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：WU Jin WANG Hongyan SHI Zhensheng WANG Qi ZHAO Qun DONG Dazhong LI Shuxin LIU Dexun SUN Shasha QIU Zhen 

机构地区：[1]PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China [2]National Energy Shale Gas R&D Experimental Center,Beijing 100083,China [3]PetroChina Foreign Cooperation Administration Department,Beijing 100007,China [4]PetroChina Coalbed Methane Company Limited,Beijing 100028,China

出　　处：《Petroleum Exploration and Development》2021年第6期1315-1328,共14页石油勘探与开发（英文版）

基　　金：China National Science and Technology Major Project(2017ZX05035).

摘　　要：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 Shan23 sub-member of Permian Shanxi Formation in the east margin of Ordos Basin was systematically analyzed in this study.The Shan23 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 Shan23 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 Shan23 sub-member developed in tide-dominated estuarine bay facies.The S-H,S-M and M-M shales have good pore struc-ture and largely organic matter pores and mineral interparticle pores,including interlayer pore in clay minerals,pyrite inter-crystalline pore,and mineral dissolution pore.C-L and S-L shales have mainly mineral interparticle pores and clay mineral in-terlayer pores,and a small amount of organic matter pores,showing poorer pore structure.The C-H shale has organic mi-cro-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 diagen-esis.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 en-hances the fracability of the shale reservoir.

关 键 词：marine-continental transitional facies shale gas favorable lithofacies reservoir characteristics Permian Shanxi Formation Ordos Basin 

分 类 号：P618.13[天文地球—矿床学]