvest of silver bream concentrations with the use of gill nets with mesh sizes of 50, 60 mm. Originality. We obtained and analyzed the new data on the current state of silver bream (Blіcca bjoerkna in Kyiv reservoir as an important element of commercial fish production. Practical Value. The results of the work allows increasing qualitative and quantitative characteristics of silver bream catches and will be used for the

  13. Effect of kaolinite as a key factor controlling the petrophysical properties of the Nubia sandstone in central Eastern Desert, Egypt

    Science.gov (United States)

    Kassab, Mohamed A.; Abu Hashish, Mohamed F.; Nabawy, Bassem S.; Elnaggar, Osama M.

    2017-01-01

    This paper presents the results of a comprehensive petrographical and petrophysical investigation for the Late Cretaceous Nubia sandstone from Wadi Kareem in central Eastern Desert to measure their fluid flow properties and to investigate the effect of kaolinite on their petrophysical characteristics. From the petrographical analyses, scanning electron microscope 'SEM' and the X-ray diffraction 'XRD' analysis, it is shown that the studied sandstone samples are quite homogeneous in mineralogy and can be distinguished into four sedimentary microfacies: quartz arenite as a clean sandstone as well as three kaolinitic microfacies; namely they are kaolinitic quartz arenite, kaolinitic subarkose, and calcareous to kaolinitc quartz arenite. The main recognized diagenetic processes that prevailed during the post-depositional history of the Nubia sandstone are; compaction, cementation, alteration and dissolution of feldspar into kaolinite. The petrophysical potentiality of the studied sandstones was studied using the helium pycnometer, gas permeability and mercury injection confining pressure 'MICP' techniques. The investigated sandstones can be classified into three petrophysical facies with varying reservoir performances. The petrophysical behaviour of these facies is dependent mostly on their kaolinite content and its impact on porosity, permeability, irreducible water saturation, R35 (pore aperture corresponding to mercury saturation of 35% pore volume), R50 (median pore-throat radius), and MHR (the mean hydraulic radius). Therefore, the studied petrophysical facies are comparable to the distinguished petrographical facies.

  14. Fractures and stresses in Bone Spring sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, J.C.; Warpinski, N.R.; Sattler, A.R.; Northrop, D.A.

    1990-09-01

    This project is a collaboration between Sandia National Laboratories and Harvey E. Yates Company being conducted under the auspices of the Oil Recovery Technology Partnership. The project seeks to apply perspectives related to the effects of natural fractures, stress, and sedimentology to the simulation and production of low-permeability gas reservoirs to low-permeability oil reservoirs as typified by the Bone Spring sandstones of the Permian Basin, southeast New Mexico. This report presents the results and analysis obtained in 1989 from 233 ft of oriented core, comprehensive suite of logs, various in situ stress measurements, and detailed well tests conducted in conjunction with the drilling of two development wells. Natural fractures were observed in core and logs in the interbed carbonates, but there was no direct evidence of fractures in the sandstones. However, production tests of the sandstones indicated permeabilities and behavior typical of a dual porosity reservoir. A general northeast trend for the maximum principal horizontal stress was observed in an elastic strain recovery measurements and in strikes of drilling-induced fractures; this direction is subparallel to the principal fracture trend observed in the interbed carbonates. Many of the results presented are believed to be new information for the Bone Spring sandstones. 57 figs., 18 tabs.

  15. 疏松砂岩油藏砾石充填防砂参数优化技术研究%Loose Sandstone Reservoir Gravel Packing Sand Control Technology Research on Parameters Optimization

    Institute of Scientific and Technical Information of China (English)

    杨巍; 温志刚; 魏旭

    2013-01-01

    In general, the loose sandstone reservoir has poor diagenesis, high shale content and serious sand production; screen gravel packing sand control is the main technology that maintained development and production in oilfield. The diameter of the sand from formation has changed, the sand filling into the gravel and mixing with the gravel during the production, so that the production is gradually decreased. Based on the study of formation sand grain size distribution, the median particle size of filling gravel in the casing layer deficit breaks through traditional 5-6 times of median formation sand, based on experiments, selected the 3-4 times of median formation sand filling gravel, sand and gravel mixed probability can be reduced. Combining classification of filling technique, the application on site achieved good results.%一般地,疏松砂岩油藏成岩性差,泥质含量高,出砂严重,筛管砾石充填防砂是维持油田开发生产的主要工艺.地层出砂粒径发生变化后,生产过程中地层砂进入充填砾石层产生了互混,使油井产液量逐渐下降.在研究地层出砂粒径分布的基础上,在套管外地层亏空处充填砾石粒度中值突破传统的5-6倍地层砂粒度中值的常规做法,以实验为基础,选择了3-4倍地层砂粒度中值的充填砾石,可降低砂砾互混的概率.结合分级充填技术,在现场应用中取得了很好的效果.

  16. ECOLOGICAL AND HEMATOLOGICAL CHARACTERISTICS OF COMMON ROACH (RUTILUS RUTILUS LINNAEUS, 1758 IN THE ZAPOROZHYE RESERVOIR

    Directory of Open Access Journals (Sweden)

    T. S. Sharamok

    2016-08-01

    Full Text Available The research was conducted in Zaporozhye Reservoir (Ukraine in the period from 2014 to 2015. Researches were taken in two parts of the reservoir, which differ in their ecological and hydrological conditions, are the main spawning areas and the most industrial mastered reservoirs. The water quality of Zaporozhye Reservoir lower areas (according to the containing of heavy metals is largely relevant to carp fisheries regulations with the exception of copper, which exceeded MАC by 7 times. In the Samara Bay the copper content exceeded by 8 times, manganese – 1.7 times, plumbum – 1.5 and cadmium – 2 times comparing to the MAC. The aim of research was to identify the characteristics of heavy metal accumulation, to set cytometric, morphological and physiological characteristics of erythrocyte and leukocyte formula in different age groups of roach (Rutilus rutilus Linnaeus, 1758. It was established that the content of heavy metals in fish did not exceed the MАC for fish as food. The 2-year roach accumulates essential elements more extensively than mature fish (4-year. The statistically significant differences between the content of some heavy metals were registered for fish specimens from different ecological parts of reservoirs. A characteristic feature of blood cells taken from 2-year and 4-year roach of polluted Samara Bay reservoir was the reducing of the relative abundance of mature forms of red blood cells and probable increasing of immature normoblasts, especially basophilic normoblasts (up to 40–60%, which indicates the suppression of erythropoiesis processes in fish. A probable increase the various kinds of pathology (anisocytosis, hypochromia, cytolysis, destroying cell membranes, kariolisis, kariopiknoz etc. in blood cells of roach from Samara Bay was revealed. The morphological-cytometric research of red blood cells showed no probable differences in fish from the two studied areas, except for nuclei areas of red blood cells, which

  17. Characteristics of the nuclear magnetic resonance logging response in fracture oil and gas reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Lizhi; Li Kui, E-mail: xiaolizhi@cup.edu.cn [State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249 (China)

    2011-04-15

    Fracture oil and gas reservoirs exist in large numbers. The accurate logging evaluation of fracture reservoirs has puzzled petroleum geologists for a long time. Nuclear magnetic resonance (NMR) logging is an effective new technology for borehole measurement and formation evaluation. It has been widely applied in non-fracture reservoirs, and good results have been obtained. But its application in fracture reservoirs has rarely been reported in the literature. This paper studies systematically the impact of fracture parameters (width, number, angle, etc), the instrument parameter (antenna length) and the borehole condition (type of drilling fluid) on NMR logging by establishing the equation of the NMR logging response in fracture reservoirs. First, the relationship between the transverse relaxation time of fluid-saturated fracture and fracture aperture in the condition of different transverse surface relaxation rates was analyzed; then, the impact of the fracture aperture, dip angle, length of two kinds of antennas and mud type was calculated through forward modeling and inversion. The results show that the existence of fractures affects the NMR logging; the characteristics of the NMR logging response become more obvious with increasing fracture aperture and number of fractures. It is also found that T{sub 2} distribution from the fracture reservoir will be affected by echo spacing, type of drilling fluids and length of antennas. A long echo spacing is more sensitive to the type of drilling fluid. A short antenna is more effective for identifying fractures. In addition, the impact of fracture dip angle on NMR logging is affected by the antenna length.

  18. Characteristics of remaining oil viscosity in water-and polymer-flooding reservoirs in Daqing Oilfield

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The experimental analysis of 21 crude oil samples shows a good correlation between high molecular-weight hydrocarbon components (C 40+) and viscosity.Forty-four remaining oil samples extracted from oil sands of oilfield development coring wells were analyzed by high-temperature gas chromatography (HTGC),for the relative abundance of C 21-,C 21-C 40 and C 40+ hydrocarbons.The relationship between viscosity of crude oil and C 40+ (%) hydrocarbons abundance is used to expect the viscosity of remaining oil.The mobility characteristics of remaining oil,the properties of remaining oil,and the next displacement methods in reservoirs either water-flooded or polymer-flooded are studied with rock permeability,oil saturation of coring wells,etc.The experimental results show that the hydrocarbons composition,viscosity,and mobility of remaining oil from both polymer-flooding and water-flooding reservoirs are heterogeneous,especially the former.Relative abundance of C 21- and C 21-C 40 hydrocarbons in polymer-flooding reservoirs is lower than that of water-flooding,but with more abundance of C 40+ hydrocarbons.It is then suggested that polymer flooding must have driven more C 40- hydrocarbons out of reservoir,which resulted in relatively enriched C 40+,more viscous oils,and poorer mobility.Remaining oil in water-flooding reservoirs is dominated by moderate viscosity oil with some low viscosity oil,while polymer-flooding mainly contained moderate viscosity oil with some high viscosity oil.In each oilfield and reservoir,displacement methods of remaining oil,viscosity,and concentration by polymer-solution can be adjusted by current viscosity of remaining oil and mobility ratio in a favorable range.A new basis and methods are suggested for the further development and enhanced oil recovery of remaining oil.

  19. Morphological, sediment and soil chemical characteristics of dry tropical shallow reservoirs in the Southern Mexican Highlands

    Directory of Open Access Journals (Sweden)

    José Luis ARREDONDO-FIGUEROA

    2011-02-01

    Full Text Available The morphometry, sediment and soil chemical characteristics of eleven dry tropical shallow reservoirs situated in Southern Mexican Highlands were studied. The reservoirs are located at 1104 to 1183 meters above sea level in a sedimentary area. Seventeen morphometric and eight sediment and soil chemical parameters were measured. The results of the morphometric parameters showed that these reservoirs presented a soft and roughness bottom, with an ellipsoid form and a concave depression that permit the mix up of water and sediments, causing turbidity and broken thermal gradients; their slight slopes allowed the colonization of submerged macrophyte and halophyte plants and improved the incidence of sunlight on water surface increasing evaporation and primary productivity. Dry tropical shallow reservoirs have fluctuations in area, and volume according to the amount of rainfall, the effect of evaporation, temperature, lost volume for irrigation, and other causes. The sand-clay was the most important sediment texture and their values fluctuated with the flooded periods. The concentration-dilution cycle showed a direct relationship in the percentage of organic matter in the soil as well as with pH, soil nitrogen and phosphorus. El Tilzate, El Candelero and El Movil were related by the shore development and high concentrations of organic matter and nitrogen in the soil. Finally, we emphasize the importance of this study, in relation to possible future changes in morphometrical parameters as a consequence of human impact.

  20. Numerical Simulations of Spread Characteristics of Toxic Cyanide in the Danjiangkou Reservoir in China under the Effects of Dam Cooperation

    Directory of Open Access Journals (Sweden)

    Libin Chen

    2014-01-01

    Full Text Available Many accidents of releasing toxic pollutants into surface water happen each year in the world. It is believed that dam cooperation can affect flow field in reservoir and then can be applied to avoiding and reducing spread speed of toxic pollutants to drinking water intake mouth. However, few studies investigated the effects of dam cooperation on the spread characteristics of toxic pollutants in reservoir, especially the source reservoir for water diversion with more than one dam. The Danjiangkou Reservoir is the source reservoir of the China’ South-to-North Water Diversion Middle Route Project. The human activities are active within this reservoir basin and cyanide-releasing accident once happened in upstream inflow. In order to simulate the spread characteristics of cyanide in the reservoir in the condition of dam cooperation, a three-dimensional water quality model based on the Environmental Fluid Dynamics Code (EFDC has been built and put into practice. The results indicated that cooperation of two dams of the Danjiangkou Reservoir could be applied to avoiding and reducing the spread speed of toxic cyanide in the reservoir directing to the water intake mouth for water diversions.

  1. Kaolinite Mobilisation in Sandstone

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Fabricius, Ida Lykke; Kets, Frans

    2013-01-01

    The effect of temperature and salinity on sandstone permeability is critical to the feasibility of heat storage in geothermal aquifers. Permeability reduction has been observed in Berea sandstone when the salinity of the pore water is reduced as well as when the sample is heated. Several authors...

  2. Brittle and compaction creep in porous sandstone

    Science.gov (United States)

    Heap, Michael; Brantut, Nicolas; Baud, Patrick; Meredith, Philip

    2015-04-01

    (from both creep and constant strain rate experiments), the characteristics (geometry, thickness) of a compaction band remain essentially the same. Several lines of evidence, notably the similarity between the differential stress dependence of creep strain rate in the dilatant and compactive regimes, suggest that, as for dilatant creep, compactant creep is driven by subcritical stress corrosion cracking. We highlight the attendant implications for time-dependent porosity loss, subsidence, and permeability reduction in sandstone reservoirs.

  3. Streamflow gain-loss characteristics of Elkhead Creek downstream from Elkhead Reservoir near Craig, Colorado, 2009

    Science.gov (United States)

    Ruddy, Barbara C.

    2010-01-01

    The U.S. Geological Survey (USGS), in cooperation with the Colorado Water Conservation Board, the Upper Colorado River Endangered Fish Recovery Program (UCREFRP), Colorado Division of Water Resources, and City of Craig studied the gain-loss characteristics of Elkhead Creek downstream from Elkhead Reservoir to the confluence with the Yampa River during August through October 2009. Earlier qualitative interpretation of streamflow data downstream from the reservoir indicated that there could be a transit loss of nearly 10 percent. This potential loss could be a significant portion of the releases from Elkhead Reservoir requested by UCREFRP during late summer and early fall for improving critical habitat for endangered fish downstream in the Yampa River. Information on the gain-loss characteristics was needed for the effective management of the reservoir releases. In order to determine streamflow gain-loss characteristics for Elkhead Creek, eight measurement sets were made at four strategic instream sites and at one diversion from August to early October 2009. An additional measurement set was made after the study period during low-flow conditions in November 2009. Streamflow measurements were made using an Acoustic Doppler Velocimeter to provide high accuracy and consistency, especially at low flows. During this study, streamflow ranged from about 5 cubic feet per second up to more than 90 cubic feet per second with step increments in between. Measurements were made at least 24 hours after a change in reservoir release (streamflow) during steady-state conditions. The instantaneous streamflow measurements and the streamflow volume comparisons show the reach of Elkhead Creek immediately downstream from Elkhead Reservoir to the streamflow-gaging station 09246500, Elkhead Creek near Craig, CO, is neither a gaining nor losing reach. The instantaneous measurements immediately downstream from the dam and the combined measurements of Norvell ditch plus streamflow

  4. Contribution to the tectonic characterization of fractured reservoirs, I: photo-elasticimetric modelling of the stress perturbations near faults and the associated fracture network: application to oil reserves, II mechanisms for the 3D joint organization in a natural reservoir analogue (flat-lying Devonian Old Red Sandstones of Caitness in North Scotland); Contribution a la caracterisation tectonique des reservoirs fractures, I: modelisation photoelecticimetrique des perturbations de contrainte au voisinage des failles et de la fracturation associee: application petroliere, II: mecanismes de developpement en 3D des diaclases dans un analogue de reservoir, le Devonien tabulaire du caithness (Ecosse)

    Energy Technology Data Exchange (ETDEWEB)

    Auzias, V.

    1995-10-27

    In order to understand joint network organisation in oil reservoirs, as a first step we have adapted to technique (the photo-elasticimetry) to study stress fields in 2D. This method allows to determine the principal stress trajectories near faults, as well as the associated joint network organisation. Natural joint networks perturbed near faults are modeled and the parameters that control stress perturbation are proposed. With the aim of extrapolating joint data from a well to the entire reservoir our modelling is based on both 3 D seismic data and local joint data. The second part of our research was dedicated to studying joint propagation mechanisms in a natural reservoir analogue (flat-lying Devonian Old Red Sandstones of Caitness in North Scotland). Several exposure observation at different scales and in 3D (horizontal and cliff sections) allow to reconstitute the fracturing geometry from centimeter to kilometer scale and to link these to the regional tectonic history. This study shows that it is possible to differentiate three types of joints major joints, `classic` joints and micro-joints, each with different vertical persistence. New concepts on the 3D joint organisation have been deduced from field quantitative data, which can be applied to reservoir fracture modeling. In particular the non-coexistence phenomenon in a single bed of two regional joint sets with close strikes. Some joint development mechanisms are discussed: interaction between joints and sedimentary interfaces, joint distribution near faults, origin of en echelon arrays associated with joints. (author) 142 refs.

  5. Greybull Sandstone Petroleum Potential on the Crow Indian Reservation, South-Central Montana

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, David A.

    2002-05-13

    The focus of this project was to explore for stratigraphic traps that may be present in valley-fill sandstone at the top of the Lower Cretaceous Kootenai Formation. This sandstone interval, generally known as the Greybull Sandstone, has been identified along the western edge of the reservation and is a known oil and gas reservoir in the surrounding region. The Greybull Sandstone was chosen as the focus of this research because it is an excellent, well-documented, productive reservoir in adjacent areas, such as Elk Basin; Mosser Dome field, a few miles northwest of the reservation; and several other oil and gas fields in the northern portion of the Bighorn Basin.

  6. [Community structure characteristics of phytoplankton and related affecting factors in Hengshan Reservoir, Zhejiang, China].

    Science.gov (United States)

    Yang, Liang-Jie; Yu, Peng-Fei; Zhu, Jun-Quan; Xu, Zhen; Lü, Guang-Han; Jin, Chun-Hua

    2014-02-01

    In order to reveal the community structure characteristics of phytoplankton and the relationships with environmental factors in Hengshan Reservoir, the phytoplankton species composition, abundance, biomass and 12 environmental factors at 4 sampling sites were analyzed from March 2011 to February 2012. A total of 246 phytoplankton species were identified, which belong to 78 genera and 7 phyla. The dominant species were Melosira varians, M. granulate, Cyclotella meneghiniana, Asterianella formosa, Synedra acus, Achnanthes exigua, Ankistrodesmus falcatus, Oscillatoria lacustris, Cryptomonas erosa, Chroomonas acuta, Phormidium tenue and Microcystis aeruginosa, etc. Seasonal variations of species were obvious. The annual abundance and biomass of the phytoplankton were 0.51 x 10(5)-14.22 x 10(5) ind x L(-1) and 0.07-1.27 mg x L(-1), respectively. The values of the Margelef index, Pielou index and Shannon index of the phytoplankton community were 1.10-3.33, 0.26-0.81 and 0.51-2.38, respectively. The phytoplankton community structure was of Bacillariophyta-Cryptophyta type in spring and winter, of Chlorophyta-Cyanophyta type in summer, and of Bacillariophyta type in autumn. Canonical correlation analysis (CCA) showed that temperature, transparency, chemical oxygen demand and pH had the closest relationships with the phytoplankton community structure in the reservoir. Water quality evaluation showed that Hengshan Reservoir was in a secondary pollution with a meso-trophic level.

  7. [Distribution Characteristics and Pollution Status Evaluation of Sediments Nutrients in a Drinking Water Reservoir].

    Science.gov (United States)

    Huang, Ting-lin; Liu, Fei; Shi, Jian-chao

    2016-01-15

    The main purpose of this paper is to illustrate the influence of nutrients distribution in sediments on the eutrophication of drinking water reservoir. The sediments of three representative locations were field-sampled and analyzed in laboratory in March 2015. The distribution characteristics of TOC, TN and TP were measured, and the pollution status of sediments was evaluated by the comprehensive pollution index and the manual for sediment quality assessment. The content of TOC in sediments decreased with depth, and there was an increasing trend of the nitrogen content. The TP was enriched in surface sediment, implying the nutrients load in Zhoucun Reservoir was aggravating as the result of human activities. Regression analysis indicated that the content of TOC in sediments was positively correlated with contents of TN and TP in sediments. The TOC/TN values reflected that the vascular land plants, which contain cellulose, were the main source of organic matter in sediments. The comprehensive pollution index analysis result showed that the surface sediments in all three sampling sites were heavily polluted. The contents of TN and TP of surface sediments in three sampling sites were 3273-4870 mg x kg(-1) and 653-2969 mg x kg(-1), and the content of TOC was 45.65-83.00 mg x g(-1). According to the manual for sediment quality assessment, the TN, TP and TOC contents in sediments exceed the standard values for the lowest level of ecotoxicity, so there is a risk of eutrophication in Zhoucun Reservoir.

  8. Experimental investigation of geochemical and mineralogical effects of CO2 sequestration on flow characteristics of reservoir rock in deep saline aquifers.

    Science.gov (United States)

    Rathnaweera, T D; Ranjith, P G; Perera, M S A

    2016-01-01

    Interactions between injected CO2, brine, and rock during CO2 sequestration in deep saline aquifers alter their natural hydro-mechanical properties, affecting the safety, and efficiency of the sequestration process. This study aims to identify such interaction-induced mineralogical changes in aquifers, and in particular their impact on the reservoir rock's flow characteristics. Sandstone samples were first exposed for 1.5 years to a mixture of brine and super-critical CO2 (scCO2), then tested to determine their altered geochemical and mineralogical properties. Changes caused uniquely by CO2 were identified by comparison with samples exposed over a similar period to either plain brine or brine saturated with N2. The results show that long-term reaction with CO2 causes a significant pH drop in the saline pore fluid, clearly due to carbonic acid (as dissolved CO2) in the brine. Free H(+) ions released into the pore fluid alter the mineralogical structure of the rock formation, through the dissolution of minerals such as calcite, siderite, barite, and quartz. Long-term CO2 injection also creates a significant CO2 drying-out effect and crystals of salt (NaCl) precipitate in the system, further changing the pore structure. Such mineralogical alterations significantly affect the saline aquifer's permeability, with important practical consequences for the sequestration process.

  9. Shale gas reservoir characteristics of Ordovician-Silurian formations in the central Yangtze area, China

    Science.gov (United States)

    Shan, Chang'an; Zhang, Tingshan; Wei, Yong; Zhang, Zhao

    2016-07-01

    The characteristics of a shale gas reservoir and the potential of a shale gas resource of Ordovician-Silurian age in the north of the central Yangtze area were determined. Core samples from three wells in the study area were subjected to thin-section examination, scanning electron microscopy, nuclear magnetic resonance testing, X-ray diffraction mineral analysis, total organic carbon (TOC) testing, maturity testing, gas-bearing analysis, and gas component and isothermal adsorption experiments. A favorable segment of the gas shale reservoir was found in both the Wufeng Formation and the lower part of the Longmaxi Formation; these formations were formed from the late Katian to early Rhuddanian. The high-quality shale layers in wells J1, J2, and J3 featured thicknesses of 54.88 m, 48.49 m, and 52.00 m, respectively, and mainly comprised carbonaceous and siliceous shales. Clay and brittle minerals showed average contents of 37.5% and 62.5% (48.9% quartz), respectively. The shale exhibited type II1 kerogens with a vitrinite reflectance ranging from 1.94% to 3.51%. TOC contents of 0.22%-6.05% (average, 2.39%) were also observed. The reservoir spaces mainly included micropores and microfractures and were characterized by low porosity and permeability. Well J3 showed generally high gas contents, i.e., 1.12-3.16 m3/t (average 2.15 m3/t), and its gas was primarily methane. The relatively thick black shale reservoir featured high TOC content, high organic material maturity, high brittle mineral content, high gas content, low porosity, and low permeability. Shale gas adsorption was positively correlated with TOC content and organic maturity, weakly positive correlated with quartz content, and weakly negatively correlated with clay content. Therefore, the Wufeng and Longmaxi formations in the north of the central Yangtze area have a good potential for shale gas exploration.

  10. Shale gas reservoir characteristics of Ordovician-Silurian formations in the central Yangtze area, China

    Science.gov (United States)

    Shan, Chang'an; Zhang, Tingshan; Wei, Yong; Zhang, Zhao

    2017-03-01

    The characteristics of a shale gas reservoir and the potential of a shale gas resource of Ordovician-Silurian age in the north of the central Yangtze area were determined. Core samples from three wells in the study area were subjected to thin-section examination, scanning electron microscopy, nuclear magnetic resonance testing, X-ray diffraction mineral analysis, total organic carbon (TOC) testing, maturity testing, gas-bearing analysis, and gas component and isothermal adsorption experiments. A favorable segment of the gas shale reservoir was found in both the Wufeng Formation and the lower part of the Longmaxi Formation; these formations were formed from the late Katian to early Rhuddanian. The high-quality shale layers in wells J1, J2, and J3 featured thicknesses of 54.88 m, 48.49 m, and 52.00 m, respectively, and mainly comprised carbonaceous and siliceous shales. Clay and brittle minerals showed average contents of 37.5% and 62.5% (48.9% quartz), respectively. The shale exhibited type II1 kerogens with a vitrinite reflectance ranging from 1.94% to 3.51%. TOC contents of 0.22%-6.05% (average, 2.39%) were also observed. The reservoir spaces mainly included micropores and microfractures and were characterized by low porosity and permeability. Well J3 showed generally high gas contents, i.e., 1.12-3.16 m3/t (average 2.15 m3/t), and its gas was primarily methane. The relatively thick black shale reservoir featured high TOC content, high organic material maturity, high brittle mineral content, high gas content, low porosity, and low permeability. Shale gas adsorption was positively correlated with TOC content and organic maturity, weakly positive correlated with quartz content, and weakly negatively correlated with clay content. Therefore, the Wufeng and Longmaxi formations in the north of the central Yangtze area have a good potential for shale gas exploration.

  11. Intersecting faults and sandstone stratigraphy at the Cerro Prieto geothermal field

    Energy Technology Data Exchange (ETDEWEB)

    Vonder Haar, S.; Howard, J.H.

    1980-02-01

    The northwest-southeast trending Cerro Prieto fault is part of a major regional lineament that extends into Sonaro and has characteristics of both a wrench fault and an oceanic transform fault. The distribution of lithologies and temperature within the field was studied by comparing data from well cuttings, cores, well logs, and geochemical analyses. Across the earliest developed portion of the field, in particular along a 1.25-km northeast-southwest section from well M-9 to M-10, interesting correlations emerge that indicate a relationship among lithology, microfracturing, and temperature distribution. In the upper portion of Reservoir A of this stratigraphic section, between 1200 and 1400 m, the percentage of sandstones ranges from 20 to 55. Temperatures are 225/sup 0/ to 275/sup 0/C based on well logs, calcite isotope maxima, and Na-K-Ca indices. The study shows that an isothermal high in this vicinity corresponds to the lowest total percentage of sandstones. Scanning electron microphotographs of well cores and cuttings from sandstone and shale units reveal clogging, mineral dissolution, and mineral precipitation along microfractures. The working hypothesis is that these sandy shale and siltstone facies are most amenable to increased microfracturing and, in turn, such microfracturing allows for higher temperature fluid to rise to shallower depths in the reservoir.

  12. Quantitative simulation of porosity-evolution in the Member 8 sandstone reservoir of the Yanchang formation in Huanxian Oilfield, Ordos Basin%鄂尔多斯盆地环县地区长8段砂岩储层孔隙度演化定量模拟

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    Thin section analysis indicated that the diagenesis of the sandstone reservoir in the research area had mainly undergone the processes of compaction, cementation and dissolution. Combined with the mathe-matical statistics method, the methodology was based on an analysis of tight sandstone reservoir characteristics, controlling factors and a study of the burial history and diagenetic history of the study area. With current porosity as boundary constraint conditions, the geological time and burial depth as variables, the whole porosity evolution from initial burial until the present was divided into two independent processes: porosity decrease and porosity increase, for which two mathematical models were established respectively. The quantitative simulation result indicates that the whole porosity-evolution quantitative simulation was a piecewise function with four sections. That is, the porosity decrease model for the mechanical compaction and cementation stages served a continuous exponential function with the geological time and burial depth as the variables, and the secondary porosity increase was caused by organic acid dissolution within a temperature window of 80∼100◦C. Therefore, the dissolution phase was of a porosity increase model, which was a composite function of the depth, burial time and porosity decrease amount. After the dissolution phase, the porosity was in the phase of compaction and maintenance. Finally, through the exemplification, it was verified that the porosity-evolution quantitative simulation established by the present researcher is consistent with actual geological conditions and can be applied to porosity calculation of any stratum in the study area.%  在充分分析研究区长8段砂岩储层特征、主控因素及地层埋藏史和成岩史的基础上,应用数理统计方法,以现今孔隙度为约束条件,将孔隙度演化分为减小和增大两个过程,分别建立了鄂尔多斯盆地环县地区长8段砂

  13. Oil/Gas Accumulation Characteristics and Exploration Methods of the Deltaic Lithologic Reservoirs in Northern Shaanxi Area

    Institute of Scientific and Technical Information of China (English)

    YangHua; FuJinhua; YuJian; DuJinliang; MuJingkui

    2004-01-01

    There are large deltaic systems in the Triassic Yanchang Formation in the northern Shaanxi area of the Ordos Basin, and developed two sets of good source-reservoir-caprock assemblages and many sets of oil-beating beds. Exploration experience demonstrates that the formation and distribution of the reservoir were controlled by the generative depression of the Yanchang Formation, and deltaic reservoir sand body is the material basis for large-scale oilfields. In addition, secondary laumontite in a low permeable area was dissolved and then a high permeable area was formed. The updip lithologic variety of reservoir sand bodies is favorable to the formation of subtle lithologic traps, and the deltaic reservoirs are characterized by large multi-beds of oil-generation and abundant hydrocarbon resources. In this paper, the petroleum geologic settings of the studied area are analyzed, and the accumulation characteristics and exploration methods of lithologic reservoirs are summarized. It is of theoretical significance for the study of the exploration theories of lithologic reservoirs, and also expedites the exploration steps of deltaic reservoirs in the northern Shaanxi area.

  14. THE IRON GATES RESERVOIR – ASPECTS CONCERNING HYDROLOGICAL CHARACTERISTICS AND WATER

    Directory of Open Access Journals (Sweden)

    Liliana ZAHARIA

    2010-06-01

    Full Text Available The paper makes a synthesis of the hydrological characteristics of the Iron Gates I reservoir and at the same time, it gives an account of its water quality state. A number of specific issues are revealed such as the feeding sources, level regime, water discharge, sediment load, and sedimentation processes. Likewise, the study highlights the alteration of the main hydrological parameters (levels, liquid and solid discharges entailed by reservoir creation, by simply comparing the present day situation with that existing before the artificial lake came into being. The analysis of hydrological characteristics relies especially on the datasets provided by the “Romanian Waters” National Administration for the Baziaş, Orşova and Drobeta Turnu Severin gauging stations, which have different recording intervals for the period 1921 – 2006. At the same time, bibliographic sources have been taken into account in order to better understand the hydrological phenomena. As far as water quality is concerned, this has been established based on the quality indicators for the periods 2000 – 2004 and 2006 – 2009, which exist in the records of the National Water Monitoring System.

  15. Pre-stack-texture-based reservoir characteristics and seismic facies analysis

    Institute of Scientific and Technical Information of China (English)

    Song Cheng-Yun; Liu Zhi-Ning; Cai Han-Peng; Qian Feng; Hu Guang-Min

    2016-01-01

    Seismic texture attributes are closely related to seismic facies and reservoir characteristics and are thus widely used in seismic data interpretation. However, information is mislaid in the stacking process when traditional texture attributes are extracted from post-stack data, which is detrimental to complex reservoir description. In this study, pre-stack texture attributes are introduced, these attributes can not only capable of precisely depicting the lateral continuity of waveforms between different reflection points but also reflect amplitude versus offset, anisotropy, and heterogeneity in the medium. Due to its strong ability to represent stratigraphics, a pre-stack-data-based seismic facies analysis method is proposed using the self-organizing map algorithm. This method is tested on wide azimuth seismic data from China, and the advantages of pre-stack texture attributes in the description of stratum lateral changes are verifi ed, in addition to the method’s ability to reveal anisotropy and heterogeneity characteristics. The pre-stack texture classification results effectively distinguish different seismic reflection patterns, thereby providing reliable evidence for use in seismic facies analysis.

  16. Weathering Characteristics of Sloping Fields in the Three Gorges Reservoir Area, China

    Institute of Scientific and Technical Information of China (English)

    JIANG Hong-Tao; XU Fei-Fei; CAI Yi; YANG Da-Yuan

    2006-01-01

    For the purpose of understanding the weathering characteristics of surface layers in purple mudstone sloping fields of the Three Gorges Reservoir area of China, oxide content of major elements, composition of clay minerals, magnetic susceptibility, and difference in weathering characteristics of surface layers under different slope gradients were determined.The results showed that the oxide content of Si, Al, and Fe ranged from 60% to 75% and the weathering coefficient with depth showed no trend along the slope gradient. Also, for gentle (10° and 15°) and intermediate (25° and 40°) slopes the clay relative diffraction peak for kaolinite at the surface between 0-10 cm and 10-20 cm declined with an increase in slope gradient, while the relative diffraction peak for kaolinite in weathered layers on steep slopes (50° and 60°) disappeared altogether. Magnetic susceptibility decreased with increasing depth and, for a given depth layer, decreased with an increase in slope gradient. Analysis of the oxide content, weathering coefficients, clay minerals, and magnetic susceptibility showed that in the Three Gorges Reservoir area, the pedogenesis of the weathering layer in purple mudstone sloping fields was weak with weaker soil formation going from gentle slope to steep slope.

  17. 冲积扇砾岩储层构型特征及其对储层开发的控制作用以准噶尔盆地西北缘某区克下组冲积扇储层为例%Characteristics of Conglomerate Reservoir Architecture of Alluvial Fan and Its Controlling Effects to Reservoir Development:Taking Alluvial Fan Reservoir in Some Area of Northwest Margin of Junggar Basin as an Example

    Institute of Scientific and Technical Information of China (English)

    陈欢庆; 梁淑贤; 舒治睿; 邓晓娟; 彭寿昌

    2015-01-01

    冲积扇砾岩储层作为陆相沉积储层十分重要的类型之一,一直是我国油气勘探开发的重点领域。以准噶尔盆地西北缘某区下克拉玛依组为例,根据砾岩储层相变快、储层非均质性强等特点,在沉积相分析的基础上,对储层构型特征进行了精细分析,将储层划分为槽流砾石体、槽滩砂砾体、漫洪内砂体、漫洪内细粒、片流砾石体、漫洪外砂体、漫洪外细粒、辫流水道、辫流砂砾坝、漫流砂体、漫流细粒、径流水道和水道间细粒共13种构型单元,其中以槽流砾石体、片流砾石体、辫流水道和辫流砂砾坝占主导。构型解剖结果显示:研究区砾岩储层槽流砾石体平面呈条带状,剖面厚度大,为2~8 m;片流砾石体沉积厚度大,一般为2~7 m;辫流水道构型单元宽度为80~400 m,剖面呈透镜状,厚度为2~7 m;辫流砂砾坝沉积厚度较大,为2~7 m。上述构型单元受北部和西北部方向物源控制明显。储层构型特征能有效反映储层非均质性、连通性等属性,对油田开发具有较强的控制作用。%Being one of the important kind of reservoir,conglomerate reservoir always was hotpot area to explorationists and developers of oilfield.Taking Lower Karamay Formation of some area in northwest margin of Junggar basin as an example,it characteristics of sedimentary facies quick changes and heterogeneity intensity.reservoir architecture characteristics were finely analyzed on the base of sedimentary facies studied.The reservoirs were carved into thirteen kind of architecture,such as, channel flow conglomerate,channel beach conglomerate,sandstone of inner belt of sheet flood,fine grained of inner belt of sheet flood,laminar flow conglomerate,sandstone of exterior belt of sheet flood, fine grained of exterior belt of sheet flood,braided channel,braided sandstone-conglomerate dam, sandstone of unconcentrated flow,fine grained of unconcentrated flow

  18. Sedimentary features, reservoir characteristics and seismic signature of an Aptian incised valley and its lateral equivalent, in the north Ben Nevis field of the Jeanne d`Arc Basin

    Energy Technology Data Exchange (ETDEWEB)

    Meehan, P.J.; Hodder, J.; Harding, S.; Zanussi, L. [Husky Oil, Calgary, AB (Canada); Plint, G. [Western Ontario Univ., London, ON (Canada)

    1998-09-01

    In 1988 three cores from an oil well in the Avalon Formation reservoir zone of the north Ben Nevis field were studied. The field is located within the Jeanne d`Arc Basin on the Grand Banks of Newfoundland. The cores indicated a shallowing-upward clastic sequence of prograding marine shoreface sandstones which end in back barrier lagoon deposits. Recent studies and current ongoing surveys using seismic logs and reservoir characterizations confirmed the original interpretation. An attempt was made to correlate two wells, the M-61 and the P-93. Correlations between the two wells indicate a gross similarity in depositional facies, but core and log analysis indicate major differences, particularly in the upper third of the Avalon Formation where the oil and gas is trapped. Two shallowing-upward shoreface successions are preserved in both wells, but local depositional variations are evident. M-61 showed much better reservoir characteristics than the same unit in P-93. New 3-D seismic data is expected to provide a better resolution of the geology. 1 fig.

  19. Time-dependent compaction band formation in sandstone

    Science.gov (United States)

    Heap, Michael J.; Brantut, Nicolas; Baud, Patrick; Meredith, Philip G.

    2015-07-01

    Compaction bands in sandstone are laterally extensive planar deformation features that are characterized by lower porosity and permeability than the surrounding host rock. As a result, this form of localization has important implications for both strain partitioning and fluid flow in the Earth's upper crust. To better understand the time dependency of compaction band growth, we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (initial porosity = 0.24) under constant stress (creep) conditions in the compactant regime. Our experiments show that inelastic strain accumulates at a constant stress in the compactant regime, manifest as compaction bands. While creep in the dilatant regime is characterized by an increase in porosity and, ultimately, an acceleration in axial strain rate to shear failure, compaction creep is characterized by a reduction in porosity and a gradual deceleration in axial strain rate. The global decrease in the rates of axial strain, acoustic emission energy, and porosity change during creep compaction is punctuated at intervals by higher rate excursions, interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence, background creep strain rate, is decreased. However, the inelastic strain associated with the growth of a compaction band remains constant over strain rates spanning several orders of magnitude (from 10-8 to 10-5 s-1). We find that despite the large differences in strain rate and growth rate (from both creep and constant strain rate experiments), the characteristics (geometry and thickness) of the compaction bands remain essentially the same. Several lines of evidence, notably the similarity between the differential stress dependence of creep strain rate in the dilatant and compactant regimes, suggest that as for dilatant creep, subcritical stress corrosion cracking is the mechanism responsible for

  20. Depositional and diagenetic variability within the Cambrian Mount Simon Sandstone: Implications for carbon dioxide sequestration

    Science.gov (United States)

    Bowen, B.B.; Ochoa, R.I.; Wilkens, N.D.; Brophy, J.; Lovell, T.R.; Fischietto, N.; Medina, C.R.; Rupp, J.A.

    2011-01-01

    The Cambrian Mount Simon Sandstone is the major target reservoir for ongoing geologic carbon dioxide (CO2) sequestration demonstrations throughout the midwest United States. The potential CO2 reservoir capacity, reactivity, and ultimate fate of injected CO2 depend on textural and compositional properties determined by depositional and diagenetic histories that vary vertically and laterally across the formation. Effective and efficient prediction and use of the available pore space requires detailed knowledge of the depositional and diagenetic textures and mineralogy, how these variables control the petrophysical character of the reservoir, and how they vary spatially. Here, we summarize the reservoir characteristics of the Mount Simon Sandstone based on examination of geophysical logs, cores, cuttings, and analysis of more than 150 thin sections. These samples represent different parts of the formation and depth ranges of more than 9000 ft (>2743 m) across the Illinois Basin and surrounding areas. This work demonstrates that overall reservoir quality and, specifically, porosity do not exhibit a simple relationship with depth, but vary both laterally and with depth because of changes in the primary depositional facies, framework composition (i.e., feldspar concentration), and diverse diagenetic modifications. Diagenetic processes that have been significant in modifying the reservoir include formation of iron oxide grain coatings, chemical compaction, feldspar precipitation and dissolution, multiple generations of quartz overgrowth cementation, clay mineral precipitation, and iron oxide cementation. These variables provide important inputs for calculating CO2 capacity potential, modeling reactivity, and are also an important baseline for comparisons after CO2 injection. Copyright ??2011. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

  1. Contamination characteristics and source apportionment of trace metals in soils around Miyun Reservoir.

    Science.gov (United States)

    Chen, Haiyang; Teng, Yanguo; Chen, Ruihui; Li, Jiao; Wang, Jinsheng

    2016-08-01

    Due to their toxicity and bioaccumulation, trace metals in soils can result in a wide range of toxic effects on animals, plants, microbes, and even humans. Recognizing the contamination characteristics of soil metals and especially apportioning their potential sources are the necessary preconditions for pollution prevention and control. Over the past decades, several receptor models have been developed for source apportionment. Among them, positive matrix factorization (PMF) has gained popularity and was recommended by the US Environmental Protection Agency as a general modeling tool. In this study, an extended chemometrics model, multivariate curve resolution-alternating least squares based on maximum likelihood principal component analysis (MCR-ALS/MLPCA), was proposed for source apportionment of soil metals and applied to identify the potential sources of trace metals in soils around Miyun Reservoir. Similar to PMF, the MCR-ALS/MLPCA model can incorporate measurement error information and non-negativity constraints in its calculation procedures. Model validation with synthetic dataset suggested that the MCR-ALS/MLPCA could extract acceptable recovered source profiles even considering relatively larger error levels. When applying to identify the sources of trace metals in soils around Miyun Reservoir, the MCR-ALS/MLPCA model obtained the highly similar profiles with PMF. On the other hand, the assessment results of contamination status showed that the soils around reservoir were polluted by trace metals in slightly moderate degree but potentially posed acceptable risks to the public. Mining activities, fertilizers and agrochemicals, and atmospheric deposition were identified as the potential anthropogenic sources with contributions of 24.8, 14.6, and 13.3 %, respectively. In order to protect the drinking water source of Beijing, special attention should be paid to the metal inputs to soils from mining and agricultural activities.

  2. 徐家围子断陷登娄库组三段成岩模拟与致密砂岩储层类型预测%Diagenetic numerical modeling and tight sandstone reservoir types prediction of the Member 3 of the Denglouku Formation of the Xujiaweizi Fault Depression

    Institute of Scientific and Technical Information of China (English)

    程仲平; 孟元林; 田伟志; 孟凡晋; 王建伟; 徐赫; 潘雪梅; 王维安; 蒋学峰

    2011-01-01

    为了预测松辽盆地徐家围子断陷深层登娄库组三段致密砂岩储层的类型和质量,根据深层的勘探实践和储层分析化验资料,将碎屑岩的成岩作用进一步细化为早成岩阶段A期、B期,中成岩阶段A1亚期,A2亚期、B1亚期、B2亚期,晚成岩阶段A期和B期3个阶段8个(亚)期,其中处于晚成岩阶段A期和B期的致密砂岩储层已不能产出工业气流。孔隙度和渗透率的统计结果表明,徐家围子断陷致密砂岩储层的物性主要受沉积相和成岩作用的影响,不同的沉积相和成岩相组合形成了致密砂岩3种类型的储层(Ⅱ、Ⅲ、Ⅳ类)。通过模拟古地温、镜质组反射率、甾烷异构化、粘土矿物转化和自生石英含量随时间的变化规律,模拟了成岩演化史、预测了成岩阶段和成岩相的平面分布。综合考虑沉积相和成岩作用对储层物性的影响,应用成岩作用数值模拟技术,通过成岩相分析,结合沉积相的研究成果,预测了登三段致密砂岩各种类型储层的平面分布特征。目前已发现的工业气流井主要位于Ⅱ、Ⅲ类储层分布的范围内。Ⅳ类储层中未发现工业气流,该类致密砂岩储层主要分布在晚成岩阶段A期—B期或处于滨浅湖相。引起成岩作用差异的主要因素是埋深。%To predict the reservoir type and quality of the tight sandstones of the Member 3 of the Denglouku Formation in the deep horizons of the Xujiaweizi Fault Depression,Songliao Basin,the diageneses of clastic rocks are divided into the period A of early diagenetic stage,the period B of early diagenetic stage,the sub-period A1 of middle diagenetic stage,the sub-period A2 of middle diagenetic stage,the sub-period B1 of middle diagenetic stage,the sub-period B2 of middle diagenetic stage,the period A of late diagenetic stage and the period B of late diagenetic stage on the base of the exploration results of the deep horizons and the reservoir

  3. Optimized Drilling Technologies for Tight Sandstone Reservoirs in Canada Daylight Oilfield%加拿大 Daylight 油田致密砂岩油藏优快钻井技术

    Institute of Scientific and Technical Information of China (English)

    侯立中; 谈心; 曲洪娜

    2014-01-01

    为经济高效地开发致密砂岩油藏,并为国内同类型油气田开发提供借鉴,进行了Daylight油田优快钻井技术研究。对Daylight油田地层岩性进行了研究,根据地层压力优化了井身结构;通过分析测井资料并结合统计数据,研制了个性化的钻头;在分析钻井技术难点、地层压力的基础上,研制了油基钻井液体系,并采取严格措施确保其性能稳定;采取防碰技术控制井眼轨迹,满足了井工厂钻井的要求;优选先进的井下工具进行配套应用。该油田油气井井身结构按地区简化为二开和三开2种;研制了适应该地区软硬交错地层的复合钻头;油基钻井液体系为井壁稳定提供了保障;提前防碰技术缩短了滑动钻进时间;振荡钻井技术和AGITATOR井下工具可以解决水平井钻井中的托压问题,黑匣子为分析钻柱涡动提供了数据支持。应用结果表明,同地区平均井深为3000 m的井,平均钻井周期由原来的18 d缩短为8 d。Daylight油田优快钻井技术研究为快速钻井提供了保证,为国内致密油藏开发提供了技术参考。%In order to develop tight sandstone reservoirs economically and efficiently ,and provide refer-ences for development of similar oil and gas fields ,the drilling technologies in Canada Daylight Oilfield have been investigated .By analyzing main affecting factors on optimized drilling technologies ,some important a-chievements have been obtained ,including casing program optimization on the basis of formation pressure ;specific bit developed through logging data analysis and statistics ;oil-base drilling fluid system developed through the analysis of drilling troubles and formation pressure ,and anti-collision drilling techniques were taken to control wellbore trajectory ,so as to meet the requirement of well factory drilling ;Optimization of advanced downhole tools for matching application ;wellbore structures

  4. Stochastic reconstruction of sandstones

    Science.gov (United States)

    Manwart; Torquato; Hilfer

    2000-07-01

    A simulated annealing algorithm is employed to generate a stochastic model for a Berea sandstone and a Fontainebleau sandstone, with each a prescribed two-point probability function, lineal-path function, and "pore size" distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolating configurations. A comparison of simple morphological quantities indicates good agreement between the reconstructions and the original sandstones. Also, the mean survival time of a random walker in the pore space is reproduced with good accuracy. However, a more detailed investigation by means of local porosity theory shows that there may be significant differences of the geometrical connectivity between the reconstructed and the experimental samples.

  5. Carbonate cementation-dissolution in deep-seated sandstones near the overpressure top in central Junggar Basin, Xinjiang, NW China

    Institute of Scientific and Technical Information of China (English)

    YANG Zhi; HE Sheng; WANG Furong; HE Zhiliang; WU Hengzhi; MENG Xianlong

    2009-01-01

    Fluid/rock interaction occurs frequently in the sandstones near the overpressure top in central Junggar Basin, and carbonate cementation-dissolution is related closely to the formation of secondary pores in the reservoir sandstones. From petrological, hydrochemical and fluid-inclusion studies of the deep-seated sandstones near the overpressure top in central Junggar Basin and the carbon and oxygen isotopic characteristics of carbonate cements in those sandstones, the following conclusions can be drawn: (1) Carbonates are the major cements. Two-stage cemen-tation was commonly developed, with late-stage ferroan carbonate cementation being dominant; several secondary porosity zones were developed vertically in the sandstones near the overpressure top, and there is a mutually com-pensatory relationship between the carbonate contents and the mean porosity; (2) the alkalescent formation-water chemical environments are in favor of carbonate precipitation; (3) there were two phases of thermal fluid activity which are related to the late-stage carbonate cementation-dissolution; (4) with the overpressure top as the boundary, carbonate cements in the sandstones have slightly negative δ13C and δ180 values, showing such a variation trend that the δ13C and δ18O values near the coal-bearing Jurassic strata are lighter, those in the overpressure top are heavier, and those at the upper part of the overpressure top are lighter, which is considered to be the result of kinetic isotope fractionation driven by episodically overpressured fluid flow; (5) carbonate cementation is closely associated with the decarboxylation of organic acids, and secondary porosity zones resultant from dissolution by organic acids and CO2 derived from Jurassic coal-beating strata, are the most important reservoir space of hydrocarbon, Studies of the mechanisms of carbonate cementation-dissolution and formation of secondary pores in the deep-seated sandstones near the overpressure top are of great

  6. An analysis of the types and distribution characteristics of natural gas reservoirs in China

    Institute of Scientific and Technical Information of China (English)

    Xu Zhangyou; Yue Dali; Wu Shenghe; Zhang Xiaoyu; Chen Ce; Ni Yuqiang

    2009-01-01

    The natural gas reservoir beds of different areas in China can be divided into three kinds,clastic natural gas reservoir bed, carbonate natural gas reservoir bed and special natural gas reservoir bed. They have different combination patterns controlled by deposition, diagenesis and tectonism. Our analysis indicates that the natural gas reservoirs are mainly distributed in the Precambrian, Palaeozoic, Mesozoic, and Tertiary-Quaternary. Craton basin, foreland basin and intracontinental rift basin which contain most of natural gas in China have special geological features and favorable accumulation conditions, and will be important exploration areas in the future.

  7. 准噶尔盆地腹部呼图壁河组优质储层特征和主控因素%Characteristics and Control Factors of High Quality Reservoirs in Hutubihe Formation in Hinterland of Junggar Basin

    Institute of Scientific and Technical Information of China (English)

    杨有星; 金振奎

    2011-01-01

    通过岩石薄片观察、扫描电镜分析、油藏压力系数、孔隙类型及大小、喉道特征等综合分析知,研究区白垩系呼图壁河组岩性油气藏储集层属于Ⅰ类储层,具有高孔隙度、中高渗透率、低排驱压力、大喉道为主、孔隙连通性较好的物性特征,为优质储层.并根据埋藏深度和颗粒接触类型对研究区压实作用进行定量分析,可知研究区为中弱压实强度.并最终研究得知,虽然研究区储层塑性岩屑含量较高,但仍为优质储层的主要原因是.研究区广泛发育辫状高能河道沉积微相,该沉积微相泥质含量比低能河道的低,故孔隙度和渗透率较高;研究区的岩屑砂岩粒径大小主要为中粒和细粒,较大的砂岩粒径值增强了砂岩的抗压性;中新生代以来,研究区地温梯度为0.02-0.022℃/m,低地温梯度减缓了成岩作用的进行;烃类的早期充注增强了储层抗压实能力,使原始粒间孔隙得以保存;后期该区构造稳定,未发生大的断裂活动破坏油气藏,使原生孔隙也没有遭到破坏.%On the basis of the thin section observation,scanning electron microscopu analysis,and comprehensive analysis involving reservoir pressure cofficient,porosity type and size,throat features,and other characteristics of the data,it is found that the study area.Hutubihe Formation's lithologic reservoir is a Class Ⅰ reservoir,and the reservoir possesses main characteristics,such as high porosity.high permeability,low displacement pressure,and a large throat.Compaction of the sand stone reservoir in the study area id from moderate-weak intensive.It is obtained from final study that although the content of the low degree maturity and the relatively poor ability plastic cuttings are higher,but the high-quality reservoirs are still to form in the sthdy area,the reson for that is mainly due to extensive development of high-energy micro-braided channel deposit,the mud conten of high

  8. SELECTED CHARACTERISTICS OF LIMESTONE AND DOLOMITE RESERVOIRS IN THE UNITED STATES.

    Science.gov (United States)

    Schmoker, James W.; Krystinik, Katherine B.; Halley, Robert B.

    1985-01-01

    Limestone reservoirs are more numerous in the United States than dolomite reservoirs (by a ratio of about 3 to 1) because limestones are more abundant than dolomite. However, in the eight states that account for over 90% of United States carbonate reservoirs, there is a statistical tendency for carbonate reservoirs to occur preferentially in dolomites. Dolomite reservoirs, on the average, are larger and deeper than those of limestone, yet they often have lower matrix porosities and permeabilities. This line of investigation offers supplemental evidence that dolomitization tends to improve the reservoir properties of a given formation, and that effective fracture systems at reservoir depths are more likely to occur in dolomites than in limestones. Refs.

  9. 中国东部W油田T区中浅层储层特征研究%Research on Middle-shallow Layer Reservoir Characteristics at T Area in W Oilfield in East China

    Institute of Scientific and Technical Information of China (English)

    董亚东; 范兴燕; 袁志云; 任涛; 肖高杰; 赵健

    2013-01-01

    W oilfield, located in the east of China, was characterized by its reservoirs' non-homogeneity. The reservoir sandstone developed irregularly, and its thickness, merely 3-20 meters, changes quickly in the field. In addition, the wave impedance characteristics of the sandstone and shale were similar in this district. It is difficult, or even impossible, to classify the sand and shale using the traditional reservoir inversion. According to the small layer division results and chose the favorable lithology sensitivity factors, the relationship between sensitivity curve with acoustic curve was build up and based on that the wave impedance inversion was done to the target layer again. Then the threshold values were marked on the cubic data of wave inversion . And the sand could be easily recognized from the three-dimensional perspective maps according to the threshold value. After that the reservoir distribution could be acquired directly . This results were proven by the drilling data and this method could be applied in this district also. Based on the regional structure evolution and the signal well facies, also the transition of the channel deposit is did preliminary analysed.%W油田位于中国东部;该油田存在多套河道砂.通过井上统计,该区砂体厚度纵向变化快,3-20 m不等;且砂泥岩在常规波阻抗上难于区分,常规储层预测方法难于区分.在细分层基础上,通过交会分析,选取岩性敏感因子,建立了敏感曲线与声波曲线的关系,通过重构曲线进行波阻抗反演.以此为基础,在波阻抗体上设定砂泥岩区分的门槛值.通过立体透视方法,大于砂岩阻抗值的定义为砂岩.通过变色显示,对T组各砂体的平面展布特征进行了定量刻画.通过对比分析,认为该方法与现有钻探结果吻合度较高,证明了该方法在本区的适用性.同时研究结合区域构造、单井相等资料,对该区河道沉积的变迁的期次进行了初步分析.

  10. Physical and chemical characteristics of Terrace Reservoir, Conejos County, Colorado, May 1994 through May 1995; interim report

    Science.gov (United States)

    Stogner, Sr., Robert W.; Edelmann, Patrick; Walton-Day, Katherine

    1996-01-01

    Terrace Reservoir receives drainage of low-pH, metal-enriched water from mineralized areas, including the Summitville Mine, within the AlamosaRiver Basin. Drainage from the Summitville Mine has contributed a substantial part of the metal load to Terrace Reservoir. From May 1994 through May 1995, a study was done by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to evaluate the physical and chemical characteristics of Terrace Reservoir.Terrace Reservoir was thermally stratified from about mid-May through August 1994. Thermal stratification was absent from September\\x111994through March 1995. During periods of stratification, underflow of the Alamosa River was predominant, and residence times of the underflow were shortened by 40 to 75\\x11percent of the theoretical residence times for a well-mixed reservoir. Transport and deposition of suspended solids in Terrace Reservoir varied spatially and temporally. Most of the suspended solids were deposited in Terrace Reservoir. The concentration of dissolved oxygen in the reservoir varied little spatially or temporally and generally was within a few tenths of the dissolved-oxygen concentration of the inflow. The pH of water in the reservoir generally ranged from about 4.0 to about 7.0, depending on date, depth, and location. The largest pH values were measured during May. A markeddecrease of about 1.5\\x11pH units occurred at site T5 in the reservoir about mid-June. The pH of the reservoir remained at or below 5.5 from mid-June through November. Dissolved-metal concentrations varied spatially and temporally in response to several factors, which included inflow characteristics, reservoir stratification and mixing, inflow-routing and flow-through patterns, residence times, sedimentation, dissolved oxygen, and pH.Inflow chemistry is the dominant controlling factor of metal chemistry within Terrace Reservoir.During periods of stratification, large vertical variations in metal

  11. Biological and ecological characteristics of Pterocuma pectinata (Malacostraca, Cumacea in Sasyk Reservoir

    Directory of Open Access Journals (Sweden)

    А. A. Khalaim

    2016-02-01

    Full Text Available Sasyk (Kunduk – estuary in the North-Western Black Sea region, is located 120 kmsouth-west of Odessa. In 1979–1980 Sasyk was separated from the sea by a dam, connected by a canal with the Danube and transformed into a reservoir. The fauna of Sasyk underwent significant changes and continues to adapt to the new conditions. This process is of great theoretical and practical interest. Cumacea – a small order, numbering about 600 species; is represented in the Black Sea-Azov basin by 23 species, 11 of them belong to the Caspian complex. Due to their high quantity indicators, they play a significant role in the diet of many species of fish. Pterocuma pectinata (Sowinski, 1893 is the most abundant species of cumacean not only in the Sasyk Reservoir, but also in many bodies of water in the region. However, the biology and ecology of this group of animals has been very inadequately studied. The material for these studies was provided by 120 benthic samples collected from 41 stations in the Sasyk Reservoir in the vegetation period 2013–2014. In this study we also used the material collected by means of H. Hungerford underwater light traps. In total 4,000 specimens of cumaceans were processed. This article shows the results of the studyof the post-embryonic development, fertility and size-mass characteristic of P. pectinata in Sasyk Reservoir. For both sexes for age stages have been distinguished and described for cumaceans: «manca», youth, prebreeding and breeding. Between breeding cycles, females live through one more preparatory (intermediate stage; the males die. This article provides a detailed morphological and morphometric description of all the stages of the ontogeny of cumaceans. The ratio of number of cumaceans at different stages of ontogeny varies considerably with the seasons. In the summer sexual development of cumacean occurs earlier than in the less warm seasons. A directly proportional relationship was found between body length

  12. Characteristic of Soil Nutrients Loss in Beiyunhe Reservoir Under the Simulated Rainfall

    Directory of Open Access Journals (Sweden)

    LIU Cao

    2016-05-01

    Full Text Available Field nutrient loss from soil became the major factor of the water pollution control in countryside in China. Beiyunhe reservoir is located in semiarid zone, where field nutrient loss distributed in summer. To assess the flied nutrient loss in Beiyunhe reservoir, we conducted experiments to study the characteristic of soil nutrients loss by analysis of the content of runoff water, soil nutrients and runoff water sediment under simulated rainfall. The results showed that the runoff happened in the rainstorm. In runoff water, the content of TN was 4.7~11.3 mg·L-1, ammonia nitrogen and nitrate nitrogen accounted for 44.51% of TN; the content of P was 0.66~1.35 mg·L-1, water soluble phosphorus accounted for 54.08% of TP. And the main loss of nutrients was in the surface soil, the loss of TN, NH4+-N, NO3--N, TP and DP were 29.79%, 52.09%, 10.21%, 16.48% and 5.27%, respectively. However, the most of field nutrient loss were in runoff sediment, the content of TN and TP were 0.66~1.27 mg·g-1 and 14.73~20 mg·g-1 in sediment, and TN and TP account for 82.28% and 99.89% of total loss of nutrient. After the rainstorm, the macro-aggregates were reduced 8.8%, and the micro-aggregates increased 9.5%.

  13. Sedimentary Characteristics and Reservoir Prediction of Paleogene in the East Part of Kuqa Foreland Basin

    Institute of Scientific and Technical Information of China (English)

    Yan Detian; Wang Hua; Wang Jiahao; Wang Qingchen

    2006-01-01

    Most of the Mesozoic and Cenozoic large-scale hydrocarbon-bearing basins in western China were formed in a similar foreland setting. Hydrocarbon exploration of the Kuqa foreland basin requires research into the sedimentary characteristics and filling evolution of the depositional sequences and their response to the basin process. Based on an analysis of outcrops, well logs and high resolution seismic data, the sedimentary system types and distribution characteristics of the Paleogene in the east part of Kuqa foreland basin were systematically studied. The results show that: ( 1 ) Three types of sedimentary systems are developed in the area: an oxidative salty wide shallow lacustrine system, a fan delta system and an evaporitic bordersea system. (2) The configuration and evolution of the depositional systems of the Paleogene in the Kuqa foreland basin were predominantly determined by foreland tectonism. Vertically, the Paleogene sedimentary sequence can be divided into three parts: the lower, middle and upper depositional system tracts. The lower and upper tracts commonly consist of progradational or aggradational sequences, while the middle part is usually comprised of a set of aggradational to transgressive third-order sequences. Laterally, the sedimentary systems in the east part of the Kuqa foreland basin spread from east to west as a whole, and the sedimentary facies obviously vary from south to north. The sand bodies of the delta front facies are excellent gas reservoirs, characterized by rather thick, extensive and continuous distribution, high porosity and permeability, and just a few barrier beds.

  14. EXPERIMENTAL STUDY ON MECHANICS CHARACTERISTICS OF SANDSTONE UNDER AXIAL UNLOADING AND RADIAL UNLOADING PATH%轴、侧向同卸荷下砂岩力学特性影响的试验研究

    Institute of Scientific and Technical Information of China (English)

    韩铁林; 师俊平; 陈蕴生; 李伟红

    2016-01-01

    This article take the actual rock mass project as a background, triaxial compression for sandstone specimen under axial unloading and radial unloading—this path is realized on WDT-1500 reactive material testing machine. The test results show that the failure of sandstone specimen don’t appear peak stress under axial unloading and radial unloading—this path, to define the inflection point of stress drop of (The maximum principal stress-minimum principal stress)∼the minimum principal stress curves of sandstone for failure strength. The stress drop and the axial strain of resilience of sandstone specimens were happened under axial unloading and radial unloading, which had no obvious elasticity and yield step before rock specimens’ failure. The lateral deformation is larger than the axial deformation in the process of test,and volumetric strain of the sandstone specimen is always in a state of expansion. The strength of sandstone is reduced relative to triaxial compression. the deformation property and strength property of sandstone under this path are mainly influenced by initial axial pressure and initial radial pressure,but the influence of the unloading speed of radial pressure is not clear. The failure characteristics of samples often present mixed zhang-shear failure under axial unloading and radial unloading.%本文以实际岩体工程为背景,利用WDT-1500仪器开展了轴向、侧向同时卸荷条件下砂岩的三轴试验。结果表明:轴、侧向同卸荷这种卸荷路径下,砂岩试样破坏时并没有出现应力峰值,为了定义试样的破坏强度,将最大与最小主应力差随最小主应力的变化关系曲线上应力跌落的拐点处的应力值定义为破坏强度。砂岩变形初始段发生应力跌落和轴向应变回弹,破坏前无明显的弹性和屈服阶段;试验的过程中,砂岩的侧向变形明显大于轴向变形,其体积应变一直处于膨胀状态;相对于砂岩的常规三

  15. Ecological and floristic characteristics of higher aquatic plants in Volgograd reservoir

    Directory of Open Access Journals (Sweden)

    Kochetkova Anna Igorevna

    2016-12-01

    Full Text Available In this paper the long-term gydro-botanical studies of Volgograd reservoir were analyzed. Flora in different parts of the reservoir, located in Volgograd and Saratov regions was compared. In the floristic investigations, several species of flora, rare in Volgograd region and previously not noted were revealed. The regularities in the floristic composition changes depending on the amplification of climate aridity and features of the hydrological regime of the Volgograd reservoir were determined. Unstable hydrological conditions in the reservoir contribute to the emergence of new free habitats, which are so necessary for the spread and establishment of different plants, including new invasive ones and formed hybrids.

  16. [Community Structure Characteristics of Diatom in Reservoirs Located in the South of Jiangsu Province, China and Its Control Factors].

    Science.gov (United States)

    Ren, Jie; Zhou, Tao; Zhu, Guang-wei; Jin, Ying-wei; Cui, Yang; Xu, Hai; Zhu, Meng-yuan; Xia, Ming-fang; Chen, Wei-min

    2016-05-15

    In order to understand the community structure characteristics of Bacillariophyta and its controlling factors in reservoirs located in the Southeast, China, in the geographic background of hills landscape and humid climate, 18 reservoirs were investigated in June, 2015, during the period with high risk of diatom bloom, covering water quality, and the community structures of phytoplankton. The correlations between Bacillariophyta and other planktons with nutrients, water depth, storage capacity, etc. were analyzed. The results showed that, 10 reservoirs reached the light extent of diatom bloom ( density between 100 x 10⁴-1,000 x 10⁴ cells · L⁻¹ reservoirs in this area were generally in mesotrophic or eutrophic state with considerably high total nitrogen concentrations; total phosphorus and trophic level index were both closely correlated with Bacillariophyta biomass. Phormidium in Cyanophyta was the dominating generus among phytoplankton in terms of density; with respect to biomass, Bacillariophyta, Chlorophyta and Cyanophyta were the top three phylum, and Bacillariophyta accounted for 46. 8% of the total phytoplankton biomass, becoming the most important one resulting in abnormal propagation of algae; Synedra (51.5%) and Cyclotella (21.4%) were the main dominating genera in Bacillariophyta, together with Achnanthes and Melosira. Deep water was favored by Bacillariophyta to dominate among different phyla. Larger ratio between catchment and reservoir storage capacity, on the other hand, caused the increase of trophic level and chlorophyll, and benefited the shift of dominating phytoplankton from Bacillariophyta to Chlorophyta and Cyanophyta, by which, the risk of algae bloom would be increased. It reveals that to alleviate the risk of algae bloom and protect drinking water resources, catchment management is crucial for the studied reservoirs. And the establishment of nutrient reduction strategies needs to consider the features of each individual reservoir, i

  17. An Evaluation of the Carbon Sequestration Potential of the Cambro-Ordovician Strata of the Illinois and Michigan Basins. Part 1. Evaluation of Phase 2 CO2 Injection Testing in the Deep Saline Gunter Sandstone Reservoir (Cambro-Ordovician Knox Group), Marvin Blan No. 1 Hancock County, Kentucky Part 2. Time-lapse Three-Dimensional Vertical Seismic Profile (3D-VSP) of Sequestration Target Interval with Injected Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Bowersox, Richard [Univ. of Illinois, Champaign, IL (United States); Hickman, John [Univ. of Illinois, Champaign, IL (United States); Leetaru, Hannes [Univ. of Illinois, Champaign, IL (United States)

    2012-12-20

    Part 1 of this report focuses on results of the western Kentucky carbon storage test, and provides a basis for evaluating injection and storage of supercritical CO2 in Cambro-Ordovician carbonate reservoirs throughout the U.S. Midcontinent. This test demonstrated that the Cambro- Ordovician Knox Group, including the Beekmantown Dolomite, Gunter Sandstone, and Copper Ridge Dolomite in stratigraphic succession from shallowest to deepest, had reservoir properties suitable for supercritical CO2 storage in a deep saline reservoir hosted in carbonate rocks, and that strata with properties sufficient for long-term confinement of supercritical CO2 were present in the deep subsurface. Injection testing with brine and CO2 was completed in two phases. The first phase, a joint project by the Kentucky Geological Survey and the Western Kentucky Carbon Storage Foundation, drilled the Marvin Blan No. 1 carbon storage research well and tested the entire Knox Group section in the open borehole – including the Beekmantown Dolomite, Gunter Sandstone, and Copper Ridge Dolomite – at 1152–2255 m, below casing cemented at 1116 m. During Phase 1 injection testing, most of the 297 tonnes of supercritical CO2 was displaced into porous and permeable sections of the lowermost Beekmantown below 1463 m and Gunter. The wellbore was then temporarily abandoned with a retrievable bridge plug in casing at 1105 m and two downhole pressure-temperature monitoring gauges below the bridge plug pending subsequent testing. Pressure and temperature data were recorded every minute for slightly more than a year, providing a unique record of subsurface reservoir conditions in the Knox. In contrast, Phase 2 testing, this study, tested a mechanically-isolated dolomitic-sandstone interval in the Gunter.

  18. A Comprehensive Appraisal on the Characteristics of Coal-Bed Methane Reservoir in Turpan-Hami Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The rich coal-bed methane resources in the Turpan-Hami Basin are mainly located in the Shisanjianfang, Hami, Shanshan, Sha'erhu, Kekeya, Kerjian, Aidinghu inclines and the Dananhu coal-bed methane reservoirs.The bigger coal-bed reservoirs are sitting at a depth of less than 1500 m.The coalbed methane generation, storage and confining conditions of the Turpan-Hami basin can be indicated by eight key parameters.They are coal-bed thickness, coal rank, missing period, permeability, Langmuir volume, rock covering ability, structural confinement and hydrodynamic sealing environment.These parameters constitute a comprehensive appraisal index system of the coal-bed methane reservoir characteristics of the Turpan-Hami basin.In these parameters, the missing period of coal-bed methane is indicated by a stratum missing intensity factor.It reflects the relative exposure period of coal series.The results of a fuzzy comprehensive judgment showed that the Shisanjianfang coal-bed methane reservoir has the best prospects for exploitation and the Sha'erhu, Shanshan, Hami coal-bed methane reservoirs are next in line.

  19. Performance of Different Acids on Sandstone Formations

    Directory of Open Access Journals (Sweden)

    M. A. Zaman

    2013-12-01

    Full Text Available Stimulation of sandstone formations is a challenging task, which involves several chemicals and physical interactions of the acid with the formation. Some of these reactions may result in formation damage. Mud acid has been successfully used to stimulate sandstone reservoirs for a number of years. It is a mixture of hydrofluoric (HF and hydrochloric (HCl acids designed to dissolve clays and siliceous fines accumulated in the near-wellbore region. Matrix acidizing may also be used to increase formation permeability in undamaged wells. The change may be up to 50% to 100% with the mud acid. For any acidizing process, the selection of acid (Formulation and Concentration and the design (Pre-flush, Main Acid, After-flush is very important. Different researchers are using different combinations of acids with different concentrations to get the best results for acidization. Mainly the common practice is combination of Hydrochloric Acid – Hydrofluoric with Concentration (3% HF – 12% HCl. This paper presents the results of a laboratory investigation of Orthophosphoric acid instead of hydrochloric acid in one combination and the second combination is Fluoboric and formic acid and the third one is formic and hydrofluoric acid. The results are compared with the mud acid and the results calculated are porosity, permeability, and FESEM Analysis and Strength tests. All of these new combinations shows that these have the potential to be used as acidizing acids on sandstone formations.

  20. GeoSys.Chem: Estimate of reservoir fluid characteristics as first step in geochemical modeling of geothermal systems

    Science.gov (United States)

    Verma, Mahendra P.

    2012-12-01

    A computer code GeoSys.Chem for the calculation of deep geothermal reservoir fluid characteristics from the measured physical-chemical parameters of separated water and condensed vapor samples obtained from drilled wells is presented. It was written as a dynamic link library (DLL) in Visual Basic in Visual Studio 2010 (VB.NET). Using this library a demonstration program GeoChem was developed in VB.NET, which accepts the input data file in the XML format. A stepwise calculation of deep reservoir fluid characteristics of 11 production wells of Los Azufres geothermal system is performed. The calculated concentration of CO2 (e.g.=1270 mmole/kg in the well AZ-09) in the vapor, discharged into the atmosphere at the weir box, from the water sample indicates some problem in the analysis of carbonic species concentrations. In the absence of good quality analysis of carbonic species it is suggested to consider the CO2 in the vapor sample at the separator and the total dissolved carbonic species concentration in the water sample (i.e., without considering the liberation of CO2 in the atmospheric vapor at the weir box) for the geothermal reservoir fluid composition calculations. Similarly, it presents various diagrams developed in Excel for the thermodynamic evolution of Los Azufres geothermal reservoir.

  1. The impact of anthropogenic pollution on limnological characteristics of a subtropical highland reservoir “Lago de Guadalupe”, Mexico

    Directory of Open Access Journals (Sweden)

    Sepulveda-Jauregui A.

    2013-08-01

    Full Text Available “Lago de Guadalupe” is an important freshwater ecosystem located in the northern part of the metropolitan area surrounding Mexico City, under high demographic pressure. It receives approximately 15 hm3·y-1 of untreated municipal wastewater from the surrounding municipalities. In order to develop a comparative assessment of the pollution effect over the limnological characteristics of Lago de Guadalupe, this lake was characterised from February 2006 to July 2009, and the results were compared with those obtained from a non-polluted lake “Lago el Llano” located in the same drainage area. Lago de Guadalupe was hypereutrophic with anoxic conditions throughout most of the water column. In contrast, Lago el Llano was mesotrophic with high dissolved oxygen concentrations throughout the entire water column with a clinograde profile. Both reservoirs had a monomictic mixing regime. The longitudinal zonation of physicochemical and biological variables were investigated in order to better understand the processes controlling the water quality across the reservoir during its residence time. This study shows the impact of anthropogenic pollution on the limnological characteristics of a subtropical reservoir and confirms that under adequate management schemes, namely avoiding pollution and wastewater discharges, subtropical reservoirs can be prevented from developing eutrophic conditions.

  2. Mathematical simulation of oil reservoir properties

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A. [Instituto Politecnico Nacional (SEPI-ESQIE-UPALM-IPN), Unidad Profesional Zacatenco, Laboratorio de Analisis Met., Edif. ' Z' y Edif. 6 planta baja., Mexico City c.p. 07300 (Mexico)], E-mail: adalop123@mailbanamex.com; Romero, A.; Chavez, F. [Instituto Politecnico Nacional (SEPI-ESQIE-UPALM-IPN), Unidad Profesional Zacatenco, Laboratorio de Analisis Met., Edif. ' Z' y Edif. 6 planta baja., Mexico City c.p. 07300 (Mexico); Carrillo, F. [Instituto Politecnico Nacional (CICATA-IPN, Altamira Tamaulipas) (Mexico); Lopez, S. [Instituto Mexicano del Petroleo - Molecular Engineering Researcher (Mexico)

    2008-11-15

    The study and computational representation of porous media properties are very important for many industries where problems of fluid flow, percolation phenomena and liquid movement and stagnation are involved, for example, in building constructions, ore processing, chemical industries, mining, corrosion sciences, etc. Nevertheless, these kinds of processes present a noneasy behavior to be predicted and mathematical models must include statistical analysis, fractal and/or stochastic procedures to do it. This work shows the characterization of sandstone berea core samples which can be found as a porous media (PM) in natural oil reservoirs, rock formations, etc. and the development of a mathematical algorithm for simulating the anisotropic characteristics of a PM based on a stochastic distribution of some of their most important properties like porosity, permeability, pressure and saturation. Finally a stochastic process is used again to simulated the topography of an oil reservoir.

  3. Optimization of Permeability Tensor Characteristics of Anisotropic Reservoir and Well Pattern Parameters

    Institute of Scientific and Technical Information of China (English)

    计秉玉; 兰玉波

    2003-01-01

    The problems of well pattern arrangement, well array direction, and well array spacing ratios for anisotropic reservoirs were studied using tensor analysis. The problems were formulated as a bilevel programming model which was solved using a genetic algorithm. The results show that if the permeability in one direction is much higher than in another direction, the wells should be aligned along the high permeability direction. The analysis provides a theoretical foundation for well pattern arrangement in fractured reservoirs as well as in channel sand reservoirs.

  4. Interdisciplinary study of reservoir compartments and heterogeneity. Final report, October 1, 1993--December 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Van Kirk, C.

    1998-01-01

    A case study approach using Terry Sandstone production from the Hambert-Aristocrat Field, Weld County, Colorado was used to document the process of integration. One specific project goal is to demonstrate how a multidisciplinary approach can be used to detect reservoir compartmentalization and improve reserve estimates. The final project goal is to derive a general strategy for integration for independent operators. Teamwork is the norm for the petroleum industry where teams of geologists, geophysicists, and petroleum engineers work together to improve profits through a better understanding of reservoir size, compartmentalization, and orientation as well as reservoir flow characteristics. In this manner, integration of data narrows the uncertainty in reserve estimates and enhances reservoir management decisions. The process of integration has proven to be iterative. Integration has helped identify reservoir compartmentalization and reduce the uncertainty in the reserve estimates. This research report documents specific examples of integration and the economic benefits of integration.

  5. Diagenesis of the sandstone of Devonian Donghetang Formation in Yuqidong area, Tarim Basin,China and its influence on the reservoirs%塔里木盆地于奇东地区东河塘组砂岩成岩作用及其对储层的影响

    Institute of Scientific and Technical Information of China (English)

    王元君; 田蒙; 王峻

    2012-01-01

    通过普通薄片、铸体薄片、扫描电镜等方法对塔里木盆地于奇东及邻区泥盆系东河塘组砂岩成岩作用、成岩演化及储层发育影响因素进行了深入的研究,明确了该套储层在理藏过程中主要经历了压实作用、胶结作用、溶蚀作用、交代作用和自生矿物的形成等作用,目前已达中成岩B期.压实作用是成岩早期使原生孔隙遭到破坏的主要因素.胶结作用有碳酸盐胶结、石英次生加大、黄铁矿和黏土矿物胶结,其中碳酸盐胶结对储层物性的贡献大于其破坏作用,石英次生加大、铁质胶结、黏土矿物胶结都对本区储层起破坏作用.早成岩B期碳酸热液和腐殖质释放出的有机酸对不稳定组分的溶解是改善储层物性的重要因素.%Through scanning the thin sections and casting thin sections by electron microscope and other methods. The paper researches the influencing factors of sandstone diagenesis. Diagenesis evolution and reservoir development in Devonian System Donghetang Formation of the Yuqidong areas and adjacent areas in Tarim Basin. It is clear and definite that this set of reservoirs in the buried process mainly experienced compaction, cementation, dissolution, metasomatism and authigenic minerals formation process. These reservoirs have reached the B phase of early diagenesis at present. The main factor of destructing the primary pores in early diagenesis is compaction. Cementation includes carbonate cementation, quartz overgrowth, pyrite and cementation of clay minerals. The contribution of the carbonate cementation to the reservoir physical properties is greater than its destruction. The damage of oil reservoirs is attributed to quartz overgrowth, ferruginous cementation and cementation of clay minerals. The important factor of improving the reservoir physical properties is the dissolution of unstable components caused by the carbonated hydrothermal and the organic acid released by humus on

  6. Characteristics of phytoplankton in Lake Karachay, a storage reservoir of medium-level radioactive waste.

    Science.gov (United States)

    Atamanyuk, Natalia I; Osipov, Denis I; Tryapitsina, Galina A; Deryabina, Larisa V; Stukalov, Pavel M; Ivanov, Ivan A; Pryakhin, Evgeny A

    2012-07-01

    The status of the phytoplankton community in Lake Karachay, a storage reservoir of liquid medium-level radioactive waste from the Mayak Production Association, Chelyabinsk Region, Russia, is reviewed. In 2010, the concentration of Sr in water of this reservoir was found to be 6.5 × 10(6) Bq L, the concentration of 137Cs was 1.6 × 10(7) Bq L, and total alpha activity amounted to 3.0 × 10(3) Bq L. An increased level of nitrates was observed in the reservoir-4.4 g L. It has been demonstrated that in this reservoir under the conditions of the maximum contamination levels known for aquatic ecosystems in the entire biosphere, a phytoplankton community exists that has a pronounced decline in species diversity, almost to the extent of a monoculture of widely-spread thread eurytopic cyanobacteria Geitlerinema amphibium.

  7. Effect of Clay Mineralogy and Exchangeable Cations on Permeability of Saudi Sandstone Reservoirs Effet de la minéralogie des argiles et des cations échangeables sur la perméabilité des réservoirs gréseux d'Arabie Saoudite

    Directory of Open Access Journals (Sweden)

    Dahab A. S.

    2006-11-01

    Full Text Available Reservoir rocks are susceptible to formation damage during secondary recovery operations due to the particular mineralogical, textural and electrochemical properties of the clay minerals they contain. This damage can be explained by the swelling of indigeneous clays present, resulting in the constricting of pores, or by the dispersion of indigeneous nonswelling particle rearrangements during fluid flow, resulting in the plugging of the pore system, or by a combination of the two. This article describes a laboratory study showing the effect of clay mineralogy on the permeability of actual Saudi sandstone reservoirs during water flooding operations. The study shows that the permeability damage of Saudi sandstone reservoirs depends upon the amount of swelling clays and exchangeable ions as well as on the nature of these ions. Monovalent cations cause more damage than multivalent ones but within the same group of metals, those with smaller atomic mass cause more damage. Les roches réservoirs peuvent être endommagées pendant les opérations de récupération secondaire à cause des propriétés minéralogiques, texturales et électrochimiques particulières des minéraux argileux qu'elles contiennent. Cet endommagement peut s'expliquer, soit par le gonflement des argiles qui conduit à un rétrécissement des pores, soit par la migration de particules non gonflantes pendant l'écoulement des fluides qui entraîne le colmatage des milieux poreux, soit par une combinaison des deux mécanismes. Cet article présente une étude de laboratoire montrant l'effet de la minéralogie des argiles sur la perméabilité des roches réservoirs réelles d'Arabie Saoudite pendant des opérations d'injection d'eau. L'étude montre que l'endommagement de la perméabilité des roches réservoirs d'Arabie Saoudite dépend de la quantité d'argiles gonflantes et d'ions échangeables, ainsi que de la nature de ces ions. Les cations monovalents provoquent plus d

  8. CHARACTERISTICS OF SEDIMENT TRANSPORT ALONG A RIVER REACH WITH A RESERVOIR

    Institute of Scientific and Technical Information of China (English)

    Jueyi SUI; Peter JACKSON; Cheng LIU; Daxian FANG; Jun WANG

    2005-01-01

    Based on long-term measurements at three gauging stations, Toudaoguai, Fugu and Hequ, and one meteorological station, this article discusses the features of discharge (Q) and sediment concentration (CS) of a river reach of the Yellow River with a reservoir located in the Loess Plateau. The impacts of the local sub-watershed between Toudaoguai and Fugu gauging stations on sediment budget to the Yellow River have been analyzed. In addition, the deposition processes in the Tianqiao Reservoir have been investigated. Results show over 80% of the precipitation that falls in the local sub-watershed is unable to contribute to the Yellow River runoff process. It is found that the annual maximum sediment concentration is usually less than 30 kg/m3 during flood seasons at Toudaoguai Gauging Station, but the sediment concentration varies dramatically at Fugu Gauging Station. About 35% of the sediment eroded in the sub-watersheds between Toudaoguai and Fugu gauging stations was produced from the Huangfuchuan sub-watershed which has a drainage area accounting only for 10% of the drainage area between Toudaoguai and Fugu gauging stations. The Tianqiao Reservoir generally has deposition during the summer flood season, and scouring during the non-flood season. On average, over 85% of deposited sediment in the reservoir occurs in the 12 km long lower reservoir reach. The volume of annual deposition in the reservoir mainly depends on the volume of water from the local region between Hequ and Fugu gauging stations.

  9. Pore evolution and gas accumulation in tight sandstone reservoir of Member 2 of Xujiahe Formation in Yuanba area of Sichuan, China%四川元坝地区须二段致密砂岩储层孔隙演化与天然气成藏

    Institute of Scientific and Technical Information of China (English)

    王威

    2012-01-01

    Based on the quantitative statistics of the clasties and matrixes in the reservoir and quantitative evolutional analysis of pores, and according to the homogeneous temperature of inclusions and buried history of the reservoir, this paper makes an approach to the pore evolution and the natural gas accumulation in the tight sandstone reservoir of Member 2 of Xujiahe Formation (T3x2) of Upper Triassic in the Yuanba area of Sichuan Basin. The dynamic recovery of the compacted history of the reservoir is achieved. In the early diagenetic stage, the porosity of the reservoir declined to 8. 7%, meanwhile, the tight reservoir formed. Following this? A scries of cementations made the primary pores decreasing. The anisotropy is heightened, too. It can be known that the gas filling time of T3x2 in the Yuanba area is in the middle diagenetic stage A when the reservoir was tightened. Totally, "first is the compaction of reservoirs, and second is natural gas accumulation". The gas moves by "piston type advancing" in the reservoir. So the gas concentration is controlled by hydrocarbon-generating intensity and high quality reservoirs. Therefore, the depressed area in the eastern of Yuanba can be regarded as a favorable area for gas exploration.%利用储层中不同碎屑颗粒、填隙物的定量统计和孔隙在压实作用下的定量演化分析以及储层中包裹体均一温度,结合储层埋藏史分析等方法,探讨了四川盆地元坝地区上三叠统须二段致密砂岩储层孔隙演化与天然气成藏的关系.早成岩阶段结束时,储层的孔隙度已经降至8.7%,致密储层业已形成,此后一系列的胶结作用导致原生孔隙进一步减少,非均质性强.而元坝地区须二段天然气大规模充注时间为中成岩A期,此时储层巳经致密,总体反映出“储层先致密,天然气后成藏”的特点,天然气在储层中以“活塞式推进”方式运移,气藏富集主要受源岩的生烃强度

  10. Hydrofacies In Sandstones. Evidence For Feedback Between Sandstone Lithofacies and Permeability Development

    Science.gov (United States)

    Bloomfield, J. P.; Newell, A.; Moreau, M.

    In order to enhance our ability to develop effective numerical models of flow and con- taminant transport in the Permo-Triassic sandstone aquifer of the UK, relationships between lithofacies, rock mass characteristics (such as porosity and pore-throat size distribution), and permeability have been investigated through a series of case studies. Flow in the Permo-Triassic sandstones is primarily through the matrix. Permeability distribution is principally a function of the pore-throat size distribution and there is a relatively weak correlation with primary sedimentary lithofacies. It is observed that matrix permeability data broadly fall into two, discontinuous, sub-populations above and below about 1 mD. It is proposed that modification of primary sedimentary litho- facies by circulation of groundwater is the main control on the development of these two permeability sub-populations or hydrofacies. Identification of these two hydrofa- cies has significant implications for numerical modelling of the sandstones.

  11. Major influencing factors of water flooding in abnormally high-pressure carbonate reservoir

    Science.gov (United States)

    Qingying, Hou; Kaiyuan, Chen; Zifei, Fan; Libing, Fu; Yefei, Chen

    2017-01-01

    The higher pressure coefficient is the major characteristics of the abnormal high pressure carbonate reservoirs, which the pressure coefficient generally exceeds 1.2 and the initial formation pressure is higher than normal sandstone reservoirs. Due to the large pressure difference between initial formation and saturated pressure, oil wells are capable to production with high flow rate by the natural energy at early production stage. When the formation pressure drops to the saturation pressure, the water or gas is usually injected to stabilize the well productivity and sustain the formation pressure. Based on the characteristics of Kenkiak oilfield, a typical abnormal high pressure carbonate reservoir, a well group model is designed to simulate and analyze the influence factors on water flooding. The conclusion is that permeability, interlayer difference and reserve abundance are the main three factors on the water flooding development in these reservoirs.

  12. Evaluating the variability in surface water reservoir planning characteristics during climate change impacts assessment

    Science.gov (United States)

    Soundharajan, Bankaru-Swamy; Adeloye, Adebayo J.; Remesan, Renji

    2016-07-01

    This study employed a Monte-Carlo simulation approach to characterise the uncertainties in climate change induced variations in storage requirements and performance (reliability (time- and volume-based), resilience, vulnerability and sustainability) of surface water reservoirs. Using a calibrated rainfall-runoff (R-R) model, the baseline runoff scenario was first simulated. The R-R inputs (rainfall and temperature) were then perturbed using plausible delta-changes to produce simulated climate change runoff scenarios. Stochastic models of the runoff were developed and used to generate ensembles of both the current and climate-change-perturbed future runoff scenarios. The resulting runoff ensembles were used to force simulation models of the behaviour of the reservoir to produce 'populations' of required reservoir storage capacity to meet demands, and the performance. Comparing these parameters between the current and the perturbed provided the population of climate change effects which was then analysed to determine the variability in the impacts. The methodology was applied to the Pong reservoir on the Beas River in northern India. The reservoir serves irrigation and hydropower needs and the hydrology of the catchment is highly influenced by Himalayan seasonal snow and glaciers, and Monsoon rainfall, both of which are predicted to change due to climate change. The results show that required reservoir capacity is highly variable with a coefficient of variation (CV) as high as 0.3 as the future climate becomes drier. Of the performance indices, the vulnerability recorded the highest variability (CV up to 0.5) while the volume-based reliability was the least variable. Such variabilities or uncertainties will, no doubt, complicate the development of climate change adaptation measures; however, knowledge of their sheer magnitudes as obtained in this study will help in the formulation of appropriate policy and technical interventions for sustaining and possibly enhancing

  13. Composition of natural gas and crude oil produced from 10 wells in the Lower Silurian "Clinton" Sandstone, Trumbull County, Ohio: Chapter G.7 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    Science.gov (United States)

    Burruss, Robert A.; Ryder, Robert T.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    Natural gases and associated crude oils in the “Clinton” sandstone, Medina Group sandstones, and equivalent Tuscarora Sandstone in the northern Appalachian basin are part of a regional, continuous-type or basin-centered accumulation. The origin of the hydrocarbon charge to regional continuoustype accumulations is poorly understood. We have analyzed the molecular and stable isotopic composition of gases and oils produced from 10 wells in the “Clinton” sandstone in Trumbull County, Ohio, in an initial attempt to identify the characteristics of the accumulated fluids. The analyses show that the fluids have remarkably uniform compositions that are similar to previously published analyses of oils (Cole and others, 1987) and gases (Laughrey and Baldasarre, 1998) in Early Silurian reservoirs elsewhere in Ohio; however, geochemical parameters in the oils and gases suggest that the fluids have experienced higher levels of thermal stress than the present-day burial conditions of the reservoir rocks. The crude oils have an unusual geochemical characteristic: they do not contain detectable levels of sterane and triterpane biomarkers. The origin of these absences is unknown.

  14. Composition of natural gas and crude oil produced from 10 wells in the Lower Silurian "Clinton" Sandstone, Trumbull County, Ohio: Chapter G.7 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    Science.gov (United States)

    Burruss, Robert A.; Ryder, Robert T.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    Natural gases and associated crude oils in the “Clinton” sandstone, Medina Group sandstones, and equivalent Tuscarora Sandstone in the northern Appalachian basin are part of a regional, continuous-type or basin-centered accumulation. The origin of the hydrocarbon charge to regional continuoustype accumulations is poorly understood. We have analyzed the molecular and stable isotopic composition of gases and oils produced from 10 wells in the “Clinton” sandstone in Trumbull County, Ohio, in an initial attempt to identify the characteristics of the accumulated fluids. The analyses show that the fluids have remarkably uniform compositions that are similar to previously published analyses of oils (Cole and others, 1987) and gases (Laughrey and Baldasarre, 1998) in Early Silurian reservoirs elsewhere in Ohio; however, geochemical parameters in the oils and gases suggest that the fluids have experienced higher levels of thermal stress than the present-day burial conditions of the reservoir rocks. The crude oils have an unusual geochemical characteristic: they do not contain detectable levels of sterane and triterpane biomarkers. The origin of these absences is unknown.

  15. The Reservoir Characteristics of Chang 8 Oil Layer Group From the Yanchang Formation in Zhenjing Area, Ordos Basin%鄂尔多斯盆地镇泾区块延长组长8油层组砂岩储层特征

    Institute of Scientific and Technical Information of China (English)

    张霞; 林春明; 陈召佑; 潘峰; 周健; 俞昊

    2012-01-01

    The Chang 8 sandstones of the Yanchang Formation in Zhenjing area of Ordos Basin, occurring as one of the major reservoirs, mainly consist of feldspathic litharenite and lithic arkose. They belong to extra-low porosity and permeability reservoirs, with dissolved intergranular pores as the chief accumulation space, and the reduced-neck, lamellar and curved lamellar pore throat as the main throat type. Based on the pattern of capillary pressure curve, porosity, permeability, displacement pressure and pore throat radius, the Chang 8 sandstones can be classified as type I, II and III, in which the type II are the main reservoirs. There are four factors affecting the reservoir characteristics of Chang 8 sandstones: sedimentary processes, diagenesis, fractures, and hydrocarbon emplacement. The best reservoir quality is developed in the subaqueous distributary channels of braided river delta fronts, and the one of medium sandstones hetter than that of fine sandstones. Otherwise, the reservoir qualifies of sandstones rich in quartz, feldspars and metamorphic rock fragments are better than those of sandstones with high contents of sedimentary and igneous rock fragments, as well as mica. The diagenetic processes have exerted dual impacts on the reservoir quality. The constructive one is characterized by dissolution and pore-lining chlorite cementation, and the sandstone intervals with them occurring together are the optimum zones for the oil and gas accumulation. The destructive one involves mechanical compaction and the late stage carbonate cementation. The fractures, with the NE-SW tectonic ones formed in the late stage of Cretaceous-Paleogene as the main type, contribute more to permeability than storage, making the heterogeneity of reservoirs intensified. The effects of hydrocarbon emplacement on reservoir quality are characterized by the reconstruction and conservation of porosity dissolved by organic acid in hydrocarbon.%延长组长8油层组是鄂尔多斯盆地镇

  16. Laboratory and simulation approach to the polymer EOR evaluation in German reservoir characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, S.; Hincapie-Reina, R.; Ganzer, L. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE

    2013-08-01

    Nowadays, polymer flooding is widely used as it enhances oil recovery. As polymer has relatively higher viscosity than water, which leads to better mobility ratio compared to it, and thus better sweep efficiency. However, this technique is limited by some factors. As normal polymers are not tolerant to high temperature or salinity or hardness, which lead to lose of most their viscosity, and thus lost their function in enhanced oil recovery. Therefore, new polymers which are resistant to high temperature, high salinity or other factors which may happen in the reservoir should be employed. In that direction, the present work focus in characterize two different polymers, Flopaam AN 125 and ZLPAM 22051, how they would be influenced by polymer concentration, salinity, shear rate and temperature, and to predict how they would work in the reservoir. A synthetic brine from a German reservoir (Valendis, Suderbruch Field) is used to analyze the polymer. In many different previous experiments is observed the divalent and monovalent effect of salt in polymers was carried out. Rheology characterization was done under the reservoir conditions to get the best approximation related to concentration, shear rate and temperature effect; filtration ratio and filterability plot are used as a quality check for the solutions. Finally, all the data is used into the Polymer Flood Predictive Model (PFPM), to figure out how polymer acted in German typical reservoir conditions, and the specific incremental in oil recovery and effect due the possible polymer application, which might provide information for future polymer flooding application decisions. (orig.)

  17. Spatiotemporal associations of reservoir nutrient characteristics and the invasive, harmful alga Prymnesium parvum in West Texas

    Science.gov (United States)

    VanLandeghem, Matthew M.; Farooqi, Mukhtar; Southard, Greg M.; Patino, Reynaldo

    2015-01-01

    Golden alga (Prymnesium parvum) is a harmful alga that has caused ecological and economic harm in freshwater and marine systems worldwide. In inland systems of North America, toxic blooms have nearly eliminated fish populations in some systems. Modifying nutrient profiles through alterations to land or water use may be a viable alternative for golden alga control in reservoirs. The main objective of this study was to improve our understanding of the nutrient dynamics that influence golden alga bloom formation and toxicity in west Texas reservoirs. We examined eight sites in the Upper Colorado River basin, Texas: three impacted reservoirs that have experienced repeated golden alga blooms; two reference reservoirs where golden alga is present but nontoxic; and three confluence sites downstream of the impacted and reference sites. Total, inorganic, and organic nitrogen and phosphorus and their ratios were quantified monthly along with golden alga abundance and ichthyotoxicity between December 2010 and July 2011. Blooms persisted for several months at the impacted sites, which were characterized by high organic nitrogen and low inorganic nitrogen. At impacted sites, abundance was positively associated with inorganic phosphorus and bloom termination coincided with increases in inorganic nitrogen and decreases in inorganic phosphorus in late spring. Management of both inorganic and organic forms of nutrients may create conditions in reservoirs unfavorable to golden alga.

  18. Petrological characteristics and provenance analysis of sandstones of Gonjo Formation in Nangqen basin%囊谦盆地贡觉组砂岩岩石学特征与物源分析

    Institute of Scientific and Technical Information of China (English)

    杜后发; 朱志军; 姜勇彪; 杨天南; 刘燕学; 郭福生

    2011-01-01

    在详细观察描述砂岩宏观特征的基础上,对贡觉组碎屑岩骨架组分、常量元素变化规律进行分析,研究了该地区砂岩的岩石学和物源特征,并指出囊谦盆地的沉积序列由下而上(Eg1~Eg5)具砂岩成分成熟度由差变好再变差的趋势.物源演变趋势分析揭示,沉积早期盆地北、西北部的构造运动强烈,为第二段(Eg2)沉积时期提供成熟度很低的碎屑物质,而第一段(Eg1)至第二段(Eg2)沉积时期长石含量降低而岩屑含量递增,构造强度逐渐增强,冲积扇-河流相处于发育阶段;第三段(Eg3)层序发育时,构造运动逐渐减弱,长石含量增高而岩屑含量逐渐降低,但盆地西北、北部继续遭受强烈剥蚀,东部和南部则下降接受沉积,并伴有岩浆活动,湖泊层序发育达到顶峰;第四段(Eg4)和第五段(Eg2)层序沉积时转而接受过渡型再旋回造山带区,长石含量先增加后降低而岩屑含量先降低后增加.%Nangqen basin is a typical representative of the medium-mini-type Paleogene basins controlled by local NNW-treading faults distributed along Jinsha River-Red River belt on the northeastern margin of Qinghai-Tibet plateau.Gonjo Formation is perfectly developed and dominated by a set of thick-bedded, purplish red, red terrigenous clastic rock formation containing gypsum rock in association with large-scale high potassium rocks in Nangqen basin.Combined with results of field geological investigation and analysis and determination of samples as well as quantitative studies of the sandstone framework detrital composition of the Paleogene strata, the authors systematically analyzed petrologic characteristics of the sandstones of the Gonjo Formation in Nangqen basin in the framework of the basin evolution.According to the analysis of geochemical features of sandstones of the Gonjo Formation, the characteristics of paleoclimate, paleoenvironment and provenance in the study area were revealed.For sandstones

  19. Nitrogen Removal Characteristics of a Newly Isolated Indigenous Aerobic Denitrifier from Oligotrophic Drinking Water Reservoir, Zoogloea sp. N299

    Directory of Open Access Journals (Sweden)

    Ting-Lin Huang

    2015-05-01

    Full Text Available Nitrogen is considered to be one of the most widespread pollutants leading to eutrophication of freshwater ecosystems, especially in drinking water reservoirs. In this study, an oligotrophic aerobic denitrifier was isolated from drinking water reservoir sediment. Nitrogen removal performance was explored. The strain was identified by 16S rRNA gene sequence analysis as Zoogloea sp. N299. This species exhibits a periplasmic nitrate reductase gene (napA. Its specific growth rate was 0.22 h−1. Obvious denitrification and perfect nitrogen removal performances occurred when cultured in nitrate and nitrite mediums, at rates of 75.53% ± 1.69% and 58.65% ± 0.61%, respectively. The ammonia removal rate reached 44.12% ± 1.61% in ammonia medium. Zoogloea sp. N299 was inoculated into sterilized and unsterilized reservoir source waters with a dissolved oxygen level of 5–9 mg/L, pH 8–9, and C/N 1.14:1. The total nitrogen removal rate reached 46.41% ± 3.17% (sterilized and 44.88% ± 4.31% (unsterilized. The cell optical density suggested the strain could survive in oligotrophic drinking water reservoir water conditions and perform nitrogen removal. Sodium acetate was the most favorable carbon source for nitrogen removal by strain N299 (p < 0.05. High C/N was beneficial for nitrate reduction (p < 0.05. The nitrate removal efficiencies showed no significant differences among the tested inoculums dosage (p > 0.05. Furthermore, strain N299 could efficiently remove nitrate at neutral and slightly alkaline and low temperature conditions. These results, therefore, demonstrate that Zoogloea sp. N299 has high removal characteristics, and can be used as a nitrogen removal microbial inoculum with simultaneous aerobic nitrification and denitrification in a micro-polluted reservoir water ecosystem.

  20. 鄂尔多斯盆地长7浊积岩特征及成藏条件分析%ANALYSES ON THE CHARACTERISTICS AND RESERVOIR FORMING CONDITIONS OF CHANG 7 GROUP TURBIDITE IN ORDOS BASIN

    Institute of Scientific and Technical Information of China (English)

    时保宏; 张艳; 张雷; 杨亚娟

    2013-01-01

    利用岩心、测井等资料对鄂尔多斯盆地长7浊积岩特征及成藏条件的分析结果表明,长7油层组沉积层理、沉积构造及砂岩粒度等反映晚三叠世延长组长7沉积时在深湖—半深湖相发育浊积岩.长7浊积岩的电性响应特征表现为自然伽马曲线具有明显的齿化现象,在地震反射剖面上则表现为不稳定沉积、相带变化大等特点.浊积岩储集体的物性条件相对较差,孔隙度平均为8.5%,渗透率平均为0.12×10-3μm2,属超低孔、低渗储层,但由于其紧邻优质烃源岩,成藏条件优越,可大面积成藏.%With the help of the data of cores and well loggings, the characteristics of the turbidite and the conditions of the reservoir formation are analyzed for the above group of Ordos Basin. The analyzed results show that the sedimentary beddings, structures, sandstone particles and so on of the reservoir group reflect the deep and semi-deep lake facies developed environments of Late Triassic Yanchang Formation. The response characteristics of electrical property of Chang 7 Group turbidite display the obvious toothed phenomenon of GR ( gamma ray) curve, and moreover show the features of the unstable sedimentation and enormous facies changes on the seismic reflection profiles. The physical conditions of the turbidite accumulating body are relatively poorer, whose average porosity and permeability are respectively 8. 5% and 0. 12 × 10-3μm2 , belong to ultra-low porosity and low permeability reservoir. However, for the body is close to the regions with high-quality source rocks and favorable hydrocarbon enriched conditions, so it can form reservoirs on a large scale.

  1. Origin of the Silurian Crude Oils and Reservoir Formation Characteristics in the Tazhong Uplift

    Institute of Scientific and Technical Information of China (English)

    YANG Haijun; LI Sumei; PANG Xiongqi; XIAO Zhongyao; GU Qiaoyuan; ZHANG Baoshou

    2010-01-01

    The Silurian stratum in the Tazhong uplift is an important horizon for exploration because it preserves some features of the hydrocarbons produced from multi-stage tectonic evolution.For this reason,the study of the origin of the Silurian oils and their formation characteristics constitutes a major part in revealing the mechanisms for the composite hydrocarbon accumulation zone in the Tazhong area.Geochemical investigations indicate that the physical properties of the Silurian oils in Tazhong vary with belts and blocks,i.e.,heavy oils are distributed in the TZ47-15 well-block in the North Slope while normal and light oils in the No.I fault belt and the TZ16 well-block,which means that the oil properties are controlled by structural patterns.Most biomarkers in the Silurian oils are similar to that of the Mid-Upper Ordovician source rocks,suggesting a good genetic relationship.However,the compound specific isotope of n-alkanes in the oils and the chemical components of the hydrocarbons in fluid inclusions indicate that these oils are mixed oils derived from both the MidUpper Ordovician and the Cambrian-Lower Ordovician source rocks.Most Silurian oils have a record of secondary alterations like earlier biodegradation,including the occurrence of "UCM" humps in the total ion current (TIC) chromatogram of saturated and aromatic hydrocarbons and 25-norhopane in saturated hydrocarbons of the crude oils,and regular changes in the abundances of light and heavy components from the structural low to the structural high.The fact that the Silurian oils are enriched in chain alkanes,e.g.,n.alkanes and 25-norhopane,suggests that they were mixed oils of the earlier degraded oils with the later normal oils.It is suggested that the Silurian oils experienced at least three episodes of petroleum charging according to the composition and distribution as well as the maturity of reservoir crude oils and the oils in fluid inclusions.The migration and accumulation models of these oils in

  2. 致密砂岩气藏可动流体赋存特征的微观地质因素:以苏里格气田东部盒8段储层为例%Microscopic Geological Factors of Movable Fluid Distribution in the Tight Sandstone Gas Reservoir:Taking the He 8 Reservoir in the East of Sulige Gas Field as An Example

    Institute of Scientific and Technical Information of China (English)

    任大忠; 孙卫; 卢涛; 李跃刚; 张茜; 周楷

    2015-01-01

    Taking the He 8 tight sandstone gas reservoir in the east of Sulige gas field as an example,the authors conducted a series of experiments including nuclear magnetic resonance,constant-speed mercury injection, casting thin slice,reservoir property,X-ray and so on.With all these techniques,we discussed the microscop-ic geological factors which affect the distribution of movable fluid.The researches show that:the saturation of movable fluid in He 8 reservoir was low while the distribution of T2 spectrum was bimodal pattern with high left side and low right side.The filling of clay mineral and pore types were the key factors that resulted in complicat-ed pore structures.Pore structure had great impact on the saturation of movable fluid.Facial porosity,throat ra-dius,the rate of pore radius and throat radius were the key factors which affected the saturation of movable flu-id.The effective pore volume and sorting coefficients affected the saturation of movable fluid obviously,while the physical properties of reservoir,clay mineral,effective throat volume and pore radius had moderate effect on the saturation of movable fluid.%以苏里格气田东部盒8段典型的致密砂岩气藏为例,运用核磁共振、恒速压汞、铸体薄片、物性、X -衍射等实验资料,探讨了影响可动流体赋存差异的微观地质因素。结果表明,盒8段储层可动流体饱和度低,T2谱分布均为左高峰右低峰的双峰态;黏土矿物的充填与孔隙类型是孔隙结构复杂的重要因素,孔隙结构是影响可动流体赋存特征的关键;面孔率、喉道半径、孔喉半径比是影响可动流体饱和度的主要因素,有效孔隙体积、分选系数对可动流体饱和度影响明显,储层物性、黏土矿物、有效喉道体积、孔隙半径对可动流体饱和度影响较弱。

  3. A vacuum filtrating device and technique to separate authigenic illites from sandstone reservoirs with microporous membrane%油气储层自生伊利石分离提纯微孔滤膜真空抽滤装置与技术

    Institute of Scientific and Technical Information of China (English)

    张有瑜; 罗修泉

    2011-01-01

    自生伊利石分离提纯是砂岩油气储层自生伊利石K-Ar同位素测年分析的关键技术之一.关于自生伊利石粘土组分的分离,国内外大多是采用高速、超高速离心分离技术.与高速、超高速离心分离技术相比,该文所介绍的微孔滤膜真空抽滤装置与技术具有较为明显的优越性,如操作简便、速度快、效率高、质量好等.文中介绍了装置构成、连接及使用说明、装置特点暨5个方面的技术创新和技术流程,论述了其分离提纯效率和质量以及应用现状和应用前景.5项技术创新克服了以往真空抽滤装置与技术的操作繁琐、效率较低、实用性不强等一系列技术难题,使其可以转化为成型固定设备投入日常生产与科研实验,为自生伊利石分离提纯开创了一种新途径,具有非常广阔的应用前景.%The separation of authigenic illite is a key point in the K-Ar dating of authigenic illite in sandstone reservoir. High speed and ultra-high speed centrifuges are used home and abroad. In this paper, a new method using microporous membrane and vacuum filtration is introduced, which is outstanding for easy operation, fast speed, high efficiency and good quality. The device structure, assemblage and operation instruction are illustrated firstly. And secondly, the characteristics or innovations in 5 aspects of the device and the technological procedure are described in details. Finally, the separating efficiency, quality, application situation and prospect of the device and the technique are discussed. Series of technological problems of the elder vacuum filtrating device, such as miscellaneous operation, low efficiency and poor practicality, have been overcome by the 5 innovations. The new device could be developed into formed equipment for daily use and for scientific research and experimentation, providing a new method for authigenic illite separation, and also have a broad potential applicability in

  4. Characteristics of water and wetland plants of the water reservoirs in the UMCS Botanical Garden in Lublin, Poland

    Directory of Open Access Journals (Sweden)

    Agnieszka Dąbrowska

    2014-07-01

    Full Text Available The aim of the study was to compile an inventory and determine the ecological characteristics of the spontaneous flora of the restored water reservoirs and their wet banks in the western part of Lublin in the years 1997–2013. The study objects are small reservoirs located at the UMCS Botanical Garden in the Czechówka River valley. These ponds are subjected to strong anthropogenic pressure. 68 plant species from 33 families and 58 genera were recorded in the flora of the ponds and their wet banks. An important feature of the described water bodies is the large proportion of native species (94% of the flora. Cryptophytes and hemicryptophytes as well as biological groups combining the features of hemicryptophytes and cryptophytes are the predominant life forms. Perennials account for 80% of the flora. The ponds and their wet banks are inhabited by 25 medicinal and 19 bee forage plants.

  5. 砂页岩中泥化夹层的工程地质特性分析%Analysis of the Engineering Geological Characteristics of the Argillation Intermediate Layer in Sandstone and Shale

    Institute of Scientific and Technical Information of China (English)

    李桂平

    2012-01-01

    针对我国华北地区分布广泛的砂页岩中存在不特定发育的泥化夹层,当作为建筑物地基时,存在软弱、变形量大、抗剪强度低等问题,文中依据多个大中型工程的地质勘察成果,在大量现场试验和室内试验资料的基础上,深入分析了泥化夹层的特点、成因、膨胀性和抗剪性能;对工程建筑物地基中有可能出现泥化夹层时,提出了在砂页岩地区进行工程地质勘察应该注意的事项和工程处理措施,以期为今后在砂页岩中建设的工程项目提供借鉴.%For the widely existing sandstone and shale areas in North China,one of the main engineering geological problems is the existance of no n-specifially developed argillation intermediate layer in the rock stratum.When it is used as the foundations of buildings,there exist several problems like weakness,large deformation,and low shear strength,which affect the foundation stability.According to the geological survey results of many large and medium-sized projects,and on the basif of a number of field test and indoor test data,this paper gave in-depth analysis of the characteristics,the cause of formation,expansion,and shear resistance properties of the argillation intermediate layer.For the building foundation with argillation intermediate layer,some announcements and engineering measures were put forward to the engineering geological investigation in the sandstone and shale areas.It provides a reference for construction projects in the sandstone and shale area in the future.

  6. Subsurface petroleum geology of Santa Rosa sandstone (Triassic), northeast New Mexico

    Science.gov (United States)

    Broadhead, R. F.

    The Santa Rose Sandstone (Triassic) occurs at depths of less than 2,000 ft over most of northeast New Mexico. Two major petroleum accumulations are known to exist in it. These outcrops of oil impregnated sandstone are known as the Santa Rosa tar sands. The oil in the tar sands is viscous and heavy. The other known petroleum accumulation is a pool of heavy oil that occurs at depths of 400 ft to 800 ft in northeast Guadalupe County. Attempts are being made to recover the heavy oil with steamflooding in two small pilot fields. The lower and upper sandstone units are blanket deposits composed mostly of fine to medium grained porous sandstones and minor red siliciclastic mudstones. The middle mudstone unit is a blanket deposit composed chiefly of red siliciclastic mudstones and minor lenticular sandstones. Stratigraphic and petrographic studies indicate that good reservoirs are widespread in the lower and upper sandstone unit. The blanket geometry of the lower and upper sandstone units indicates that structure probably plays an important or even dominant role in the trapping of any undiscovered hydrocarbons in the Santa Rosa. Oil proximal to the outcrop belt of the Santa Rosa Sandstone has probably been flushed by recently recharged fresh ground water. Although the source of the oil in Santa Rosa Sandstone is not definitely known, geochemical studies point to the San Andres Formation (Permian) or possibly Pennsylanian rocks.

  7. Diagenesis and porosity evolution of tight sand reservoirs in Carboniferous Benxi Formation, Southeast Ordos Basin

    Science.gov (United States)

    Hu, Peng; Yu, Xinghe; Shan, Xin; Su, Dongxu; Wang, Jiao; Li, Yalong; Shi, Xin; Xu, Liqiang

    2016-04-01

    The Ordos Basin, situated in west-central China, is one of the oldest and most important fossil-fuel energy base, which contains large reserves of coal, oil and natural gas. The Upper Palaeozoic strata are widely distributed with rich gas-bearing and large natural gas resources, whose potential is tremendous. Recent years have witnessed a great tight gas exploration improvement of the Upper Paleozoic in Southeastern Ordos basin. The Carboniferous Benxi Formation, mainly buried more than 2,500m, is the key target strata for hydrocarbon exploration, which was deposited in a barrier island and tidal flat environment. The sandy bars and flats are the favorable sedimentary microfacies. With an integrated approach of thin-section petrophysics, constant velocity mercury injection test, scanning electron microscopy and X-ray diffractometry, diagenesis and porosity evolution of tight sand reservoirs of Benxi Formation were analyzed in detail. The result shows that the main lithology of sandstone in this area is dominated by moderately to well sorted quartz sandstone. The average porosity and permeability is 4.72% and 1.22mD. The reservoirs of Benxi Formation holds a variety of pore types and the pore throats, with obvious heterogeneity and poor connection. Based on the capillary pressure curve morphological characteristics and parameters, combined with thin section and phycical property data, the reservoir pore structure of Benxi Formation can be divided into 4 types, including mid pore mid throat type(I), mid pore fine throat type(II), small pore fine throat type(III) and micro pro micro throat type(Ⅳ). The reservoirs primarily fall in B-subsate of middle diagenesis and late diagenesis, which mainly undergo compaction, cmentation, dissolution and fracturing process. Employing the empirical formula of different sorting for unconsolideated sandstone porosity, the initial sandstone porosity is 38.32% on average. Quantitative evaluation of the increase and decrease of

  8. Heavy mineral concentrations in the sandstones of Amij Formation with particular emphasis on the mineral chemistry and petrographic characteristics of monazite, western desert of Iraq

    Science.gov (United States)

    Kettanah, Yawooz A.; Ismail, Sabah A.

    2016-11-01

    The heavy minerals in the clastic unit of the Lower Jurassic Amij Formation exposed in the western desert of Iraq were studied. The uppermost part of the clastic unit contains thin, placer-like black sandstone horizons that are radioactive and abnormally rich in heavy minerals (0.6-56%), dominated by opaque (65%) and transparent (35%) heavy minerals. The minerals, in the order of decreasing abundance are pseudorutile, goethite, zircon, hematite, magnetite, monazite, rutile, leucoxene, tourmaline, ilmenite, chromite, and few others. Electron probe microanalysis (EPMA), microscopic and autoradiographic observations and analysis showed that the monazite is monazite-(Ce) type with an average composition of (Ce0.39Nd0.16La0.19Pr0.04Sm0.02Gd0.02Eu0.01Y0·04Th0·06U0·01Ca0·05Fe0.01)(P0·98Si0.03)O4. Monazite consists predominantly of REE-oxides (57.93%) and P2O5 (29.31%), with minor amounts of ThO2 (6.60%), Y2O3 (1.92%), UO2 (0.76%), CaO (1.14%), SiO2 (0.69%), and FeOt (0.17%). The dominant compositional substitution operating between REE and P were a mixture of the complex cheralite type substitution ([REE]-2 [Th][Ca]) and the coupled huttonite type substitution ([REE]-1 [P]-1 [Th][Si]). The chondrite-normalized REE distribution patterns of monazite show enrichment in LREE with positive Eu- and Pr-anomalies of 1.46 and 9.13, respectively. The median values of (La/Sm)CN and (La/Nd)CN ratios are 4.35 and 1.97, respectively. Zircon which is the dominant transparent mineral is Hf-rich that is composed of 30.61% SiO2, 57.58% ZrO2, 7.03% HfO2, 2.04% Y2O3, 0.56% ThO2, 0.19% UO2, and 0.19% Al2O3 corresponding to a formula (Zr0.909Hf0.065Th0·004U0·001Y0.031)Σ1.011(Si3·966Al0.028)Σ0.999O4. Rutile and tourmaline form 7% and 4% of the heavy minerals. Ilmenite which is one of the predominant heavy minerals forms 2.5% of the opaques because it is pervasively altered to Ti-Fe oxides. In addition of zircon and monazite, the chemical compositions of most of the other heavy

  9. A study of relations between physicochemical properties of crude oils and microbiological characteristics of reservoir microflora

    Science.gov (United States)

    Yashchenko, I. G.; Polishchuk, Yu. M.; Peremitina, T. O.

    2015-10-01

    The dependence of the population and activity of reservoir microflora upon the chemical composition and viscosity of crude oils has been investigated, since it allows the problem of improvement in the technologies and enhancement of oil recovery as applied to production of difficult types of oils with anomalous properties (viscous, heavy, waxy, high resin) to be solved. The effect of the chemical composition of the oil on the number, distribution, and activity of reservoir microflora has been studied using data on the microbiological properties of reservoir water of 16 different fields in oil and gas basins of Russia, Mongolia, China, and Vietnam. Information on the physicochemical properties of crude oils of these fields has been obtained from the database created at the Institute of Petroleum Chemistry, Siberian Branch on the physicochemical properties of oils throughout the world. It has been found that formation water in viscous oil reservoirs is char acterized by a large population of heterotrophic and sulfate reducing bacteria and the water of oil fields with a high paraffin content, by population of denitrifying bacteria.

  10. Combined geophysical, geochemical and geological investigations of geothermal reservoir characteristics in Lower Saxony, Germany

    Science.gov (United States)

    Hahne, B.; Thomas, R.

    2012-04-01

    The North German basin provides a significant geothermal potential, although temperature gradients are moderate. However, deep drilling up to several thousand meters is required to reach temperatures high enough for efficient generation of geothermal heat and electric power. In these depths we have not much information yet about relevant physical properties like porosity or permeability of the rock formations. Therefore the costs of developing a geothermal reservoir and the risk of missing the optimum drilling location are high. The collaborative research association "Geothermal Energy and High Performance Drilling" (gebo) unites several universities and research institutes in Lower Saxony, Germany. It aims at a significant increase of economic efficiency by introducing innovative technology and high tech materials resisting temperatures up to 200 °C in the drilling process. Furthermore, a better understanding of the geothermal reservoir is essential. gebo is structured into four main fields: Drilling Technology, Materials, Technical Systems and Geosystem. Here, we show the combined work of the Geosystem group, which focuses on the exploration of geological fault zones as a potential geothermal reservoir as well as on modeling the stress field, heat transport, coupled thermo-hydro-mechanical processes, geochemical interactions and prediction of the long-term behavior of the reservoir. First results include combined seismic and geoelectric images of the Leinetalgraben fault system, a comparison of seismic images from P- and S-wave measurements, mechanical properties of North German rocks from field and laboratory measurements as well as from drill cores, seismological characterization of stimulated reservoirs, a thermodynamic "gebo" database for modeling hydrogeochemical processes in North German formation waters with high salinity and at high temperatures, stress models for specific sites in northern Germany, and modeling results of permeability and heat transport

  11. Petrological Characteristics of the Silurian Asphaltic Sandstones in Talimu Basin and the Significance of Studying Them%塔里木盆地志留系沥青砂岩岩石学特征及其意义

    Institute of Scientific and Technical Information of China (English)

    刘洛夫; 方家虎; 王鸿燕

    2001-01-01

    In order to investigate the origin and evolution of the Silurian asphaltic sandstones in Talimu Basin, the authors studied in detail the macrocharacter, microcharacter, reflectance (Ro%) and fluoroscopic character of the asphalts in the sandstones, the characteristics of the sandstones in petrology and diagenesis, diagenetic succession and diagenetic stage division by means of petrology and organic petrology. In the Silurian asphaltic sandstones from Talimu Basin, there are grayish-black—brownish-gray dry asphalts, soft asphalt and viscous crude oil. Macroscopically, there are two types of asphalt distribution, one is uniform distribution (massive), and another is non-uniform distribution (mottled, being further divided into bedding, lenticular and fracturing). Microscopically, they are classified into packing and disseminating distributions. The diagenetic succession of the sandstones is as follows: mechanical compaction (plastic deformation of grains)→ formation and conversion of clay film→ authigenic overgrowth of quartz and dissolution of aluminosilicate→ precipitation of crystal stock calcite→ pressolutional overgrowth of quartz→ conversion form calcite to ankerite→ precipitation of chlorite. The diagenetic stage can be divided into subphase A of eodiagenesis, subphase B of eodiagenesis, subphase A of telodiagenesis and subphase B of telodiagenesis. The asphalt reflectance (BRo) shows that formation of the asphalt was hardly affected by thermal action. Practically, the Silurian asphaltic sandstones were formed mainly by intense bio-degradation and the BRo value reflects the bio-degradation grade of the asphalt. Diagenesis data indicate that the Silurian asphaltic sandstones are the products of multiple fillings of hydrocarbon.%为了探讨塔里木盆地志留系沥青砂岩的成因和演化期次,利用岩石学、有机岩石学的方法,研究了该套沥青砂岩中沥青的表观特征、显微特征、沥青反射率和荧光

  12. Experimental Analysis of Sandstone and Travertine

    Directory of Open Access Journals (Sweden)

    T. Doležel

    2004-01-01

    Full Text Available Sandstone and travertine are sedimentary rocks. The former is clastic, while the latter is sourced by chemical precipitation from hot springs. Their applications in civil engineering structures are mostly influenced by the ability to carry compression loading. A three-point bending experiment is usually used to determine material characteristics. However it does not correspond very well to applicatiosn in structures. For this reason we used a uniaxial compression test to obtain the modulus of elasticity and the stress-strain diagram. To obtain detailed information about the crystalline structure of sandstone and travertine a microscopic analysis wascarried out, using optical microscopy and an EDAX multichannel spectrometer for elementary microanalysis. 

  13. Characteristics of a fault zone in Triassic Lower Bunter as an outcrop analogue of a potential geothermal reservoir of the Upper Rhine Graben.

    Science.gov (United States)

    Bauer, Johanna F.; Meier, Silke; Philipp, Sonja L.

    2014-05-01

    rebound hardness, or the compressive strength, respectively, decreases near the fault core. The core zone can be divided into a central and a distal part with different deformation characteristics. The distal part combines characteristics from the central core zone and the damage zone and contains the highest fracture frequency. But since there occur also deformation bands the permeability is presumably lower than in the damage zone. In contrast, the most common features in the central fault core are slip surfaces, deformation bands and host rock lenses. We conclude that damage zones in Triassic sandstones may increase fluid flow and are potential drilling targets for geothermal projects. Because the fracture connectivity is low hydraulic stimulations may be needed to get a hydraulically active fracture network. This project is part of the Research and Development Project AuGE (Outcrop Analogue Studies in Geothermal Exploration). Project partners are the companies Geothermal Engineering GmbH and GeoEnergy GmbH as well as the Universities of Heidelberg and Erlangen. The project is funded by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) within the framework of the 5th Energy Research Program (FKZ 0325302).

  14. Study on the cutting plane friction law of sandstone

    Institute of Scientific and Technical Information of China (English)

    ZHAI Ying-da (翟英达); KANG Li-xun(康立勋)

    2003-01-01

    The friction characteristics of rock damage plane have important impact on the stability of block structure formed after the stratum is broken. The mechanics properties of rock damage plane are described by parameters such as roughness coefficient, wall compress strength and basic friction angle. These three coefficients for fine grain sandstone and medium-granular sandstone and grit sandstone are test. The friction stress is researched at the condition of different normal compressive stress acting on the tension damage plane. The friction law of tension damage plane of sandstone abided by is summed up. This law will provide scientific basis for block structure stability judging in basic roof stratum and roof pressure intensity calculating.

  15. Anisotropic characteristics of electrical responses of fractured reservoir with multiple sets of fractures

    Institute of Scientific and Technical Information of China (English)

    Shen Jinsong; Su Benyu; Guo Naichuan

    2009-01-01

    In fractured reservoirs, the fractures not only provide the storage space for hydrocarbons, but also form the main flow channels which connect the pores of the matrix, so fractures dominate the productivity of reservoirs.However, because of the heterogeneity and randomness of the distribution of fractures, exploration and evaluation of fractured reservoirs is still one of the most difficult problems in the oil industry.In recent years, seismic anisotropy has been applied to the assessment of fractured formations, whereas electrical anisotropy which is more intense in fractured formations than seismic anisotropy has not been studied or used so extensively.In this study, fractured reservoir models which considered multiple sets of fractures with smooth and partly closed, rough surfaces were established based on the fractures and pore network, and the vertical and horizontal electrical resistivities were derived as a function of the matrix and fracture porosities according to Ohm's law.By using the anisotropic resistivity equations, variations of the electrical anisotropy of three types of fractured models under the conditions of free pressure and confining pressure were analyzed through the variations of the exerted pressure, matrix porosity, fracture aperture and formation water resistivity.The differences of the vertical and horizontal resistivities and the anisotropy between the connected and non-connected fractures were also analyzed.It is known from the simulated results that an increase of the confining pressure causes a decrease of electrical anisotropy because of the elasticity of the closed fractures and the decrease of the fracture aperture.For a fixed fracture porosity, the higher the matrix porosity, the weaker the electrical anisotropy in the rock formation.

  16. 苏里格致密砂岩气田储层岩石孔隙结构及储集性能特征%Characteristics of the pore structure and storage capability of Sulige tight sandstone gasfield

    Institute of Scientific and Technical Information of China (English)

    王国亭; 何东博; 王少飞; 程立华

    2013-01-01

    基于覆压条件下储层渗透率的变化特征,分析认为苏里格气田整体为致密砂岩气田.在50~60 MPa的覆压下,渗透率相对变化量的1/3次方与常压渗透率的1/2次方表现为线性关系.储层孔隙度表现出一定的覆压敏感性,覆压孔隙度与常压孔隙度比值的1/3次方与常压孔隙度表现出较好的线性关系.扫描电镜及常规压汞实验分析表明,储层孔隙半径表现为百微米级至纳米级尺度的连续分布,渗透率越小的储层微米级孔隙所占比例越少,纳米级孔隙越多;储层喉道半径总体小于1 μm,表现为纳米级尺度的连续分布.束缚饱和度与渗透率具有一定的负相关性,与特定渗透率值对应的束缚饱和度并非定值,而是一个数值范围.拟合分析表明常压孔隙度与单位厚度储能系数呈较好的幂函数关系.由于物性越差的储层覆压敏感性越强,含气饱和度越低,其储气能力也越差,因此蕴含的天然气资源也越小,物性较好的储层则反之.%The Sulige gasfield is on the whole regarded as a tight sandstone field based on the permeability of reservoirs under overburden.There exists a linear relation between the permeability with a relative variation range to the 1/3 power and the normal one to the 1 /2 power under 50~60 MPa.The porosity of reservoirs is sensitive to overburden stress to some extent and a fairly good linear relation is also found between the 1/3 power of the overburden porosity/normal porosity ratio and the normal porosity.Data of the SEM and mercury-injection experiment indicate that the pore radius shows a continuum distribution from the hundred micrometer scale to the nanometer one.The lower the permeability of reservoirs,the less proportion the micron-pore has and the more pore-space the nano pore takes.Most throat radius is less than 1 μm,representing a nanometer-scale continuum distribution.There exists a negative correlation between the irreducible water

  17. Quantitative studies of hydrocarbon loss of the Silurian bitumen sandstone in the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The evolution of Tarim Basin experienced several tectonic movements,of which Caledonian movement caused a serious damage to reservoirs of Silurian. The earlier reservoirs size and the later hydrocarbon loss are two key factors to exploration prospect of Silurian. On the basis of net thickness of bituminous sandstone and recovery coefficient of crude oil converting to bitumen,the scale of the hydrocarbon loss of palaeo-accumulation in bitumen sandstone of Silurian was calculated (86.30×108t). The deter-mination of net thickness of bitumen sandstone was completed mainly by several methods,such as physical property demarcation,observing lithology,grains with oil inclusion (GOI) technology,and quantitative grains fluorescence (QGF) technology. The samples of black sandstone and white sand-stone were collected and compared by means of the methods mentioned above. The results showed that there was little hydrocarbon,or none,in the white sandstone. The recovery coefficient was ob-tained by the analyses of plentiful physical parameters of crude oil and bitumen sandstone,based on the hypothesis that nonhydrocarbon compounds and bitumen were invariable in the process of bitu-men forming. The calculated result,which is more scientific and actual,indicates the exploration pros-pect is more promising in Silurian of the Tarim Basin.

  18. The Silurian Reservoir Bed-Differentiated Asphalts in Tarim Basin and Modeling Experiments on Their Origin

    Institute of Scientific and Technical Information of China (English)

    刘洛夫; 刘宏江; 王洪玉; 曾溅辉

    2002-01-01

    There is a type of asphalt that originated from differentiation from reservoir bed (named reservoir bed-differentiated asphalt) in the Silurian asphaltic sandstones of the Tarim Basin. These asphalts are the result of second-time charging of hydrocarbons into the Silurian reservoir, which were derived from Lower Paleozoic source rocks. Asphalt was differentiated from the reservoir bed in the hydrocarbon gathering area of secondary migration. The differen tiation is caused by changes in reservoir physical properties when pearl or chain hydrocarbons migrating through and gathering in the reservoir bed, and light components are lost and heavy ones are involved in the formation of asphalt or heavy oil. There are two kinds of occurrence of these asphalts in the Silurian system of the Tarim Basin. One is the poor heavy oil layer with lower oil saturation in trap and the other is scattered hydrocarbon distributed along the transport layer and unconformity surface. Reservoir bed-differentiated asphalts have two characteristics: total hydrocarbon content is high in extractable organic matter and the ratio of saturated to aromatic hydrocarbon is usually greater than unity. The physically modeling experiment has confirmed these characteristics and the genesis of the reservoir bed-differentiated asphalts.

  19. Testing study of long-term strength characteristics of red sandstone%红砂岩长期强度特性的试验研究

    Institute of Scientific and Technical Information of China (English)

    沈明荣; 谌洪菊

    2011-01-01

    岩石的流变特性是岩石的重要力学特性之一,其中岩石的长期强度是绝大多数岩土工程所必须引起重视的力学特性,然而就目前研究现状而言,与蠕变特性相比较是极不对称的.由岩石蠕变试验确定岩石的长期强度是现有最常用的方法,具有重要的现实意义.通过对完整红砂岩在CSS-2950岩石双轴流变试验机上进行的单轴压缩蠕变试验,利用过渡蠕变法、等时曲线法探讨了这些方法确定岩石长期强度在理论上的正确性和试验方法的可操作性,同时,将蠕变曲线与应力-应变曲线结合,提出了确定岩石长期强度的新方法,预测了岩石在荷载作用下可能破坏的时间.分析结果表明,将蠕变曲线与应力-应变曲线结合确定岩石长期强度对岩土工程设计具有重要的指导意义.%Rheological property is one of the most important mechanical properties of rock. Great importance shall be attached to long-term strength of the rock among mechanical properties in most geotechnical engineering, while the present study of it is asymmetrical compared with the creep property. Creep test is the most common and practical way to confirm long-term strength of rock. Based on uniaxial compression creep test of red sandstone rock in the CSS-2950 biaxial rheological testing machine; theory accuracy and operability of transition creep and isochronous curve methods are discussed in the research of testing long-term strength of the rock. Meanwhile, a new method to confirm long-term strength of the rock is proposed; and the time for rock to be destroyed under load is predicted by the combination of creep curve and stress-strain curve. The results show that the combination of creep curve and stress-strain curve plays a leading role in the confirmation of long-term strength of the rock in geotechnical engineering field.

  20. Discontinuities Characteristics of the Upper Jurassic Arab-D Reservoir Equivalent Tight Carbonates Outcrops, Central Saudi Arabia

    Science.gov (United States)

    Abdlmutalib, Ammar; Abdullatif, Osman

    2017-04-01

    Jurassic carbonates represent an important part of the Mesozoic petroleum system in the Arabian Peninsula in terms of source rocks, reservoirs, and seals. Jurassic Outcrop equivalents are well exposed in central Saudi Arabia and which allow examining and measuring different scales of geological heterogeneities that are difficult to collect from the subsurface due to limitations of data and techniques. Identifying carbonates Discontinuities characteristics at outcrops might help to understand and predict their properties and behavior in the subsurface. The main objective of this study is to identify the lithofacies and the discontinuities properties of the upper Jurassic carbonates of the Arab D member and the Jubaila Formation (Arab-D reservoir) based on their outcrop equivalent strata in central Saudi Arabia. The sedimentologic analysis revealed several lithofacies types that vary in their thickness, abundances, cyclicity and vertical and lateral stacking patterns. The carbonates lithofacies included mudstone, wackestone, packstone, and grainstone. These lithofacies indicate deposition within tidal flat, skeletal banks and shallow to deep lagoonal paleoenvironmental settings. Field investigations of the outcrops revealed two types of discontinuities within Arab D Member and Upper Jubaila. These are depositional discontinuities and tectonic fractures and which all vary in their orientation, intensity, spacing, aperture and displacements. It seems that both regional and local controls have affected the fracture development within these carbonate rocks. On the regional scale, the fractures seem to be structurally controlled by the Central Arabian Graben System, which affected central Saudi Arabia. While, locally, at the outcrop scale, stratigraphic, depositional and diagenetic controls appear to have influenced the fracture development and intensity. The fracture sets and orientations identified on outcrops show similarity to those fracture sets revealed in the upper

  1. Evaluation of Reservoir Characteristics of Well Kot-Sarang-2, Potwar Plateau, Pakistan Using Geophysical Logs

    Directory of Open Access Journals (Sweden)

    Syed Waqas Haider

    2016-12-01

    Full Text Available Present study deals with reservoir characterization of Kot-Sarang-2 well, located in central part of Potwar plateau of Upper Indus Basin, District Chakwal. The geological structure of the Potwar Basin is the product of the Tertiary Himalayan orogeny, which resulted in the formation of complex fold and thrust belt in this region. In the present work, an attempt has been made to delineate zones having fair shows of hydrocarbons accumulation. In addition to this, estimation of reservoir properties and formation evaluation using wireline logs is also the foremost objective of this study. Based on the wireline logging results, three zones have been marked. Paleocene Lockhart Limestone (3967m to 4045m, Permian Wargal Limestone (4160m to 4245m and Permian Amb Formation (4246m to 4285m are possible reservoirs encountered. Physical properties i.e. total porosity (Øt, effective porosity (ØE, resistivity of water (Rw, saturation of water (Sw and saturation of hydrocarbons (Sh are calculated. For the calculation of saturation of water (Sw both Archie’s equation (Swa and Indonesian equation (Swi are applied. Results show that Amb and Wargal formations are showing fair to good saturation of Hydrocarbons (Sh i.e.73% and 88% respectively, but this is due to high resistivity values of these formations and porosity log also giving very low values. Effective porosity for zones Lockhart, Wargal and Amb are 2.56%, 3.5% and 1.32% respectively. Based on these results it is inferred that these formations have low potential for an economically feasible production of hydrocarbons.

  2. Taxonomical and ecological characteristics of the desmids placoderms in reservoir: analyzing the spatial and temporal distribution

    Directory of Open Access Journals (Sweden)

    Sirlene Aparecida Felisberto

    2014-12-01

    Full Text Available AIM: This study aimed to evaluate the influence of river-dam axis and abiotic factors on the composition of Closteriaceae, Gonatozygaceae, Mesotaeniaceae and Peniaceae in a tropical reservoir METHODS: Water samples for physical, chemical and periphyton analysis were collected in April and August 2002 in different regions along the axis of the river-dam of Rosana Reservoir, River Basin Paranapanema. The substrates collected, always in the litoranea region, were petioles of Eichhornia azurea (Swartz Kunth. To examine the relationship of abiotic variables with reservoir zones and between the floristic composition of desmids, we used principal component analysis (PCA and canonical correspondence analysis (CCA RESULTS: The results of the PCA explained 81.3% of the total variability in the first two axes. In the first axis, the variables of conductivity, water temperature and the pH were related to the sampling regions of April with higher values, while for the month of August, nitrate, total phosphorus and dissolved oxygen showed higher values. We identified 20 taxa, distributed in the genera Closterium (14, Gonatozygon (4, Netrium (1 and Penium (1. Spatially, the higher taxa were recorded in the lacustrine region for both collection periods. The canonical correspondence analysis (CCA summarized 62.2% of total data variability of taxa in the first two axes, and in August, Closterium incurvum Brébisson, C. cornu Ehrenberg ex Ralfs and Gonatozygon monotaenium De Bary, were related to higher values of turbidity and nitrate to the lacustrine and intermediate regions CONCLUSION: Thus, the formation of groups was due to the regions along the longitudinal axis, then the seasonal period, which must be related to the low current velocity, the higher values of temperature and the water transparency, especially in late summer

  3. Layer structure,petroleum accumulation system and characteristic of subtle reservoir of continental basins in eastern China:Taking Jiyang depression for example

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The concept and division method for petroleum accumulation system,based on layer structure,are presented according to characteristics of layer structure and reservoirs. The petroleum accumulation system of Jiyang depression can be divided into four levels,namely petroleum accumulation system combination,petroleum accumulation system,oil-gas reservoir combination and reservoir. The petro-leum accumulation system combination includes three types of genetic pattern: other-source bur-ied-ridge accumulation system combination in pre-Paleogene,medium-deep layer self-source accu-mulation system combination in Paleogene,and shallow layer other-source accumulation system combination in Neogene. This paper also describes the reservoir types and their distribution charac-teristics of different petroleum accumulation system combinations and their interior units.

  4. Research and Development of Beach -Bar Sandstone Reservoir in Bamianhe Oilfield%八面河地区滩坝砂储层研究及开发实践--以面4-面14区沙四1砂组为例

    Institute of Scientific and Technical Information of China (English)

    杨伟; 陈军霞

    2015-01-01

    There is a large range of beach-bar sandstone reservoir in Bamianhe Oilfield with a large scale of reserves among which untouched reserves of thin oil suitable for water -flooding and Class 1 heavy oil are majorly distributed in 1st sand group of Sha-4 member of Mian 4-14 at the main tectonic belt .Based on Static and dynamic data ,in‐terpretation standard is reenacted to interpret the reservoir again and estimate its oiliness and physical property . Three years of development practice in the new district proves that early water -flooding ,proper shortening of well spacing and beforehand filling modification are suitable to such a reservoir .%八面河油田滩坝砂储层分布范围较广,未动用储量达两千余万吨,储量规模大。其中适合注水开发的稀油和普通稠油Ⅰ类油藏未动用储量主要分布在主体构造带的面4-面14区沙四段1砂组。此次主要通过岩芯、生产动态等静动态资料,重新制定解释标准,对储层进行二次解释。并结合测井资料归一化成果,对储层含油性、物性特征做出评价。进而综合开发方式及配套工艺优化组合研究成果,优选区域开展评价和新区产能建设。通过近三年的新区产建实践,证实先期注水开发、适当缩小井距的开发方式及预充填改造等配套工艺是适合该区域储层,能够满足其储层开发需要。

  5. MECHANICAL PROPERTIES AND ULTRASONIC TIME-FREQUENCY CHARACTERISTICS OF THERMALLY DAMAGED SANDSTONE%热损伤砂岩力学与超声时频特性研究

    Institute of Scientific and Technical Information of China (English)

    王鹏; 许金余; 刘石; 刘少赫

    2014-01-01

    Thermal damage of rock occurs after experience of high temperature of different levels. The mechanical properties of thermally damaged sandstone specimens experienced temperature treatments of different levels, including 25 ℃,100 ℃,200 ℃,400 ℃,600 ℃,800 ℃ and 1 000 ℃,were studied with the uniaxial compression tests. The ultrasonic characteristics in both the time and frequency domains according to wavelet transform were analyzed based on the data from the ultrasonic longitudinal wave testing. The kurtosis of frequency spectrum(KFS) was proposed to describe the degree of the clutter/concentration of the ultrasonic signal frequency distribution. It was found that with the temperature rising,the surface tone of sandstone specimen turned warmer, the longitudinal wave velocity was reduced significantly and the waveform tended to disorder. The peak strain increased. However,the peak stress and the elastic modulus varied nonlinearly. By the analysis of ultrasonic signals in frequency domain,the centroid frequency and the KFS of the receiving spectrum changed non-monotonic with the temperature,just as the relationship between the peak stress and the modulus of elasticity. The sandstone is a typical mineral cemented rock. The mineral grains and cements produce different changes and thus have different effects on the characteristics of the rock after the treatment of high temperature.%岩石经历高温作用后会产生不同程度的热损伤。通过单轴压缩试验,对经历25℃,100℃,200℃,400℃,600℃,800℃,1000℃高温作用后的砂岩试样力学特性进行分析;通过超声纵波试验,基于小波变换方法,在时域和频域对其超声特性进行研究。提出频谱峰度(KFS)的概念,用以描述超声信号频率分布的杂乱/集中程度。研究发现:随着作用温度的升高,砂岩试样表面色调变暖,纵波波速显著降低,波形趋于紊乱,峰值应变增大,峰值应力、弹性

  6. Implications of changing water cycle for the performance and yield characteristics of the multi-purpose Beas Reservoir in India

    Science.gov (United States)

    Adeloye, A. J.; Ojha, C. S.; Soundharajan, B.; Remesan, R.

    2013-12-01

    There is considerable change in both the spatial and temporal patterns of monsoon rainfall in India, with implications for water resources availability and security. 'Mitigating the Impacts of Climate Change on India Agriculture' (MICCI) is one of five on-going scientific efforts being sponsored as part of the UK-NERC/India-MOES Changing Water Cycle (South Asia) initiative to further the understanding of the problem and proffer solutions that are robust and effective. This paper focuses on assessing the implications of projected climate change on the yield and performance characteristics of the Pong Reservoir on the Beas River, Himachal Pradesh, India. The Pong serves both hydropower and irrigation needs and is therefore strategic for the socio-economic well-being of the region as well as sustaining the livelihoods of millions of farmers that rely on it for irrigation. Simulated baseline and climate-change perturbed hydro-climate scenarios developed as part of a companion Work Package of MICCI formed the basis of the analysis. For both of these scenarios, reservoir analyses were carried out using the Sequent Peak Algorithm (SPA) and Pong's existing level of releases to derive rule curves for the reservoir. These rule curves then formed the basis of further reservoir behaviour simulations in WEAP and the resulting performance of the reservoir was summarised in terms of reliability, resilience, vulnerability and sustainability. The whole exercise was implemented within a Monte Carlo framework for the benefit of characterising the variability in the assessments. The results show that the rule curves developed using future hydro-climate are significantly changed from the baseline in that higher storages will be required to be maintained in the Pong in the future to achieve reliable performance. As far as the overall performance of the reservoir is concerned, future reliability (both time-based and volume-based) is not significantly different from the baseline, provided

  7. The time-dependence of compaction localization in a porous sandstone

    Science.gov (United States)

    Heap, M. J.; Brantut, N.; Baud, P.; Meredith, P. G.

    2015-12-01

    Compaction bands in sandstone are laterally-extensive planar deformation features that are characterized by lower porosity and permeability than the surrounding host rock. As a result, this form of localization has important implications for both strain partitioning and fluid flow in the Earth's upper crust. To better understand the time-dependency of compaction band growth, we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (initial porosity = 0.24) under constant stress (creep) conditions in the compactant regime. Our experiments show that inelastic strain accumulates at a constant stress in the compactant regime, manifest as compaction bands. While creep in the dilatant regime is characterized by an increase in porosity and, ultimately, an acceleration in axial strain rate to shear failure, compaction creep is characterized by a reduction in porosity and a gradual deceleration in axial strain rate. The global decrease in the rates of axial strain, acoustic emission energy, and porosity change during creep compaction is punctuated at intervals by higher rate excursions, interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence background creep strain rate, is decreased. However, the inelastic strain associated with the growth of a compaction band remains constant over strain rates spanning several orders of magnitude (from 10-8 to 10-5 s-1). We find that, despite the large differences in strain rate and growth rate (from both creep and constant strain rate experiments), the characteristics (geometry, thickness) of the compaction bands remain essentially the same. Several lines of evidence, notably the similarity between the differential stress dependence of creep strain rate in the dilatant and compactant regimes, suggest that, as for dilatant creep, subcritical stress corrosion cracking is the mechanism responsible for

  8. A Sand Control System for Light Oil Reservoir

    Institute of Scientific and Technical Information of China (English)

    Xiang Yuzhang

    1996-01-01

    @@ Over 30-year water flooding in light oil sandstone reservoirs with loose argillaceous cement in Karamay oilfield results in severe sand production, varying from well to well with the different date of well completion.

  9. Insights into Andean slope hydrology: reservoir characteristics of the thermal Pica spring system, Pampa del Tamarugal, northern Chile

    Science.gov (United States)

    Scheihing, Konstantin W.; Moya, Claudio E.; Tröger, Uwe

    2017-09-01

    The thermal Pica springs, at ˜1,400 m above sea level (asl) in the Pampa del Tamarugal (Chile), represent a low-saline spring system at the eastern margin of the hyper-arid Atacama Desert, where groundwater resources are scarce. This study investigates the hydrogeological and geothermal characteristics of their feed reservoir, fostered by the interpretation of a 20-km east-west-heading reflection-seismic line in the transition zone from the Andean Precordillera to the Pampa del Tamarugal. Additional hydrochemical, isotope and hydrologic time-series data support the integrated analysis. One of the main factors that enabled the development of the spring-related vertical fracture system at Pica, is a disruption zone in the Mesozoic Basement caused by intrusive formations. This destabilized the younger Oligocene units under the given tectonic stress conditions; thus, the respective groundwater reservoir is made up of fractured Oligocene units of low to moderate permeability. Groundwater recharge takes place in the Precordillera at ˜3,800 m asl. From there groundwater flow covers a height difference of ˜3,000 m with a maximum circulation depth of ˜800-950 m, where the waters obtain their geothermal imprint. The maximal expected reservoir temperature, as confirmed by geothermometers, is ˜55 °C. Corrected mean residence times of spring water and groundwater plot at 1,200-4,300 years BP and yield average interstitial velocities of 6.5-22 m/year. At the same time, the hydraulic head signal, as induced by recharge events in the Precordillera, is transmitted within 20-24 months over a distance of ˜32 km towards the Andean foothills at Pica and Puquio Nunez.

  10. Reservoir Protection Technology in China: Research & Application

    Institute of Scientific and Technical Information of China (English)

    Li Qiangui; Wu Juan; Kang Yili

    2006-01-01

    @@ Great development of reservoir protection technology (RPT) has been achieved since 1996, including oil and gas reservoir protection for exploration wells, reservoir protection during underbalanced drilling, protection of fractured tight sandstone gas reservoir, and reservoir protection while increase production and reconstructing, development and enhanced oil recovery (EOR) etc. It has stepped into a new situation with special features and advantage. These technical advancements marked that China's RTP have realized leaps from porous reservoirs to fractured reservoirs,from conventional medium-to-low permeability reservoirs to unconventional reservoirs, from oil and gas producers to exploration wells, and from application mainly in drilling and completion processes to application in stimulation,development, production and EOR processes.

  11. Nitrogen removal characteristics of enhanced in situ indigenous aerobic denitrification bacteria for micro-polluted reservoir source water.

    Science.gov (United States)

    Zhou, Shilei; Huang, Tinglin; Zhang, Haihan; Zeng, Mingzheng; Liu, Fei; Bai, Shiyuan; Shi, Jianchao; Qiu, Xiaopeng; Yang, Xiao

    2016-02-01

    Indigenous oligotrophic aerobic denitrifiers nitrogen removal characteristics, community metabolic activity and functional genes were analyzed in a micro-polluted reservoir. The results showed that the nitrate in the enhanced system decreased from 1.71±0.01 to 0.80±0.06mg/L, while the control system did little to remove and there was no nitrite accumulation. The total nitrogen (TN) removal rate of the enhanced system reached 38.33±1.50% and the TN removal rate of surface sediment in the enhanced system reached 23.85±2.52%. TN removal in the control system experienced an 85.48±2.37% increase. The densities of aerobic denitrifiers in the enhanced system ranged from 2.24×10(5) to 8.13×10(7)cfu/mL. The abundance of nirS and nirK genes in the enhanced system were higher than those of in the control system. These results suggest that the enhanced in situ indigenous aerobic denitrifiers have potential applications for the bioremediation of micro-polluted reservoir system. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. The Silurian Reservoir Bed—Differentiated Asphalts in Tarim Basin and Modeling Experiments on Their Origin

    Institute of Scientific and Technical Information of China (English)

    刘洛夫; 刘宏江; 等

    2002-01-01

    There is a type of asphalt that originated from differentiation from reservoir bed (named reservoir bed-differentiated asphalt)in the Silurian asphaltic sandstones of the Tarim Basin.These asphalts are the result of second-time charging of hydrocarbons into the Silurian reservoir,which were derived from Lower Paleozoic source rocks.Asphalt was differentiated from the reservoir bed in the hydrocarbon gathering area of secondary migration.The different-tiation is caused by changes in reservoir physical properties when pearl or chain hydrocarbons migrating through and gathering in the reservoir bed,and light components are lost and heavy ones are involved in the formation of asphalt or heavy oil.There are two kinds of occurrence of these asphalts in the Silurian system of the Tarim Basin.One is the poor heavy oil layer with lower oil saturation in trap and the other is scattered hydrocarbon distributed along the trans-port layer and unconformity surface.Reservoir bed-differentiated asphalts have two characteris-tics:total hydrocarbon content is high in extractable organic matter and the ratio of saturated to aromatic hydrocarbon is usually greater than unity.The physically modeling experiment has confirmed these characteristics and the genesis of the reservoir bed-differentiated asphalts.

  13. Natural and Laboratory-Induced Compaction Bands in Aztec Sandstone

    Science.gov (United States)

    Haimson, B. C.; Lee, H.

    2002-12-01

    zone ahead of the fracture-like breakout tip and the natural compaction band provides strong evidence and reinforces earlier contentions that the former is itself a compaction band, resulting from the stress concentration transferred to it as the breakout advances along the \\sigmah springline. The development of the narrow tabular breakout supports our previous assertions that high porosity sandstones possessing mainly quartz grains held together primarily by suturing tend to form compaction bands upon drilling, which are then emptied by the circulating drilling fluid. The Aztec sandstone is the weakest and least cemented natural sandstone that we have successfully tested, and it is perhaps the closest to the poorly consolidated sandstones encountered in some oil reservoirs.

  14. A RESEARCH ON THE CHARACTERISTIC PARAMETERS OF LOW PERMEABILITY RESERVOIRS AND ITS APPLICATION%低渗透储层特征参数研究与应用

    Institute of Scientific and Technical Information of China (English)

    杨百全; 黄华梁; 李玉华; 黄启奎

    2001-01-01

    Through studying the characteristic parameters of lowpermeability reservoirs,the permeability—a key characteristic parameter of low permeability reservoirs was found and some valuable characteristic parameters,as porosity,displacement pressure,pore throat medium-radius,minimum non-mercury saturation percentage,related to permeability most closely were chosen. The numerical model of permeability corresponding to major characteristic parameters is investigated;by use of grey association analysis method,the associability and associated sequence are calculated through a self-making program;the numerical models of the carbonate reservoir bed of Carboniferous gas reservoir in Wubaiti gas field,the carbonate reservoir bed at the low permeability area of Lei-1' gas reservoir in Moxi gas field,the clastic reservoir bed at the low permeability area of Xu-4 gas reservoir in Bajiaochang gas field and the clastic reservoir bed at the low permeability area of Xu-2 gas reservoir in Pingluoba gas field are set up and a quanlified description and comprehensive evaluation of these reservoir beds are carried out in the paper.%通过对低渗透储层特征参数的研究,抓住了低渗透储层关键特征参数——渗透率。选择与渗透率关系最密切的、有价值的特征参数,如孔隙度、排驱压力、孔喉中值半径、最小非汞饱和度百分数。研究了渗透率与其相对应的主要特征参数的数值模型,采用灰色关联分析方法,自编程序计算了关联度和关联序,建立了四川盆地五百梯石炭系气藏碳酸盐岩储层、磨溪雷一1亚段气藏低渗区碳酸盐岩储层、八角场须四段气藏低渗区碎屑岩储层和平落坝须二段气藏低渗区碎屑岩储层的数值模式,并对储层进行了定量化描述及综合评价。

  15. Stratigraphy and petroleum potential of Trout Creek and Twentymile sandstones (Upper Cretaceous), Sand Wash Basin, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Siepman, B.R.

    1985-05-01

    The Trout Creek and Twentymile Sandstones (Mesaverde Group) in Moffat and Routt Counties, Colorado, are thick, upward-coarsening sequences that were deposited along the western margin of the Western Interior basin during Campanian time. These units trend northeast-southwest and undergo a facies change to coal-bearing strata on the northwest. Surface data collected along the southeastern rim of the Sand Wash basin were combined with well-log data from approximately 100 drill holes that have penetrated the Trout Creek or Twentymile in the subsurface. The sandstones exhibit distinctive vertical profiles with regard to grain size, sedimentary structures, and biogenic structures. A depositional model that incorporates the key elements of the modern Nile River (northeast Africa) and Nayarit (west-central Mexico) coastal systems is proposed for the Trout Creek and Twentymile sandstones and associated strata. The model depicts a wave-dominated deltaic, strand-plain, and barrier-island system. Depositional cycles are asymmetrical in cross section as they are largely progradational and lack significant transgressive deposits. Source rock-reservoir rock relationships are ideal as marine shales underlie, and coal-bearing strata overlie sheetlike reservoir sandstones. Humic coal, the dominant source of Mesaverde gas, generates major quantities of methane upon reaching thermal maturity. Existing Mesaverde gas fields are largely structural traps, but stratigraphic and combination traps may prove to be equally important. The sparsely drilled deeper part of the basin warrants testing as large, overpressured-gas accumulations in tight-sandstone reservoirs are likely to be found.

  16. 核磁共振岩心实验分析在低孔渗储层评价中的应用%Application of NMR core experimental analysis in evaluation of low-porosity and low-permeability sandstone reservoirs

    Institute of Scientific and Technical Information of China (English)

    王振华; 陈刚; 李书恒; 章辉若; 黄得顺; 杨甫; 雷盼盼; 刘小伸

    2014-01-01

    Nuclear magnetic resonance ( NMR) core experimental analysis is a new developing technique in experi⁃mental geology. Based on the principles and methods of NMR core experimental analysis, as well as some improved parametric models, a series of reservoir parameters of Chang6 low⁃porosity and low⁃permeability oil⁃bearing sand⁃stone core samples from well 3062 in the ZC Oil Field in the eastern Ordos Basin were systematically measured by NMR. Additionally, the accuracy and relative error of the NMR analysis were calculated and discussed by means of recognized exact method of conventional core experimental analysis as control group. It is revealed that the Chang6 oil⁃bearing sandstones are typical low⁃porosity and low⁃permeability reservoirs, with porosity ranging from 8.6% to 13.0%, and permeability from 0.07×10-3 to 1.27×10-3μm2 . NMR core experimental analysis has advantages of con⁃venience, high efficiency and accepted accuracy with a smaller relative error for testing the low⁃porosity and low⁃permeability reservoir parameters of porosity, microscopic pore structure and irreducible water saturation. However, compared with the results of conventional core analysis, there is a larger relative error in NMR prediction for the permeability parameters, which is most probably due to some uncertainty of the reservoir permeability predictive models.%根据核磁共振( NMR)岩心实验分析的基本原理、方法和相关参数模型的研究进展,对鄂尔多斯盆地东部ZC油田3062井延长组长6油层组低孔渗砂岩样品进行了储层物性、孔隙结构和束缚水饱和度等参数的NMR岩心实验分析,并将其与常规岩心测试参数进行了分析与对比,探讨了低孔渗储层NMR岩心实验分析的精度及其应用效果。结果表明,3062井长6油层组砂岩属于典型的低孔渗储层,孔隙度在8.6%~13.0%,渗透率在(0.07~1.27)×10-3μm2;低孔渗砂岩样品NMR岩

  17. Investigating the effect of unloading on artificial sandstone behaviour using the Discrete Element Method

    Science.gov (United States)

    Huang, Yueqin; Cheng, Yi Pik; Coop, Matthew

    2017-06-01

    The Discrete Element Method (DEM) was used to simulate the mechanical behaviour of a reservoir sandstone. Triaxial tests were carried out using 3D-DEM to simulate the stress-strain behaviour of a sandstone with comparisons made between the numerical tests and the laboratory tests. The influence of isotropic unloading was investigated, which was found to have impacts on bond breakages and was successfully captured in the 3D shearing processes. It was found that bond breakages correlated strongly with the stress-strain behaviour of the sandstone affecting the peak strength. It was also found that unloading affected the bond breakages, which then changed the mechanical behaviour of sandstone. The tangent stiffnesses of simulated virgin and cored samples under different confining stresses were compared. From the tangent stiffnesses, gross yield envelopes and the yielding surfaces for unloaded samples and virgin samples were plotted and analysed in detail.

  18. Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

    Directory of Open Access Journals (Sweden)

    Qian Feng

    2016-09-01

    Full Text Available Hydrological processes play important roles in soil erosion processes of the hillslopes. This study was conducted to investigate the hydrological processes and the associated erosional responses on the purple soil slope. Based on a comprehensive survey of the Wangjiaqiao watershed in the Three Gorges Reservoir, four typical slope gradients (5°, 10°, 15°and 20° were applied to five rainfall intensities (0.6, 1.1, 1.61, 2.12 and 2.54 mm·min-1. The results showed that both surface and subsurface runoff varied greatly depending on the rainfall intensity and slope gradient. Surface runoff volume was 48.1 to 280.1 times of that for subsurface runoff. The critical slope gradient was about 10°. The sediment yield rate increased with increases in both rainfall intensity and slope gradient, while the effect of rainfall intensity on the sediment yield rate was greater than slope gradient. There was a good linear relationship between sediment yield rate and Reynolds numbers, flow velocity and stream power, while Froude numbers, Darcy-Weisbach and Manning friction coefficients were not good hydraulic indicators of the sediment yield rate of purple soil erosion. Among the three good indicators (Re, v and w, stream power was the best predictor of sediment yield rate (R2 = 0.884. Finally, based on the power regression relationship between sediment yield rate, runoff rate, slope gradient and rainfall intensity, an erosion model was proposed to predict the purple soil erosion (R2 = 0.897. The results can help us to understand the relationship between flow hydraulics and sediment generation of slope erosion and offer useful data for the building of erosion model in purple soil.

  19. New Acid Combination for a Successful Sandstone Acidizing

    Science.gov (United States)

    Shafiq, M. U.; Mahmud, H. K. B.; Rezaee, R.

    2017-05-01

    With the development of new enhanced oil recovery techniques, sandstone acidizing has been introduced and played a pivotal role in the petroleum industry. Different acid combinations have been applied, which react with the formation, dissolve the soluble particles; thus increase the production of hydrocarbons. To solve the problems which occurred using current preflush sandstone acidizing technology (hydrochloric acid); a new acid combination has been developed. Core flooding experiments on sandstone core samples with dimensions 1.5 in. × 3 in. were conducted at a flow rate of 2 cm3/min. A series of hydrochloric-acetic acid mixtures with different ratios were tested under 150°F temperature. The core flooding experiments performed are aimed to dissolve carbonate, sodium, potassium and calcium particles from the core samples. These experiments are followed by few important tests which include, porosity-permeability, pH value, Inductively Coupled Plasma (ICP) analysis and Nuclear Magnetic Resonance (NMR measurements). All the results are compared with the results of conventional hydrochloric acid technology. NMR and porosity analysis concluded that the new acid combination is more effective in creating fresh pore spaces and thus increasing the reservoir permeability. It can be seen from the pore distribution before and after the acidizing. Prior applying acid; the large size of pores appears most frequently in the pore distribution while with the applied acid, it was found that the small pore size is most the predominant of the pore distribution. These results are validated using ICP analysis which shows the effective removal of calcium and other positive ions from the core sample. This study concludes that the combination of acetic-hydrochloric acid can be a potential candidate for the preflush stage of sandstone acidizing at high temperature reservoirs.

  20. Diagenesis of Paleogene sandstone from Kong 1 Member of Southern Kongdian in Huanghua depression

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Huanghua depression is one of the richest areas in petroleum and natural gas in China. The Paleogene mainly consists of sandstone with facies of river, delta, fan delta and littoral-shallow lacustrine. Diagenesis played an important role in the properties of reservoir rocks. Applying X-ray diffraction, on the basis of analyzing many cores and thin sections, the authors studied diagenesis of Paleogene sandstone reservoir rocks in kongl Menber of southern Kongdian in Huanghua depression. Diagenetic complexity shows that the sandstone in this area underwent compaction, cementation, isolation, recrystallization during the burying of sediments, and the first three compose the major diagenesis. The compaction and cementation led to decreasing porosity, and the solution of unsteady minerals also results in increasing in porosity.

  1. Analysis on the spatiotemporal characteristics of water quality and trophic states in Tiegang Reservoir: A public drinking water supply reservoir in South China

    Science.gov (United States)

    Song, Yun-long; Zhu, Jia; Li, Wang; Tao, Yi; Zhang, Jin-song

    2017-08-01

    Shenzhen is the most densely populated city in China and with a severe shortage of water. The per capita water resource is less than 200 m3, which is approximately 1/12 of the national average level. In 2016, nearly 90% of Shenzhen’s drinking water needed to be imported from the Pearl River. After arrived at Shenzhen, overseas water was firstly stockpiled in local reservoirs and then was supplied to nearby water works. Tiegang Reservoir is the largest drinking water supply reservoir and its water quality has played an important role to the city’s drinking water security. A fifteen-month’s field observation was conducted from April 2013 to June 2014 in Tiegang Reservoir, in order to analyze the temporal and spatial distribution of water quality factors and seasonal variation of trophic states. One-way ANOVA showed that significant difference was found in water quality factors on month (p latter rainy period > high temperature and rain free period > temperature jump period > winter drought period, while SD showed the contrary. Two-way ANOVA showed that months rather than locations were the key influencing factors of water quality factors succession. Tiegang reservoir was seriously polluted by TN, as a result WQI were at IV∼V level. If TN was not taken into account, WQI were atI∼III level. TLI (Σ) were about 35∼60, suggesting Tiegang reservoir was in mesotrophic and light-eutrophic trophic states. The WQI and TLI (Σ) in sampling sites 9 and 10 were poorer than that of other sites. The 14 water quality factors were divided into 5 groups by factor analysis (FA). The total interpretation rate was 73.54%. F1 represents the climatic change represented by water temperature. F2 and F4 represent the concentration of nutrients. F3 and F5 represent the sensory indexes of water body, such as turbidity, transparency. The FA results indicated that water quality potential risk factors was total nitrogen (TN), and potential risk factors also include chlorophyll-a and

  2. COMPARATIVE CHARACTERISTICS OF MORPHOMETRIC PARAMETERS OF MONKEY GOBY (NEOGOBIUS FLUVIATILIS PALLAS OF FRESH AND SALINE WATER RESERVOIRS IN UKRAINE

    Directory of Open Access Journals (Sweden)

    Onoprienko V.

    2014-04-01

    physiological processes. The result of this effect is the difference in weight, size and body parts. To clarify, as our model species was taken Cottus Sandpiper (Neogobius fluviatilis Pallas. The reason for this was the fact that this species, along with other Ponto- Caspian solonovato - freshwater gobies, the International Union for Conservation of Nature classified as species biology are poorly understood and require further research. This fact that deepened interest of ichthyologists in this group of fish, in this regard appeared in the literature as material for the bulls and in Sandpiper. Based on the above, the purpose of this paper is a comparative morphometric parameters characteristic of individuals of this species of fresh and salt water bodies of Ukraine. All this affects the absolute morphometric parameters, which decrease in the direction from sea to the river. However, it should be noted that in rivers with rich feeding grounds sheer size of some individuals close to the size and species of sea Kakhovskoe reservoir. This situation is observed in the Sandpiper Grouse River. Here are some specimens reach a length (TL 118-148 mm and a weight of 15-36 g, Kakhovskoe Reservoir: 106-150 mm 11-38 g, in the Sea of Azov: 115-174 mm 17-58 g. For relative parameters Sandpiper with these reservoirs are more similar, however, for some of them, there are differences. Among the latter is most clearly distinguished the ratio SL / N. This indicator podovzhenist (prohonystist body. As pointed out by VP Mitrofanov (1977, this indicator shows the hydrodynamic qualities of fish: the larger the index, the more active lifestyle is individual. When compared with individuals with a little water and a large stream, in the latter case, individuals are more elongated. This is confirmed by our material: the ratio SL / L for the smallest species of sea of Azov (4.96, slightly more for Kakhovsky reservoir (5.52 and even more for rivers Grouse, Trubizh, Desna, Ros (respectively 5, 86, 6.22 , 6

  3. COMPARATIVE CHARACTERISTICS OF MORPHOMETRIC PARAMETERS OF MONKEY GOBY (NEOGOBIUS FLUVIATILIS PALLAS OF FRESH AND SALINE WATER RESERVOIRS IN UKRAINE

    Directory of Open Access Journals (Sweden)

    V. P. Onoprienko

    2014-04-01

    physiological processes. The result of this effect is the difference in weight, size and body parts. To clarify, as our model species was taken Cottus Sandpiper (Neogobius fluviatilis Pallas. The reason for this was the fact that this species, along with other Ponto- Caspian solonovato - freshwater gobies, the International Union for Conservation of Nature classified as species biology are poorly understood and require further research. This fact that deepened interest of ichthyologists in this group of fish, in this regard appeared in the literature as material for the bulls and in Sandpiper. Based on the above, the purpose of this paper is a comparative morphometric parameters characteristic of individuals of this species of fresh and salt water bodies of Ukraine. All this affects the absolute morphometric parameters, which decrease in the direction from sea to the river. However, it should be noted that in rivers with rich feeding grounds sheer size of some individuals close to the size and species of sea Kakhovskoe reservoir. This situation is observed in the Sandpiper Grouse River. Here are some specimens reach a length (TL 118-148 mm and a weight of 15-36 g, Kakhovskoe Reservoir: 106-150 mm 11-38 g, in the Sea of ​​Azov: 115-174 mm 17-58 g. For relative parameters Sandpiper with these reservoirs are more similar, however, for some of them, there are differences. Among the latter is most clearly distinguished the ratio SL / N. This indicator podovzhenist (prohonystist body. As pointed out by VP Mitrofanov (1977, this indicator shows the hydrodynamic qualities of fish: the larger the index, the more active lifestyle is individual. When compared with individuals with a little water and a large stream, in the latter case, individuals are more elongated. This is confirmed by our material: the ratio SL / L for the smallest species of sea of ​​Azov (4.96, slightly more for Kakhovsky reservoir (5.52 and even more for rivers Grouse, Trubizh, Desna, Ros (respectively 5, 86

  4. Caractériser l'argilosité des réservoirs gréseux : utilisation et comparaison des techniques usuelles Characterizing the Shaliness of Sandstone Reservoirs : Using and Comparing Standard Techniques

    Directory of Open Access Journals (Sweden)

    Giouse H.

    2006-11-01

    Full Text Available Une étude de caractérisation et de quantification de l'argilosité de 18 échantillons de grès argileux, a été mise en oeuvre avec les moyens usuels dont dispose l'expérimentateur pétrophysicien. Trois aspects de l'argile sont approchés : son type minéralogique, sa quantité, sa texture. L'accent est mis sur le manque de précision des mesures courantes portant sur les argiles et la nécessité d'en effectuer plusieurs pour s'approcher d'une quantification. La mesure de capacité d'échange de cations (obtenue par 3 méthodes différentes qui sont comparées reflète la quantité d'argile et sa minéralogie, mais pas sa morphologie. Celle-ci doit être observée au microscope électronique à balayage et appréciée par l'examen de la courbe porosimétrique. A characterization and quantification study of shaliness was performed on 18 shaly sand samples with current methods available to petrophysicists. Three aspects of clay are discussed: (1 its mineralogical type (2 its total quantity and (3 its texture. The lack of accuracy of all ordinary measurements of clays is emphasized. It is shown that several measurement are often necessary to obtain an idea of real quantities. The cation exchange capacity (which was measured by three methods takes into account the total amount and the mineralogy of clay, but not its morphology. This last characteristic must be observed by scanning electronic microscopy and evaluated with porosimetric data.

  5. Wettability from Capillarity of CO2-Brine-Rock Systems at Reservoir Conditions

    Science.gov (United States)

    Al-Menhali, Ali; Niu, Ben; Krevor, Samuel

    2015-04-01

    The wettability of CO2-brine-rock systems will have a major impact on the management of carbon sequestration in subsurface geological formations. Recent contact angle measurement studies have reported sensitivity in wetting behaviour of this system to pressure, temperature and brine salinity. We report results of an investigation into the impact of reservoir conditions on wetting through direct observations of their impact on the capillary strength of the system. Eight capillary pressure characteristic curves were measured using CO2 and brine in a single fired Berea sandstone at pressures (5 to 20 MPa), temperatures (25 to 50 °C) and ionic strengths (0 to 5 M kg-1 NaCl) representative of subsurface reservoirs. A ninth measurement using an N2-water system provided a benchmark for capillarity with a strongly water wet system. The semi-dynamic capillary pressure core flooding technique was used with in situ saturation monitoring. In all cases, the capillarity of the system, scaled by the interfacial tension, were equivalent to the N2-water system within measurement uncertainty. Thus reservoir conditions did not have a significant impact on the capillary strength of the CO2-brine system through a variation in wetting. Two steady-state relative permeability measurements with CO2 and brine and one with N2 and brine similarly show little variation between conditions, consistent with the observation that the CO2-brine-sandstone system is strongly water wetting and invariant across a wide range of reservoir conditions.

  6. CHARACTERISTIC FINITE DIFFERENCEALTERNATING-DIRECTION METHOD AND ANALYSIS FOR NUMERICAL RESERVOIR SIMULATION

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Petroleum science has made remarkable progress in organic geochemistry and in the research into the theories of petroleum origin,its transport and accumulation.In estimating the oil-gas resources of a basin.the knowledge of its evolutionary history and especially the numerical computation of fluid flow and.the history of its changes under heat is vital.The mathematical model can be described as a coupled system of nonlinear partial differentical equations with initial-boundary value problems.This thesis,from actual conditions such as the effect of fluid compressibility and the characteristic of largescal science-engineering computalion,puts forward a kind of characteristic finite difference alternating-direction scheme.Optimal order estimates in L2 norm are derived for the error in the approximate solutions.

  7. Assessment of potential shale oil and tight sandstone gas resources of the Assam, Bombay, Cauvery, and Krishna-Godavari Provinces, India, 2013

    Science.gov (United States)

    Klett, Timothy R.; Schenk, Christopher J.; Wandrey, Craig J.; Brownfield, Michael E.; Charpentier, Ronald R.; Tennyson, Marilyn E.; Gautier, Donald L.

    2014-01-01

    Using a well performance-based geologic assessment methodology, the U.S. Geological Survey estimated a technically recoverable mean volume of 62 million barrels of oil in shale oil reservoirs, and more than 3,700 billion cubic feet of gas in tight sandstone gas reservoirs in the Bombay and Krishna-Godavari Provinces of India. The term “provinces” refer to geologically defined units assessed by the USGS for the purposes of this report and carries no political or diplomatic connotation. Shale oil and tight sandstone gas reservoirs were evaluated in the Assam and Cauvery Provinces, but these reservoirs were not quantitatively assessed.

  8. The study of permeabilities, measured at various scales, of a fluviatile sandstone reservoir. Development and application of a well test numerical simulator; Etude des permeabilites mesurees a differentes echelles d`un reservoir greseux fluviatile. Developpement et application d`un simulateur numerique de tests de puits

    Energy Technology Data Exchange (ETDEWEB)

    Jacquin, T.

    1997-10-10

    The general problem of a single phase fluid flow through heterogenous porous media, is studied, focusing on well test data interpretation in the context of reservoir characterization; a 3D finite volume code, with capacity of local refinement, is developed to simulate well tests. After a review of traditional techniques used to interpret well test data, and their extension to heterogenous media using a weighting function that depends upon the flow geometry, an analysis is carried out for 2D correlated lognormal permeability distributions: it compares well to numerical well tests performed on low variance permeability distributions but needs further investigation for high variance. For 3D heterogenous permeability fields, well bore pressure cannot be estimated by analytical means; therefore a more empirical approach is used to study the permeability field of a reservoir used by Gaz de France as an underground gas storage. Simulated well tests are performed on a reservoir model based upon core measurements and log analysis. The numerical investigation reveals inconsistencies in the treatment of available data, which can be corrected so geology is better taken into account

  9. Status of Wheeler Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    1990-09-01

    This is one in a series of status reports prepared by the Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overview of Wheeler Reservoir summarizes reservoir purposes and operation, reservoir and watershed characteristics, reservoir uses and use impairments, and water quality and aquatic biological conditions. The information presented here is from the most recent reports, publications, and original data available. If no recent data were available, historical data were summarized. If data were completely lacking, environmental professionals with special knowledge of the resource were interviewed. 12 refs., 2 figs.

  10. Status of Cherokee Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    1990-08-01

    This is the first in a series of reports prepared by Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overviews of Cherokee Reservoir summarizes reservoir and watershed characteristics, reservoir uses and use impairments, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most current reports, publications, and data available, and interviews with water resource professionals in various Federal, state, and local agencies and in public and private water supply and wastewater treatment facilities. 11 refs., 4 figs., 1 tab.

  11. Status of Cherokee Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    1990-08-01

    This is the first in a series of reports prepared by Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overviews of Cherokee Reservoir summarizes reservoir and watershed characteristics, reservoir uses and use impairments, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most current reports, publications, and data available, and interviews with water resource professionals in various Federal, state, and local agencies and in public and private water supply and wastewater treatment facilities. 11 refs., 4 figs., 1 tab.

  12. Diagenesis, provenance and depositional environments of the Bunter Sandstone Formation

    DEFF Research Database (Denmark)

    Olivarius, Mette; Weibel, Rikke; Friis, Henrik

    The Bunter Sandstone Formation in the northern North German Basin has large geothermal potential with high porosity and permeability (generally >15% and >100 mD, respectively) and with pore fluid temperatures that are adequate for geothermal energy production (c. 55–60˚C). A combined investigation...... of diagenesis, provenance and depositional environments is used to identify the reservoir rocks that possess the best quality. This is accomplished by integrating various methods including: seismic reflection data, sedimentological description of cores, mineral quantification by point counting, measurement...

  13. Discussions on the gas source of the Triassic Xujiahe Formation tight sandstone gas reservoirs in Yuanba and Tongnanba, Sichuan Basin:An answer to Yinfeng et al.%四川盆地元坝和通南巴地区须家河组致密砂岩气藏气源探讨--兼答印峰等

    Institute of Scientific and Technical Information of China (English)

    戴金星; 廖凤蓉; 倪云燕

    2013-01-01

    Gas-source correlation is generally focused on the genetic type of the main gas components, dominantly oil-associated gas or coal-derived gas. Gases from the Yuanba and Tongnanba gas reservoirs are dominated by methane with an average content of 95.36%. The average contents of ethane, propane, butane are 1.60%, 0.29%and 0.09%, respectively. In general, for the Yuanba and Tongnanba gas reservoirs, alkane gas has an average content of 97.34%, and CO2 has an average content of 0.63%, which only accounts for 6.5‰of the methane. According to the discrimination criteria thatδ13C2 value is greater than–28‰for coal-derived gas and lower than–28.5‰for the oil-associated gas, Yin et al. suggested that the gases from the Yuanba gas reservoir be a mixture of coal-derived and oil-associated gases, and the gases from the Tongnanba gas reservoir be oil-associated gas. However, the discrimination criteria of δ13C2 for coal-derived and oil-associated gases are only valid when the alkane gases have not undergone secondary alteration and have positive carbon isotopic series among C1-C4 alkanes. Hence, it is concluded that gases from the Yuanba and Tongnanba gas reservoirs are coal-derived gases due to their high content and heavy carbon isotopic values of methane (–31.3‰), which is typical for high mature coal-derived gases in the world. Though Yin et al. suggested that abiogenic CO2 of these two reservoirs is originated from metamorphism or hydrolysis of deep carbonate rocks, we proposed that these CO2 gases be self-generated and self-accumulated under the corrosion of calcarenaceous sandstone of the Triassic Xujiahe Formation.%  气藏的气源系指其中主要组分气的成因类型,通常为油型气或煤成气.元坝和通南巴气藏主要组分甲烷平均含量为95.36%,乙烷、丙烷和丁烷平均含量分别为1.60%、0.29%和0.09%,烷烃气总平均含量为97.34%,而 CO2平均含量仅0.63%,为甲烷的6.5‰.印峰等文中仅应用δ13

  14. Nanoparticle Stabilized Foam in Carbonate and Sandstone Reservoirs

    NARCIS (Netherlands)

    Roebroeks, J.; Eftekhari, A.A.; Farajzadeh, R.; Vincent-Bonnieu, S.

    2015-01-01

    Foam flooding as a mechanism to enhance oil recovery has been intensively studied and is the subject of multiple research groups. However, limited stability of surfactant-generated foam in presence of oil and low chemical stability of surfactants in the high temperature and high salinity of an oil r

  15. Large reservoirs: Chapter 17

    Science.gov (United States)

    Miranda, Leandro E.; Bettoli, Phillip William

    2010-01-01

    expressed effects, such as turbidity and water quality, zooplankton density and size composition, or fish growth rates and assemblage composition, are the upshot of large-scale factors operating outside reservoirs and not under the direct control of reservoir managers. Realistically, abiotic and biotic conditions in reservoirs are shaped by factors working inside and outside reservoirs, with the relative importance of external factors differing among reservoirs. With this perspective, large reservoirs are viewed from a habitat standpoint within the framework of a conceptual model in which individual reservoir characteristics are influenced by both local- and landscape-scale factors (Figure 17.1). In the sections that follow, how each element of this hierarchical model influences habitat and fish assemblages in reservoirs is considered. Important in-reservoir habitat issues and reservoirs as part of larger systems, where reservoir management requires looking for real solutions outside individual reservoirs are described.

  16. Tectonic Setting and Characteristics of Natural Fractures in MesaVerde and Dakota Reservoirs of the San Juan Basin

    Energy Technology Data Exchange (ETDEWEB)

    LORENZ,JOHN C.; COOPER,SCOTT P.

    2000-12-20

    The Cretaceous strata that fill the San Juan Basin of northwestern New Mexico and southwestern Colorado were shortened in a generally N-S to NN13-SSW direction during the Laramide orogeny. This shortening was the result of compression of the strata between southward indentation of the San Juan Uplift at the north edge of the basin and northward to northeastward indentation of the Zuni Uplift from the south. Right-lateral strike-slip motion was concentrated at the eastern and western basin margins of the basin to form the Hogback Monocline and the Nacimiento Uplift at the same time, and small amounts of shear may have been pervasive within the basin as well. Vertical extension fractures, striking N-S to NNE-SSW with local variations (parallel to the Laramide maximum horizontal compressive stress), formed in both Mesaverde and Dakota sandstones under this system, and are found in outcrops and in the subsurface of the San Juan Basin. The immature Mesaverde sandstones typically contain relatively long, irregular, vertical extension fractures, whereas the quartzitic Dakota sandstones contain more numerous, shorter, sub-parallel, closely spaced, extension fractures. Conjugate shear planes in several orientations are also present locally in the Dakota strata.

  17. Smart Waterflooding in Carbonate Reservoirs

    DEFF Research Database (Denmark)

    Zahid, Adeel

    During the last decade, smart waterflooding has been developed into an emerging EOR technology both for carbonate and sandstone reservoirs that does not require toxic or expensive chemicals. Although it is widely accepted that different salinity brines may increase the oil recovery for carbonate...... reservoirs, understanding of the mechanism of this increase is still developing. To understand this smart waterflooding process, an extensive research has been carried out covering a broad range of disciplines within surface chemistry, thermodynamics of crude oil and brine, as well as their behavior...

  18. Mapping 3D thin shale and permeability pathway within a reservoir system: Case study from the Sleipner Field

    Science.gov (United States)

    Ponfa Bitrus, Roy; Iacopini, David; Bond, Clare

    2016-04-01

    Reservoir architecture plays an integral part of seismic reservoir characterization. The characteristics of a reservoir which includes its external and internal geometry are important as they influence the production and development strategy employed in the oil and gas sector. Reservoir architecture is defined by the interpretation of seismic data, thus identifying the basic structural and stratigraphic geometrical framework of a trapping and flow system for hydrocarbon and fluids. One major issue though is the interpretation of thin shales and identification of permeability pathways within the reservoir system. This paper employs a method using attributes to map thin shales and identify permeability pathways or transmissitives that exist within a reservoir taking into consideration the seismic resolution and available data. Case study is the Utsira Formation in the Sleipner field, Norwegian North sea. The Utsira formation presents a classic case of thin beds within a sandstone formation and transmissitives that exist as chimneys within the formation. A total of 10 intra reservoir horizon units of shales where interpreted using complex trace seismic attributes. These interpreted horizons where further analysed through spectral decomposition to reveal possible facies distribution and unit thickness within the horizon. Reservoir transmissitives identified as vertical curvilinear structures were also analysed using unique seismic attributes in other to delineate their extent and characterise their occurrence These interpreted shales and pathway transmissitives illuminate the geometry of the formation, the reservoir heterogeneities on a finer-scale and, in the long term, constrain the migration prediction of reservoir fluids, hydrocarbons and injected CO2 when matched across a 4D seismic data survey. As such, useful insights into the key elements operating within the reservoir can be provided, giving a good indication of the long and short term reservoir performance.

  19. Petrofacies Analysis - A Petrophysical Tool for Geologic/Engineering Reservoir Characterization

    Science.gov (United States)

    Watney, W.L.; Guy, W.J.; Doveton, J.H.; Bhattacharya, S.; Gerlach, P.M.; Bohling, G.C.; Carr, T.R.

    1998-01-01

    Petrofacies analysis is defined as the characterization and classification of pore types and fluid saturations as revealed by petrophysical measurements of a reservoir. The word "petrofacies" makes an explicit link between petroleum engineers' concerns with pore characteristics as arbiters of production performance and the facies paradigm of geologists as a methodology for genetic understanding and prediction. In petrofacies analysis, the porosity and resistivity axes of the classical Pickett plot are used to map water saturation, bulk volume water, and estimated permeability, as well as capillary pressure information where it is available. When data points are connected in order of depth within a reservoir, the characteristic patterns reflect reservoir rock character and its interplay with the hydrocarbon column. A third variable can be presented at each point on the crossplot by assigning a color scale that is based on other well logs, often gamma ray or photoelectric effect, or other derived variables. Contrasts between reservoir pore types and fluid saturations are reflected in changing patterns on the crossplot and can help discriminate and characterize reservoir heterogeneity. Many hundreds of analyses of well logs facilitated by spreadsheet and object-oriented programming have provided the means to distinguish patterns typical of certain complex pore types (size and connectedness) for sandstones and carbonate reservoirs, occurrences of irreducible water saturation, and presence of transition zones. The result has been an improved means to evaluate potential production, such as bypassed pay behind pipe and in old exploration wells, or to assess zonation and continuity of the reservoir. Petrofacies analysis in this study was applied to distinguishing flow units and including discriminating pore type as an assessment of reservoir conformance and continuity. The analysis is facilitated through the use of colorimage cross sections depicting depositional sequences

  20. Fluid circulation and diagenesis of carbonated and sandstone reservoirs in the fronts and fore-lands of folded chains: the Salt Range case - Poswar (Pakistan); Circulation des fluides et diagenese des reservoirs carbonates et greseux dans les fronts de chaines plissees et leur avant pays: le cas du Salt Range - Poswar (Pakistan)

    Energy Technology Data Exchange (ETDEWEB)

    Benchilla, L.

    2003-05-01

    The Salt Range-Poswar Province is located in the western foothills of the Himalayas, in northern Pakistan. It extends over 170 km from the Main Boundary Thrust (MBT) in the north to the Salt Range in the south. The Salt Range itself is dominantly an ENE-trending structure, but it comprises also a NNW-trending lateral ramp which connects to the west with the Surghar Range. The Salt Range constitutes the frontal part of a detached allochthonous thrust sheet. The sedimentary cover is indeed entirely detached from its substratum along Infracambrian salt horizons. Palaeozoic to Eocene platform series are well exposed in the hanging wall, whereas Neogene molasse has been extensively under-thrust in the footwall of this large over-thrust. The North Potwar Basin is bordered by the Khari-Murat Ridge and coeval back-thrusts in the south, by the northern flank of the Soan syncline in the southeast, and by the MBT in the north. In addition to Neogene outcrops, it also comprises a number of surface anticlines and thrust fronts along which the Eocene platform carbonates are exposed. The Datta Formation is the main Jurassic oil reservoir in the Potwar Basin. It is a fluvio-deltaic deposit which comprises large porous and permeable channels associated to many-calcareous interbeds. The formations crop out well in both the Nammal and Chichali Gorges. The oil field of Toot, located in the western part of the basin, is producing from this reservoir. The petrographic observations show that diagenesis occurred mainly early and was controlled by the fluvio-deltaic environment. (author)

  1. Quantifying the uncertainties of climate change effects on the storage-yield and performance characteristics of the Pong multi-purpose reservoir, India

    Science.gov (United States)

    Soundharajan, B.; Adeloye, A. J.; Remesan, R.

    2015-06-01

    Climate change is predicted to affect water resources infrastructure due to its effect on rainfall, temperature and evapotranspiration. However, there are huge uncertainties on both the magnitude and direction of these effects. The Pong reservoir on the Beas River in northern India serves irrigation and hydropower needs. The hydrology of the catchment is highly influenced by Himalayan seasonal snow and glaciers, and Monsoon rainfall; the changing pattern of the latter and the predicted disappearance of the former will have profound effects on the performance of the reservoir. This study employed a Monte-Carlo simulation approach to characterise the uncertainties in the future storage requirements and performance of the reservoir. Using a calibrated rainfall-runoff (R-R) model, the baseline runoff scenario was first simulated. The R-R inputs (rainfall and temperature) were then perturbed using plausible delta-changes to produce simulated climate change runoff scenarios. Stochastic models of the runoff were developed and used to generate ensembles of both the current and climate-change perturbed future scenarios. The resulting runoff ensembles were used to simulate the behaviour of the reservoir and determine "populations" of reservoir storage capacity and performance characteristics. Comparing these parameters between the current and the perturbed provided the population of climate change effects which was then analysed to determine the uncertainties. The results show that contrary to the usual practice of using single records, there is wide variability in the assessed impacts. This variability or uncertainty will, no doubt, complicate the development of climate change adaptation measures; however, knowledge of its sheer magnitude as demonstrated in this study will help in the formulation of appropriate policy and technical interventions for sustaining and possibly enhancing water security for irrigation and other uses served by Pong reservoir.

  2. Mineralogical controls on NMR rock surface relaxivity: A case study of the Fontainebleau Sandstone

    Science.gov (United States)

    Livo, Kurt

    Pore size distribution is derived from nuclear magnetic resonance, but is scaled by surface relaxivity. While nuclear magnetic resonance studies generally focus on the difficulty of determining pore size distribution in unconventional shale reservoirs, there is a lack of discussion concerning pure quartz sandstones. Long surface relaxivity causes complications analyzing nuclear magnetic resonance data for pore size distribution determination. Currently, I am unaware of research that addresses the complicated pore size distribution determination in long relaxing, pure sandstone formations, which is essential to accurate downhole petrophysical modeling. The Fontainebleau sandstone is well known for its homogenous mineralogical makeup and wide range of porosity and permeability. The Hibernia sandstone exhibits a similar mineralogy and is characterized by a similar and porosity-permeability range to the Fontainebleau sandstones, but with a significantly higher portion of clay minerals (1-6%). I present systematic petrophysical properties such as porosity, pore size distribution from nuclear magnetic resonance transverse relaxation times, permeability, and volumetric magnetic susceptibility to aide in characterization of the Fontainebleau sandstone. Analysis of collected nuclear magnetic resonance data is then compared to other petrophysical studies from literature such as helium porosity and permeability, magnetic susceptibility, and electrical conductivity. I find that the lack of impurities on the grain surfaces of pure quartz samples imparts a lower surface relaxivity as compared to clay containing sandstones and makes nuclear magnetic resonance analysis more complex. Thus, inverted nuclear magnetic resonance data from cleaner outcrop samples incorrectly models pore size distribution without accounting for wider surface relaxivity variation and is improperly used when characterizing the Fontainebleau sandstone. This is further supported by evidence from less

  3. Influence of Land Use and Watershed Characteristics on Protozoa Contamination in a Potential Drinking Water Resources Reservoir

    Science.gov (United States)

    Relative changes in the microbial quality of Lake Texoma, on the border of Texas and Oklahoma, were investigated by monitoring protozoan pathogens, fecal indicators, and factors influencing the intensity of the microbiological contamination of surface water reservoirs. The waters...

  4. Influence of Land Use and Watershed Characteristics on Protozoa Contamination in a Potential Drinking Water Resources Reservoir

    Science.gov (United States)

    Relative changes in the microbial quality of Lake Texoma, on the border of Texas and Oklahoma, were investigated by monitoring protozoan pathogens, fecal indicators, and factors influencing the intensity of the microbiological contamination of surface water reservoirs. The waters...

  5. Pollution characteristics and ecological risk assessment of heavy metals in the surface sediments from a source water reservoir

    Directory of Open Access Journals (Sweden)

    Changming Yang

    2016-10-01

    Full Text Available Surface sediment samples were collected from a source water reservoir in Zhejiang Province, East of China to investigate pollution characteristics and potential ecological risk of heavy metals. The BCR sequential extraction method was used to determine the four chemical fractions of heavy metals such as acid soluble, easily reducible, easily oxidizable and residual fractions. The heavy metals pollution and potential ecological risk were evaluated systematically using geoaccumulation index (Igeo and Hakanson potential ecological risk index (H′. The results showed that the sampling sites from the estuaries of tributary flowing through downtowns and heavy industrial parks showed significantly (p < 0.05 higher average concentrations of heavy metals in the surface sediments, as compared to the other sampling sites. Chemical fractionation showed that Mn existed mainly in acid extractable fraction, Cu and Pb were mainly in reducible fraction, and As existed mainly in residual fraction in the surface sediments despite sampling sites. The sampling sites from the estuary of tributary flowing through downtown showed significantly (p < 0.05 higher proportions of acid extractable and reducible fractions than the other sampling sites, which would pose a potential toxic risk to aquatic organisms as well as a potential threat to drinking water safety. As, Pb, Ni and Cu were at relatively high potential ecological risk with high Igeo values for some sampling locations. Hakanson potential ecological risk index (H′ showed the surface sediments from the tributary estuaries with high population density and rapid industrial development showed significantly (p < 0.05 higher heavy metal pollution levels and potential ecological risk in the surface sediments, as compared to the other sampling sites.

  6. Types and characteristics of carbonate reservoirs and their implication on hydrocarbon exploration: A case study from the eastern Tarim Basin, NW China

    Directory of Open Access Journals (Sweden)

    Shiwei Huang

    2017-02-01

    Full Text Available Carbonate rocks are deposited in the Ordovician, Cambrian, and Sinian of eastern Tarim Basin with a cumulative maximum thickness exceeding 2000 m. They are the main carriers of oil and gas, and a great deal of natural gas has been found there in the past five years. Based on lithofacies and reservoir differences, natural gas exploration domains of eastern Tarim Basin can be classified into five types: Ordovician platform limestone; Ordovician platform dolomite; Cambrian platform margin mound shoal; Cambrian slope gravity flow deposits, and; Sinian dolomite. Carbonate reservoir characteristics of all the types were synthetically analyzed through observation on drilling core and thin sections, porosity and permeability measurement, and logging data of over 10 drilling wells. We find distribution of part of good fracture and cave reservoir in carbonate platform limestone of Ordovician. In the Ordovician, platform facies dolomite is better than limestone, and in the Cambrian, platform margin mound shoal dolomite has large stacking thickness. Good quality and significantly thick carbonate gravity deposit flow can be found in the Cambrian slope, and effective reservoir has also been found in Sinian dolomite. Commercial gas has been found in the limestone and dolomite of Ordovician in Shunnan and Gucheng areas. Exploration experiences from these two areas are instructive, enabling a deeper understanding of this scene.

  7. Characteristics of reservoir density flow in stratified water environment%分层环境中水库密度流运动特性研究

    Institute of Scientific and Technical Information of China (English)

    任实; 张小峰; 陆俊卿

    2013-01-01

    A flume experiment for the motion of reservoir density current in steady temperature stratified environment was used. Through different tests, simulated the density flow movement under the conditions of different temperature stratification, and analyzed the effects of stratified strength and outlet condition on density flow movement. The density flow movement characteristics under different reservoir operation modes were researched on the basis of model simulation. The research results can provide reference for the management about the water quality of the reservoir and aquatic environment, also can give reference for the early warning plan of reservoir emergency.%该文采用水槽试验对稳定温度分层水库的密度流运动进行了模拟.通过不同的试验方案,模拟了不同温度分层条件下密度流运动形态,分析了水体分层强度和出口条件对密度流运动的影响,并在此基础上,对不同水库运行方式下密度流运动特征进行了模拟研究.该文研究结果为水库水质、水生环境管理与调度以及水库应急预警方案的制定提供了参考.

  8. Element mobility during diagenesis: sulphate cementation of Rotliegend sandstones, Southern North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Gluyas, J. [BP Venezuela, Caracas (Venezuela); Jolley, L.; Primmer, T. [BP Exploration, Aberdeen (United Kingdom)

    1998-11-01

    Several wells in the Amethyst gas field of the North Sea`s Southern Basin are poor producers and have been since they were drilled. The lack of gas flow from these wells is due to pervasive cementation of the Rotliegend sandstone reservoir by either anhydrite and/or barite. Both minerals precipitated late in the diagenetic history of the sandstones. Such cements form up to 20% of the total rock. Isotopic and geochemical evidence indicate that the source of the elements for these sulphate cements was outside the Rotliegend sandstone. The sulphur and oxygen isotope data for the anhydrite and barite are unlike those which could have precipitated in Lower Permian times from an evaporating marine basin. Both the timing and distribution of these cements is taken to indicate that faulting allowed, or indeed promoted, mixing of sulphate-rich and barium-rich formation waters derived from the Zechstein and Carboniferous, respectively. (author)

  9. Petrography and Diagenesis of Palaeocene -Eocene Sandstones in the Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari

    it is generally associated with thick coatings of opal/microquartz on the detrital framework grains.   This study also presents the occurrence and compositional variance of the authigenic zeolites in the Siri Canyon sandstones, and discusses the physico-chemical conditions, which prevailed during formation...... are microquartz, large syntaxial quartz overgrowth, calcite, and chlorite.    Chlorite forms an intra-reservoir hydrocarbon seal, and our study demonstrates the influence of early diagenetic quartz on the formation of the chlorite seal.  Early opal and microquartz are precipitated close to shale contacts...... and prevent the interaction between abundant detrital glaucony and pore-fluid and thus the formation of grain-coating berthierine.  It also preserves porosity and permeability in marginal and isolated parts of the sandstone. In other parts of the sandstone grain coating berthierine precipitated...

  10. Reservoir characteristics and its main controlling factors of the Pinghu Formation in Pinghu structural belt, Xihu Depression%西湖凹陷平湖构造带平湖组砂岩储层特征及其主控因素

    Institute of Scientific and Technical Information of China (English)

    胡明毅; 沈娇; 胡蝶

    2013-01-01

    Based on comprehensive analysis of various data such as core observation,casting thin sections,scanning electron microscope,physical property analysis,mercury penetration and production test,we studied the characteristics and the main controlling factors of the sandstone reservoirs in the Pinghu Formation of Pinghu tectonic belt in Xihu depression.The results show that the reservoir rocks are dominated by feldspathic quartz sandstone with good sorting and roundness,moderate compositional maturity and high texture maturity.The reservoir is characterized by low porosity and low permeability or moderate porosity and moderate permeability,as well as a good correlation between porosity and permeability.The pores are dominated by intergmular dissolution pores and relic primary intergmular pores,the pore throats are mainly of necking throat,laminated throat and curved lamellar throat,and the pore-throat assemblages are dominated by moderate pore-coarse throat.The main controlling factors of reservoir development in the research region were studied in respects of sedimentary facies,diagenesis and abnormal high pressure.Sedimentary facies is one of the main factors controlling the reservoir quality.The sandstone reservoirs of delta plain distributary channel facies are the best in physical properties,followed by delta front underwater distributary channel facies.Compaction and cementation are destructive to reservoir physical property,while dissolution is constructive to reservoir physical property as it can generate secondary porosity.The existence of abnormal high pressure is also constructive to reservoir physical property,for it is helpful to the preservation of the original intergranular pores and to the improvement of dissolution of the early carbonate cement,resulting in intergranular dissolution pores and improving the reservoir physical properties.%以岩心和铸体薄片观察为基础,结合扫描电镜、储层物性、压汞及试采等综合资料分析,对

  11. Petrofacies analysis - the petrophysical tool for geologic/engineering reservoir characterization

    Energy Technology Data Exchange (ETDEWEB)

    Watney, W.L.; Guy, W.J.; Gerlach, P.M. [Kansas Geological Survey, Lawrence, KS (United States)] [and others

    1997-08-01

    Petrofacies analysis is defined as the characterization and classification of pore types and fluid saturations as revealed by petrophysical measures of a reservoir. The word {open_quotes}petrofacies{close_quotes} makes an explicit link between petroleum engineers concerns with pore characteristics as arbiters of production performance, and the facies paradigm of geologists as a methodology for genetic understanding and prediction. In petrofacies analysis, the porosity and resistivity axes of the classical Pickett plot are used to map water saturation, bulk volume water, and estimated permeability, as well as capillary pressure information, where it is available. When data points are connected in order of depth within a reservoir, the characteristic patterns reflect reservoir rock character and its interplay with the hydrocarbon column. A third variable can be presented at each point on the crossplot by assigning a color scale that is based on other well logs, often gamma ray or photoelectric effect, or other derived variables. Contrasts between reservoir pore types and fluid saturations will be reflected in changing patterns on the crossplot and can help discriminate and characterize reservoir heterogeneity. Many hundreds of analyses of well logs facilitated by spreadsheet and object-oriented programming have provided the means to distinguish patterns typical of certain complex pore types for sandstones and carbonate reservoirs, occurrences of irreducible water saturation, and presence of transition zones. The result has been an improved means to evaluate potential production such as bypassed pay behind pipe and in old exploration holes, or to assess zonation and continuity of the reservoir. Petrofacies analysis is applied in this example to distinguishing flow units including discrimination of pore type as assessment of reservoir conformance and continuity. The analysis is facilitated through the use of color cross sections and cluster analysis.

  12. Relation between facies, diagenesis, and reservoir quality of Rotliegende reservoirs in north Germany

    Energy Technology Data Exchange (ETDEWEB)

    David, F.; Gast, R.; Kraft, T. (BEB Erdgas Erdol GmbH, Hannover (Germany))

    1993-09-01

    In north Germany, the majority of Rotliegende gas fields is confined to an approximately 50 km-wide east-west-orientated belt, which is situated on the gently north-dipping flank of the southern Permian basin. Approximately 400 billion m[sup 3] of natural gas has been found in Rotliegende reservoir sandstones with average porosities of depths ranging from 3500 to 5000 m. Rotliegende deposition was controlled by the Autunian paleo-relief, and arid climate and cyclic transgressions of the desert lake. In general, wadis and large dunefields occur in the hinterland, sebkhas with small isolate dunes and shorelines define the coastal area, and a desert lake occurs to the north. The sandstones deposited in large dunefields contain only minor amounts of illite, anhydrite, and calcite and form good reservoirs. In contrast, the small dunes formed in the sebkha areas were affected by fluctuations of the desert lake groundwaters, causing the infiltration of detrital clay and precipitation of gypsum and calcite. These cements were transformed to illite, anhydrite, and calcite-II during later diagenesis, leading to a significant reduction of the reservoir quality. The best reservoirs occur in the shoreline sandstones because porosity and permeability were preserved by early magnesium-chlorite diagenesis. Since facies controls diagenesis and consequently reservoir quality, mapping of facies also indicates the distribution of reservoir and nonreservoir rocks. This information is used to identify play area and to interpret and calibrate three-dimensional seismic data.

  13. [Characteristics of sediment heavy metal pollution in three water supply reservoirs in Huizhou, Guangdong Province of South China].

    Science.gov (United States)

    Chen, Xiu-Kang; Zhang, Hua-Jun; Gu, Ji-Guang; Hu, Ren; Yang, Hao-Wen; Chen, Jing-An

    2012-05-01

    To understand the present status of the heavy metal (Cr, Cu, Zn, Cd, Pb and Hg) pollution of the sediments in water supply reservoirs in Huizhou, sediment cores were sampled from three representative reservoirs. The heavy metal concentrations were analyzed by ICP-MS, and the pollution status was assessed by geo-accumulation index (Igeo) and potential ecological risk index (RI). In the meantime, the possible sources of the heavy metals were analyzed by the principal component analysis (PCA). In the sediments of the three reservoirs, the test heavy metals had different vertical distribution, some had less change, the others decreased or increased with depth, and the distribution patterns differed with the reservoirs. According to the Igeo, the sediments in the reservoirs were seriously polluted by Zn and Pb (Zn: 49.98-640.29 mg x kg(-1); Pb: 21.94-300.66 mg x kg(-1)), reaching slight to high pollution, and the middle or bottom part of the sediments was slightly polluted by Cu (16.85-45.46 mg x kg(-1)). On the whole, the sediments were not polluted by Cr, Cd and Hg. According to the RI and the potential ecological risk coefficient [Er(i)], the sediments in the three reservoirs were under low potential ecological risk. Based on the PCA and relevant information, the human activities such as mining and smelting, urbanization, and agriculture and forestry had great contribution to the heavy metal pollution. The Zn and Pb pollution mainly originated from mining and smelting, Pb pollution also came from motor vehicle exhaust emission and domestic wastes, and Cu pollution mainly derived from agriculture and forestry.

  14. Densification Modes of Sandstone Reservoir in the 8th Member of the Lower Shihezi Formation,Permian,in Su-6 Area of Sulige Gas Field,Ordos Basin%鄂尔多斯盆地苏里格气田苏6区块二叠系下石盒子组8段砂岩储层致密成因模式

    Institute of Scientific and Technical Information of China (English)

    毕明威; 刘金; 陈世悦; 周兆华; 郑国强; 张满郎; 高立祥; 钱爱华; 谷江锐; 石石

    2015-01-01

    Densification modes of tight sandstone reservoir of the 8th Member of Lower Shihezi Formation, Permian,in Su -6 Area of the Sulige Gas Field,Ordos Basin,are quantitatively analysised by means of slice identification,scan electron microscope,electron probe micro -analysis and energy spectrum,homogenization temperatures and raman microprobe research of fluid inclusions.The results are as follows:(1 )Densification process can be divided into the following stages,compaction during early diagenesis and the 1st stage siliceous cementation→—the 2nd stage siliceous cementat ion and grain -coating chlorite→—the 1st stage dissolution (hydrocarbon charge →—) compaction during late diagenesis and the 3rd stage siliceous cementation (densification of reservoir )→—the 2nd stage dissolution and the 4th stage sil iceous cementation→—cementation and replacement of chlorite→—cementation and replacement of carbonate.(2)Densification modes of reservoir can be divided into three types:densification of medium -coarse grained litharenite by strong compaction;densification of medium -coarse grained lithic quartzarenite by strong siliceous cementation and medium to strong compaction;densification of fine grained (feldspathic ) litharenite by strong compaction and medium to strong siliceous cementation.(3)The main reasons for densification of reservoir are compaction and siliceous cementation.And the 2nd stage dissolution under enclosed environment has less ascension of porosity,which is another important reason for densification.(4)The two types of medium -coarse grained sandstones are densification after hydrocarbon charge,which experience injection of organic acid and make dissolved pore to be the major storage space.Fine grained (feldspathic)litharenite is densification before hydrocarbon charge,which experience weak dissolution. (5)Difference of densification modes lead to the porosity,permeability ,correlation of permeability and porosity of medium -coarse

  15. 松辽盆地南部海坨子地区超低渗透储层特征与形成因素%Characteristics and form factors of ultralow permeable reservoir in Haituozi area in the southern Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    李德勇; 张金亮; 于孝玉; 张辉; 李京涛

    2012-01-01

    通过详细的岩心观察和描述,同时结合铸体薄片、扫描电镜、x-射线衍射、压汞、核磁共振以及物性等资料的研究,认为海坨子地区扶余油层为末端扇中部亚相沉积,储层岩石类型主要为岩屑长石砂岩和长石岩屑砂岩,孔喉结构为小孔隙、细喉或微细喉型,束缚水饱和度高,渗流能力差,属于超低渗透储层.沉积作用和成岩作用是扶余油层超低渗透储层形成的关键.末端扇沉积控制了扶余油层原始沉积物的粒度、碎屑成分以及填隙物成分和含量,使得储层初始孔渗性较差,同时强烈的机械压实作用导致扶余油层原生粒间孔隙体积直线下降,而胶结作用,尤其碳酸盐连晶状基底胶结几乎完全封堵了孔喉,喉道内伊利石等粘土矿物的搭桥生长,也使孔喉变得越来越曲折、狭窄,储层渗流能力因此遭受严重破坏.此外,末端扇储层中大量非渗透性隔夹层导致的强非均质性也是超低渗透储层形成的一个因素.溶蚀作用对扶余油层渗透性的改善有限,但成岩微裂缝和构造裂缝的发育对海坨子地区超低渗透油藏的开发起着至关重要的作用.%According to careful observation of core and analysis of cast thin section, SEM, X-ray, mercury penetration, nuclear magnetic resonance and physical property, the Fuyu reservoir is part of middle-terminal fan sand which is chiefly composed of lithic arkose and arkose. The sandstone reservoir is ultralow permeable reservoir with high bound water saturation, small pore and micro to fine porous throats. Sedimentation and diagenesis are key factors of Fuyu ultralow permeable reservoir. The Fuyu reservoir is mainly controlled by deposition and diagenesis. Terminal deposit which affects grain size, clastic constituents and interstitial material result in low original poroperm characteristics. Strong compaction destroyed great quantity of inter granular pores. Cementation, especially basal

  16. Water resources review: Ocoee reservoirs, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Cox, J.P.

    1990-08-01

    Tennessee Valley Authority (TVA) is preparing a series of reports to make technical information on individual TVA reservoirs readily accessible. These reports provide a summary of reservoir purpose and operation; physical characteristics of the reservoir and watershed; water quality conditions; aquatic biological conditions; and designated, actual and potential uses of the reservoir and impairments of those use. This reservoir status report addressed the three Ocoee Reservoirs in Polk County, Tennessee.

  17. Subaqueous systems fed by glacially derived hyperpycnal flows: a depositional model for Carboniferous-Permian sandstones of the Itarare Group, Parana Basin; Sistemas subaquosos alimentados por fluxos hiperpicnais glaciogenicos: modelo deposicional para arenitos do Grupo Itarare, Permocarbonifero da Bacia do Parana

    Energy Technology Data Exchange (ETDEWEB)

    Vesely, Fernando Farias [PETROBRAS, Rio de Janeiro, RJ (Brazil). E e P. Gerencia de Estratigrafia]. E-mail: vesely@petrobras.br

    2006-11-15

    The glacial Itarare Group constitutes the lower interval of the Carboniferous-Permian mega sequence in the Parana Basin. Thick glacially related sandstone reservoirs present in this unit contain gas and condensate sourced by Devonian marine shales. Based on outcrop data from the eastern basin margin, the sedimentary facies and stacking patterns were analyzed in order to propose a depositional model for these sandstone successions. It is suggested that the sandstones were deposited subaqueously as pro glacial fans due to melt water-derived highly concentrated hyperpycnal flows. Regional Itarare Group's stratigraphy can be expressed as several unconformity-bounded sequences deposited in a marine glaciated basin during repeated deglaciation episodes. The lower half of each sequence is constituted of thick sand-rich successions typically showing fining-upward and a retrogradational stacking pattern. Eleven facies were recognized, ranging from conglomerates to fine-grained sandstones, massive, graded or stratified. Conglomerates and cross-bedded coarse sandstones represent proximal Subaqueous deposits and were formed as ice-contact out wash fans/aprons due to melt water-derived hyper concentrated and concentrated flows and traction dominated bottom currents. These flows served as feeder systems to stratified, massive or graded turbiditic sandstone lobes deposited more distally. Parallel bedding and climbing ripples present in these beds were formed due to continuous aggradation from waxing and/or waning long-lived turbidity currents. These characteristics typify hyperpycnites and suggest that melt water derived hyperpycnal flows were the main trigger mechanisms to turbidity currents in the Itarare Group. (author)

  18. GREYBULL SANDSTONE PETROLEUM POTENTIAL ON THE CROW INDIAN RESERVATION, SOUTH-CENTRAL MONTANA

    Energy Technology Data Exchange (ETDEWEB)

    David A. Lopez

    2000-12-14

    . With continued transgression, the Greybull fluvial sand graded upward into marginal marine (probably estuarine) sand (upper Greybull) and finally was capped by marine shale and the Fall River Sandstone. Subsurface mapping, incorporated with surface data, has revealed five major Greybull channels crossing the Crow Reservation. The Greybull Sandstone is a proven petroleum reservoir in the Crow Reservation region. Greybull combination traps require the presence of channel sandstone as well as structural closure. With sparse reservation well control, subsurface structural and isopach maps are highly interpretive. Three potential Greybull exploration leads were identified where possible structural closures are coincident with mapped Greybull channels: the Little Woody, Woody Dome, and Crow Agency prospects. Of these, the Crow Agency prospect was confirmed by a significant soil-gas anomaly and appears to have the greatest probability of having trapped a hydrocarbon accumulation.

  19. 厄瓜多尔奥连特盆地白垩系M1油藏沉积储层新认识%New understanding of sedimentation and reservoir characteristics of M1zone in Cretaceous strata of Oriente Basin,Ecuador

    Institute of Scientific and Technical Information of China (English)

    陈诗望; 姜在兴; 滕彬彬; 徐德军

    2012-01-01

    The paleo-geomorphology of Block 14and 17which is high in the east and low in the west in the region is further characterized and an N-S trend paleo-barrier island is identified in H oilfield according to sand thickness,structural inversion,core and kaolinite content in drilled wells.The sedimentary microfacies of M1are described under the guidance of sedimentary model.The results show that H oilfield is mud flat and mixed flat,N oilfield is sand flat and tidal channel,K-S oilfield is located in sub-tidal zone while W oilfield deposits tidal-dominated delta sediments.The analysis of reservoir and oil-bearing characteristics controlled by microfacies indicates that tidal channel and sand flat sandstones are favorable reservoirs with mid-high porosity and extra-high permeability,mainly distributing in the slope.Meanwhile,reservoirs in mixed flat and mud flat with thin sandstone and limited distribution are poor oil layers or dry layers on the top of the structure.Therefore,structural-lithological oil reservoirs are formed due to the special matching relationship between both structure and reservoir.%在14、17区块古地貌东高西低的区域性认识基础上,根据砂岩厚度分布规律、构造反演、岩心以及录井中高岭石的相对含量,确定了古地貌特征,指出在H油田存在南北向古海岛。结合沉积模式,描述了M1层沉积微相展布。结果表明:H油田位于泥坪和混合坪亚相,N油田位于砂坪亚相和潮道发育区,K—S油田位于潮下带,W油田为潮控三角洲沉积。并对沉积相控制的储层特征和含油性特征进行了分析,指出有利储层为潮道和砂坪砂岩,为中高孔特高渗储层,此类储层分布在目前构造的斜坡部位;混合坪和泥坪中储层分布局限,易形成差油层或干层,此类储层分布在目前构造顶部。由于构造和储层的特殊匹配关系,形成构造岩性复合油藏。

  20. Geochemical Characteristics and Origin of Tar Mats from the Yaha Field in Tarim Basin,China

    Institute of Scientific and Technical Information of China (English)

    张敏; 张俊; 等

    1999-01-01

    Tar mats were firstly discovered and determined accurately in terrestrial oil and gas reservoirs associated with Lower Tertiary sandstone reservoirs in the Yaha field of the Tarim Basin,China,by thin-layer chromatography-flame ionization detector(TLC-FID)and Rock-Eval analysis.The relative content of asphaltene in gross composition of tar mat extracts accounts for more than 30%,that in the corresponding oil leg less than 20%.In the geochemical description profile of oil gas reservoirs,drastic changes in asphaltene contents between tar mats and oil legs could be discovered.This in an important marker to determine tar mats.Distribution characteristics of saturated and aromaic hydrocarbons from reservoir core extracts and crude oils in the Yaha oil and gas reservoirs in the Tarim Basin are described systematically in this paper,and the results show there are similarities among n-alkane distribution characteristics,biomarker distribution characteristics and their combined characteristics of saturated hydrocarbons,and the geochemical characteristics of aromatic hydrocarbons for tar mats.oil leg,asphaltic sand and crude oil.These characteristics suggest the hydrocarbons in these samples were originated from the common source rocks.However,the geochemical characteristics of tar mats reveales that the mechanism of formation of tar mats is the precipitation of asphaltene from crude oils in petroleum reservoirs caused by increased dissolved gas in oil legs(gas injection).

  1. Comparative analysis of morphometric characteristics of bivalves Anodonta piscinalis from the reservoirs of techa cascade of Mayak Production Association

    Energy Technology Data Exchange (ETDEWEB)

    Yegoreichenkov, E.; Pryakhin, E.; Akleyev, A. [Urals Research Center for Radiation Medicine - URCRM (Russian Federation)

    2014-07-01

    The reservoirs R-11, R-10 and R-4 of the Techa cascade (Chelyabinsk region) are used as low-active radioactive wastes storages, and are separated from open hydrographical network by a system of dams and by-pass channels. The values of specific activity of radionuclides in water and bottom sediments increases in the row: R-11, R-10, R-4, and at the same time the dose rate for zoo-benthos is increased on an order from reservoir to reservoir. Bivalves, which are obligate filter feeders and produce a significant part of water community biomass, are an important part of energy and matter transformation chain inside the hydro-biocenosis. Among this group of animals, the Anodonta piscinalis, a massive bivalve, takes the most part in biomass of Techa reservoirs cascade. Several studies show that in polluted environment the shell morphology changes are possible: the ratio of most morphometric values changes; the level of fluctuated asymmetry and shell polymorphism increases. For morphological studies of bivalves populations, 34 specimens of Anodonta were taken from R-11, 43 specimens from R-10 and 4 specimens from R-4. The specimens selection was arranged in May 2013, using hydro-biological drag. The shell shape was analyzed using TPS DIG software. Besides the measurements of maximal shell length, shell height, and the distance between shell's top and maximally distant point of front edge of the shell were measured. The ratio between the length and the height of the shell, between the length and the distance from the top to the front edge were calculated. The data analysis was arranged using R statistics. As a result of the data analysis the significant difference between shell's length to height ratios were registered between populations of R-4 and R-10 (p = 0.002). The ratio of maximal length of the shell to the distance from the top to the front edge also significantly differs between the animals of the R-4 and R-10 reservoirs (?= 0.03). Between the animals of

  2. The characteristics and sources of natural gases from Ordovician weath-ered crust reservoirs in the Central Gas Field in the Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    LI Xianqing; HU Guoyi; LI Jian; HOU Dujie; DONG Peng; SONG Zhihong; YANG Yunfeng

    2008-01-01

    The Central Gas Field is a famous large-sized gas field in the Ordos Basin of China. However, identification of main gas sources of the Ordovician reservoirs in this gas field remains puzzling. On the basis of a lot of geochemical data and geological research on natural gases, the characteristics and sources of natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin were studied. The results indicated that natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin have similar chemical and isotopic com-positions to highly mature and over-mature dry gases. Both coal-derived gases and oil-type gases coexist in the Central Gas Field in the Ordos Basin. The former was derived mainly from Carboniferous-Permian coal measures and the latter from Lower Paleozoic marine carbonates. It is suggested that coal-derived gases occur in the eastern part of the Central Gas Field while oil-type gases may be pro-duced mainly in the northern, western and southern parts of the Central Gas Field in the Ordos Basin.

  3. Microstructural changes of sandstone specimens during CO2 injection

    Science.gov (United States)

    Park, J. H.; Son, J.; Oh, M.; Park, H. D.

    2014-12-01

    Carbon dioxide capture and storage (CCS) is a technology to isolate CO2 from atmosphere, by capturing it from sources, transporting it to injection area, and injecting it into suitable geological formation, ocean, or mineral carbonation plant. Geological storage of carbon dioxide is the most effective and economical method, and until now a lot of demonstration projects were carried out successfully such as Sleipner, Weyburn, and In Salah. In Republic of Korea, small-scale CO2 injection demonstration project is now under investigation in offshore Pohang Basin with sandstone reservoir and the mudstone caprock. When CO2 is injected in target site, the rock around injection well can be deteriorated because of extreme change of temperature and pressure. In this study supercritical CO2 was injected in sandstone specimen and the initiation and propagation of fracture inside the specimens were observed using X-ray computed tomography (CT). X-ray CT method is a computer technology to observe inner density of target object in three dimensional image. Because of its non-destructivity and high resolution, it is suitable for consistent observation of the same specimen. Porosity and permeability of the specimens were measured using X-ray CT images and both of them were increased after injection. P- and S-wave velocity were also measured to assess the change of mechanical property and both of them were decreased after injection because of growth of inner fractures. The data from this research can be used as input data of CCS site.

  4. Imaging cross fault multiphase flow using time resolved high pressure-temperature synchrotron fluid tomography: implications for the geological storage of carbon dioxide within sandstone saline aquifers

    Science.gov (United States)

    Seers, Thomas; Andrew, Matthew; Bijeljic, Branko; Blunt, Martin; Dobson, Kate; Hodgetts, David; Lee, Peter; Menke, Hannah; Singh, Kamaljit; Parsons, Aaron

    2015-04-01

    Applied shear stresses within high porosity granular rocks result in characteristic deformation responses (rigid grain reorganisation, dilation, isovolumetric strain, grain fracturing and/or crushing) emanating from elevated stress concentrations at grain contacts. The strain localisation features produced by these processes are generically termed as microfaults (also shear bands), which occur as narrow tabular regions of disaggregated, rotated and/or crushed grains. Because the textural priors that favour microfault formation make their host rocks (esp. porous sandstones) conducive to the storage of geo-fluids, such structures are often abundant features within hydrocarbon reservoirs, aquifers and potential sites of CO2 storage (i.e. sandstone saline aquifers). The porosity collapse which accompanies microfault formation typically results in localised permeability reduction, often encompassing several orders of magnitude. Given that permeability is the key physical parameter that governs fluid circulation in the upper crust, this petrophysical degradation implicates microfaults as being flow impeding structures which may act as major baffles and/or barriers to fluid flow within the subsurface. Such features therefore have the potential to negatively impact upon hydrocarbon production or CO2 injection, making their petrophysical characterisation of considerable interest. Despite their significance, little is known about the pore-scale processes involved in fluid trapping and transfer within microfaults, particularly in the presence of multiphase flow analogous to oil accumulation, production and CO2 injection. With respect to the geological storage of CO2 within sandstone saline aquifers it has been proposed that even fault rocks with relatively low phyllosilicate content or minimal quartz cementation may act as major baffles or barriers to migrating CO2 plume. Alternatively, as ubiquitous intra-reservoir heterogeneities, micro-faults also have the potential to

  5. Diagenesis of Cambrian and lower Carboniferous sandstones, southwest Sinai, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Wahab, A.A.; Salem, A.M.K. [Tanta Univ., Kafr El-Sheikh (Egypt); McBride, E.F. [Univ. of Texas, Austin, TX (United States)

    1996-12-31

    Quartzose and feldspathic Cambrian and Lower Carboniferous sandstones (fluvial > marine > eolian) deposited on the Arabian shield in southwestern Sinai were not buried more than 1 to 1.5 km until Late Cretaceous and younger time, when the deepest rocks reached 2.5 km. Porosity was reduced by compaction to about 26%. Grain rearrangement was the main mechanism of compaction; intergranular pressure solution and ductile grain deformation are insignificant. Cementation by iron oxide (5%), quartz (3%), calcite (2%), kaolinite (2%) and K-feldspar (< 1%) reduced porosity to 12-15% except in silcretes and some ferricretes, where porosity was reduced to non-reservoir quality. Cements have no selectivity for certain textures or stratigraphic positions.

  6. Diagenesis of Cambrian and lower Carboniferous sandstones, southwest Sinai, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Wahab, A.A.; Salem, A.M.K. (Tanta Univ., Kafr El-Sheikh (Egypt)); McBride, E.F. (Univ. of Texas, Austin, TX (United States))

    1996-01-01

    Quartzose and feldspathic Cambrian and Lower Carboniferous sandstones (fluvial > marine > eolian) deposited on the Arabian shield in southwestern Sinai were not buried more than 1 to 1.5 km until Late Cretaceous and younger time, when the deepest rocks reached 2.5 km. Porosity was reduced by compaction to about 26%. Grain rearrangement was the main mechanism of compaction; intergranular pressure solution and ductile grain deformation are insignificant. Cementation by iron oxide (5%), quartz (3%), calcite (2%), kaolinite (2%) and K-feldspar (< 1%) reduced porosity to 12-15% except in silcretes and some ferricretes, where porosity was reduced to non-reservoir quality. Cements have no selectivity for certain textures or stratigraphic positions.

  7. Area of Interest 1, CO2 at the Interface. Nature and Dynamics of the Reservoir/Caprock Contact and Implications for Carbon Storage Performance

    Energy Technology Data Exchange (ETDEWEB)

    Mozley, Peter [New Mexico Institute Of Mining And Technology, Socorro, NM (United States); Evans, James [New Mexico Institute Of Mining And Technology, Socorro, NM (United States); Dewers, Thomas [New Mexico Institute Of Mining And Technology, Socorro, NM (United States)

    2014-10-31

    We examined the influence of geologic features present at the reservoir/caprock interface on the transmission of supercritical CO2 into and through caprock. We focused on the case of deformation-band faults in reservoir lithologies that intersect the interface and transition to opening-mode fractures in caprock lithologies. Deformation-band faults are exceeding common in potential CO2 injection units and our fieldwork in Utah indicates that this sort of transition is common. To quantify the impact of these interface features on flow and transport we first described the sedimentology and permeability characteristics of selected sites along the Navajo Sandstone (reservoir lithology) and Carmel Formation (caprock lithology) interface, and along the Slickrock Member (reservoir lithology) and Earthy Member (caprock lithology) of the Entrada Sandstone interface, and used this information to construct conceptual permeability models for numerical analysis. We then examined the impact of these structures on flow using single-phase and multiphase numerical flow models for these study sites. Key findings include: (1) Deformation-band faults strongly compartmentalize the reservoir and largely block cross-fault flow of supercritical CO2. (2) Significant flow of CO2 through the fractures is possible, however, the magnitude is dependent on the small-scale geometry of the contact between the opening-mode fracture and the deformation band fault. (3) Due to the presence of permeable units in the caprock, caprock units are capable of storing significant volumes of CO2, particularly when the fracture network does not extend all the way through the caprock. The large-scale distribution of these deformation-bandfault-to-opening-mode-fractures is related to the curvature of the beds, with greater densities of fractures in high curvature regions. We also examined core and outcrops from the Mount Simon Sandstone and Eau Claire

  8. Fish mercury development in relation to abiotic characteristics and carbon sources in a six-year-old, Brazilian reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Tuomola, Leena; Niklasson, Terese [Evolutionary Biology Centre and Department of Limnology, Uppsala University, Norbyvaegen 20, S-752 36 Uppsala (Sweden); Castro e Silva, Edinaldo de [Departamento de Quimica, Universidade Federal de Mato Grosso (UFMT), Av. Fernando C. Costa/sn, 78 090-900 Cuiaba-MT (Brazil); Hylander, Lars D. [Department of Earth Sciences, Air, Water and Landscape Science, Uppsala University, Villavaegen 16, S-752 36 Uppsala (Sweden)], E-mail: Lars.Hylander@hyd.uu.se

    2008-02-01

    Time series on fish mercury (Hg) development are rare for hydroelectric reservoirs in the tropics. In the central-western part of Brazil, a hydroelectric reservoir, called Lago Manso, was completed in 1999 after that background levels of fish Hg concentrations had been determined. The development for the first 3 years was studied in 2002. The objective of the present study was to determine development of fish Hg concentrations for a second three-year period after flooding. The bioaccumulation factor and certain abiotic and biotic factors, possibly affecting the availability and accumulation of Hg, were also examined. The results show that Hg levels in fish from Lago Manso have increased more than five times compared to the background levels observed before construction of the reservoir. At the same time, dissolved organic carbon has increased while dissolved oxygen has decreased indicating enhanced bioavailability of Hg. In the reservoir, Salminus brasiliensis had in average a Hg content of 1.1 {mu}g g{sup -1} f.w., Pseudoplatystoma fasciatum 1.2, Serrasalmus marginatus/spilopleura 0.9, and Brycon hilarii 0.6 {mu}g g{sup -1} f.w. The average fish Hg contents were higher downstream, except for B. hilarii. In the reservoir, the average Hg content of each species was in 2005 always over the consumption limit (0.55 {mu}g total Hg g{sup -1} f.w.) recommended by WHO. Therefore, the people living around Lago Manso should be informed of the health effects of Hg, and fish consumption recommendations should be carried out. The accumulation of Hg varies widely between species as shown by the bioaccumulation factor which ranges between 5.08 and 5.59 log units. The observed variation is explained by differences in diet and trophic position with piscivorous fish exhibiting the highest mean Hg concentration, followed by carnivorous and omnivorous species. Carbon isotope analyses imply that trophic position is not the only cause of the observed differences in Hg levels between

  9. Fish mercury development in relation to abiotic characteristics and carbon sources in a six-year-old, Brazilian reservoir.

    Science.gov (United States)

    Tuomola, Leena; Niklasson, Terese; de Castro E Silva, Edinaldo; Hylander, Lars D

    2008-02-01

    Time series on fish mercury (Hg) development are rare for hydroelectric reservoirs in the tropics. In the central-western part of Brazil, a hydroelectric reservoir, called Lago Manso, was completed in 1999 after that background levels of fish Hg concentrations had been determined. The development for the first 3 years was studied in 2002. The objective of the present study was to determine development of fish Hg concentrations for a second three-year period after flooding. The bioaccumulation factor and certain abiotic and biotic factors, possibly affecting the availability and accumulation of Hg, were also examined. The results show that Hg levels in fish from Lago Manso have increased more than five times compared to the background levels observed before construction of the reservoir. At the same time, dissolved organic carbon has increased while dissolved oxygen has decreased indicating enhanced bioavailability of Hg. In the reservoir, Salminus brasiliensis had in average a Hg content of 1.1 microg g(-1) f.w., Pseudoplatystoma fasciatum 1.2, Serrasalmus marginatus/spilopleura 0.9, and Brycon hilarii 0.6 microg g(-1) f.w. The average fish Hg contents were higher downstream, except for B. hilarii. In the reservoir, the average Hg content of each species was in 2005 always over the consumption limit (0.55 microg total Hg g(-1) f.w.) recommended by WHO. Therefore, the people living around Lago Manso should be informed of the health effects of Hg, and fish consumption recommendations should be carried out. The accumulation of Hg varies widely between species as shown by the bioaccumulation factor which ranges between 5.08 and 5.59 log units. The observed variation is explained by differences in diet and trophic position with piscivorous fish exhibiting the highest mean Hg concentration, followed by carnivorous and omnivorous species. Carbon isotope analyses imply that trophic position is not the only cause of the observed differences in Hg levels between omnivorous B

  10. Limnological characteristics of a reservoir in semiarid Northeastern Brazil subject to intensive tilapia farming (Orechromis niloticus Linnaeus, 1758

    Directory of Open Access Journals (Sweden)

    Luis Artur Valões Bezerra

    2014-03-01

    Full Text Available AIM: There is currently no consensus regarding the physical and chemical variability of tropical reservoirs. In semiarid Northeastern Brazil, reservoirs are among other things used for human consumption, industrial water supply and intensive fish farming, all of which can impact water quality. The objective of this study was to evaluate the physical and chemical variability of the water in Sítios Novos, a reservoir in semiarid Northeastern Brazil, comparing samples collected in areas of intensive tilapia (Oreochromis niloticus farming to samples from areas not directly impacted by aquaculture, in both the dry and the rainy season. METHODS: Between October 2010 and July 2011, data were collected on temperature, conductivity, pH, turbidity, salinity, chlorophyll a, dissolved oxygen, oxygen demand, total phosphorus and total nitrogen levels in the water column using a multiparametric probe at four different sampling locations. Physical and chemical differences between the four locations were evaluated with the Kruskal-Wallis (KW test and Dunn's post test, while the t test, followed by Welchʼs correction, was used to compare samples collected in different seasons. RESULTS: No influence of intensive aquaculture was detected when comparing sampling locations near fish farms (180C and 300C to locations not directly impacted by aquaculture (LIMN1, near the dam, and LIMN2, near the debouch of the São Gonçalo river. However, the sampling locations differed significantly (p<0.05 with regard to conductivity, pH, turbidity and chlorophyll a levels. CONCLUSIONS: The physical and chemical variability was greater between seasons than between locations when the data were analyzed with the t test. That analysis showed significant differences for 22 of 40 comparisons between the 10 physical and chemical parameters in the two seasons at the four sampling locations. In conclusion, the physical and chemical variability registered for the Sítios Novos reservoir

  11. Seismic and well logging interpretation for evaluation of the lower Bahariya reservoir, southwest Qarun (SWQ) Field, Gindi Basin, Egypt

    Science.gov (United States)

    Sarhan, Mohammad Abdelfattah; Basal, A. M. K.; Ibrahim, Ibrahim Mohamed

    2017-09-01

    This paper focuses on seismic and well log interpretations for evaluating the sandstones of the Cenomanian Bahariya Formation in the southwest Qarun Field, Gindi Basin, northern Western Desert of Egypt. The seismic profiles display a clear anticlinal structure intersected by reverse faults in the study area. This faulted anticline has been interpreted to be one of the Syrian arc system folds formed by Upper Cretaceous tectonic inversion, which resulted from the NW movement of the African Plate relative to Laurasia. This anticline has been recommended as a target for exploration by the present work as it may represent a structural trap for hydrocarbon accumulation. The sandstones of the Lower Bahariya Formation in the southwest Qarun Field display good reservoir characteristics. The interpretation of the available well log data for the SWQ-21 and SWQ-25 wells for the Lower Bahariya Formation reflects a good reservoir quality for oil production in its topmost part. This reservoir possesses low SW (<50%), high porosity (16%), low SW/SXO and low BVW (<0.09) which all reflect a high potential for oil production.

  12. Experimental strain analysis of Clarens Sandstone colonised by endolithic lichens

    Directory of Open Access Journals (Sweden)

    D. Wessels

    1995-09-01

    Full Text Available Endolithic lichens occur commonly on Clarens Sandstone in South Africa, where they significantly contribute to the weathering of sandstone by means of mechanical and chemical weathering processes. This preliminary investigation reports on the success- ful use of strain gauges in detecting strain differences between sandstone without epilithic lichens and sandstone colonised by the euendolithic lichen Lecidea aff. sarcogynoides Korb. Mechanical weathering, expressed as strain changes, in Clarens Sandstone was studied during the transition from relatively dry winter to wet summer conditions. Daily weathering of sandstone due to thermal expansion and contraction of colonised and uncolonised sandstone could be shown. Our results show that liquid water in sandstone enhances the mechanical weathering of uncolonised Clarens Sandstone while water in the gaseous phase enhances mechanical weathering of sandstone by euendolithic lichens.

  13. Wettability Alteration of Sandstones by Silica Nanoparticle Dispersions with Light and Heavy Crude Oil

    Science.gov (United States)

    Pales, A. R.; Huibers, B. M. J.; Bai, L.; Li, C.; Mu, L.; Ladner, D.; Daigle, H.; Darnault, C. J. G.

    2016-12-01

    In enhanced oil recovery (EOR), nanoparticles with their unique physico-chemical properties present a promising method for altering wettability. Nanoparticles could create a water-wet surface in a reservoir rather than an oil-wet one which would ease petroleum recovery. This research examines how uncoated silica nanoparticles alter the wettability of two sandstone surfaces, Berea and Boise, by measuring the contact angle and interfacial tension of different systems as an indicator of wettability. The silica nanoparticles were suspended in brine and brine plus a nonionic surfactant at concentrations of 0, 0.001, and 0.01 wt%. The differential impact on heavy and light crude oils was characterized as well. The study showed that surfactants had a greater impact on interfacial tension (IFT). The IFT decreased with the introduction of surfactants by 79% and 54% for light and heavy crude oils respectively. This reduction in IFT translates to less pressure needed for petroleum recovery. For the contact angle, images collected depict the reduction of contact angle with increased nanoparticle concentration across all oil, sandstone, and reservoir types. In addition to the images taken, the contact angles measured significantly decreased when nanoparticles were introduced with reductions reaching up to 93% between 0 and 0.001 wt% nanoparticles with light oil on the Berea sandstone. As nanoparticle concentration increased, the sandstones became increasingly water-wet for both oil types, and the increasing concentration impacted the light crude oil more than the heavy crude oil. The research evinced that nanoparticles can be used with surfactants in light and heavy crude oil systems to increase the hydrophilicity of Berea and Boise sandstones.

  14. Application of Advanced Reservoir Characterization, Simulation, and Production Optimization Strategies to Maximize Recovery in Slope and Basin Clastic Reservoirs, West Texas (Delaware Basin), Class III

    Energy Technology Data Exchange (ETDEWEB)

    Dutton, Shirley P.; Flanders, William A.

    2001-11-04

    The objective of this Class III project was demonstrate that reservoir characterization and enhanced oil recovery (EOR) by CO2 flood can increase production from slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico. Phase 1 of the project, reservoir characterization, focused on Geraldine Ford and East Ford fields, which are Delaware Mountain Group fields that produce from the upper Bell Canyon Formation (Ramsey sandstone). The demonstration phase of the project was a CO2 flood conducted in East Ford field, which is operated by Orla Petco, Inc., as the East Ford unit.

  15. Structural diagenesis in Upper Carboniferous tight gas sandstones. Lessons learned from the Piesberg analog study

    Energy Technology Data Exchange (ETDEWEB)

    Steindorf, P.; Hoehne, M.; Becker, S.; Hilgers, C. [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group (EMR); Koehrer, B. [Wintershall Holding GmbH, Barnstorf (Germany)

    2013-08-01

    Upper Carboniferous tight gas sandstone reservoirs in NW-Germany consist of thick successions of cyclothems. Our focus is the Westphalian D of the Piesberg quarry near Osnabrueck, which exposes cemented, faulted and jointed third-order coarse- to fine-grained sandstone cycles separated by anthracite coal seams. We characterize the rocks and the lateral variation of rock properties such as porosity to better constrain input data for reservoir modelling. Three cycles are exposed, each approximately 50 m thick. Rock types can be clearly distinguished by spectral gamma ray in the quarry. Sandstones are intensely compacted and cemented with quartz and generally characterized by low porosities < 8 % (Hepycnometry on plugs and cuttings). Porosities are secondary and mainly related to detrital carbonate dissolution. Around faults dissolution is higher and the porosities can increase to up to 25%. The normal faults show different throws in the quarry and bands of shale and coal have smeared into the fault at juxtaposed beds, which may result in compartments. They dominantly strike W-E and NNW-SSE, but subordinate NE-SW striking fault patterns are also present. Joints were analyzed in a 50 x 50 m section of the quarry wall using Lidar (Light detection and ranging) laser scanning, which allows the characterization of the lithology and quantitative measurement of bedding and fracture orientation data in inaccessible areas. NNE-SSW and W-E joint sets are accompanied by northeasterly and northwesterly striking sets. Around faults, fault planes and fractures are cemented with quartz veins, showing localized mass transport. Due to the intense cementation, the sandstones can reach uniaxial strengths of more than 100 MPa normal to bedding, and approximately 50 MPa parallel to bedding. Sandstone beds within and close to faults are leached by fluids, and their uniaxial strength is reduced by a factor of more than two. Our high resolution field data enables a better understanding of

  16. Depositional Environments of the Upper Permian Quartzose Sandstone (Shandong Province, North China):Insight from Trace Element Geochemistry

    Institute of Scientific and Technical Information of China (English)

    Dawei L; Zengxue Li; Jitao Chen; Ying Liu; Zengqi Zhang; Jipo Liang; Haiyan Liu

    2015-01-01

    The depositional environment of the Upper Permian quartzose sandstone (Kuishan sand-stone in Shihezi Formation of Upper Permian) in the North China epicontinental basin is controversial. In order to test the previous hypotheses, we analyzed sedimentological characteristics of the Kuishan sandstones in outcrops and boreholes, and carried out trace element geochemical analysis by electron probe microanalyzer. Three lithofacies were recognized, including normal-graded conglomerate (Cng), trough and planar cross-bedded coarse sandstone (CStpc), and planar cross-bedded medium sandstone (MSpc). Normal-graded conglomerate (Cng) formed in the meandering river or deltaic distributary channels. Trough and planar cross-bedded coarse sandstone (CStpc) formed in meandering river or distributary channels of near-source deltaic plain. Planar cross-bedded medium sandstone (MSpc) formed in the siliciclastic beach with high-to moderate-energy conditions. By the petrology and trace elements analysis, three relatively large-scale transgressions were revealed. Each transgression was re-flected by the lower content of Ba and ratios of Fe/Mn, and the high content of B and ratios of B/Ga. The ratios of Ni/Co of all samples are all lower than 2, suggesting oxygen-enriched shallower water en-vironment during deposition of the Kuishan sandstones.

  17. Integration of Petrophysical Methods and 3D Printing Technology to Replicate Reservoir Pore Systems

    Science.gov (United States)

    Ishutov, S.; Hasiuk, F.; Gray, J.; Harding, C.

    2014-12-01

    Pore-scale imaging and modeling are becoming routine geoscience techniques of reservoir analysis and simulation in oil and gas industry. Three-dimensional printing may facilitate the transformation of pore-space imagery into rock models, which can be compared to traditional laboratory methods and literature data. Although current methodologies for rapid rock modeling and printing obscure many details of grain geometry, computed tomography data is one route to refine pore networks and experimentally test hypotheses related to rock properties, such as porosity and permeability. This study uses three-dimensional printing as a novel way of interacting with x-ray computed tomography data from reservoir core plugs based on digital modeling of pore systems in coarse-grained sandstones and limestones. The advantages of using artificial rocks as a proxy are to better understand the contributions of pore system characteristics at various scales to petrophysical properties in oil and gas reservoirs. Pore radii of reservoir sandstones used in this study range from 1 to 100s of microns, whereas the pore radii for limestones vary from 0.01 to 10s of microns. The resolution of computed tomography imaging is ~10 microns; the resolution of 3D digital printing used in the study varies from 2.5 to 300 microns. For this technology to be useful, loss of pore network information must be minimized in the course of data acquisition, modeling, and production as well as verified against core-scale measurements. The ultimate goal of this study is to develop a reservoir rock "photocopier" that couples 3D scanning and modeling with 3D printing to reproduce a) petrophyscially accurate copies of reservoir pore systems and b) digitally modified pore systems for testing hypotheses about reservoir flow. By allowing us to build porous media with known properties (porosity, permeability, surface area), technology will also advance our understanding of the tools used to measure these quantities (e

  18. Genesis Types and Diagenesis Compaction Mechanisms of Sandstone Rreservoirs in Dynamic Environments in Oil/Gas Basins in China

    Institute of Scientific and Technical Information of China (English)

    Shou Jianfeng; Si Chunsong; Wang Xin

    2006-01-01

    The diversity of sandstone diagenes