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Depositional features and growth pattern of large shallow-water deltas in depression basin
YUAN Xuanjun, ZHOU Hongying, ZHANG Zhijie, WANG Ziye, CHENG Dawei, GUO Hao, ZHANG Youyan, DONG Wentong
2021, Vol.33(1): 1–11
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489 )
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Main exploration progress and future key fields of stratigraphic reservoirs
ZHU Rukai, CUI Jingwei, MAO Zhiguo, CAO Zhenglin, WANG Xingzhi, GAO Changhai, LIU Yongfu
2021, Vol.33(1): 12–24
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538 )
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(6268 KB)
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449
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New progress in study of play and trap evaluation technology for lithostratigraphic reservoirs
LIU Huaqing, LIU Zongbao, WU Kongyou, XU Huaimin, YANG Zhanlong, SUN Xiping, NI Changkuan, KANG Jilun, WANG Mu, JIN Jikun
2021, Vol.33(1): 25–36
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339 )
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(8842 KB)
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546
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Simulation of oil and gas migration pathways for Jurassic in hinterland of Junggar Basin
GUO Qiulin, WU Xiaozhi, WEI Yanzhao, LIU-ZHUANG Xiaoxue, LIU Jifeng, CHEN Ningsheng
2021, Vol.33(1): 37–45
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310 )
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Transport system and its control on reservoir formation of Jurassic-Cretaceous in hinterland of Junggar Basin
CHEN Gang, BIAN Baoli, LI Xiao, LIU Gang, GONG Deyu, ZENG Delong
2021, Vol.33(1): 46–56
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260 )
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(8249 KB)
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Sedimentary characteristics and controlling factors of fan-delta of the Upper Urho Formation of Permian in Mahu Sag
MA Yongping, ZHANG Xianwen, ZHU Ka, WANG Guodong, PAN Shuxin, HUANG Linjun, ZHANG Han, GUAN Xin
2021, Vol.33(1): 57–70
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327 )
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Characteristics and main controlling factors of Permian-Triassic superimposed reservoirs in central Mahu Sag,Junggar Basin
CHEN Jing, CHEN Jun, LI Hui, NUERAILI Zhaman
2021, Vol.33(1): 71–80
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385 )
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(4988 KB)
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361
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Identification of faults in the south slope of Mahu Sag and its control on hydrocarbon accumulation
YU Xing, YOU Xincai, BAI Yu, LI Peng, ZHU Tao
2021, Vol.33(1): 81–89
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245 )
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(6471 KB)
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337
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Discovery and hydrocarbon exploration potential of beach-bar sand in Shawan Sag,Junggar Basin
GUAN Xin, PAN Shuxin, QU Yongqiang, XU Duonian, ZHANG Han, MA Yongping, WANG Guodong, CHEN Xuezhen
2021, Vol.33(1): 90–98
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377 )
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(8487 KB)
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Petrophysical facies of Triassic Baikouquan Formation in northern Mahu Sag,Junggar Basin
YANG Fanfan, YAO Zongquan, YANG Fan, DELECHIATI Ganatayi, ZHANG Lei, CAO Tianru
2021, Vol.33(1): 99–108
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251 )
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(7094 KB)
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319
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Characteristics of formation water and its geological significance of lower combination of Yanchang Formation in Ordos Basin
ZHOU Xinping, DENG Xiuqin, LI Shixiang, ZUO Jing, ZHANG Wenxuan, LI Taotao, LIAO Yongle
2021, Vol.33(1): 109–120
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411 )
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Accumulation characteristics of Upper Paleozoic tight sandstone in Shenfu block,northeastern margin of Ordos Basin
GAO Jixian, SUN Wenju, WU Peng, DUAN Changjiang
2021, Vol.33(1): 121–130
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337 )
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(6037 KB)
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383
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Hydrocarbon accumulation differences and main controlling factors of Jurassic petroleum system in Altun piedmont of Qaidam Basin
TIAN Guangrong, WANG Jiangong, SUN Xiujian, LI Hongzhe, YANG Wei, BAI Yadong, PEI Mingli, ZHOU Fei, SI Dan
2021, Vol.33(1): 131–144
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272 )
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Hydrocarbon accumulation conditions and favorable exploration plays in Yingxiongling structural belt,Qaidam Basin
LONG Guohui, WANG Yanqing, ZHU Chao, XIA Zhiyuan, ZHAO Jian, TANG Pengcheng, FANG Yongsheng, LI Haipeng, ZHANG Na, LIU Jian
2021, Vol.33(1): 145–160
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Characteristics of fault activity and its control on hydrocarbon accumulation in southern Yingxiongling area,Qaidam Basin
LU Enjun, LIU Shaobo, YU Zhichao, LU Xuesong, CHENG Dingshu
2021, Vol.33(1): 161–174
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333 )
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Hydrocarbon accumulation conditions in Eboliang structural belt and its exploration implications
KONG Hongxi, WANG Yuanfei, ZHOU Fei, ZHU Jun, CHEN Yangyang, SONG Dekang
2021, Vol.33(1): 175–185
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Sedimentary characteristics and reservoir prediction of Xiagou Formation in Kulongshan structural belt,Qingxi Sag,Jiuquan Basin
ZHANG Wenting, LONG Liwen, XIAO Wenhua, WEI Haoyuan, LI Tiefeng, DONG Zhenyu
2021, Vol.33(1): 186–197
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312 )
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Sedimentary characteristics and controlling factors of slump gravity flow in delta front: a case study of Qing 1 member in Da'an area,Songliao Basin
FU Yong, LI Zhongcheng, WAN Pu, QUE Yijuan, WANG Zhenjun, JI Yu, HUANG Li, LUO Jinglan, BAO Zhidong
2021, Vol.33(1): 198–208
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Geochemical characteristics and geological significance of Shaximiao Formation in northeastern Sichuan Basin: a case study fromWubaochang area
XU Yuxuan, DAI Zongyang, HU Xiaodong, XU Zhiming, LI Dan
2021, Vol.33(1): 209–219
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379 )
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Reservoir prediction for weathering and leaching zone of bedrock buried hill based on seismic pre-stack depth migration
SUN Xiping, ZHANG Xin, LI Xuan, HAN Yongke, WANG Chunming, WEI Jun, HU Ying, XU Guangcheng, ZHANG Ming, DAI Xiaofeng
2021, Vol.33(1): 220–228
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279 )
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A new method for thin reservoir identification based on sparse Bayesian learning and its application
YUAN Cheng, SU Mingjun, NI Changkuan
2021, Vol.33(1): 229–238
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(9313 KB)
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Prediction technology of tight oil thin sand reservoir and its application effect: a case study of Lower Cretaceous Quantou Formation in Aonan block,Songliao Basin
CAO Sijia, SUN Zengjiu, DANG Huqiang, CAO Shuai, LIU Dongmin, HU Shaohua
2021, Vol.33(1): 239–247
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254 )
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Prediction of high-quality source rock distribution based on pseudo-3D multi-attribute inversion
YAO Jun, LE Xingfu, CHEN Juan, SU Wang, ZHANG Yongfeng
2021, Vol.33(1): 248–257
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Lithology identification of Carboniferous volcanic rocks in Xiquan area, eastern Junggar Basin
LI Shubo, GUO Xuguang, ZHENG Menglin, WANG Zesheng, LIU Xinlong
2021, Vol.33(1): 258–266
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Application of 2D NMR logging in fluid identification of glutenite reservoir
NING Congqian, ZHOU Mingshun, CHENG Jie, SU Rui, HAO Peng, WANG Min, PAN Jingli
2021, Vol.33(1): 267–274
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Depositional features and growth pattern of large shallow-water deltas in depression basin
YUAN Xuanjun, ZHOU Hongying, ZHANG Zhijie, WANG Ziye, CHENG Dawei, GUO Hao, ZHANG Youyan, DONG Wentong
2021, Vol.33(1): 1–11
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doi: https://doi.org/10.12108/yxyqc.20210101
Large shallow-water deltas in depression basin contribute to the main potential increase of onshore lithologic reservoirs in China. The Baoqian delta of the Upper Cretaceous in southern Songliao Basin and the modern Ganjiang delta in Poyang Lake were analyzed. The particular focus was put on the paleo-environment, depositional features and growth pattern of this type of delta.(1)Depression basins are favorable for large shallow-water deltas. Unconfined morphology results in the frequent rise and fall of lake-level,which controls the delta dimension in dip direction.(2)There are two different types of deltas in the Upper Cretaceous of southern Songliao Basin. One is deep-water delta characterized by lobe shape and easily-identified depositional facies, mainly including distributary channels,mouth bars,and interdistributary bays. Another is shallow-water delta characterized by bird's foot shape and obscure boundaries between depositional facies,mainly including distributary channels and interdistributary bays,with mouth bar less developed.(3)The remote sensing for modern sedimentary systems reveals the evolution of Ganjiang middle delta in Poyang Lake in recent 50 years,showing the transition from disperse branch shape to connective network shape.(4)Large shallow-water delta in depression basins is a complex consisting of several deltas formed in multi-scenarios. The sand-bodies of distributary channels are the most significant reservoir and carry massive lithologic reservoirs. They are distributed horizontally in a net pattern and control the distribution of lithologic reservoirs.
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Main exploration progress and future key fields of stratigraphic reservoirs
ZHU Rukai, CUI Jingwei, MAO Zhiguo, CAO Zhenglin, WANG Xingzhi, GAO Changhai, LIU Yongfu
2021, Vol.33(1): 12–24
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doi: https://doi.org/10.12108/yxyqc.20210102
In recent years,remarkable progress has been made in the exploration of stratigraphic reservoirs. In order to review the exploration progress of stratigraphic reservoirs in China during the 13th Five-Year Plan period and to look forward to the key exploration fields in the future,the anatomy of typical stratigraphic reservoirs was carried out,then the accumulation laws in three different types of stratigraphic reservoirs were studied,including large-scale clastic rock overlap-cut type,carbonate weathered crust type,volcanic or metamorphic rock type, and finally the resource potential of stratigraphic reservoirs was evaluated. The results show that:(1)The exploration have achieved significant progress in stratigraphic reservoirs of the Permian and Carboniferous in Junggar Basin,the Sinian Top-Ordovician of the three major craton basins in China(Sichuan,Tarim,Ordos),and the bedrock of Songliao Basin,whose oil and gas equivalents obtained are all in the billion-ton-odds.(2)Largescale stratigraphic reservoirs are controlled by long-term inherited ancient slopes,regional unconformities,and transport systems at the basin margin or inner-basin uplift periphery,and develop giant-large stratigraphic hydrocarbon accumulations in quasi-layered clusters way. There are two types of stratigraphic reservoirs including weathered crust type and inner surface type,and both can be accumulated in a large scale.(3)The key areas for exploration of stratigraphic oil and gas reservoirs are the unconformity weathering crust inner or between Sinian-Ordovician carbonate beds among the three major cratons in China,overlap-cut stratum of the Permian clastic rocks in the six slope areas of Junggar Basin,and bedrock dominated by volcanic rock or metamorphic rock.(4)Future exploration technologies are expected to strengthen the identification of multi-level unconformities in the basin, the comprehensive analysis of accumulation factors,and the integration of geophysical exploration technologies. The accumulation theory of large-scale stratigraphic reservoirs would be built and promote the exploration of them in China by focusing on the discovery of new oil and gas layers in the longitudinal direction and extension of new oil and gas areas in the plane dimension. The research results have an important guiding role for the development of future exploration technology and the deployment of key areas of stratigraphic reservoirs.
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New progress in study of play and trap evaluation technology for lithostratigraphic reservoirs
LIU Huaqing, LIU Zongbao, WU Kongyou, XU Huaimin, YANG Zhanlong, SUN Xiping, NI Changkuan, KANG Jilun, WANG Mu, JIN Jikun
2021, Vol.33(1): 25–36
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546
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doi: https://doi.org/10.12108/yxyqc.20210103
Based on the research results during the 13th Five-Year Plan period,two sets of technology system of play evaluation,trap boundary identification and effectiveness evaluation for lithostratigraphic reservoirs were summarized by combining geology with geophysical exploration and highlighting the application of intelligent technology.(1)The play evaluation technology system for lithostratigraphic reservoirs outside the source area is based on quantitative evaluation of fault/sand body migration system,effectiveness evaluation of fault-related mudstone seals,weathered-clay identification in unconformity belt and quantitative evaluation of sealing ability. (2)The trap boundary identification and effectiveness evaluation technology system for lithostratigraphic reservoirs is based on the recognition of subtle sequence boundary and the establishment of high-frequency sequence framework,seismic prediction of sedimentary system distribution based on multi-attribute clustering in laterally changing seismic window,and thin interbedded reservoir prediction based on sparse theoretical seismic inversion and stratal slicing using minimum seismic interference frequency data. After being popularized and applied, these technologies provide strong technological support for deploying risk exploration wells in related basins.
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Simulation of oil and gas migration pathways for Jurassic in hinterland of Junggar Basin
GUO Qiulin, WU Xiaozhi, WEI Yanzhao, LIU-ZHUANG Xiaoxue, LIU Jifeng, CHEN Ningsheng
2021, Vol.33(1): 37–45
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doi: https://doi.org/10.12108/yxyqc.20210104
A major breakthrough was made in well Qianshao-2 in Junggar Basin in 2019,which indicates that Jurassic in the hinterland of basin has broad exploration prospects. Distant and secondary oil and gas reservoirs are developed in the hinterland of the basin. The distance between source and reservoir is large,and the hydrocarbon migration pathway determines the distribution of oil and gas reservoirs. Based on the characteristics of Jurassic oil and gas migration along the vertical direction of faults and the lateral movement along sand bodies in the study area,this paper formulated a research idea with three-dimensional geological modeling,parameter research and simulation calculation as the core,proposed a three-dimensional geological modeling method for section grids,a three-dimensional invasion percolation model considering fault factors and a quantitative model for crude oil wax content,and constructed a three-dimensional geological body for Jurassic,including 54 844 individual grids,12 370 surface grids and corresponding geological parameters. The simulation results show that the migration pathway has a good correlation with the distribution of oil and gas reservoirs,and the wax content of crude oil is close to the measured value,indicating that the simulated migration pathway is consistent with the exploration results,and the quantitative model of wax content of crude oil is effective. After comprehensively considering factors such as hydrocarbon migration pathway,oil and gas saturation and sedimentary facies distribution, five favorable areas were determined,including Cheng 1 well area,Shidong 1 well west area,Dixi 2 well area, Dong 1 well north area and Basin 6 well north area. The research results can provide a reference for the prediction of the distribution of potential exploration targets in the study area.
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Transport system and its control on reservoir formation of Jurassic-Cretaceous in hinterland of Junggar Basin
CHEN Gang, BIAN Baoli, LI Xiao, LIU Gang, GONG Deyu, ZENG Delong
2021, Vol.33(1): 46–56
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doi: https://doi.org/10.12108/yxyqc.20210105
Jurassic-Cretaceous reservoirs are characterized by distant source and secondary-filled in hinterland of Junggar Basin. Transport system plays an important role in controlling hydrocarbon accumulation. Based on the systematic description of fault,sand layer and unconformity and the study of their spatial combination relationship, three types of transport were sorted out,including vertical single fault transport type,fault blanket sand terrace type and fault unconformity composite transport type. Combined with the spatiotemporal coupling relationship among migration system,reservoir forming process and reservoir forming elements,three types of hydrocarbon accumulation models under the control of the dominant transport system were summarized:three-dimensional hydrocarbon accumulation model under the control of vertical single transportation of fault, ring convex hydrocarbon accumulation model under the control of fault blanket sand step transportation,and continuous hydrocarbon accumulation model under the control of fault unconformity composite transportation. Based on the distribution of transport elements and hydrocarbon accumulation background, it is pointed out that the Upper Jurassic and Lower Cretaceous are important replacement areas for searching for efficient oil and gas reservoirs.
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Sedimentary characteristics and controlling factors of fan-delta of the Upper Urho Formation of Permian in Mahu Sag
MA Yongping, ZHANG Xianwen, ZHU Ka, WANG Guodong, PAN Shuxin, HUANG Linjun, ZHANG Han, GUAN Xin
2021, Vol.33(1): 57–70
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doi: https://doi.org/10.12108/yxyqc.20210106
In recent years,a great breakthrough has been made in oil and gas exploration of glutenite reservoirs of the Upper Permian in Mahu Sag,Junggar Basin. In order to study the sedimentary characteristics and controlling factors of the fan-delta of the Upper Urho Formation,the analyses of lithofacies,polarizing microscope identification,physical property and diagenesis were carried out. The results show that:(1)The reservoir studied developed in a retrogradation fan-delta complex that is the grain size of glutenite reservoirs of the upper Urho Formation gradually became finer and the gravel content gradually decreased from bottom to top,which is a typical lake transgressive and retrogressive deposit.(2)There are three categories and 11 kinds of lithofacies developed in the Upper Urho Formation. The rock structure and reservoir properties of different lithofacies are obviously different under the transformation of sedimentary and diagenetic processes. The lithofacies formed by traction flow and density flow has higher reservoir quality.(3)The reservoir quality of the Upper Urho Formation gets better from bottom to top. The sedimentary environment controls the macroscopic changes of the reservoir quality,the mud matrix destroys the pore connectivity,and the concentration degree and development range of grain size control the scale of the high-quality reservoir. Dissolution effectively improved the reservoir capacity,with an average porosity increment of 3.2%. The research results are of reference significance for glutenite exploration of Upper Urho formation in Mahu Sag.
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Characteristics and main controlling factors of Permian-Triassic superimposed reservoirs in central Mahu Sag,Junggar Basin
CHEN Jing, CHEN Jun, LI Hui, NUERAILI Zhaman
2021, Vol.33(1): 71–80
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doi: https://doi.org/10.12108/yxyqc.20210107
Mahu Sag is a hydrocarbon generation deperession with the highest hydrocarbon accumulation degree in Junggar Basin,and Permian-Triassic has great exploration potential. In order to study the characteristics and main controlling factors of its superimposed reservoirs,a large number of analyses of mud-logging, well logging,core analysis and oil test data were carried out,and 3D seismic data was interpreted. The results show that:(1)There are two sets of high-quality reservoirs developed in central Mahu Sag,including Permian lower Urho Formation and Triassic Baikouquan Formation. The front edge of fan delta is a favorable belt for oil and gas enrichment. Under the background of lacustrine transgression,sand bodies are superimposed and connected in many stages,which has geological conditions for forming large lithologic trap group.(2)The reservoir-cap assemblage is well configured, sand bodies are vertically overlapped,and lateral faults and overlying delta plain subfacies mudstone can provide shelter for hydrocarbon accumulation.(3)High-angle strike-slip faults and a series of associated structures are developed in the study area. Deep faults communicate with oil sources,and shallow faults control traps and reservoirs,together with unconformities, they form a highly efficient transport system,which is an important controlling factor for multi-layer superimposed reservoirs. The research results have reference significance for mid-deep oil and gas exploration in central Mahu Sag.
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Identification of faults in the south slope of Mahu Sag and its control on hydrocarbon accumulation
YU Xing, YOU Xincai, BAI Yu, LI Peng, ZHU Tao
2021, Vol.33(1): 81–89
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doi: https://doi.org/10.12108/yxyqc.20210108
Recently,extra-high industrial oil flow was obtained in Jurassic Badaowan Formation in well MH015 in the south slope of Mahu Sag of Junggar Basin,which has opened up a new prospect of medium and shallow oil and gas pre-exploration in this area. In order to further explore the characteristics of faults,the control of faults on reservoirs,oil and gas enrichment rules and exploration potential in the south slope of Mahu Sag,field geological outcrop,logging data and seismic fault identification technology were applied to comprehensively analyze the fault formation period,fault spatial combination and hydrocarbon accumulation model in the study area. The results show that:the reverse faults in the Late Hercynian-Indosinian and strike-slip faults in Indosinian-Yanshanian are the key factors of oil and gas migration in south slope of Mahu Sag. The hydrocarbon accumulation in this area has the characteristics of hydrocarbon supply from near source rocks,vertical three-dimensional transport of multistage faults,fault lithology controlling accumulation and three-dimensional oil-bearing. The research results point out the direction for the subsequent oil and gas exploration deployment in this area.
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Discovery and hydrocarbon exploration potential of beach-bar sand in Shawan Sag,Junggar Basin
GUAN Xin, PAN Shuxin, QU Yongqiang, XU Duonian, ZHANG Han, MA Yongping, WANG Guodong, CHEN Xuezhen
2021, Vol.33(1): 90–98
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doi: https://doi.org/10.12108/yxyqc.20210109
Recently,well ST1 in Shawan Sag of Junggar Basin has achieved major breakthrough in Upper Urho Formation,of which the geological characteristics regarding hydrocarbon accumulation and reservoir forming are clearly different from those in Mahu Sag,and present typical features of beach-bar sand deposition. In order to explore a new field of hydrocarbon exploration,confirm the planar distribution and exploration potential of beach-bar sand,on the basis of high-resolution three-dimensional seismic data,combined with data collected during drilling,formation testing,well logging and core analyses,the plane distribution characteristics of beachbar sand of Upper Urho Formation in Shawan Sag were depicted by using seismic techniques such as attribute extraction and stratal slicing,and its hydrocarbon accumulation potential was discussed. The results show that the target layer in the study area presents apparent characteristics of beach-bar sand,which is band-shaped distri-buting along the lake shoreline,and it forms good hydrocarbon accumulation conditions and has a huge area for exploration. The discovery and confirmation of the beach-bar sand field provides a model to shed light on the exploration of beach-bar sand oil and gas reservoir across the Shawan Sag,as well as a new exploration field for the "Greater Mahu" area in Junggar Basin.
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Petrophysical facies of Triassic Baikouquan Formation in northern Mahu Sag,Junggar Basin
YANG Fanfan, YAO Zongquan, YANG Fan, DELECHIATI Ganatayi, ZHANG Lei, CAO Tianru
2021, Vol.33(1): 99–108
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doi: https://doi.org/10.12108/yxyqc.20210110
The reservoir heterogeneity of Triassic Baikouquan Formation in northern Mahu Sag of Junggar Basin is strong,and multi factor comprehensive analysis has become an important means of fine reservoir research in recent years. Through core description,casting thin section,logging curve and grain size analysis,the studies on petrophysical facies including reservoir sedimentary microfacies,diagenetic facies and fracture facies were carried out,and cluster analysis on the divided petrophysical facies was carry out to predict favorable reservoirs in the study area. The results show that:(1)Fan delta sedimentary microfacies are mainly composed of distributary channel, braided branch channel,underwater distributary channel and underwater distributary bay.(2)Diagenetic facies include three kinds of tight diagenetic facies(compacted tight diagenetic facies,illite/smectite filling diagenetic facies and siliceous cementation diagenetic facies)and two kinds of dilatancy diagenetic facies(chlorite lining weak dissolution diagenetic facies and unstable component dissolution diagenetic facies).(3)Under the background of gentle slope,the fracture density is less than 1/m due to the local development of horizontal fractures, which has little impact on reservoir physical properties.(4)According to the superposition principle of "sedimentary microfacies + diagenetic facies + fracture facies",the classification of petrophysical facies was determined, and 10 kinds of petrophysical facies were divided,such as underwater distributary channel-chlorite lining weak dissolution diagenesis facies and so on.(5)PF1 corresponds to type Ⅰ reservoir,with the best reservoir physical properties,mainly developed in Bai 2 member,and the development scale of the Bai 3 member is relatively small. PF2 corresponds to type Ⅱ reservoir with medium physical properties and relatively developed in Baikouquan Formation. PF3 corresponds to type Ⅲ reservoir,with relatively poor physical properties and relatively developed in Bai 3 member. The research method of petrophysical facies in northern Mahu Sag can provide guidance for oil and gas exploration of Baikouquan Formation.
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Characteristics of formation water and its geological significance of lower combination of Yanchang Formation in Ordos Basin
ZHOU Xinping, DENG Xiuqin, LI Shixiang, ZUO Jing, ZHANG Wenxuan, LI Taotao, LIAO Yongle
2021, Vol.33(1): 109–120
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451
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doi: https://doi.org/10.12108/yxyqc.20210111
The distribution relationship between oil and water of the lower combination Chang 10 to Chang 8 of Mesozoic Yanchang Formation in Ordos Basin is complex,and the characteristics of formation water and its relevance with reservoir are lack of systematic study. In order to clarify the formation water property and its relationship with reservoir,and the influence of formation water salinity on well logging interpretation,based on the selection of formation water samples,through the analysis of more than 10000 formation water samples from Yanchang Formation in Ordos Basin,the properties and distribution characteristics of formation water were studied, and the geological significance of formation water salinity and characteristic parameters were analyzed. The results show that the formation water of Yanchang Formation has the characteristics of zonal spreading distribution. The salinity of formation water of each oil layer group increases first and then decreases from the western margin thrust belt and the axis of Tianhuan depression to the center of the lacustrine basin. The formation water of the lower combination of Yanchang Formation has relatively low salinity,with an average value of 28.4 g/L,which belongs to saline formation water,mainly of CaCl2 type. The ion composition,salinity,isotope and characteristic parameters of formation water are similar,and obviously different from other formation water characteristics,belonging to the same fluid system. The feature parameters of Na+/Cl- coefficient,desulfuration coefficient and metamorphism coefficient of formation water show that reservoir sealing property of the lower combination of Yanchang Formation is good as a whole. The reservoirs and oil production wells are mainly distributed in the area with relatively high salinity of formation water. Some reservoirs in the western thrust belt have been adjusted and reformed due to the influence of tectonism,and the sealing property of the reservoir became poor. The water layer with high resistivity in the central lacustrine basin and the oil layer with low resistivity in the axis of Tianhuan Depression are developed,and formation water salinity is an important factor affecting well logging interpretation. The research results could provide a basis for the study of fluid system of Mesozoic Yanchang Formation and fine identification of complex oil-water relationship distribution in Ordos Basin.
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Accumulation characteristics of Upper Paleozoic tight sandstone in Shenfu block,northeastern margin of Ordos Basin
GAO Jixian, SUN Wenju, WU Peng, DUAN Changjiang
2021, Vol.33(1): 121–130
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doi: https://doi.org/10.12108/yxyqc.20210112
In order to further expand the exploration degree of tight gas in the eastern margin of Ordos Basin, based on the analysis of regional source rock,reservoir,caprock and hydrocarbon transport system,combined with fluid inclusion test,the tight gas accumulation conditions of Carboniferous-Permian in Shenfu block were studied. The results show that the main coal seams are thick and stable,and the better hydrocarbon generation intensity constitutes the basic conditions for accumulation. The reservoir is characterized by low porosity and low permeability, with residual intergranular pores and intragranular dissolved pores as the main reservoir space. The mudstone widely developed in Carboniferous-Permian has good sealing capacity. The homogenization temperature of fluid inclusions indicates the first stage of continuous reservoir formation,and three reservoir-cap assemblage models,namely,within source,near source and far source,can be divided. The difference of source reser-voir configuration in different layers controls the formation of different accumulation models. The related achievements and understanding further expand the prospect of petroleum exploration and development in Ordos Basin,and provide a theoretical basis for oil and gas exploration in the study area and similar tight gas fields.
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Hydrocarbon accumulation differences and main controlling factors of Jurassic petroleum system in Altun piedmont of Qaidam Basin
TIAN Guangrong, WANG Jiangong, SUN Xiujian, LI Hongzhe, YANG Wei, BAI Yadong, PEI Mingli, ZHOU Fei, SI Dan
2021, Vol.33(1): 131–144
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doi: https://doi.org/10.12108/yxyqc.20210113
In order to clarify the differential accumulation and enrichment rules of oil and gas in the eastern part of Altun piedmont in Qaidam Basin,a large number of geological and geochemical test data were used to study the characteristics of oil and gas reservoirs around Jurassic petroleum system,analyze the accumulation periods, identify the key accumulation factors and establish the accumulation model. The results show that:(1)There are obvious differences in hydrocarbon accumulation in Altun piedmont. Natural gas maturity is low in Niudong area, dry gas and wet gas coexist,mainly in the middle and late Oligocene and the early and middle Miocene,with multi-layer accumulation vertically. Dongping area is dominated by dry gas,with great changes in maturity,and the gas reservoir is continuously filled and characterized by multi-stage accumulation from early Oligocene to Holocene, mainly enriched by bedrock. Jianbei area is dominated by dry gas with high maturity,and only bedrock enriches oil and gas in early and middle Miocene.(2)The vertical migration of oil and gas is controlled by the fault system connecting the Jurassic hydrocarbon-generating kitchen,the structural form of unconformity surface in the key accumulation stage controls the oil and gas migration direction,and the development degree of gypsum mudstone caprock in Lulehe Formation controls the enrichment layer series of oil and gas reservoir.(3) There are three kinds of hydrocarbon accumulation models in Altun piedmont:three-dimensional accumulation model with vertical fault transportation,step-by-step composite accumulation model with far-source transportation and subsalt accumulation model with far-source transportation. The research results have a guiding role in the exploration of Jurassic oil and gas system in foothill belt.
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Hydrocarbon accumulation conditions and favorable exploration plays in Yingxiongling structural belt,Qaidam Basin
LONG Guohui, WANG Yanqing, ZHU Chao, XIA Zhiyuan, ZHAO Jian, TANG Pengcheng, FANG Yongsheng, LI Haipeng, ZHANG Na, LIU Jian
2021, Vol.33(1): 145–160
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doi: https://doi.org/10.12108/yxyqc.20210114
In order to ascertain the hydrocarbon accumulation conditions in Yingxiongling structural belt,and to explore the oil and gas exploration field and exploration direction,through the data of oil and gas showed in drilling, organic geochemistry,polarized light microscope thin-section investigation,experimental test,geophysics, oil and gas testing,the geological conditions of oil and gas accumulation were analyzed,and favorable exploration plays were predicted. The results show that on reservoir conditions,multiple sets of source rocks are developed, mainly in the Upper of Lower Ganchaigou Formation of Paleogene and the Upper Ganchaigou Formation of the Neogene. There are three types of oil and gas reservoirs,namely clastic rocks and lacustrine carbonate rocks and diamictite,and three types of source-reservoir assemblages namely integrated source-reservoir type, upper-source and lower-reservoir type,and lower-source and upper-reservoir type. Yingxiongling structural belt has favor-able hydrocarbon accumulation conditions,such as superior source rock conditions,good oil and gas resource foundations,various reservoir types,excellent reservoir performance,good matching between late tectonic acti-vity and hydrocarbon generation and expulsion period,and favorable conditions for continuous oil and gas filling. For favorable exploration areas,the exploration direction of Paleogene clastic rocks(delta front sand bodies)is in Huatugou-Hongliuquan and Youshashan-Gasi areas in the structural belt, and the exploration direction of carbonate rocks is in Yingxi-Youyuangou and gasi-Yuejin areas in the structural belt. The exploration direction of Neogene clastic rocks(coastal beach bar sand)is in Shizigou-Huatugou-Youyuangou-Youshashan-Yingdong and the west areas in the structural belt. The exploration direction of carbonate rocks(algae limestone, mixed rock and lime dolomite)is in Youquanzi-Kate-Huangguamao areas on the east side of the structural belt. The results show that Yingxiongling structural belt has the exploration potential to discover large-scale oil and gas fields.
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Characteristics of fault activity and its control on hydrocarbon accumulation in southern Yingxiongling area,Qaidam Basin
LU Enjun, LIU Shaobo, YU Zhichao, LU Xuesong, CHENG Dingshu
2021, Vol.33(1): 161–174
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doi: https://doi.org/10.12108/yxyqc.20210115
Faults are widely distributed in southern Yingxiongling area,Qaidam Basin. The control of the faults on hydrocarbon accumulation is unclear. Through reinterpretation of seismic profiles in this area,five main faults were analyzed:Shizigou fault,Ⅰ fault,Ⅱ fault,Youshashan fault and Ⅺ fault. The fault grade,structural style, activity intensity and evolution process were studied,and the control effect of faults on hydrocarbon accumulation was discussed by analyzing the characteristics of biomarkers and oil and gas filling periods in southern Yingxiongling area. The results show that:(1)Ⅰ,Ⅱ and Ⅺ faults belong to the faults under the weak layer (gypsum salt rock + mudstone)and formed in Paleogene,among which Ⅱ fault and Ⅺ fault were formed by superposition of multiple faults,while Shizigou and Youshashan faults belong to faults above the weak layer,and be formed by single fault growth in Neogene.(2)Oil and gas in shallow structural belt are the result of upward migration of deep oil and gas. The activity of reservoir controlling faults matches with hydrocarbon generation period and the formation period of traps.(3)The evolution of the fault-controlling reservoir model can be divided into three stages:basement faults control the formation of source rocks in the upper Xiaganchaigou Formation;detachment faults control the accumulation of low-mature oil and gas reservoirs in the lower Youshashan Formation. detachment faults control mature hydrocarbon accumulation in the upper Youshashan Formation,and reform the early low mature oil and gas reservoirs. The difference of different fault activity characteristics is one of the main controlling factors for the difference of hydrocarbon accumulation in southern Yingxiongling area.
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Hydrocarbon accumulation conditions in Eboliang structural belt and its exploration implications
KONG Hongxi, WANG Yuanfei, ZHOU Fei, ZHU Jun, CHEN Yangyang, SONG Dekang
2021, Vol.33(1): 175–185
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doi: https://doi.org/10.12108/yxyqc.20210116
Exploration wells have been drilled in each structure of Eboliang structural belt with Paleogene and Neogene as the target layer,but the gas abundance is very low,so actual exploration breakthrough has not been achieved. At the same time,due to the large buried depth of Jurassic source rocks,the accumulation and enrichment rules are not clear. In recent years,with the continuous improvement of exploration degree,many exploration wells have been drilled to Jurassic,which lays a foundation for further study. Based on the analysis of hydrocarbon source rocks,geochemical characteristics of natural gas and migration and accumulation conditions of Eboliang structural belt,a comprehensive study on hydrocarbon accumulation conditions was carried out. The results show that the organic matter abundance is not high and the maturity is very low in Niudong nose-shaped uplift and Eboliang No. 1 structure,so they do not have the source rock conditions for large-scale natural gas formation. At present,the discovered natural gas is highly mature and over mature coal type gas,which comes from the highly mature source rocks formed in the center of the depression. The unconformities widely developed on the top of Jurassic and the faults connecting the source rocks are the main transport channels. The area with high maturity of source rock in the center of depression should be selected for the next exploration in Eboliang structural belt,and the target layer should be as close as possible to the source rocks. The research results indicate favorable exploration areas for further exploration in Eboliang structural belt.
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Sedimentary characteristics and reservoir prediction of Xiagou Formation in Kulongshan structural belt,Qingxi Sag,Jiuquan Basin
ZHANG Wenting, LONG Liwen, XIAO Wenhua, WEI Haoyuan, LI Tiefeng, DONG Zhenyu
2021, Vol.33(1): 186–197
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doi: https://doi.org/10.12108/yxyqc.20210117
The K1g1 and K1g0 of Lower Cretaceous Xiagou Formation are the main productive layers in Kulongshan structural belt of Qingxi Sag in Jiuquan Basin. In order to clarify the sedimentary characteristics and favorable reservoir distribution,high-resolution sequence stratigraphic division,provenance analysis and sedimentary microfacies distribution study were carried out by using core,logging,seismic and analysis data,and the reservoir characteristics and main controlling factors were expounded. The favorable reservoir distribution was predicted by using deep learning nonlinear inversion technology. The results show that:The K1g1 and K1g0 of Xiagou Formation in Kulongshan structural belt can be divided into four mid-term base level cycles(MSC1-MSC4)and eight short-term base level cycles(SSC1-SSC8)from bottom to top. The K1g1 and K1g0 of Xiagou Formation in Kulongshan structural belt are dominated by retrogradational fan delta,with three provenances in the west,south, and east. The fan deltas have a high degree of development in the middle and lower parts of K1g1 and K1g0,and have a wide distribution range. Fracture is an important factor to improve the physical properties of the reservoir. Together with secondary pores,it constitutes the main reservoir space,which can be divided into pore type reservoirs, pore-fracture type reservoirs and tight reservoirs. The deep learning nonlinear inversion technology was used to predict the favorable reservoir area of 14.7 km2. The research results can provide reference for Cretaceous oil and gas exploration in Kulongshan structural belt.
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Sedimentary characteristics and controlling factors of slump gravity flow in delta front: a case study of Qing 1 member in Da'an area,Songliao Basin
FU Yong, LI Zhongcheng, WAN Pu, QUE Yijuan, WANG Zhenjun, JI Yu, HUANG Li, LUO Jinglan, BAO Zhidong
2021, Vol.33(1): 198–208
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doi: https://doi.org/10.12108/yxyqc.20210118
Gravity flow sand body is an important part of the source-reservoir assemblage in source rocks and has great potential for exploration and development. Based on the data of cores,3D seismic,grain size analysis, wire-logging and mud-logging,combined with regional geological background,the types,identification marks, sedimentary characteristics,formation and distribution controlling factors,and exploration and development potential of slump gravity flow in delta front of the first member of Qingshankou Formation in Da'an area of Songliao Basin were analyzed systematically. The results show that there are three types of slump gravity flow developed in Qing 1 member in the study area,including sliding-slump,sandy debris flow and turbidity flow,which are distributed adjacently or alternately distributed in the vertical direction,and evolve sequentially in the plane. Slope break zone and base level change have a controlling effect on the formation and distribution of these three types of gravity flow. Sliding-slump,sandy debris flow and turbidity flow are distributed at the foot of slope, slope and basin plain,respectively. The sandy debris flow shows different sedimentary characteristics and fluid properties during base level rising and falling period. The base level rising period is a favorable period for the development of gravity flow sand body,and the sandy debris flow is distributed in a sheet shape,with completely developed gravity flow sedimentary sequence. In the early stage of base level falling,the distribution of gravity flow sand bodies is relatively restricted,and the sandy debris flow shows a river channel distribution pattern that is of dual fluid properties of traction flow and gravity flow. The sandy debris flow and turbidite sand layer are relatively thin and often associated with lacustrine source rocks to form lithologic traps,and the single well production often tends to be higher.
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Geochemical characteristics and geological significance of Shaximiao Formation in northeastern Sichuan Basin: a case study fromWubaochang area
XU Yuxuan, DAI Zongyang, HU Xiaodong, XU Zhiming, LI Dan
2021, Vol.33(1): 209–219
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doi: https://doi.org/10.12108/yxyqc.20210119
The shallow tight gas of Jurassic Shaximiao Formation in northeastern Sichuan Basin has many advantages, such as low investment cost,quick effect,wide distribution,large amount of resources and shallow burial depth,so it is an efficient exploration and development object. Through the collection of natural gas of Jurassic Shaximiao Formation and underlying source rocks in Wubaochang area of northeastern Sichuan Basin,the natural gas components,carbon isotopes,vitrinite reflectance,microscopic components and total organic carbon content were determined. Combined with analysis of natural gas and source rock samples,the gas source of Jurassic Shaximiao Formation in northeastern Sichuan Basin was discussed. Combined with typical reservoir accumulation section of Shaximiao Formation and the present development degree of tight gas in northeastern Sichuan Basin, the typical reservoir accumulation model of Jurassic Shaximiao Formation in northeastern Sichuan Basin was analyzed. The results show that the natural gas of Jurassic Shaximiao Formation in northeastern Sichuan Basin mainly comes from the underlying lacustrine source rocks of Jurassic Ziliujing Formation and coal measure source rocks of Triassic Xujiahe Formation. The source rocks of Jurassic Ziliujing Formation in northeastern Sichuan Basin are type Ⅱ1-Ⅱ2 high mature medium-good source rocks,and the source rocks of Xujiahe Formation are type Ⅲ over-mature source rocks. The Wubaochang and Dukouhe areas in the front margin of the Daba Mountain in northeastern Sichuan Basin have good conditions for tight gas accumulation,and are the key areas for next shallow tight gas exploration. The exploration should focus on finding favorable zones of Shaximiao Formation,increase the exploration wells of underlying Ziliujing Formation and Xujiahe Formation to obtain more geological data, and expand the exploration and development scope outwards withWubaochang and Dukouhe areas as the center.
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Reservoir prediction for weathering and leaching zone of bedrock buried hill based on seismic pre-stack depth migration
SUN Xiping, ZHANG Xin, LI Xuan, HAN Yongke, WANG Chunming, WEI Jun, HU Ying, XU Guangcheng, ZHANG Ming, DAI Xiaofeng
2021, Vol.33(1): 220–228
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doi: https://doi.org/10.12108/yxyqc.20210120
The weathering crust of bedrock buried hill is an important field of oil and gas exploration. However, because of the deep buried depth,the complex surface and underground structure,it is difficult to obtain seismic imaging and the seismic amplitude is hard to be preserved. Moreover,it is difficult to predict the reservoir in weathering and leaching zone. In order to accurately depict the reservoir in weathering and leaching zone of bedrock buried hill,the velocity modeling technology from near-surface and amplitude-preserved pre-stack depth migration technology were used to improve the seismic imaging accuracy and amplitude preservation effect of complex structural area. Based on the layered characteristics of weathering and leaching zone of bedrock buried hill,combined seismic data with geological data,the internal layered structure of buried hill reservoir was established. The fracture distribution law was identified by using coherence cube and ant tracking technology,then combined with the classification characteristics of seismic amplitude,the effective thickness prediction of inner bedrock buried hill was carried out. The actual application in Ya'erxia buried hill proved that the high-yield reservoir area delineated according to reservoir development made a good match with the reservoir thickness prediction of the weathering and leaching zone by this method. This method can provide effective support for the characterization of inner reservoir targets in bedrock buried hill.
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A new method for thin reservoir identification based on sparse Bayesian learning and its application
YUAN Cheng, SU Mingjun, NI Changkuan
2021, Vol.33(1): 229–238
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doi: https://doi.org/10.12108/yxyqc.20210121
In recent years,thin reservoir is one of the main targets of oil and gas exploration in China. To enhance the ability of thin reservoir identification can be significant for detecting the residual hydrocarbon resources. Due to the limitation of seismic resolution and the interference of seismic reflection among neighboring thin layers,it is a tricky task to directly evaluate thin reservoir based on the seismic reflection data. Therefore,a new method of seismic reflectivity inversion based on sparse Bayesian learning was adopted,and then the relative acoustic impedance of underground strata was estimated by the inverted seismic reflectivity. A linear FIR filtering was also introduced to eliminate the low-frequency accumulative errors which were generated in the processing of relative impedance calculation. Thin reservoir can be finally identified based on the filtered relative impedance with higher confidence. Field application shows that the accuracy of seismic reflectivity can be improved significantly by seismic reflectivity inversion based on sparse Bayesian learning,laying a solid foundation for a better estimation of relative impedance of underground formation. The designed linear FIR filter can effectively suppress the low-frequency accumulative errors in the estimated relative impedance,improving the accuracy of thin reservoir detection. Comparing with the traditional seismic amplitude,the relative impedance estimated by the proposed method can reveal the lateral distribution of thin reservoir more accurately,and finally improves the success rate of thin reservoir exploration.
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Prediction technology of tight oil thin sand reservoir and its application effect: a case study of Lower Cretaceous Quantou Formation in Aonan block,Songliao Basin
CAO Sijia, SUN Zengjiu, DANG Huqiang, CAO Shuai, LIU Dongmin, HU Shaohua
2021, Vol.33(1): 239–247
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doi: https://doi.org/10.12108/yxyqc.20210122
Aonan block,located in northern Songliao Basin,is an important resource potential area of tight oil in China. The Lower Cretaceous Quantou Formation is distributary channel sand deposit of shallow-water delta front,which is characterized by "mud-coated sand",thin thickness and small scale. Conventional seismic prediction technologies such as seismic inversion cannot accurately identify and predict this type of sand body. The blue filter target processing technology was used to improve the quality and resolution of seismic data. The optimization and analysis of sensitive seismic attributes were carried out to predict the macroscopic distribution characteristics of thin sand body qualitatively. The thin sand body was predicted quantitatively by combining the technique of well-seismic joint geostatistical inversion and stochastic co-simulation,and then the spatial distribution of sand body in the main layer of Fuyu oil layer was described. The predicted results are in good agreement with the drilling results. This method has important guiding significance for tight oil and gas development in other areas.
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Prediction of high-quality source rock distribution based on pseudo-3D multi-attribute inversion
YAO Jun, LE Xingfu, CHEN Juan, SU Wang, ZHANG Yongfeng
2021, Vol.33(1): 248–257
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doi: https://doi.org/10.12108/yxyqc.20210123
The Xujiahe Formation in the transitional zone of central-western Sichuan Basin is a typical "sandwich" structure,with source and reservoir being stacked vertically. The effective prediction of high-quality source rock distribution is one of the major determinants of tight gas exploration in this formation. Based on the measured value of core TOC,conventional logging curves,multiple linear regression algorithm was applied to calculate TOC curve of single well,a pseudo-three dimensional seismic network was built with two-dimensional seismic data,and then multi-attribute inversion and data selection were carried out to complete the distribution prediction of high-quality source rocks in the first,third and fifth members of Xujiahe Formation. The method improves the utilization of two-dimensional seismic data,enhances the accuracy of prediction results of highquality source rock distribution,and improves the calculation efficiency of multi-attribute inversion. The application of pseudo-3D multi-attribute inversion to the effective prediction of high-quality source rock distribution lays a solid foundation for the further exploration of tight gas in the two-dimensional seismic deployment area.
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Lithology identification of Carboniferous volcanic rocks in Xiquan area, eastern Junggar Basin
LI Shubo, GUO Xuguang, ZHENG Menglin, WANG Zesheng, LIU Xinlong
2021, Vol.33(1): 258–266
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doi: https://doi.org/10.12108/yxyqc.20210124
Effective and accurate lithology identification is one of the most important foundations for volcanic reservoir exploration. Aiming at the Carboniferous volcanic rocks in Xiquan area of the eastern Junggar Basin, based on a large amount of coring data and micro-slice data,six well logging curves which were sensitive to lithology were selected,and each of them were standardized to establish a random sample by principal component analysis,and two comprehensive variables Y1 and Y2 with a cumulative variance contribution rate of 86.798% were constructed to improve the sensitivity of logging response characteristics between different lithologies. The typical discriminant analysis method was used to establish discriminant models for nine different lithologies of Carboniferous volcanic rocks in the study area to identify volcanic rocks. The back-judgmental inspection and cross-validation of the original samples show that the accuracy of lithology identification was improved by using this method,its comprehensive accuracy of lithology identification was over 91%. The correlation and overlap of lithologic information carried by logging curves were effectively eliminated,and the accuracy of this method is higher than that of conventional lithology identification methods in thin interbedded volcanic rocks identification. The study provides a reference for accurate lithology identification of volcanic rocks in the study area.
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Application of 2D NMR logging in fluid identification of glutenite reservoir
NING Congqian, ZHOU Mingshun, CHENG Jie, SU Rui, HAO Peng, WANG Min, PAN Jingli
2021, Vol.33(1): 267–274
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doi: https://doi.org/10.12108/yxyqc.20210125
The glutenite reservoir in Wulanhua Sag of Erlian Basin is characterized by various mineral components and complex pore structure. The conventional electrical characteristics are difficult to reflect the fluid properties of the reservoir. The one-dimensional NMR fluid identification methods are of ambiguity,so it is difficult to distinguish oil and water layer. The D-T2 2D NMR method takes into account the diffusion and transverse relaxation characteristics of reservoir fluid,reduces ambiguity of logging interpretation,and reduces the operation and data processing difficulty of 2D NMR logging application. This method provides an effective means to accurately identify the fluid properties of complex glutenite reservoirs,and provides the possibility of applying 2D NMR reservoir identification technology in a wider range.