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    2019年, 第40卷, 第zk(English) 期 刊出日期:2020-01-01 上一期    下一期
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    Petroleum Exploration Achievements and Future Targets of Tarim Basin
    TIAN Jun
    2019, 40 (zk(English) ):  1-11. 
    摘要 ( 108 )   PDF(2304KB) ( 223 )  
    Ever since the foundation of Tarim Oilfield Company on April 10, 1989, great achievements have been obtained in 3 major fields: Kuqa foreland depression, carbonate rocks and clastics in the platform region with the cumulative proved oil and gas reserves amounting to 2.88 billion tons (equivalent). Tarim oilfield has become the major source area for the West-to-East natural gas transmission project and the third large oil and gas field in the mainland China. During the past 30 years of exploration practice, geological understandings about the foreland Kuqa depression, Southwest depression, carbonate rocks in the platform region and clastics in the platform region were continuously deepened, and the source rock, reservoir cap rock assemblage, structure style, trap and reservoir model were identified for the 3 petroleum systems such as Kuqa depression, platform region and Southwest depression. The remaining exploration potentials of Tarim Basin are enormous. The fine exploration should be carried out in the Kelasu tectonic belt of Kuqa depression, clastics in the western Tabei uplift, Ordovician Yijianfang formation in Tabei-Manxi area. The researches and exploration of Qiulitage tectonic belt in Kuqa depression, Jurassic series in the northern tectonic belt, Ordovician deep series in the platform region, Cambrian subsalt strata and piedmont area in the Southwest depression should be strengthened and the strategic breakthrough can be made.
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    Discovery of Kelasu Subsalt Deep Large Gas Field, Tarim Basin
    YANG Haijun, LI Yong, TANG Yan'gang, LEI Ganglin, ZHOU Lu, ZHOU Peng
    2019, 40 (zk(English) ):  12-20. 
    摘要 ( 105 )   PDF(5710KB) ( 223 )  
    Kelasu tectonic belt is located in the northern Kuqa depression and the discovered subsalt large-deep gas field in the tectonic belt belongs to ultra-deep high-pressure gas fields with low-porosity high-yield fractured sandstones. Up to now 22 oil and gas reservoirs have been discovered in the gas field, which are the major production areas for natural gas in Tarim basin. There was no significant break-through after the discovery of Kela 2 gas field in 1998. Since 2006, the research of the deep zones in Kelasu tectonic belt has been strengthened, and in Aug., 2008 commercial gas flows were gained from the Cretaceous Bashijiqike formation in the Well Keshen-2 which is located in the Keshen-2 structure of Keshen area and the daily gas production was 40×104 m3, marking a great breakthrough has been gained. Then over 10 years of study, technological breakthroughs have been made on foreland basin exploration technology, petroleum geological theory and production practice, which provides guidance for the discovery of the Kelasu subsalt deep large gas field. The researches on trap identification in complex mountain areas, reservoir forming mechanism and hydrocarbon accumulation, speedy drilling and reservoir reformation effectively support the efficient exploration and development of the Kelasu subsalt deep large gas field.
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    Subsalt Structural Styles of Keshen Section in the Kelasu Tectonic Belt
    HOU Guiting, SUN Shuai, ZHENG Chunfang, TANG Yangang, ZHOU Lu, MO Tao
    2019, 40 (zk(English) ):  21-26. 
    摘要 ( 74 )   PDF(3069KB) ( 151 )  
    The exploration and development practices in the Cretaceous Bashijiqike formation of the Kelasu tectonic belt in Kuqa depression reveal that the fractures are featured with vertical zonation, which are possibly constrained by neutral surfaces of anticlines. It is necessary to rebuild the structural style of the Kelasu tectonic belt because the present model for structural style classification cann’t explain thevertical zonation of fractures. Selecting the Keshen section of the Kelasu tectonic belt as the study area, taking the interlimb angle of fold asthe main element and combining with the fault combination configuration, the paper rebuilds the subsalt structural styles of the Keshen section in the Kelasu tectonic belt on the basis of 3D seismic interpretation. The results show that the structural styles of the Keshen section canbe divided into 2 types such as gentle fold and open fold according to the interlimb angle of fold; according to the fault combination configuration, the gentle fold is further divided into double-thrust gentle fold, back-thrust gentle fold and recoil gentle fold, and the open fold is divided into double-thrust and back-thrust open folds. The structures to the north of the Keshen fault are imbricate faulted anticlines made up ofopen and gentle folds, and the structures to the south of the Keshen fault are imbricate structures of gentle-fold faulted anticline. The distribution of fractures is closely related to the interlimb angle, the thickness and the distribution range of tension fissure zones in the open foldsare much larger than those in the gentle folds, and faults has an influence on the distribution of the fractures around them. The classificationof the structural style provides a foundation for the further study on the fracture development and genetic mechanism of different structuralstyles.
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    A Dumpflood Coupling Calculation Model of Fractured-Vuggy Reservoirs in Halahatang Oilfield
    JIANG Tongwen, XIAO Yang, LIU Zilong, LUO Shenchao, ZHANG Liying, WANG Dun
    2019, 40 (zk(English) ):  74-78. 
    摘要 ( 70 )   PDF(798KB) ( 130 )  
    Water injection is needed in the middle and late development stages of the fractured-vuggy reservoirs in the Halahatang oilfield. The research on self-flow water injection in China is still in its preliminary stage, lacking a complete dumpflood flow model and a development effect optimization software. Starting from the key nodes such as partial perforated water layer, perforation hole, water valve and fracture-vug complex and so on, a flow model is established for fractured-vuggy water layer-fracture-vug complex unit. The software COMSOL is used to simulate the flow of these key nodes, the flow equations of each node are coupled to establish a system-wide flow coupling model, and the numerical simulation and verification are carried out by using Eclipse. The comparative verification results show that the dump-flood numerical simulation model proposed in this paper can be used to predict the self-flow water injection volume and formation pressure variation trend of fractured-vuggy reservoirs, which could provide references for dumpflood design optimization.
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    Application of TTI Anisotropic Prestack Depth Migration Technology in Complex Mountain Areas of Kuqa Depression
    WU Chao, XU Anming, SHANG Jiangwei, CHEN Weili, ZHU Jing, ZHANG Guowei
    2019, 40 (zk(English) ):  103-107. 
    摘要 ( 70 )   PDF(4203KB) ( 115 )  
    The complex mountain areas in Kuqa depression are characterized by complicated surface and underground conditions, large elevation difference, developed mountains and many gullies. The Paleogene gypsum salt rock suffered from serious deformation with large variations in thickness. The post-salt layer is high and steep and thrust imbricated faults are developed in the pre-salt target zone, resulting in low signal-to-noise ratio and poor image effect of seismic data. Over many years of research on seismic data processing in complex mountain areas, TTI anisotropic prestack depth migration technology has been developed for relief surfaces. The small smooth datum is used in prestack depth migration modeling. Thickness, time and velocity for static correction are calculated through microlog constrained tomography inversion and high-precision velocity model for shallow layers is established. A reasonable model is established for mid-deep layers by comprehensively using the data of surface outcrop, gravity-magnetic-electronic method, geology and drilling. The qualities and accuracies of the velocity models are improved by using TTI anisotropic parameter extraction and grid tomogrqaphic imaging technology. Based on the TTI anisotropic prestack depth migration processing in the complex mountain areas of Kuqa depression, the signal-to-noise ratio and imaging quality are significantly improved, which lays a foundation for regional geological study and trap identification.
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    Structural Characteristics and Petroleum Exploration in Sikeshu Sag, Southern Margin of Junggar Basin
    YANG Disheng, XIAO Lixin, YAN Guihua, WEI Lingyun, WANG Xin, WANG Xinqiang
    2019, 40 (zk(English) ):  138-144. 
    摘要 ( 111 )   PDF(5006KB) ( 174 )  
    Sikeshu sag is located in the intersection area of the northwestern and southern margins of Junggar basin. Because of the complex structural deformation, ascertaining traps in the area is vital for petroleum exploration. Based on 2D and 3D seismic geometry and kinematics analysis and combined with regional structural mapping, the research adopts the ideas and techniques of structural modeling to build a deformation model of "two periods of superimposition and double layered structure" for Sikeshu sag. It is considered that deep and shallow structural layers are developed in the sag by taking the Cretaceous Tugulu mudstone and the detachment layer of mudstone of Paleogene Anjihaihe formation as boundaries. The deep structural layer is mainly composed of Mesozoic NW-SE trending strike-slip faults and en echelon-like folds and the shallow structural layer is a Cenozoic detachment thrust structure. The two periods of structures superimpose vertically and exhibit a Mesozoic en echelon-like structural framework laterally. Based on the comprehensive research of oil and gas accumulation, a hydrocarbon accumulation model of vertical superimposition is proposed for Sikeshu sag. The reservoir in the shallow structural layer is influenced by fault connection and its distribution is controlled by Cenozoic faults; the deep structural layer is very near to hydrocarbon generation center in which structural traps formed early and late deformation was weak, which benefits long-term hydrocarbon migration. The commercial oil and gas flow with the daily production more than 1000 tons obtained from the Well Gaotan-1 in January, 2019 can prove that the hydrocarbon accumulation conditions of Sikeshu sag is favorable.
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    A Method to Study Time Effectiveness of Fault-Sand Configuration Transporting Hydrocarbon and Its Application
    FU Guang, PENG Wantao, XU Yanbin, XU Jiachao, AO Damu
    2019, 40 (zk(English) ):  156-160. 
    摘要 ( 66 )   PDF(511KB) ( 123 )  
    In order to study the distribution of hydrocarbon which was generated in the lower source rocks and accumulated in the upper reservoirs in the source-reservoir-caprock combinations of a petroliferous basin, aiming at the time effectiveness of fault-sand configuration transporting hydrocarbon currently, and based on the determination of fault transporting- and sand transporting-hydrocarbon time, the time of fault-sand configuration transporting hydrocarbon is determined. Then compared with the hydrocarbon expulsion peak time, the paper establishes a method to study the time effectiveness of fault-sand transporting hydrocarbon and applies the method in Ed2 and Ed3 reservoirs in the Laoyemiao structure of the Nanpu sag. The study results show that the fault-sand transporting hydrocarbon time of Ed2 and Ed3 reservoirs in the Laoyemiao structure should be the deposition period of the upper Minghuazhen formation, later than the first hydrocarbon expulsion peak (middle deposition period of Guantao formation) of the source rocks of Es3 and Es1, which was not conducive to the hydrocarbon migration in this first peak period. However, the time of fault-sand configuration transporting hydrocarbon was slightly later than the second hydrocarbon expulsion peak (late deposition period of the lower Minghuazhen formation) of the source rock of the Es3 and Es1 and a certain amount of hydrocarbon could be transported, which was good for hydrocarbon accumulation. The results are consistent with the distribution of the hydrocarbon discovered in Ed2 and Ed3, which shows that the method is feasible to be used in time effectiveness research of the fault-sand configuration transporting hydrocarbon.
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    Laumontite Cementation Characteristics and Their Influences on Reservoir Physical Properties in Chang 6 Member of Qilicun Oilfield, Ordos Basin
    DU Guichao, SHI Lihua, MA Xiaofeng, CAO Qing, DING Chao, SHEN Zhenzhen
    2019, 40 (zk(English) ):  174-180. 
    摘要 ( 60 )   PDF(4073KB) ( 150 )  
    To deepen the understandings about geological features of oil and gas in Qilicun oilfield, regarding laumontite development, cementation mechanism and their influences on reservoir physical properties in Chang 6 member of Yanchang formation and based on the porosity and permeability analysis, thin section identification and SEM analysis, the paper performs a systematic study on the diagenesis of sandstones in Chang 6 member. The results show that 3 stages of laumontite are developed in the Chang 6 member, namely syndiagenetic, early diagenetic stage A and late diagenetic stage A. In the syndiagenetic stage, laumontite cementation was mainly influenced by sedimentary environment and provenance, and the hydrations of metamorphic debris and vitric minerals in igneous rock debris in the sandstone of Chang 6 member provided enough materials for the generation of the early laumontite. In the early diagenetic stage A, albitization of anorthose provided the important material basis for the cementation of laumontite. In the late diagenetic stage A, the cementation was related to the oversaturated precipitation of laumontite, and the Ca2+ and SiO2 came from the dissolutions of early laumontite, feldspar and debris. The laumontite cementation was closely related to the reservoir physical properties of Chang 6 member. The early laumontite cementation prevented debris from further compaction and also provided favorable conditions for the formation of secondary pores during late dissolutions. The dissolution of the laumontite expanded the pore spaces of the reservoir and improved the pore throat structure and connectivity during the late diagenetic stage A.
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    Internal Configuration of Meandering River Point Bar in the Fifth Member of Guantao Formation in the Western District 7, Gudong Oilfield
    CHEN Depo, LIU Huancheng, CHEN Shuning
    2019, 40 (zk(English) ):  188-193. 
    摘要 ( 65 )   PDF(562KB) ( 107 )  
    The fifth member of Guantao formation is the main oil layer in the western District 7 of Gudong oilfield and the reservoir belongs to loose sandstones of meandering river deposition. At present, the remaining oil saturation of the target zone in newly-drilled wells is not consistent with the expected one during the oilfield development, so the original designed objects cann't be achieved. The effects of well adjustment and potential tapping in the existing wells don't match with the geological understanding, which increases the difficulties of oilfield stimulation and it is urgent to verify the relationship between the internal configuration elements of meandering-river point bar reservoirs and the remaining oil distribution. Based on the study of the cores obtained from sealed coring wells, the paper summarizes the amount of the lateral accretion layers and rock types within the point bar, analyzes the flowing characteristics of the lateral accretion layers with different lithologies and the remaining oil distribution within the point bar, unravels the key elements of the internal configuration of the point bar, obtains the thickness, occurrence and distribution of the lateral accretion layer, and then calculates the length and width of the point bar and the bankfull depth and width of the meandering river. Based on the data of logging, core and lab analysis, the internal configuration of the point bar in paired wells is analyzed and the high remaining oil saturation in the newly-drilled wells adjacent to water injection wells is reasonably explained. The study results show that the internal configuration of the point bar is the most important factor controlling remaining oil distribution and the remaining oil is mainly distributed in the reservoirs above the lateral accretion layers with relatively poor physical properties.
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    Recognition of Single Channel Sandbody of Meandering River With Logging-Seismic Combination
    FAN Xiaoyi, XUE Guoqini, LIU Bin, HUANG Yintao, XIE Qi, LI Weicai
    2019, 40 (zk(English) ):  228-234. 
    摘要 ( 91 )   PDF(4695KB) ( 153 )  
    The sedimentary system of the Neogene Shawan Formation in Chunguang oilfield is dominated by meandering river deposits. Due to the continuous river channel migration and diversion, frequent vertical superposition of sand bodies and sparse well pattern, it is hard to identify the boundary of a single channel. Besides, the oil-water relationship is contradictory in some wellblocks, which limits the further remaining oil potential tapping. To detailedly characterize the single channel boundaries and achieve the goal of fine oil and gas development and on the basis of logging response, the paper concludes four typical indicators to depict the boundary of single channel, establishes an original geological model and summarizes seismic identification indicators. According to the responses of sandstone and mudstone on the strata slice, the distribution characteristics and development positions of single channels of different periods are identified. The logging-seismic combination method can overcome the uncertainty of lateral logging data prediction and improve the accuracy of single channel characterization.
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    Meandering River Deposit and Sand Body Architecture in Qigu Formation of Jiangong Coal Mine Section in the Southern Margin of Junggar Basin
    GUAN Xutong, WU Jian, WEI Lingyun, ZHAO Jinyong, FENG Geng, LI Yan
    2019, 40 (zk(English) ):  290-297. 
    摘要 ( 82 )   PDF(4376KB) ( 132 )  
    Guided by the theories of sedimentary and architectural-element analysis, the paper analyzed the architectural elements of the meandering river sand body in Upper Jurassic Qigu formation in the southern margin of Junggar basin, counted the scale and shapes of the architectural elements and sand bodies and classified the superimposition types. In this field outcrop, 7 lithofacies are found, boundaries with 6 levels are classified and 4 key architectural elements are identified. When the A/S is bigger than 1, the isolated channel sand bodies are developed. As the A/S decreases and approaches to 1, the bridging channel sand bodies and superimposed channel sand bodies are developed. When the A/S is smaller than 1, the truncated channel sand bodies are developed. During the deposition of Qigu formation, the climate was arid and hot. During the deposition of Toutunhe formation, the broad lake level dropped, a sandy meandering river formed with the depth of about 33.3 m, width of 139.2 m, bankfull width of 805.2 m and single meander belt width of 6405.2 m. In the early stage of the deposition of Qigu formation, the A/S was smaller than 1, corresponding to the development of isolated channel and flood lake sand bodies, in the middle stage, the bridging channel sand bodies, superimposed channel sand bodies and the truncated channel sand bodies were developed. In the late stage, the A/S increased again corresponding to the development of the isolated channel sand bodies.
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    Time-Varying Sequence Analysis of Generalized Vogel Equation for Fracturing Wells in Fractured Volcanic Reservoirs
    WANG Liqiang, CUI Yinghuai, JING Wenbo, FU Yonghong, DONG Ming, WANG Xuewu
    2019, 40 (zk(English) ):  307-311. 
    摘要 ( 69 )   PDF(590KB) ( 127 )  
    From the non-dimensional typical chart of bottom hole pressure during fracturing, combining with the generalized Vogel equation for fractured reservoirs, the article establishes a solving method of the inflow performance curves with different producing days in fractured reservoir fracturing wells. The reliability of the research results is verified by an example and the variations of the inflow performance curves with different producing days and different non-dimensional fracture conductivity are analyzed. The results show that when the non-dimensional fracture conductivity is large, the initial well production is high but the production decline is large and it is difficult to maintain the well production. Therefore, selecting a reasonable non-dimensional fracture conductivity value has practical significance for efficient development of fractured volcanic reservoirs.
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    Key Geological Factors of High-Yield Coalbed Methane Development in Fukang Syncline
    GE Yanyan, LI Xin, GAO Lin, JIAO Chunlin, WANG Haichao, FENG Shuo
    2019, 40 (zk(English) ):  328-333. 
    摘要 ( 83 )   PDF(746KB) ( 142 )  
    Based on the geological units divided by pervious researchers for coalbed methane development and combined with logging and production data obtained from coalbed methane wells, the paper studies the geological characteristics of high-yield coalbed methane wells in Fukang syncline. The results show that in the fourteen geological units divided in Fukang syncline, the fissure water between coal beds in the stagnant area mainly come from pore phreatic water in loose rock mass and the lateral supply of the aquifer in the same zone, coalbed methane may easily accumulate under the action of hydraulic sealing and plugging and the production in the stagnant area is higher than that in the runoff area; due to the influence of burial depth on reservoir vertical stress, the stagnant area with medium burial depth has relatively good permeability, whose production is higher than that of the deep-burial stagnant area; the dual lateral resistivity logs are used to judge the development degree of cracks in the coal beds, the reservoir with slight deformation in deep strata has good permeability, whose production is higher than that with serious deformation. It is considered that the combined development of coal-series conventional natural gas is helpful for the high yield of coalbed methane wells.
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    Difficulties and Countermeasures of Shale Oil Development in Lucaogou Formation of Jimsar Sag
    HUO Jin, HE Jixiang, GAO Yang, DONG Yan, XU Dongsheng, LI Yingyan
    2019, 40 (zk(English) ):  379-388. 
    摘要 ( 136 )   PDF(2502KB) ( 193 )  
    To realize the effective producing and development of the shale oil resources in the Lucaogou Formation of Jimsar sag and topush the scaled productivity construction of China’s terrestrial shale oil, the paper detailedly compares the geological characteristics of the shale oil reservoirs in China and abroad, analyzes the geological differences between China’s terrestrial shale oil and the marine shale oilin north America, and establishes a series of technical countermeasures for high efficient development of the shale oil in the Lucaogou formation of Jimsar sag based on the researches and practices of the exploration and development in the formation. The study results show thatthe shale oil in the Lucaogou formation of Jimsar sag is characterized by deep burial, poor physical properties and serious heterogeneityetc., and the difficulties encountered during the development mainly include incomplete criterion of sweet spot identification, low degree ofoverall effective producing, uncertain technical parameters for development and lots of difficulties in cost decreasing and benefit increasing, the following work has been carried out to overcome the difficulties encountered during development: 1)Based on the studies of reservoir, logging, mud log, seismic and fundamental mechanics experiment, a set of criterion of “sweet spot” evaluation has been established to optimize favorable geological and engineering area; 2)The study on geology-engineering integration has been performed to optimize well pattern deployment parameters and reasonable working system based on field well-spacing test and production performance analysis. 3) The main factor influencing crude oil fluidity is determined as the viscosity based on the analysis of crude oil fluidity experiment, and then Pad-CO2 fracturing technology can be used to effectively reduce viscosity and increase efficiency. 4) The large-scaled platform batch drillingand fracturing processes have been applied to reduce the impacts of fracturing interference and casing failure on scaled productivity construction, and then to determine the technological direction for decreasing cost and increasing efficiency. The countermeasures formed during the shale oil development in Jimsar sag have a good demonstration effect on large-scaled production of the shale oil resources in China.
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    Geological Characteristics, Resource Potential and Exploration Direction of Shale Oil in Middle‑Lower Permian, Junggar Basin
    ZHI Dongming, SONG Yong, HE Wenjun, JIA Xiyu, ZOU Yang, HUANG Liliang
    2019, 40 (zk(English) ):  389-401. 
    摘要 ( 118 )   PDF(4273KB) ( 251 )  
    The Middle-Lower Permian series, the most important source rocks in Junggar basin, are dominated by multi-source, fine-grained mixed sediments deposited in a terrestrial salty lake environment and have good conditions for shale oil generation. A shale oil province with the OOIP of one billion tons has been discovered in the Lucaogou Formation of Jimsar sag. Based on the previous study results and combined with the available geological data, the paper systematically summarizes the geological characteristics of the favorable shale oil areas in the Middle-Lower Permian of the basin. Meanwhile, on the basis of benchmarking with the geological characteristics of the shale oil in the Lucaogou Formation of Jimsar sag, the shale oil exploration potential in the Fengcheng Formation of Mahu sag and the Pingdiquan Formation of Wucaiwan-Shishugou sag is analyzed and the next exploration direction for the shale oil in the basin is discussed. The study results show that the multi-source fine-grained mixed sediments of shore-shallow lacustrine-semi-deep lacustrine facies in the Middle-Lower Permian strata of the basin are the high-quality source rocks where tight sweet spot reservoirs are developed, and the reservoir combination is characterized by source rock-reservoir superposition and frequent interbed with each other vertically, which lays a foundation for shale oil accumulation in the Middle-Lower Permian strata. Typical terrestrial shale oil characteristics such as hydrocarbon mainly coming from neighboring source rocks, self generation as the complementary and in-situ accumulation can be obviously seen. The maximum proven resources of the shale oil in the basin is 27.25×108 t. The geological conditions of the Fengcheng shale oil in the Mahu sag are better than those of the Lucaogou shale oil in Jimsar sag, therefore, the Fengcheng Formation in Mahu sag is considered as the next key area for shale oil exploration. The geological conditions of the Pingdiquan shale oil in Wucaiwan-Shishugou sag are relatively poor, and the shale oil here can only be considered as a prospect area for exploration. Additionally, the Luocaogou Formation in the piedmont of Bogda Mountain and the Pingdiquan Formation in the slope area of Fukang-Dongdaohaizi sag are the potential areas for shale oil exploration and at present comprehensive geological research should be performed to gain more geological understandings and to complete technical preparation work.
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    Predicting Total Organic Carbon Content in Marine Shale Reservoirs With Nuclear Logging Data
    ZHAO Bing
    2019, 40 (zk(English) ):  499-504. 
    摘要 ( 65 )   PDF(777KB) ( 142 )  
    Total organic carbon (TOC) content is an important parameter reflecting the amount of shale reservoir resources, and nuclear logging data can provide a lot of information about the abundance of organic matter in source rocks. In this paper, the correlations between the response values of various nuclear logging curves and TOC in Wells X1, X2 and X3 in the southeastern Sichuan basin are analyzed. Considering the geological factors that affect the content of TOC, the single nuclear logging curve which is sensitive to TOC content and the combination of the nuclear logging curves that can reflect the genesis of TOC are selected. Then a TOC content prediction model with nuclear logging curves suitable for this area is established through BP neural network. Finally, the model was applied to Well X4 in the southeastern Sichuan basin. Compared with the TOC contents obtained from the core analysis of 113 core samples, the mean relative error of the model prediction results is 0.41, indicating that the prediction accuracy of the new model is high, which can meet the actual production demands in the area. Then the model was applied to the marine shale reservoirs in W and Y blocks of the southern Sichuan basin and good effects have been gained, which can prove the good operability, wide versatility and high evaluation accuracy of the model. The new method provides an effective technological mean for the evaluation of total organic carbon content in marine shale reservoirs.
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    Identification and Prediction of Effective Source Rocks for Tight Oil in Zhahaquan Area, Qaidam Basin
    TIAN Mingzhi, LIU Zhanguo, SONG Guangyong, LI Chang, TIAN Han, LI Yafeng, XIA Xiaomin
    2019, 40 (zk(English) ):  536-542. 
    摘要 ( 74 )   PDF(1413KB) ( 142 )  
    Since 2013, large-scale tight oil reservoirs have been discovered in the upper Ganchaigou formation of Neogene in Zhahaquan area of Qaidam basin. In order to evaluate the availability of the source rocks in the area and to effectively support the well deployment, a core-calibrated logging method to identify effective source rocks is established on the basis of core observation, whole rock analysis, geochemical analysis, sedimentary environment analysis and log response comparison. The logging response characteristics of the source rocks in study area are not very typical, and the TOC is poorly correlated with logging parameters such as interval transit time, natural gamma ray, resistivity and density. It is found that the TOC is well correlated with the difference between total natural gamma ray and de-uranium natural gamma ray, and the ratio of thorium to uranium, respectively; and then a formula is built to calculate TOC. The method is simple and effective. The vitrinite reflectance of the source rocks in study area is 0.624%-1.265%, which is in the mature stage and is conducive to oil generation. After identifying the effective source rocks of 24 wells in study area, it is found that the effective source rock development zones in the Ⅳ to Ⅰ sand member gradually migrate from the northwest to the southeast. Furthermore, the source rocks and the beach bar overlap each other vertically in shallow lake area, forming a good source-storage configuration. The method can be a guidance for source rock evaluation and tight oil exploration and deployment.
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    Prediction of Multi-Provenance Sand Body Distribution in Triassic Baikouquan Formation of Madong Area, Junggar Basin
    SONG Yong, ZHOU Lu, WU Yong, YOU Xincai, NIU Zhijie, REN Benbing
    2019, 40 (zk(English) ):  631-637. 
    摘要 ( 48 )   PDF(10441KB) ( 29 )  
    Aiming at the complex relationship among the sand bodies controlled by different fans under the multi-provenance condition sand based on the structural interpretation results of the contiguous 3D seismic data formed by several 3D seismic survey networks in the Madong area of the Mahu sag, Junggar basin. The paper clarifies the forming conditions and paleo-tectonic characteristics of the multiple provenances in the area on the basis of structural interpretation and paleo-geomorphic analysis of the Triassic Baikouquan Formation in the Madong area; performs identification and prediction of the fan boundaries and their relations with multiple provenances in different intervals of the Baikouquan Formation in the Madong area by using seismic waveform classification method. Using seismic attribute and seismic inversion prediction methods, the authors comprehensively analyze the distribution of the sand bodies in the fan delta fronts of different fans and conclude the features of complex superimposition vertically and continuity but disconnection laterally, or spot-like isolated distribution.
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    Productivity Differences of Gas Reservoirs in the Fourth Member of Sinian Dengying Formation in Gaoshiti-Moxi Area, Central Sichuan Basin
    TIAN Xingwang, ZHANG Xihua, PENG Hanlin, MA Kui, YANG Dailin, SUN Yiting
    2019, 40 (zk(English) ):  673-679. 
    摘要 ( 68 )   PDF(3015KB) ( 133 )  
    Sinian Dengying Formation in Gaoshiti-Moxi area of central Sichuan basin is characterized by complicated lithologies and strong heterogeneity. The productivity in the western platform margin area is higher than that in eastern platform area and efficient exploration is facing great challenges. Using the data of core, logging and seismic and starting from sedimentary environment, reservoir diagenesis and hydrocarbon charging distance, the paper discusses the main factors controlling the productivity differences of the gas reservoirs in the fourth member of Dengying formation in the study area and proposes technical countermeasures on geological engineering. The results show that the tested productions in the western platform margin and the eastern platform are significantly different, the tested production of the western platform margin area is high due to large thickness of the gas zone, while that of the eastern platform is low due to small thickness of the gas zone; the main influencing factors for the productivity difference include the distribution of favorable dome-beach facies, intensity of karstification at the end of Tongwan movement, reservoir vertical distribution and position, and lateral distance to hydrocarbon-generating center etc. According to the characteristics of the reservoir and its seismic responses, vertical well, highlydeviated well and horizontal well are selected to improve high quality reservoir penetration ratio and single well production, which can effectively guide the natural gas exploration and development and good effects have been gained in the study area.
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    Flow Mechanism of Shale Oil Reservoir in Jimsar Sag
    WANG Ziqiang, LI Chuntao, ZHANG Daiyan, ZHANG Hao
    2019, 40 (zk(English) ):  695-700. 
    摘要 ( 62 )   PDF(1197KB) ( 106 )  
    To understand the rules of flow in shale oil reservoir, taking the Lucaogou formation of Jimsar sag in the Junggar basin as an example, the micro-pore structures and flow mechanism of the shale oil reservoir were studied by means of laboratory physical experiments and digital core technology. Based on the physical experiment of single-phase flow through shale oil cores, a non-linear mathematical model of single-phase flow based on starting pressure gradient and an empirical formula of permeability related to pore structure parameters were obtained. Digital core technology and Lattice Boltzmann method were used to simulate the single-phase fluid of shale oil and to realize the fine characterization of fluid flow. The results show that the relation between seepage velocity and pressure gradient in the shale oil reservoir has a typical non-Darcy flow characteristic, which is a cubic function relation with a good correlation.
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