LIU Guoyong, XU Duonian, HU Tingting, PAN Shuxin, PAN Tuo, WANG Guodong, MA Yongping, GUAN Xin
2023, Vol.35(5): 110
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ZHANG Changmin, ZHANG Xianghui, ZHU Rui, FENG Wenjie, YIN Taiju, YIN Yanshu, Adrian J. HARTLEY
2023, Vol.35(5): 1125
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PAN Shuxin, XU Duonian, TANG Yong, QU Yongqiang, WANG Guodong, DONG Xuemei, HU Tingting, MA Yongping
2023, Vol.35(5): 2636
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DU Jiangmin, CUI Zihao, JIA Zhiwei, ZHANG Yi, NIE Wancai, LONG Pengyu, LIU Boyuan
2023, Vol.35(5): 3748
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LI Shengqian, ZENG Jianhui, LIU Yazhou, LI Miao, JIAO Panpan
2023, Vol.35(5): 4961
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WEI Quanchao, LI Xiaojia, LI Feng, HAO Jingyu, DENG Shuanglin, WU Juan, DENG Bin, WANG Daojun
2023, Vol.35(5): 6270
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WEN Siyu, ZHANG Bing, YAO Yongjun, MA Kai, WANG Yan, YANG Kai
2023, Vol.35(5): 7180
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NIE Lishang, MA Jinghui, TANG Xiaofei, YANG Zhi, ZHANG Wanjin, LI Hongrui
2023, Vol.35(5): 8191
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HU Wangshui, GAO Feiyue, LI Ming, GUO Zhijie, WANG Shichao, LI Xiangming, LI Shengming, JIE Qiong
2023, Vol.35(5): 9299
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XU Zhongbo, WANG Libing, SHEN Chunsheng, CHEN Mingyang, GAN Liqin
2023, Vol.35(5): 100107
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QI Yukai, GUO Jingxiang, LUO Liang, LUO Fusong, ZHOU Xuewen, YAO Wei, ZHANG Tan, LIN Huixi
2023, Vol.35(5): 108119
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WEI Jiayi, WANG Hongwei, LIU Gang, LI Han, CAO Qian
2023, Vol.35(5): 120130
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ZHU Xiuxiang, ZHAO Rui, ZHAO Teng
2023, Vol.35(5): 131138
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GUO Jinhao, HU Guoyi, HE Kun, MI Jingkui, TIAN Lianjie, HE Fei, GUO Chuyuan, LU Mengdie
2023, Vol.35(5): 139152
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YUE Shijun, LIU Yingru, XIANG Yiwei, WANG Yulin, CHEN Fenjun, ZHENG Changlong, JING Ziyan, ZHANG Tingjing
2023, Vol.35(5): 153160
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ZHAO Changhong, SUN Xinge, LU Yingbo, WANG Li, HU Pengcheng, XING Xiangrong, WANG Guiqing
2023, Vol.35(5): 161168
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LIU Guoyong, XU Duonian, HU Tingting, PAN Shuxin, PAN Tuo, WANG Guodong, MA Yongping, GUAN Xin
2023, Vol.35(5): 110
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doi: https://doi.org/10.12108/yxyqc.20230501
Beach sand body is one of the essential reservoir types in continental basins in China. Based on core testing, drilling,logging and 3D seismic data,the sedimentary characteristics of the beach sand bodies of Jurassic Badaowan Formation in Shawan Sag of Junggar Basin were systematically analyzed,and their distribution,depositional model and exploration potential were discussed. The results show that: (1)The beach sand bodies of Badaowan Formation in Shawan Sag comprise beach ridges and troughs. The beach ridges are rich in sand,mainly composed of sandy conglomerate,pebbly sandstone and sandstone,with massive bedding,wave cross-bedding and local soft sedimentary deformation bedding being developed,showing multi-phase beach ridge superposition. The beach trough is poor in sand and dominated by thin siltstone,with reversed grain sequence in vertical. The single beach ridge comprises three sedimentary sequences, and each sequence has grain size probability curves in three-stage.(2)The beach ridges in the study area show a reflection characteristic of strong amplitude lenticular discontinuity on seismic section,and the stratal slices show beach ridges distributed in rows and belts along the lake shoreline. Beach sand bodies are distributed in strips along the lake shorelines in the recessed area between the two big delta fan bodies in the west ring belt, and beach ridges and troughs are distributed alternately. The single beach ridge has small area, with large number,up to 12. Appearing in groups and belts,the area of beach ridge sand body group is up to 145 km2.(3)The ridged trough beach sand bodies at the bottom of Badaowan Formation in the study area have excellent exploration and development potential,with a considerable thickness of sand bodies, good physical properties,and a wide distribution area. The trough can be used as a lateral barrier layer to form suitable reservoirs and traps. The high-quality source rocks of the alkaline lake of Permian Fengcheng Formation provide oil and gas sources, and the unconformity surface and faults are favorable oil and gas transport systems.
ZHANG Changmin, ZHANG Xianghui, ZHU Rui, FENG Wenjie, YIN Taiju, YIN Yanshu, Adrian J. HARTLEY
2023, Vol.35(5): 1125
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doi: https://doi.org/10.12108/yxyqc.20230502
Based on literature research and geological analysis,the research progress,application prospect and development trend of distributive fluvial system(DFS)theory were reviewed. The results show that:(1)There are five important problems should be claimed in current DFS research,including to excavate the scientific connotation of DFS through case analysis and explore its application value;DFS is a multi-channel coexisting depositional system which cannot be thought as a new pattern of channel;channels network and channels transition,as well as their evolution,are important issues in DFS study;it is urgent to build and to perfect the depositional model; predictable reservoir modelling is the way to realize the basin-scale reservoir prediction.(2)DFS are prospected to be widely developed in petroliferous basins and the researches are of great theoretical significance and application value for promoting the theoretical sedimentary innovation and oil and gas resources exploration.(3)The current study should be focused on DFS sedimentary database construction,DFS facies identification model construction,the research of quantitative DFS channel network prediction and their evolution and hierarchical DFS reservoir geological model integration. Future trend in DFS research should combine sedimentology with geomorphology,geography and Earth Information Science and technology,with the help of big data and intelligent technology, to realize quantitative depositional system prediction and reservoir characterization.
PAN Shuxin, XU Duonian, TANG Yong, QU Yongqiang, WANG Guodong, DONG Xuemei, HU Tingting, MA Yongping
2023, Vol.35(5): 2636
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doi: https://doi.org/10.12108/yxyqc.20230503
Shawan Sag and Mahu Sag in Junggar Basin have similar tectonic,sedimentary and reservoir-forming backgrounds. Based on the study of lithofacies paleogeographic pattern and source-sink system of Shawan Sag, it was proposed that a large-scale far-source depositional system from the northwest direction was developed in the center of the sag, namely Liushugou river system,and the sedimentary evolution characteristics and hydrocarbon accumulation conditions of Shawan Sag were analyzed about this water system. The results show that:(1)Liushugou river in Shawan Sag originated from Zaire Mountain and formed a large fluvial delta depositional system in the central Shawan Sag after flowing through Zhongguai uplift. The large-scale reservoirs such as meandering river point sand bar, delta front underwater distributary channel,estuary bar and sheet sand are formed in the sag.(2)The Liushugou River developed inheritantly from Permian to Jurassic,experienced the processes of Permian transgression,early regression and mid-late transgression of Triassic, and lake water body shock development successively of Jurassic, forming scale source rocks of Middle-Lower Permian. Large delta fans of Permian-Early Triassic, multi-stage channel superimposed reservoirs of Jurassic,and regional cap rocks of late Late Permian and late Early Triassic, formed multi-sets of vertically advantageous assemblages of source-reservoir-cap rock. The unconformities and fault systems formed by multi-stage tectonic movements have constructed a favorable transport system for oil and gas migration and adjustment in Shawan Sag.(3)The discovery of Liushugou river system has changed the traditional understanding that there is no large remote river system in Shawan Sag and only near-source fan delta developed. The center of Shawan Sag and the lower part of slope are new areas for searching for large-scale oil and gas reservoirs.
DU Jiangmin, CUI Zihao, JIA Zhiwei, ZHANG Yi, NIE Wancai, LONG Pengyu, LIU Boyuan
2023, Vol.35(5): 3748
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doi: https://doi.org/10.12108/yxyqc.20230504
The exploration potential of Ma 55 sub-member of Ordovician Majiagou Formation in Sulige area of Ordos Basin is huge. Through core observation,thin section identification,scanning electron microscope and geochemical testing,combined with geophysical technologies,the sedimentary characteristics of Ma 55 sub-member of Ordovician Majiagou Formation in Sulige area were studied,and its petroleum geological significance was discussed. The results show that: (1)The Ma 55 sub-member of Ordovician Majiagou Formation in Sulige area belongs to carbonate platform facies which inclines to the east under the background of overall transgression and late regressions. Open platform and restricted platform subfacies are developed,which can be subdivided into dolomite flat,carbonate flat,and intraplatform shoal,dolomite-carbonate flat and carbonate-dolomite flat according to the composition.(2)In the plane,the sedimentary environment is typical banded distribution,the salinity of the sedimentary water in the western region is relatively high,with restricted platform characteristics,while the salinity of the sedimentary water in the eastern region is low and has the characteristics of open platform.(3)The low-lying areas within the restricted platform and the open platform in the study area,where high-density and Mg-rich seawater converges,are favorable areas for dolomite development.(4)The restricted/open dolomite flat,intraplatform shoal and gypsum-bearing dolomite flat microfacies mainly develop various kinds of dolomite reservoirs. The western and northern areas with contiguous dolomites are potential replacement areas for oil and gas exploration.
LI Shengqian, ZENG Jianhui, LIU Yazhou, LI Miao, JIAO Panpan
2023, Vol.35(5): 4961
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doi: https://doi.org/10.12108/yxyqc.20230505
Kongqueting area in Xihu Sag of the East China Sea Basin is highly explored and rich in oil and gas. Through the data of cast thin section,scanning electron microscope and X-diffraction,the diagenesis of Pinghu Formation and its influence on pore evolution in Kongqueting area of Xihu Sag were analyzed. The results show that:(1)The Pinghu Formation in Kongqueting area of the East China Sea Basin is mainly delta-bay sedimentary environment. The lower and upper parts of the lower member of Pinghu Formation are mainly tidal flat sedimentary environment,and the middle and upper members of Pinghu Formation transit from tidal flat to delta sedimentary environment.(2)The reservoir rocks of Pinghu Formation in Kongqueting area are mainly feldspathic lithic sandstone,with medium composition maturity and high structural maturity. It is a low porosity and low permeability reservoir,with an average porosity of 10.44% and an average permeability of 25.65 mD.(3)The study area has experienced a variety of diagenesis. Compaction reduces reservoir physical properties,cementation makes the reservoir physical properties poor,but to a certain extent,the cements can resist compaction and protect the primary intergranular pores,and dissolution is an important factor to improve reservoir physical properties.(4)The reservoir in the study area is mainly in the late diagenetic A2 stage. Two secondary pore development zones were formed at 3 000-3 500 m and 4 000-4 400 m. The relatively high quality reservoirs are conducive to hydrocarbon accumulation.
WEI Quanchao, LI Xiaojia, LI Feng, HAO Jingyu, DENG Shuanglin, WU Juan, DENG Bin, WANG Daojun
2023, Vol.35(5): 6270
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doi: https://doi.org/10.12108/yxyqc.20230506
Through thin section observation,fluid inclusion analysis,rock geochemical testing and basin numerical simulation,the development characteristics of veins of Lower Cambrian Qiongzhusi Formation in Wangcang area at Micang Mountain front,Sichuan Basin,were studied,and the fluid activity stages and fluid properties in the sedimentary period were distinguished. The results show that: (1)There are two stages of calcite veins and one stage of quartz veins developed in Qiongzhusi Formation in Wangcang area,and the quartz veins were formed later than the calcite veins. The first stage of calcite veins was formed in the Early Silurian,and the vein forming fluids were mainly inner formation water,which were affected by a small amount of atmospheric fresh water and seawater,and filled veins together with liquid hydrocarbon fluids. The homogenization temperature ranged from 83.1 ℃ to 136.2 ℃,and the salinity was 0.4%-12.2%. The second stage of calcite veins was formed in the Early Jurassic. The vein forming fluids were inner formation water,which filled calcite veins together with liquid hydrocarbon and high density methane in gas phase. The homogenization temperature ranged from 140.2 ℃ to 185.4 ℃, and the salinity was 5.7%-17.3%. The quartz veins were formed in the Early Cretaceous,and the vein forming fluids were siliceous fluids in Qiongzhusi Formation,which filled the quartz veins with methane. The homogenization temperature was 162.1 ℃,and the salinity was 13.8%.(2)The δ18OPDB values of calcite vein samples from Qiongzhusi Formation in the study area range from -14.95‰ to -9.17‰,and the measured average δ18OPDB value of most calcite veins is smaller than that of global seawater of the Early Cambrian. The negative migration characteristics are controlled by temperature and δ18O abundance of the vein forming fluids. Rare earth elements are enriched in calcite veins and wall rocks,both of which have Eu positive anomaly and Ce no anomaly,and the fluids came from inner formation water.(3)Qiongzhusi Formation in the study area was affected less by external fluids, and the development of joints and fractures did not connect with the upper and lower strata,which was conducive to the accumulation and closed preservation of shale gas in Qiongzhusi Formation in the piedmont zones.
WEN Siyu, ZHANG Bing, YAO Yongjun, MA Kai, WANG Yan, YANG Kai
2023, Vol.35(5): 7180
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doi: https://doi.org/10.12108/yxyqc.20230507
Through microscopic thin section identification,X-ray diffraction analysis,major and trace elements test of shale samples from Permian Wujiaping Formation in eastern Sichuan Basin,the pyrite characteristics and anoxic events in shales of Permian Wujiaping Formation in eastern Sichuan Basin were studied. The results show that:(1)The shale mineral composition of Wujiaping Formation in eastern Sichuan Basin is relatively complex,rich in clay minerals,and pyrite is developed. The lithofacies are mainly divided into calcareous siliceous mixed shale,siliceous shale and clay shale.(2)The sensitive parameters of oxidation-reduction environment including U/Th,Ni/Co and V/Cr indicate that the sedimentary environment of Wujiaping Formation shale in the study area is generally suboxic environment,presenting the characteristics of transition from oxidation environment to anoxic environment from bottom to top vertically.(3)The grain size of framboidal pyrite in the study area is 5.18-10.75 μm,and it gradually decreases from bottom to top. This change in grain size can be regarded as its response to the Late Permian oceanic anoxic event.(4)The anoxic event caused by the eruption of the Emeishan basalt involves the late stage of Maokou Formation,and the stage of Wujiaping Formation and Dalong/Changxing Formation. Since the eruption of the Emeishan basalt,CO2 has been continuously dissolved in the water,plankton has increased greatly,and the oxygen content in the water has continued to decline. By the stage of Dalong/Changxing Formation, the water in eastern Sichuan Basin has been completely in an anoxic or even sulfide environment.
NIE Lishang, MA Jinghui, TANG Xiaofei, YANG Zhi, ZHANG Wanjin, LI Hongrui
2023, Vol.35(5): 8191
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doi: https://doi.org/10.12108/yxyqc.20230508
On the basis of field outcrops, drilling and seismic data, through the methods of regional unconformity identification,apatite fission track age analysis and buried hydrocarbon generation history recovery,the main tectonic events of Meso-Cenozoic in Zhangpenggou area in the eastern Junggar Basin and their effects on hydrocarbon accumulation were studied. The results show that: (1)There are four stages of regional unconformity in the Meso-Cenozoic era in Zhangpenggou area,namely,the unconformity between Jurassic Badaowan Formation and Triassic Xiaoquangou Formation(J1b/T2-3xq),the unconformity between Cretaceous Tugulu Group and Jurassic Shishugou Group(K1tg/J2-3sh),the unconformity between Neogene Shawan Formation and Cretaceous Tugulu Group(N1s/K1tg)and the unconformity between Quaternary and Neogene Shawan Formation(Q/N1s),which respectively correspond to four tectonic uplift events,namely,the Late Triassic to Early Jurassic compressional uplift,Late Jurassic to Early Cretaceous compressional uplift,Late Cretaceous to Paleocene uplift and tilting, and Miocene to present continuous uplift and denudation. Each tectonic event has obvious regional tectonic background and geological response such as folds and faults.(2)The uplift of the Late Triassic to Early Jurassic in the study area resulted in a decrease in the rate of hydrocarbon generation of the source rocks and the thermal evolution of hydrocarbon. The fault generated by the Late Jurassic-Early Cretaceous compressional uplift event became an effective channel for hydrocarbon transmission,which matched well with the hydrocarbon filling period,and was a key structural event for hydrocarbon accumulation. Late Cretaceous to Paleocene uplift and tilting,and Miocene to present continuous uplift play a role in the reconstruction and destruction of later oil reservoirs. The formation of Kelameili fault has a controlling effect on hydrocarbon accumulation in the study area.(3)The oil source in the study area mainly comes from Middle Permian Pingdiquan Formation,and the reservoir accumulation model is near-source lateral migration self-generation and self-storage type. Hydrocarbon accmulated in lithologic shielding area and high structural parts of the anticline wing. The faults and unconformities generated by tectonic movement control the plane hydrocarbon distribution. The Permian Pingdiquan Formation near faults and unconformities is a favorable area for hydrocarbon exploration.
HU Wangshui, GAO Feiyue, LI Ming, GUO Zhijie, WANG Shichao, LI Xiangming, LI Shengming, JIE Qiong
2023, Vol.35(5): 9299
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doi: https://doi.org/10.12108/yxyqc.20230509
Based on data of core facies,logging facies and rock fragment analysis,the microstructure,reservoir unit types and oil-water connectivity of Paleogene Shahejie Formation in Langgu Sag of Bohai Bay Basin were studied using a point-line-surface representation method. The results show that:(1)The Paleogene Shahejie Formation in Langgu Sag mainly has two types of reservoir units,namley,structural reservoir units and “fault sand configuration” reservoir units. There are six,five,three and two reservoir units in No. 1 to No. 4 sublayers of Es4-Ⅰ sand group in An 11 well area,respectively. There are five reservoir units in both No. 3 and No. 7 sublayers of Es3-Ⅱ sand group in An 22 well area,while the number of reservoir units in other sublayers varies.(2)The reservoir units of the upper Es4-Ⅰ sand group in An 11 well area have high connectivity of sand bodies and fluids, while the reservoir units of middle Es3 in An 22 well area have complex types,complex distribution,high sand body connectivity and relatively low fluid connectivity.(3)After implementing the reservoir units as development units,the daily crude oil production of each sublayer in An 11 and An 22 well area has increased. Fine characterization of reservoir units is favorable for indentifing the rolling evaluation objectives in exploration and development,and it also can determine accurate reservoir thickness,reservoir boundaries and reservoir distribution range for the calibration of dynamic reserves and economically recoverable reserves during the development process.
XU Zhongbo, WANG Libing, SHEN Chunsheng, CHEN Mingyang, GAN Liqin
2023, Vol.35(5): 100107
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doi: https://doi.org/10.12108/yxyqc.20230510
It is important to carry out fine characterization of different levels of reservoir architecture units in the composite sand bodies for the optimization of the development plan of the lower Minghuazhen Formation in Penglai 19-3 oilfield in Bohai Sea. The cores,logging and 3D seismic data were used to characterize fifth to thirdorder architecture units based on multi-attribute intelligent fusion in the second sublayer of Ⅳ oil group of lower Minghuazhen Formation in the third region of Penglai 19-3 oilfield. The results show that:(1)It can be divided into different levels of reservoir architecture units such as single meander belts, single point bar sand body and single lateral deposit in Penglai 19-3 oilfield.(2)Through the optimization of seismic attributes, the maximum amplitude, reflection intensity and relative impedance are more sensitive to reservoir response. The neural network multi-attribute fusion based on parameter supervision further improves the accuracy and reliability of reservoir prediction.(3)A single meander belt with fifth-order configuration unit is developed in the study area, which is narrow in the middle and wide at both ends in the north-south direction. The fourth-order architecture unit of single point bar is distributed in a string of beads, and the point bars are cut and transformed with each other. The lateral deposit is positive rhythm, and the dip angle of the lateral deposit is 2°-5°.(4)The geometric shape, scale and structure of the configuration units of different genetic types are relevant, which is of great significance for adjusting the well location, improving the injection-production well pattern and improving the efficiency of oilfield development.
QI Yukai, GUO Jingxiang, LUO Liang, LUO Fusong, ZHOU Xuewen, YAO Wei, ZHANG Tan, LIN Huixi
2023, Vol.35(5): 108119
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doi: https://doi.org/10.12108/yxyqc.20230511
Through the dissection of typical subtle oil and gas reservoirs in the southern slope of Kuqa Depression,the structure, sedimentological conditions, trap development types and models of subtle traps were sorted out,and the exploration direction was pointed out. The results show that:(1)Three types of subtle traps are mainly developed in the southern slope belt of Kuqa Depression,including stratigraphic overlap trap,sandstone updip pinchout lithologic trap and fault lithologic compound trap.(2)Two types of traps are developed in Xinhe and adjacent areas: sandstone updip pinchout traps formed by structural tilting after sedimentation and large-scale fan delta stratigraphic overlap trap developed under the control of ancient uplift, and sandstone updip pinch out trap is the main exploration target in the next step.(3)At the top of Bashijiqike Formation, a lacustrine transgressive systems tract was developed, and lacustrine transgressive mudstone separated multidirectional source systems, which can form large-scale lithologic traps. The Triassic source rock has reached mature to high mature evolution stage in Xinhe area. The “dual source hydrocarbon supply” system provides sufficient oil and gas sources for subtle oil and gas reservoirs in this area, which has great exploration potential.
WEI Jiayi, WANG Hongwei, LIU Gang, LI Han, CAO Qian
2023, Vol.35(5): 120130
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doi: https://doi.org/10.12108/yxyqc.20230512
Based on drilling,logging,logging and seismic data,combined with rock and mineral characteristics,paleontological fossils and geochemical characteristics,the sedimentary facies characteristics and distribution rules of Carboniferous Yanghugou Formation in the western margin of Ordos Basin were systematically studied. The results show that:(1)The Yanghugou Formation in the western margin of Ordos Basin is mainly composed of mudstone,carbonaceous mudstone and coal seams,intercalated with argillaceous siltstone and sandstone. It was formed in a marine and continental transitional sedimentary environment,and the paleoclimate during the deposition was warm and humid. The salinity of the lake basin of Jingyuan-Yanghugou Formation gradually increased,the paleoclimate transited from the early warm and humid climate to dry and hot climate,the sedimentary environment transited from the early oxidation environment to the middle and late oxidation-reduction environment,the relative paleo water depth transited from shallow to deep,and to the late depositional period of Yanghugou Formation,rapid water regression occurred.(2)The Yanghugou Formation in the study area is mainly composed of mixed sediments,developed with delta,barrier coast and shore shallow sea sedimentary system,which belongs to a typical marine-continental transitional facies. Lagoon-barrier island sedimentary facies belt were developed in Weizhou-Shigouyi area,which can be divided into two regional transgression and regression cycles. The lower transgressive cycle was dominated by bay-tidal flat deposition,and the upper regressive cycle was dominated by delta deposition.(3)The sedimentary water body of Yanghugou Formation was relatively shallow,delta was developed around,and internal barrier sand bar was relatively developed,forming a favorable sedimentary facies zone. Vertically,the regional transgression regression cycle change of bay-tidal flat-barrier island-lagoon-swamp facies was developed in Jingyuan-Yanghugou Formation.
ZHU Xiuxiang, ZHAO Rui, ZHAO Teng
2023, Vol.35(5): 131138
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doi: https://doi.org/10.12108/yxyqc.20230513
The extra-deep fault-controlled fractured-vuggy reservoirs distributed along strike-slip fault zones in Shunbei area of Tarim Basin have obvious subsection differences. Through interpretation of 3D seismic data, combined with data of drilling,logging and production test,the characteristics of the strike-slip segments of Shunbei No. 1 fault zone and the differences and causes of internal reservoir structure in different geometric segments were studied,and favorable reservoirs were selected. The results show that: (1)Shunbei No. 1 fault zone is formed by the oblique superposition of eight geometric segments,each of which forms a set of independent reservoir units. The internal fracture cave structure of a single reservoir unit is basically the same,but the internal fracture cave structure of adjacent reservoir units is obviously different,and the oil and gas reservoirs are not connected with each other.(2)The internal fracture cavity structure of the geometric segments is controlled by the activity intensity of strike-slip structure,according to which,internal and external fracture structures,double hole fracture structures,large-scale homogeneous reservoirs and other internal reservoir structure can be divided. Among them,large-scale homogeneous reservoirs develop multiple sets of fracture cavity bodies,with large size, large number and strong internal connectivity, which is conducive to oil and gas enrichment.
GUO Jinhao, HU Guoyi, HE Kun, MI Jingkui, TIAN Lianjie, HE Fei, GUO Chuyuan, LU Mengdie
2023, Vol.35(5): 139152
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doi: https://doi.org/10.12108/yxyqc.20230514
Through systematic sampling and geochemical characteristics analysis of three field profiles of Upper Permian Dalong Formation in northern Sichuan Basin,the sedimentary environment of source rocks was analyzed from four aspects of sedimentary background,hydrothermal activity and upwelling,paleoclimate and paleosalinity, and water environment,and the organic matter accumulation model and exploration potential were discussed. The results show that:(1)The Permian Dalong Formation in northern Sichuan Basin has argillaceous and siliceous source rocks with an effective thickness of 10-40 m,a high abundance of organic matters(the average content of organic carbon is 4.58%), good types of organic matters(type Ⅱ2 organic matter is dominant), and great hydrocarbon generation potential(the average pyrolysis hydrocarbon generation potential is 5.90 mg/g). The Changjianggou profile and Xibeixiang profile in Guangyuan area at the margin of Sichuan Basin are in mature stage,with Ro values of 0.72% and 1.06%,respectively. The average Tmax value of Daliangxiang profile in the eastern part of the basin is 604 ℃,reaching an over mature stage. The gas generation of Dalong Formation in Guangyuan-Liangping trough reaches 432.38×1012 m3,with conventional natural gas resource of 1.70×1012 m3 and shale gas resource in trillions of cubic meters,which is a set of marine high-quality source rocks with large gas potential.(2)The high-quality source rocks of Dalong Formation in the study area were formed in a continental margin environment with semi-limited cycle of water hypoxia,and experienced two stages of the evolution of water environment,including embryonic stage and expansion stage of the trough development. In the early stage,there was anoxic-local anaerobic-anoxic unvulcanized and sulphide environment,and organic matter was not developed. In the middle and late stages,there was an oxygen-poor-anoxic-main anaerobic-anoxic environment. Organic matter enrichment was closely related to hydrothermal activity and upwelling. The acid gas from volcanic eruptions and the semi enclosed water environment jointly formed a long-term and large-scale anaerobic hydrodesulfurization environment,which was conducive to the enrichment and preservation of organic matters. It shows a high TOC value in the slope shelf areas such as Xibeixiang and Changjianggou. The TOC value is the greatest in the weak sulfuration environment,followed by the moderate sulfuration environment,and the TOC value is the smallest in a strong retention vulcanization environment.(3)Shale gas of Dalong Formation and high-quality reservoir gas from Changxing-Feixianguan Formation in Guangyuan-Liangping trough are the main exploration directions.
YUE Shijun, LIU Yingru, XIANG Yiwei, WANG Yulin, CHEN Fenjun, ZHENG Changlong, JING Ziyan, ZHANG Tingjing
2023, Vol.35(5): 153160
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doi: https://doi.org/10.12108/yxyqc.20230515
Taking a homogeneous radial gas reservoir with edge water as an example,based on the material balance theory of water drive gas reservoirs,the relationship between the average water saturation of the formation and the exit-end water saturation was derived. Water storage volume coefficient was introduced to establish the relationhsips of average water saturation with dynamic reserves and water influx of gas reservoirs,so as to calculate the dynamic reserves and water influx of gas reservoirs. This method was applied to the sixth layer of Quaternary Sebei Formation in Tainan gas field of Qaidam Basin,the dynamic geological reserves were verified using the apparent geological reserves method,and the calculation results of water influx were verified using numerical simulation method. The results show that:(1)In homogeneous radial gas reservoir with edge water,the average water saturation of the formation is linearly positively correlated with the exit-end water saturation.(2)When calculating the dynamic reserves of gas reservoirs through average saturation,the data that tends to stabilize in the middle and later stages of development should be selected. At this time,the pressure drop of the formation affects the reservoir boundary,which can reflect the real dynamic reserves of the entire work area. However,the results calculated by early data are relatively small.(3)The dynamic geological reserves of the sixth layer of Quaternary Sebei Formation in Tainan gas field of Qaidam Basin calculated by average saturation are 8.1×108 m3,with an error of 1% compared with the dynamic geological reserves calculated by apparent geological reserves method. The error between the water influx calculated by average saturation and the water influx calculated by numerical simulation method is about 10%.
ZHAO Changhong, SUN Xinge, LU Yingbo, WANG Li, HU Pengcheng, XING Xiangrong, WANG Guiqing
2023, Vol.35(5): 161168
Abstract
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doi: https://doi.org/10.12108/yxyqc.20230516
The 2D and 3D physical simulation experiments and numerical simulation studies were carried out on the reservoirs of Jurassic Qigu Formation in F well area of Fengcheng oilfield,Xinjiang,revealing the evolution law and production mechanism in the compound development of steam chamber. The results show that:(1)Under the action of steam overlay and pressure relief traction at the recovery point,the main body of the leading edge of the steam chamber advanced to the horizontal section,and the shape of the leading edge of the steam chamber evolved from “spout” type to “bell” type,and finally became “cap” type. The three-dimensional shape of the steam chamber first presented an “isolated island” type around the vertical well,then connected into a “corridor bridge” type,and finally converged into a large cavity.(2)According to the evolution law of steam chamber, the whole simulation experiment process was divided into injection-production connection stage,steam chamber formation stage,steam chamber lateral expansion stage and steam chamber decline stage. The recovery rate of the whole production cycle can reach 55.6%,the oil-steam ratio is 0.17,and good experimental results have been obtained.(3)The physical simulation experiment and numerical simulation results reveal the oil displacement mechanism of steam displacement in the early stage and gravity drainage in the middle and later stage of compound development,characterizing the evolution law of steam chamber,which provide technical support for the efficient development of similar reservoirs.