东昆仑八宝山盆地上三叠统页岩气成藏地质条件分析  

Geological condition analysis of the formation of shale gas reservoirs of the Upper Triassic in Babaoshan Basin,East Kunlun

作　　者：徐永锋 郭敏 陈建洲 薛晟 巩志远 晁海德 XU Yongfeng;GUO Min;CHEN Jianzhou;XUE Sheng;GONG Zhiyuan;CHAO Haide(The Fourth Geological Exploration Institute of Qinghai Province,Xining 810008,Qinghai,China;Key Laboratory of shale gas resources of Qinghai Province,Xining 810008,Qinghai,China;Seventh Brigade of Guizhou Nonferrous Metals and Nuclear Industry Geological Exploration Bureau,Guiyang 550005,Guizhou,China)

机构地区：[1]青海省第四地质勘查院,青海西宁810008 [2]青海省页岩气资源重点实验室,青海西宁810008 [3]贵州省有色金属和核工业地质勘查局七总队,贵州贵阳550005

出　　处：《矿产与地质》2024年第3期418-433,共16页Mineral Resources and Geology

基　　金：青海省地质矿产勘查开发局“青海省东昆仑八宝山地区晚三叠世—早中侏罗世沉积体系特征及油气勘探方向”项目(任务书编号:青地矿科[2021]61号);青海省清洁能源矿产专项“青海省都兰县八宝山地区页岩气调查评价”项目(编号:2018137090kc054)共同资助。

摘　　要：为探讨八宝山盆地上三叠统页岩气的成藏潜力,通过野外地质剖面测量、二维地震、调查井施工、录井、解析、样品采集及分析测试等工作,对研究区八宝山组的形成背景、泥页岩规模、生烃条件(TOC、Ro、有机质类型)、储集条件(矿物特征、储集空间、孔结构参数)、含气性、埋藏史和热演化史等进行研究。结果表明:①东昆仑八宝山盆地三叠纪以来经历了基底形成、断陷演化及隆升改造三个演化阶段,昆中、昆南断裂控制盆地沉积格局,在晚三叠世断陷期沉积滨浅湖、半深湖—深湖相的泥页岩夹砂岩、粉砂岩,受沉积相控制,自山前向盆地内泥页岩厚度逐渐增大,大部分地段累积厚度超过300 m,有效厚度在16.24~79.63 m之间,为八宝山组页岩气聚集成藏提供了物质基础;②井内714件样品的TOC含量分布在0.01%~49.14%,有机质类型以Ⅲ型为主,Ro在2.37%~3.45%,泥页岩有机质含量、热演化程度高,有机质类型好,生气条件优越;③八宝山组上段石英、黏土矿物含量平均为40.83%、46.06%;八宝山组下段石英、黏土矿物含量平均为39.62%、47.08%,与Barnett页岩、Marcellus页岩及四川盆地海相富有机质泥页岩相比,脆性矿物含量略低,黏土矿物含量稍高。八宝山组上、下段含气量平均为4.19 m^(3)/t、5.44 m^(3)/t,泥页岩中发育大量微裂缝、溶蚀孔隙、裂缝孔隙、粒间孔隙、有机质孔隙等,其比表面积、孔体积、孔径平均值分别为6.9403 m^②/g、0.0116 cm^(3)/g、8.5138 nm,有利于页岩气富集和吸附;④埋藏史、生烃史结果显示:八宝山盆地具有早期浅埋、中期深埋、晚期抬升的特点,上覆侏罗系羊曲组的硅质砾岩、碎屑岩及新生代沉积地层广泛分布,作为区域性盖层对页岩气藏起到了很好地封盖作用,综合研究认为八宝山盆地页岩气资源远景广阔。Since the Triassic,Babaoshan Basin in the East Kunlun Mountains has gone through three evolutionary stages,basement formation,fault depression evolution and uplift transformation.The Kunzhong and Kunnan faults control the sedimentary pattern of the basin.During the Late Triassic fault depression period,mud shale mixes with sandstone and siltstone is deposited in shallow lake,semi deep lake to deep lake facies.Under the controlling effect of sedimentary faces,the thickness of mud shale gradually increases from the mountain front to the basin,with a cumulative thickness of over 300 m in most areas.The effective thickness ranges from 16.24 to 79.63 m,providing a material basis for the shale gas reservoir formation in Babaoshan Formation.Through analysis of 714 samples in the well,the TOC content distribution is between 0.01%and 49.14%,with the organic matter type mainly being TypeⅢ,with R o ranging from 2.37%to 3.45%.The organic matter content and thermal evolution degree of shale are high,with good organic matter type and superior gas generation condition.The average content of quartz and clay minerals in the Upper Section of Babaoshan Formation is 40.83%and 46.06%,respectively.The average content of quartz and clay minerals in the Lower Section of Babaoshan Formation is 39.62%and 47.08%,respectively.Compared with Barnett shale,Marcellus shale and marine organic rich shale in the Sichuan Basin,the content of brittle minerals is slightly lower,while the content of clay minerals is slightly higher.The average gas content in the Upper and Lower Sections of Babaoshan Formation is 4.19 m^(3)/t and 5.44 m^(3)/t,respectively.There are a large number of microfractures,dissolution pores,fracture pores,intergranular pores,organic matter pores,etc.developed in the shale.The average specific surface area,pore volume and pore size are 6.9403 m^(2)/g,0.0116 cm^(3)/g and 8.5138 nm,respectively,which are conducive to shale gas enrichment and adsorption.The result of burial history and hydrocarbon generation history shows that Ba

关 键 词：八宝山盆地 上三叠统 八宝山组 页岩气 成藏地质条件 

分 类 号：P618.13[天文地球—矿床学]