Sedimentary Facies of Marine Shale Gas Formations in Southern China： The Lower Silurian Longmaxi Formation in the Southern Sichuan Basin

作     者：Yizhen Li Xingzhi Wang Bin Wu Guoqin Li Dule Wang Yizhen Li

作者机构：State Key Laboratory of Oil and Gas Reservoir Geology and ExploitationSouthwest Petroleum UniversityChengdu 610500China Geological Exploration and Development Research InstituteCNPC Chuanqing Drilling Engineering Company LimitedChengdu 610051China Chongqing Mineral Resources Development Company LimitedChongqing 400060China 

出 版 物：《Journal of Earth Science》 (地球科学学刊（英文版）)

年 卷 期：2016年第27卷第5期

页      面：807-822页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0704[理学-天文学] 

基　　金：supported by the National Science and Technology Major Projects of China(No.2012ZX05018-006-006) the National Natural Science Foundation of China(No.U1262209) 

主　　题：Sichuan Basin shale gas Longmaxi Formation sedimentary facies continental shelf. 

摘      要：Sedimentary facies is an important factor influencing shale gas accumulation. It not only controlls hydrocarbon generation, but also affects reservoir characteristics and distribution. This paper discusses the Lower Silurian Longmaxi Formation in the south of the Sichuan Basin. Outcrop, core, drilling and logging data identify the sedimentary facies of the formation as continental shelf facies, which is divided into two subfacies： an inner shelf and an outer shelf subfacies. These two subfacies can be further divided into seven microfacies： muddy silty shallow shelf, calcareous silty shallow shelf, muddy limy shallow shelf, storm flow, muddy deep shelf, silty muddy deep shelf and contour current microfacies. Vertical and horizontal distribution of microfacies establishes a sedimentation model of the continental shelf facies. Combined with analization or calculation of geochemical, mineralogical, physical and gas-bearing properties of samples, sedimentary microfacies is evaluated using nine parameters： total organic carbon content, effective shale continuous thickness, vitrinite reflectance, kerogen type, mineral components, porosity, permeability, water saturation and gas content. The evaluation revealed that the most favorable facies for shale gas exploration and development are the muddy deep shelf and part of the silty muddy deep shelf microfacies, with TOC more than 2%, siliceous component over 50%, clay less than 30%, porosity more than 3%, water saturation lower than 40%, gas content greater than 2 m3/t. These results provide a theoretical basis for deciston-making on the most promising areas for shale gas exploration in the Sichuan Basin and for marine shale gas exploration and development in South China.