Quantitative study on hydrocarbon expulsion mechanism based on micro-fracture
The significance of source rocks for oil and gas accumulation has been indisputably acknowledged. Moreover, it has been gradually realized that there is difference between hydrocarbon generation capacity and hydrocarbon expulsion capacity, and this has prompted research on hydrocarbon expulsion effi...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2020-11-01
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| Series: | Geoscience Frontiers |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987120301328 |
| _version_ | 1797709152972177408 |
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| author | Kaiming Su Jungang Lu Huanxu Zhang Shijia Chen Yong Li Zhenglu Xiao Wen Qiu Meimei Han |
| author_facet | Kaiming Su Jungang Lu Huanxu Zhang Shijia Chen Yong Li Zhenglu Xiao Wen Qiu Meimei Han |
| author_sort | Kaiming Su |
| collection | DOAJ |
| description | The significance of source rocks for oil and gas accumulation has been indisputably acknowledged. Moreover, it has been gradually realized that there is difference between hydrocarbon generation capacity and hydrocarbon expulsion capacity, and this has prompted research on hydrocarbon expulsion efficiency. However, these studies dominantly highlight the results of hydrocarbon expulsion, and investigation into the corresponding process and mechanism is primarily from a macroscopic perspective. Despite its wide acceptance as the most direct hydrocarbon expulsion mode, hydrocarbon expulsion through micro-fractures is still not sufficiently understood. Therefore, this study obtains observations and performs experiments on two types of source rocks (mudstones and shales) of the Chang 7 oil group of the Yanchang Formation in Ordos Basin, China. Microscopy reveals that organic matter is non-uniformly distributed in both types of source rocks. Specifically, mudstones are characterized by a cluster-like organic matter distribution, whereas shales are characterized by a layered organic matter distribution. Thermal evolution simulation experiments demonstrate that the hydrocarbon generation process is accompanied by the emergence of micro-fractures, which are favorable for hydrocarbon expulsion. Moreover, based on the theories of rock physics and fracture mechanics, this study establishes micro-fracture development models for both types of source rocks, associated with the calculation of the fracture pressure that is needed for the initiation of fracture development. Furthermore, the relationship between the fluid pressure, fracture pressure, and micro-fracture expansion length during micro-fracture development is quantitatively explored, which helps identify the micro-fracture expansion length. The results indicate that the development of micro-fractures is commonly impacted by the morphology and distribution pattern of the organic matter as well as the mechanical properties of the source rocks. The micro-fractures in turn further affect the hydrocarbon expulsion capacity of the source rocks. The results of this study are expected to provide theoretical and practical guidance for the exploration and exploitation of tight oil and shale oil. |
| first_indexed | 2024-03-12T06:32:17Z |
| format | Article |
| id | doaj.art-a7c1abed1ba0476e9ef5053ce4a2b8e7 |
| institution | Directory Open Access Journal |
| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T06:32:17Z |
| publishDate | 2020-11-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Geoscience Frontiers |
| spelling | doaj.art-a7c1abed1ba0476e9ef5053ce4a2b8e72023-09-03T01:32:59ZengElsevierGeoscience Frontiers1674-98712020-11-0111619011913Quantitative study on hydrocarbon expulsion mechanism based on micro-fractureKaiming Su0Jungang Lu1Huanxu Zhang2Shijia Chen3Yong Li4Zhenglu Xiao5Wen Qiu6Meimei Han7State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, 610500, China; School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, 610500, China; School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, China; Corresponding author. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, 610500, China.Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals, Qingdao, 266590, China; Power and Environmental Energy Research Institute of California, San Francisco, 94101, United StatesState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, 610500, China; School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, 610500, China; School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, 610500, China; School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, 610500, China; School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, 610500, China; School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, ChinaThe significance of source rocks for oil and gas accumulation has been indisputably acknowledged. Moreover, it has been gradually realized that there is difference between hydrocarbon generation capacity and hydrocarbon expulsion capacity, and this has prompted research on hydrocarbon expulsion efficiency. However, these studies dominantly highlight the results of hydrocarbon expulsion, and investigation into the corresponding process and mechanism is primarily from a macroscopic perspective. Despite its wide acceptance as the most direct hydrocarbon expulsion mode, hydrocarbon expulsion through micro-fractures is still not sufficiently understood. Therefore, this study obtains observations and performs experiments on two types of source rocks (mudstones and shales) of the Chang 7 oil group of the Yanchang Formation in Ordos Basin, China. Microscopy reveals that organic matter is non-uniformly distributed in both types of source rocks. Specifically, mudstones are characterized by a cluster-like organic matter distribution, whereas shales are characterized by a layered organic matter distribution. Thermal evolution simulation experiments demonstrate that the hydrocarbon generation process is accompanied by the emergence of micro-fractures, which are favorable for hydrocarbon expulsion. Moreover, based on the theories of rock physics and fracture mechanics, this study establishes micro-fracture development models for both types of source rocks, associated with the calculation of the fracture pressure that is needed for the initiation of fracture development. Furthermore, the relationship between the fluid pressure, fracture pressure, and micro-fracture expansion length during micro-fracture development is quantitatively explored, which helps identify the micro-fracture expansion length. The results indicate that the development of micro-fractures is commonly impacted by the morphology and distribution pattern of the organic matter as well as the mechanical properties of the source rocks. The micro-fractures in turn further affect the hydrocarbon expulsion capacity of the source rocks. The results of this study are expected to provide theoretical and practical guidance for the exploration and exploitation of tight oil and shale oil.http://www.sciencedirect.com/science/article/pii/S1674987120301328Quantitative studyPrimary migrationHydrocarbon generation micro-fracturesMechanical analysisThermal evolution simulationOrdos basin |
| spellingShingle | Kaiming Su Jungang Lu Huanxu Zhang Shijia Chen Yong Li Zhenglu Xiao Wen Qiu Meimei Han Quantitative study on hydrocarbon expulsion mechanism based on micro-fracture Geoscience Frontiers Quantitative study Primary migration Hydrocarbon generation micro-fractures Mechanical analysis Thermal evolution simulation Ordos basin |
| title | Quantitative study on hydrocarbon expulsion mechanism based on micro-fracture |
| title_full | Quantitative study on hydrocarbon expulsion mechanism based on micro-fracture |
| title_fullStr | Quantitative study on hydrocarbon expulsion mechanism based on micro-fracture |
| title_full_unstemmed | Quantitative study on hydrocarbon expulsion mechanism based on micro-fracture |
| title_short | Quantitative study on hydrocarbon expulsion mechanism based on micro-fracture |
| title_sort | quantitative study on hydrocarbon expulsion mechanism based on micro fracture |
| topic | Quantitative study Primary migration Hydrocarbon generation micro-fractures Mechanical analysis Thermal evolution simulation Ordos basin |
| url | http://www.sciencedirect.com/science/article/pii/S1674987120301328 |
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