海陆过渡相黑色页岩优势岩相类型及成因机制--以鄂尔多斯盆地东缘二叠系山西组为例  

Favorable lithofacies types and genesis of marine-continental transitional black shale:A case study of Permian Shanxi Formation in the eastern margin of Ordos Basin,NW China

作　　者：武瑾[1,2] 王红岩 施振生[1,2] 王琦 赵群[1,2] 董大忠 李树新[4] 刘德勋[1,2] 孙莎莎 邱振[1,2] WU Jin;WANG Hongyan;SHI Zhensheng;WANG Qi;ZHAO Qun;DONG Dazhong;LI Shuxin;LIU Dexun;SUN Shasha;QIU Zhen(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;National Energy Shale Gas R&D Experimental Center,Beijing 100083,China;PetroChina Foreign Cooperation Administration Department,Beijing 100007,China;PetroChina Coalbed Methane Company Limited,Beijing 100028,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]国家能源页岩气研发(实验)中心,北京100083 [3]中国石油天然气股份有限公司对外合作经理部,北京100007 [4]中国石油煤层气有限责任公司,北京100028

出　　处：《石油勘探与开发》2021年第6期1137-1149,共13页Petroleum Exploration and Development

基　　金：国家科技重大专项“四川盆地及周缘页岩气形成富集条件、选区评价技术与应用”(2017ZX05035)。

摘　　要：基于岩心观察结果,综合利用薄片鉴定、X-衍射矿物分析、场发射扫描电镜、低温气体吸附及高压压汞等技术手段,对鄂尔多斯盆地东缘二叠系山西组山2^(3)亚段页岩岩相进行系统分析。研究表明,山西组山2^(3)亚段发育低TOC黏土质页岩相(C-L)、低TOC硅质页岩相(S-L)、中TOC硅质页岩相(S-M)、中TOC混合质页岩相(M-M)、高TOC硅质页岩相(S-H)、高TOC黏土质页岩相(C-H)6种岩相。其中,S-H岩相为储集条件最优的岩相,S-M、M-M岩相次之。C-L、C-H岩相位于山_(2)^(3)亚段中上部,普遍发育于潮控三角洲相;S-L、S-M、S-H和M-M 4类岩相位于山2^(3)亚段下部,发育于潮控河口海湾相。S-H、S-M和M-M岩相以有机质孔缝和矿物粒间孔为主,发育黏土矿物层间孔、黄铁矿晶间孔、矿物溶蚀孔,孔隙结构整体优;C-L、S-L岩相发育矿物粒间孔、黏土矿物层间孔缝及少量有机质微孔,孔隙结构较差;C-H岩相发育有机质微孔及少量黏土矿物层间孔缝,微孔孔隙结构优,中孔、宏孔孔隙结构差。优势岩相的形成受沉积环境和成岩作用共同控制,浅海海湾—潟湖沉积环境有利于Ⅱ_(2)型干酪根形成,易于产生大量蜂窝状有机质气泡孔,富生物成因硅有利于各类孔隙的保存,并增强了储集层的可压裂性。Based on core description,thin section identification,X-ray diffraction analysis,scanning electron microscopy,low-temperature gas adsorption and high-pressure mercury intrusion porosimetry,the shale lithofacies of Shan2^(3) sub-member of Permian Shanxi Formation in the east margin of Ordos Basin was systematically analyzed in this study.The Shan2^(3) sub-member has six lithofacies,namely,low TOC clay shale(C-L),low TOC siliceous shale(S-L),medium TOC siliceous shale(S-M),medium TOC hybrid shale(M-M),high TOC siliceous shale(S-H),and high TOC clay shale(C-H).Among them,S-H is the best lithofacies,S-M and M-M are the second best.The C-L and C-H lithofacies,mainly found in the upper part of Shan2^(3) sub-member,generally developed in tide-dominated delta facies;the S-L,S-M,S-H and M-M shales occurring in the lower part of Shan2^(3) sub-member developed in tide-dominated estuarine bay facies.The S-H,S-M and M-M shales have good pore structure and largely organic matter pores and mineral interparticle pores,including interlayer pore in clay minerals,pyrite intercrystalline pore,and mineral dissolution pore.C-L and S-L shales have mainly mineral interparticle pores and clay mineral interlayer pores,and a small amount of organic matter pores,showing poorer pore structure.The C-H shale has organic micro-pores and a small number of interlayer fissures of clay minerals,showing good micro-pore structure,and poor meso-pore and macro-pore structure.The formation of favorable lithofacies is jointly controlled by depositional environment and diagenesis.Shallow bay-lagoon depositional environment is conducive to the formation of type II2 kerogen which can produce a large number of organic cellular pores.Besides,the rich biogenic silica is conducive to the preservation of primary pores and enhances the fracability of the shale reservoir.

关 键 词：海陆过渡相 页岩气 优势岩相 储集层特征 二叠系山西组 鄂尔多斯盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]