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  

Shale Gas(CBM)Potential of Longtan Formation in Shibao Mining Area,Southeast Sichuan:A Case Study of Well SD1

作　　者：邓敏[1,2] 兰叶芳 程锦翔 王正和[1,2] 余谦 刘安然[4] 赵安坤 DENG Min;LAN Ye-fang;CHENG Jin-xiang;WANG Zheng-he;YU Qian;LIU An-ran;ZHAO An-kun(Chengdu Center,China Geological Survey,Chengdu,Sichuan 610081;Key Laboratory of Sedimentary Basin and Oil and Gas Resources,Ministry of Natural Resources,Chengdu,Sichuan 610081;School of Mining Engineering,Guizhou University of Engineering Science,Bijie,Guizhou 551700;Sichuan Energy Investment Oil&Gas Exploration and Development Co.,Ltd.,Chengdu,Sichuan 610023)

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081 [2]自然资源部沉积盆地与油气资源重点实验室,四川成都610081 [3]贵州工程应用技术学院矿业工程学院,贵州毕节551700 [4]四川省能投油气勘探开发有限公司,四川成都610023

出　　处：《地球学报》2022年第3期295-308,共14页Acta Geoscientica Sinica

基　　金：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)联合资助。

摘　　要：二叠系龙潭组是四川盆地最主要的海陆过渡相页岩气勘探层位。通过钻井岩芯和薄片观察、X射线衍射、扫描电镜、有机地球化学分析、孔渗测试、现场解吸和等温吸附等手段,以SD1井为例,对川东南石宝矿区龙潭组烃源岩特征和页岩气潜力进行研究。结果表明:1)研究区SD1井龙潭组泥页岩累计厚度约47.74 m,与煤层及粉-细砂岩交互出现,主要为分流间湾和沼泽微相沉积;2)泥页岩总体黏土矿物含量高(平均值为49.7%),富菱铁矿、黄铁矿和锐钛矿,缺乏长石和其他碳酸盐矿物;3)有机质主要由镜质组构成,干酪根δ^(13)C集中分布在–22.8‰~–24.2‰之间,以Ⅲ型干酪根为主,有机质丰度高(TOC平均值为7.37%),处于过成熟生干气阶段,生烃潜力大;4)储集空间主要包括微裂缝、有机质孔、溶蚀孔和晶间孔,孔隙度变化在3.05%~4.35%之间,平均值为3.79%;渗透率约为0.486μD,远小于0.1 mD,具超低孔超低渗特征;5)现场解吸泥页岩含气量为0.61~4.70 m^(3)/t,平均值为2.16 m^(3)/t,含气性相对较好,饱和吸附气含量均大于2.00 m^(3)/t,显示出良好的吸附性能。综合研究认为,川东南石宝矿区龙潭组页岩气开发潜力较大,龙潭组上段中部C_(14)–C_(17)碳质泥岩夹煤层组合和龙潭组中段上部C_(20)–C_(24)碳质泥岩夹煤层组合为主力勘查层段。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.Theδ^(13)C 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 0.486μD,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 m^(3)/t to 4.70 m^(3)/t,with an average of 2.16 m^(3)/t,indicating relatively high gas content.Saturated adsorption gas content was greater than 2.00 m^(3)/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 C_(14)-C_(17) carbonaceous mudstone/shale with c

关 键 词：龙潭组 海陆过渡相 烃源岩 页岩气 川东南 

分 类 号：P618.13[天文地球—矿床学]