Multifractal Methods in Characterizing Pore Structure Heterogeneity During Hydrous Pyrolysis of Lacustrine Shale
By using gas physisorption and multifractal theory, this study analyzes pore structure heterogeneity and influencing factors during thermal maturation of naturally immature but artificially matured shale from the Kongdian Formation after being subjected to hydrous pyrolysis from 250 °C to 425 °C. As...
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2024-11-01
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| author | Xiaofei Liang Qinhong Hu Xiugang Pu Wei Li Qiming Wang Mengdi Sun Wenzhong Han |
| author_facet | Xiaofei Liang Qinhong Hu Xiugang Pu Wei Li Qiming Wang Mengdi Sun Wenzhong Han |
| author_sort | Xiaofei Liang |
| collection | DOAJ |
| description | By using gas physisorption and multifractal theory, this study analyzes pore structure heterogeneity and influencing factors during thermal maturation of naturally immature but artificially matured shale from the Kongdian Formation after being subjected to hydrous pyrolysis from 250 °C to 425 °C. As thermal maturity increases, the transformation of organic matter, generation, retention, and expulsion of hydrocarbons, and formation of various pore types, lead to changes in pore structure heterogeneity. The entire process is divided into three stages: bitumen generation stage (250–300 °C), oil generation stage (325–375 °C), and oil cracking stage (400–425 °C). During the bitumen generation stage, retained hydrocarbons decrease total-pore and mesopore volumes. Fractal parameters ΔD indicative of pore connectivity shows little change, while Hurst exponent H values for pore structure heterogeneity drop significantly, indicating reduced pore connectivity due to bitumen clogging. During the peak oil generation stage, both ΔD and H values increase, indicating enhanced pore heterogeneity and connectivity due to the expulsion of retained hydrocarbons. In the oil cracking stage, ΔD increases significantly, and H value rises slowly, attributed to the generation of gaseous hydrocarbons further consuming retained hydrocarbons and organic matter, forming more small-diameter pores and increased pore heterogeneity. A strongly negative correlation between ΔD and retained hydrocarbon content, and a strongly positive correlation with gaseous hydrocarbon yield, highlight the dynamic interaction between hydrocarbon phases and pore structure evolution. This study overall provides valuable insights for petroleum generation, storage, and production. |
| format | Article |
| id | doaj-art-ab5d019b871f43df8088319b78064c6e |
| institution | OA Journals |
| issn | 2504-3110 |
| language | English |
| publishDate | 2024-11-01 |
| publisher | MDPI AG |
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| series | Fractal and Fractional |
| spelling | doaj-art-ab5d019b871f43df8088319b78064c6e2025-08-20T01:53:41ZengMDPI AGFractal and Fractional2504-31102024-11-0181165710.3390/fractalfract8110657Multifractal Methods in Characterizing Pore Structure Heterogeneity During Hydrous Pyrolysis of Lacustrine ShaleXiaofei Liang0Qinhong Hu1Xiugang Pu2Wei Li3Qiming Wang4Mengdi Sun5Wenzhong Han6Research Institute of Petroleum Exploration and Development, Tarim Oilfield Company, PetroChina, Korla 841000, ChinaState Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao 266580, ChinaExploration and Development Research Institute, Dagang Oilfield of China National Petroleum Corporation, Tianjin 300280, ChinaBohai Rim Energy Research Institute, Northeast Petroleum University, Qinhuangdao 066099, ChinaState Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao 266580, ChinaBohai Rim Energy Research Institute, Northeast Petroleum University, Qinhuangdao 066099, ChinaExploration and Development Research Institute, Dagang Oilfield of China National Petroleum Corporation, Tianjin 300280, ChinaBy using gas physisorption and multifractal theory, this study analyzes pore structure heterogeneity and influencing factors during thermal maturation of naturally immature but artificially matured shale from the Kongdian Formation after being subjected to hydrous pyrolysis from 250 °C to 425 °C. As thermal maturity increases, the transformation of organic matter, generation, retention, and expulsion of hydrocarbons, and formation of various pore types, lead to changes in pore structure heterogeneity. The entire process is divided into three stages: bitumen generation stage (250–300 °C), oil generation stage (325–375 °C), and oil cracking stage (400–425 °C). During the bitumen generation stage, retained hydrocarbons decrease total-pore and mesopore volumes. Fractal parameters ΔD indicative of pore connectivity shows little change, while Hurst exponent H values for pore structure heterogeneity drop significantly, indicating reduced pore connectivity due to bitumen clogging. During the peak oil generation stage, both ΔD and H values increase, indicating enhanced pore heterogeneity and connectivity due to the expulsion of retained hydrocarbons. In the oil cracking stage, ΔD increases significantly, and H value rises slowly, attributed to the generation of gaseous hydrocarbons further consuming retained hydrocarbons and organic matter, forming more small-diameter pores and increased pore heterogeneity. A strongly negative correlation between ΔD and retained hydrocarbon content, and a strongly positive correlation with gaseous hydrocarbon yield, highlight the dynamic interaction between hydrocarbon phases and pore structure evolution. This study overall provides valuable insights for petroleum generation, storage, and production.https://www.mdpi.com/2504-3110/8/11/657lacustrine shalethermal maturationpore structuremultifractal methods |
| spellingShingle | Xiaofei Liang Qinhong Hu Xiugang Pu Wei Li Qiming Wang Mengdi Sun Wenzhong Han Multifractal Methods in Characterizing Pore Structure Heterogeneity During Hydrous Pyrolysis of Lacustrine Shale Fractal and Fractional lacustrine shale thermal maturation pore structure multifractal methods |
| title | Multifractal Methods in Characterizing Pore Structure Heterogeneity During Hydrous Pyrolysis of Lacustrine Shale |
| title_full | Multifractal Methods in Characterizing Pore Structure Heterogeneity During Hydrous Pyrolysis of Lacustrine Shale |
| title_fullStr | Multifractal Methods in Characterizing Pore Structure Heterogeneity During Hydrous Pyrolysis of Lacustrine Shale |
| title_full_unstemmed | Multifractal Methods in Characterizing Pore Structure Heterogeneity During Hydrous Pyrolysis of Lacustrine Shale |
| title_short | Multifractal Methods in Characterizing Pore Structure Heterogeneity During Hydrous Pyrolysis of Lacustrine Shale |
| title_sort | multifractal methods in characterizing pore structure heterogeneity during hydrous pyrolysis of lacustrine shale |
| topic | lacustrine shale thermal maturation pore structure multifractal methods |
| url | https://www.mdpi.com/2504-3110/8/11/657 |
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