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Collaborating Authors
Source and reservoir characteristics of the Upper Triassic lacustrine Chang 6 tight oil play in the Zhangjiagou area, Ordos Basin, China
Cao, Yan (Southwest Petroleum University, Peking University, Peking University, Shanxi Research Institute for Clear Energy Tsinghua University) | Han, Hui (Southwest Petroleum University, Shandong University of Science and Technology, Southwest Petroleum University) | Chen, Shijia (Southwest Petroleum University) | Liu, Rui (Southwest Petroleum University) | Zhang, Jingyue (Southwest Petroleum University, PetroChina Southwest Oil and Gas Field Company Exploration and Development Research Institute) | Guo, Chen (Southwest Petroleum University) | Pang, Peng (Southwest Petroleum University)
Abstract To explore the source and reservoir characteristics of Chang 6 tight oil in the Zhangjiagou area, we have extracted a suite of Chang 6 tight sandstones and the source rocks from the seventh to ninth members of the Upper Cretaceous Yanchang Formation in the Ordos Basin, China, respectively, using chloroform. We examined group components by fractionations of extracted organic matter. Using low-pressure gas adsorptions and gas chromatography-mass spectrometry, respectively, we analyzed the pore structure of the studied samples before and after extraction and the oil source of the separate saturated hydrocarbon components. The results indicate that the porosity of the Chang 6 tight sandstone is mainly distributed in the 8%–14% range, averaging 10.5%, the permeability of the studied reservoir is only approximately 0.16 × 10 μm, and the pore-throat radius is mainly less than 2 μm. The major type of pores of the reservoir includes the residual intergranular pore, secondary intergranular dissolved pore, and intragranular dissolved pore. The micropore volume of the Chang 6 tight sandstone is in the range of 0.0071–0.0092 cm/g, and the mesopore volume of the Chang 6 tight sandstone is in the range of 0.0237–0.0343 cm/g. The micropore volume and micropore surface area significantly increased after chloroform extractions, and soluble hydrocarbons could be stored in micropores of the Chang 6 tight sandstone. The three sets of source rocks from the seventh to ninth members of the Upper Cretaceous Yanchang Formation are high quality by the evaluation of source rocks, and the Chang 7 has the highest value of source rocks, followed by Chang 9 and Chang 8. The pentacyclic triterpene characteristics (Ts-C30H-C30*) of Chang 6 crude oil are similar to those of Chang 7 source rock, and the tight oil of the Chang 6 member in the Zhangjiagou area originated from Chang 7 source rocks.
- Asia > China > Gansu Province (0.72)
- Asia > China > Shanxi Province (0.63)
- Asia > China > Shaanxi Province (0.63)
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous (0.45)
- Phanerozoic > Mesozoic > Triassic > Upper Triassic (0.41)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Asia > China > Sichuan > Sichuan Basin > Southwest Field > Longwangmiao Formation (0.99)
- Asia > China > Shanxi > Ordos Basin (0.99)
- Asia > China > Shaanxi > Ordos Basin (0.99)
- (2 more...)
To: “Evaluation of the matrix influence on the microscopic pore-throat structures of deep-water tight sandstone: A case study from the Upper Triassic Chang 6 oil group of the Yanchang Formation in the Huaqing area, Ordos Basin, China,”Zhaobing Chen, Chuangfei Zhou, Xinjing Chen, Yujie Zhu, and Yushuang Zhu, Interpretation, 8, no. 4, T763–T776, doi: 10.1190/INT-2020-0036.1.
Chen, Zhaobing, Zhou, Chuangfei, Chen, Xinjing, Zhu, Yujie, Zhu, Yushuang
- Asia > China > Shanxi Province (0.60)
- Asia > China > Shaanxi Province (0.60)
- Asia > China > Gansu Province (0.60)
Abstract The Yanchang Formation in the Ordos Basin in North Central China represents a large, long-lived lacustrine system of the late Triassic Period. The extensive shales within this system provide hydrocarbons (HCs) for conventional and unconventional oil and gas reservoirs. In the formation, the Chang 7 shale is the thickest shale with the best geochemical parameters, and it is the main source rock in this area. In recent years, the discovery of shale gas in the Chang 7 shale has promoted the exploration and development of lacustrine shale gas in China. We have estimated the shale gas resource potential based on the analysis of the geologic conditions of the Chang 7 shale. The average thickness of the Chang 7 shale reaches 42.6 m, and the main organic matter types are types and . The average content of organic carbon is more than 3%, and the average HC potential is . However, the thermal maturity of the Chang 7 shale is low with a vitrinite reflectance ranging from 0.83% to 1.10%. The Chang 7 shale lithology consists of shale and sandy laminations or thin sandstones. The shale is characterized by high clay mineral content and poor porosity and permeability, with an average porosity of 1.8% and an average permeability of . The sandy laminations or thin sandstones are characterized by relatively higher brittle mineral content, relatively lower clay mineral content, and higher porosity and permeability. The pores of the Chang 7 shale include primary intergranular and intragranular pores, secondary intragranular and intragranular dissolved pores, fracture pores, and organic-matter-hosted pores. The proportion of adsorbed gas, free gas, and dissolved gas is approximately 52%, 37%, and 11%, respectively, and the shale gas resources of the Chang 7 shale are .
- Asia > China > Shaanxi Province (0.73)
- Asia > China > Shanxi Province (0.64)
- Asia > China > Gansu Province (0.64)
- North America > United States > Texas (0.46)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > Michigan > Michigan Basin > Antrim Shale Formation (0.99)
- Asia > China > Sichuan > Sichuan Basin (0.99)
- (6 more...)
Geochemical characteristics and source of Chang 8 crude oil in the east part of the Shanbei Slope, Ordos Basin, China
Xiao, Zhenglu (State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University) | Chen, Shijia (State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University) | Yin, Xiangdong (Southwest Petroleum University) | Wang, Pan (No.1 Gas Production Plant of PetroChina Changqing Oilfield) | Zhu, Jiang (Southwest Petroleum University) | Han, Meimei (Southwest Petroleum University)
Abstract There are three sets of potential source rocks in the Yanchang Formation in the east part of the Shanbei Slope in the Ordos Basin. Based on the experimental results of total organic carbon, vitrinite reflectance, rock organic matter extraction, and saturated hydrocarbon chromatography (GC-MS), we have analyzed the geochemical and biomarker characteristics of the Chang 7, Chang 8, and Chang 9 source rocks, and the Chang 8 reservoir extracts and find that the Chang 7, Chang 8, and Chang 9 source rocks were deposited in the sedimentary environment of weak oxidation and weak reduction. Higher plants contribute more in the parent materials of the Chang 7 and Chang 9 source rocks, whereas lower aquatic organisms contribute more to the Chang 8 source rock. However, the source of the Chang 8 crude oil in the east part of Shanbei Slope does not match the chemical fingerprint of the Chang 8 source rock. To address this problem, we examined samples taken from the Zhidan oilfield, where our results show that the Chang 7, Chang 8, and Chang 9 source rocks all have hydrocarbon-supplying capacity. The relative abundance of regular steranes (C27, C28, C29) and hopane (17α(H), 21β(H)-hopane, 17β(H)-rearranged hopane, 18α(H)-22,29,30-trinorhopane) provides a means to assign the crude oil components to a given. Further analysis of the biomarkers of the three source rocks and those of the Chang 8 crude oil indicate that crude oil in the Chang 8 reservoir was not generated in situ; rather, it was supplied by the underlying Chang 9 source rock.
- Asia > China > Shanxi Province (0.74)
- Asia > China > Shaanxi Province (0.74)
- Asia > China > Gansu Province (0.74)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (0.54)
- Asia > China > Sichuan > Sichuan Basin (0.99)
- Asia > China > Shanxi > Ordos Basin > Changqing Field (0.99)
- Asia > China > Shaanxi > Ordos Basin > Changqing Field (0.99)
- (4 more...)
Depocenter migration of the Ordos Basin in the late Triassic and its controls on shale distribution
Wang, Jing (Northwest Branch of PetroChina Research Institute of Petroleum) | Li, Xiangbo (Northwest Branch of PetroChina Research Institute of Petroleum) | Liu, Huaqing (Northwest Branch of PetroChina Research Institute of Petroleum) | Deng, Xiuqin (Exploration and Development Research Institute of PetroChina) | Wanyan, Rong (Northwest Branch of PetroChina Research Institute of Petroleum)
Abstract The Ordos Basin has abundant conventional and unconventional oil and gas resources. Focusing on shale oil in the Ordos Basin, we studied the distribution, depositional features, and resource potential of shales in the upper Triassic Yanchang Formation based on the Ordos Basin development and depocenter migration. During the late Triassic, the Ordos Basin was a large cratonic sedimentary basin that bordered to the Hexi Corridor to the west, the southern North China block to the east, the Qilian and western Qinling orogenic zone to the south, and the foot of the Yin Mountains to the north. During deposition of the Yanchang Formation, its depocenter was not fixed. It migrated to the west before deposition of the Chang 7 oil layer and to the south after deposition of the Chang 7 oil layer. Controlled by the depocenter migration and relevant deep-lake facies, the Yanchang Formation mainly developed two sets of source rocks. The dark mudstone and shale in the Chang 9 oil layer is chiefly distributed in the south-central region of the basin, with thicknesses of 4–16 m and covers an area of approximately . The shales in the Chang 7 oil layer can be divided into two types, black oil shale and dark mudstone, and they are much thicker and more widespread than the dark mudstone in the Chang 9 oil layer. The black shale alone can be up to 60 m thick, and covers an area of more than . The shales in the Chang 7 and 9 oil layers were mainly formed in a deep-lake environment that produced high concentrations of organic matter and large hydrocarbon generation potential. According to preliminary estimates, the Chang 7 oil shale may contain of oil, thereby representing a huge resource potential with broad exploration prospectivity.
- Asia > China > Shanxi Province (1.00)
- Asia > China > Shaanxi Province (1.00)
- Asia > China > Gansu Province (1.00)
- North America > United States > California > Sacramento Basin > 2 Formation (0.99)
- North America > Trinidad and Tobago > Trinidad > Southern Basin (0.99)
- Asia > China > Shanxi > Ordos Basin > Changqing Field (0.99)
- (12 more...)