| 川东南石宝矿区龙潭组页岩气(煤层气)潜力分析——以SD1井为例 |
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| 关键词:Longtan Formation marine-continental transitional facies hydrocarbon source rocks shale gas southeast Sichuan |
| 基金项目:中国地质调查局地质调查项目(编号: DD20221661);四川省能源投资集团有限公司委托科技项目“川南地区石宝矿段龙潭组煤层气;致密气;页岩气资源潜力综合评价”(编号: NM-SB-2015-04);贵州省科技计划项目(编号: 黔科合基础[2017]1407);贵州工程应用技术学院高层次人才科研启动项目(编号: 院科合字G2017006) |
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| Shale Gas (CBM) Potential of Longtan Formation in Shibao Mining Area, Southeast Sichuan: A Case Study of Well SD1 |
| The Permian Longtan Formation is one of the most important shale gas exploration strata of marine-continental transitional facies in Sichuan Basin. Based on drilling core and thin section observation, X-ray diffraction analysis, scanning electron microscopy, organic geochemical analysis, porosity and permeability testing, in-situ gas content analysis, and Langmuir adsorption isotherm, the characteristics of source rock and shale gas potential of Longtan Formation in Shibao mining area, southeast Sichuan were studied, using Well SD1 as an example. The results showed that: 1) The cumulative thickness of shale in Longtan Formation was approximately 47.74 m, which interacted with coal seam and fine sandstone, and was mainly deposited in microfacies of inter-distributary bay and marsh. 2) The shale was characterized by high clay mineral content (49.7% on an average); was rich in siderite, pyrite, and anatase; and lacked feldspar and other carbonate minerals. 3) The organic matter was mainly composed of vitrinite. The δ13C of kerogen was concentrated in the range of –22.8‰ to –24.2‰. The Longtan shale had a high total organic carbon (TOC) of 7.37% and contained type III gas-prone organic matter. The thermal evolution of organic matter was in the over-mature stage, indicating good hydrocarbon potential. 4) The pore types mainly included microfractures and organic matter, dissolution, and intercrystalline pores. The porosity varied from 3.05% to 4.35% with an average of 3.79%. The permeability was about 0.486 μD, far below 1 mD. Therefore, Longtan Formation had an obvious ultra-low porosity and ultra-low permeability reservoir. 5) The in-situ gas content of shale varied from 0.61 m3/t to 4.70 m3/t, with an average of 2.16 m3/t, indicating relatively high gas content. Saturated adsorption gas content was greater than 2.00 m3/t, indicating good adsorption performance. Generally, the comprehensive study showed that the shale gas development potential of Longtan Formation was great in Shibao mining area, and the C14–C17 carbonaceous mudstone/shale with coal seam assemblage in the middle part of upper Longtan Formation and the C20–C24 carbonaceous mudstone/shale with coal seam assemblage in the upper part were the main exploration sections. |
| DENG Min,LAN Ye-fang,CHENG Jin-xiang,WANG Zheng-he,YU Qian,LIU An-ran,ZHAO An-kun.2022.Shale Gas (CBM) Potential of Longtan Formation in Shibao Mining Area, Southeast Sichuan: A Case Study of Well SD1[J].Acta Geoscientica Sinica,43(3):295-308. |
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