Enrichment model of shale gas in southeastern Sichuan Basin: a case study of Upper Ordovician Wufeng and Lower Silurian Longmaxi formations in Dingshan area
Based on the understanding of the basic geological conditions of shale gas from the Upper Ordovician Wufeng Formation to the Lower Silurian Longmaxi Formation in Dingshan area of the southeastern Sichuan Basin, the occurrence, migration mode and intensity of natural gas in the shale gas system were...
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| Format: | Article |
| Language: | zho |
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Editorial Office of Petroleum Geology and Experiment
2021-07-01
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| Series: | Shiyou shiyan dizhi |
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| Online Access: | https://www.sysydz.net/cn/article/doi/10.11781/sysydz202104580 |
| _version_ | 1797277240699912192 |
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| author | Kai NI Mingfa WANG Xiang LI |
| author_facet | Kai NI Mingfa WANG Xiang LI |
| author_sort | Kai NI |
| collection | DOAJ |
| description | Based on the understanding of the basic geological conditions of shale gas from the Upper Ordovician Wufeng Formation to the Lower Silurian Longmaxi Formation in Dingshan area of the southeastern Sichuan Basin, the occurrence, migration mode and intensity of natural gas in the shale gas system were discussed according to the results of drilling, logging, fracturing test, laboratory test and structural interpretation, moreover, a shale gas enrichment mode suitable for the study area was proposed. In shale gas systems, high-angle fractures extend for a short distance, while horizontal fractures such as bedding-parallel detachment and interlayer bedding fractures extend for a long distance. As a result, the permeability in the bedding direction is much greater than that in the vertical direction. These characteristics together determined that natural gas in shale gas system was usually transported horizontally, and sometimes both horizontally and vertically. For the Qiyueshan fault zone, the burial depth of shale reservoir and the distance to Qiyueshan fault zone are the major constrains for shale gas enrichment in the Wufeng-Longmaxi formations in the study area. The Qiyueshan fault zone is a basin-controlling fault zone with fractures and associated fractures developed, and is a shale gas escaping area. In the shallow-buried area in the southeastern part, high-angle fractures were relatively developed, by which horizontal fractures were opened. The proportion of free gas was less than 60%. A normal pressure system indicates a semi-retention area for shale gas. In the middle-to deep-buried area in the northwest, high-angle fractures were relatively undeveloped, and horizontal fractures were closed. The vertical and horizontal migrations were blocked, and most of shale gas was trapped in shale reservoirs. The proportion of free gas is more than 60%. A high-to ultra-high pressure system indicates a shale gas accumulation area. |
| first_indexed | 2024-03-07T15:45:49Z |
| format | Article |
| id | doaj.art-b1644891ef474eeb99fbed68bdd60804 |
| institution | Directory Open Access Journal |
| issn | 1001-6112 |
| language | zho |
| last_indexed | 2024-03-07T15:45:49Z |
| publishDate | 2021-07-01 |
| publisher | Editorial Office of Petroleum Geology and Experiment |
| record_format | Article |
| series | Shiyou shiyan dizhi |
| spelling | doaj.art-b1644891ef474eeb99fbed68bdd608042024-03-05T04:38:06ZzhoEditorial Office of Petroleum Geology and ExperimentShiyou shiyan dizhi1001-61122021-07-0143458058810.11781/sysydz202104580sysydz-43-4-580Enrichment model of shale gas in southeastern Sichuan Basin: a case study of Upper Ordovician Wufeng and Lower Silurian Longmaxi formations in Dingshan areaKai NI0Mingfa WANG1Xiang LI2SINOPEC Exploration Company, Chengdu, Sichuan 610041, ChinaSINOPEC Exploration Company, Chengdu, Sichuan 610041, ChinaSINOPEC Exploration Company, Chengdu, Sichuan 610041, ChinaBased on the understanding of the basic geological conditions of shale gas from the Upper Ordovician Wufeng Formation to the Lower Silurian Longmaxi Formation in Dingshan area of the southeastern Sichuan Basin, the occurrence, migration mode and intensity of natural gas in the shale gas system were discussed according to the results of drilling, logging, fracturing test, laboratory test and structural interpretation, moreover, a shale gas enrichment mode suitable for the study area was proposed. In shale gas systems, high-angle fractures extend for a short distance, while horizontal fractures such as bedding-parallel detachment and interlayer bedding fractures extend for a long distance. As a result, the permeability in the bedding direction is much greater than that in the vertical direction. These characteristics together determined that natural gas in shale gas system was usually transported horizontally, and sometimes both horizontally and vertically. For the Qiyueshan fault zone, the burial depth of shale reservoir and the distance to Qiyueshan fault zone are the major constrains for shale gas enrichment in the Wufeng-Longmaxi formations in the study area. The Qiyueshan fault zone is a basin-controlling fault zone with fractures and associated fractures developed, and is a shale gas escaping area. In the shallow-buried area in the southeastern part, high-angle fractures were relatively developed, by which horizontal fractures were opened. The proportion of free gas was less than 60%. A normal pressure system indicates a semi-retention area for shale gas. In the middle-to deep-buried area in the northwest, high-angle fractures were relatively undeveloped, and horizontal fractures were closed. The vertical and horizontal migrations were blocked, and most of shale gas was trapped in shale reservoirs. The proportion of free gas is more than 60%. A high-to ultra-high pressure system indicates a shale gas accumulation area.https://www.sysydz.net/cn/article/doi/10.11781/sysydz202104580horizontal migrationenrichmentescapeshale gaswufeng-longmaxi formationsdingshan areasichuan basin |
| spellingShingle | Kai NI Mingfa WANG Xiang LI Enrichment model of shale gas in southeastern Sichuan Basin: a case study of Upper Ordovician Wufeng and Lower Silurian Longmaxi formations in Dingshan area Shiyou shiyan dizhi horizontal migration enrichment escape shale gas wufeng-longmaxi formations dingshan area sichuan basin |
| title | Enrichment model of shale gas in southeastern Sichuan Basin: a case study of Upper Ordovician Wufeng and Lower Silurian Longmaxi formations in Dingshan area |
| title_full | Enrichment model of shale gas in southeastern Sichuan Basin: a case study of Upper Ordovician Wufeng and Lower Silurian Longmaxi formations in Dingshan area |
| title_fullStr | Enrichment model of shale gas in southeastern Sichuan Basin: a case study of Upper Ordovician Wufeng and Lower Silurian Longmaxi formations in Dingshan area |
| title_full_unstemmed | Enrichment model of shale gas in southeastern Sichuan Basin: a case study of Upper Ordovician Wufeng and Lower Silurian Longmaxi formations in Dingshan area |
| title_short | Enrichment model of shale gas in southeastern Sichuan Basin: a case study of Upper Ordovician Wufeng and Lower Silurian Longmaxi formations in Dingshan area |
| title_sort | enrichment model of shale gas in southeastern sichuan basin a case study of upper ordovician wufeng and lower silurian longmaxi formations in dingshan area |
| topic | horizontal migration enrichment escape shale gas wufeng-longmaxi formations dingshan area sichuan basin |
| url | https://www.sysydz.net/cn/article/doi/10.11781/sysydz202104580 |
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