Sedimentary environment controls on the accumulation of organic matter in the Upper Ordovician Wufeng–Lower Silurian Longmaxi mudstones in the Southeastern Sichuan Basin of China  

作　　者：Lei Yang Bo Ran Yu-Yue Han Shu-Gen Liu Yue-Hao Ye Christopher Xiao Wei Sun Di Yang Guo-Dong Xia Shi-Yu Wang 

机构地区：[1]School of Earth Sciences and Resources, China University of Geosciences [2]State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology [3]University of Houston [4]Research Institute of Yanchang Petroleum (Group) Co.Ltd

出　　处：《Petroleum Science》2019年第1期44-57,共14页石油科学（英文版）

基　　金：supported by the Science and Technology Support Program of Sichuan Province(No.15ZC1390);National Natural Science Foundation of China(No.41102064)

摘　　要：The Upper Ordovician–Lower Silurian mudstones(including the Wufeng, Guanyinqiao and Longmaxi Formations) in the Sichuan Basin are some of the most important shale gas plays in China. In order to enhance our understanding of the process of formation of organic carbon up to 10%, optical, microscopy and geochemical methods have been used to investigate the petrographic and geochemical characteristics of the formation. Firstly, three mudstone lithofacies were identified based on a wide variety of mudstone laminations. These are:(a) indistinctly laminated mudstone;(b) parallellaminated mudstone; and(c) nonparallel-laminated mudstone. Then, combining with the evidence from depocenter migration, Th/U ratios and total organic carbon, the abundant organo-minerallic fabrics suggest that organic carbon was preferentially deposited and preserved in anoxic, low energy and stagnant water conditions during deposition of the Wufeng and Longmaxi Formations. On the contrary, the Guanyinqiao Formation with poor organic carbon was deposited in oxic and high-energy water conditions.The Upper Ordovician–Lower Silurian mudstones(including the Wufeng, Guanyinqiao and Longmaxi Formations) in the Sichuan Basin are some of the most important shale gas plays in China. In order to enhance our understanding of the process of formation of organic carbon up to 10%, optical, microscopy and geochemical methods have been used to investigate the petrographic and geochemical characteristics of the formation. Firstly, three mudstone lithofacies were identified based on a wide variety of mudstone laminations. These are:(a) indistinctly laminated mudstone;(b) parallellaminated mudstone; and(c) nonparallel-laminated mudstone. Then, combining with the evidence from depocenter migration, Th/U ratios and total organic carbon, the abundant organo-minerallic fabrics suggest that organic carbon was preferentially deposited and preserved in anoxic, low energy and stagnant water conditions during deposition of the Wufeng and Longmaxi Formations. On the contrary, the Guanyinqiao Formation with poor organic carbon was deposited in oxic and high-energy water conditions.

关 键 词：Guanyinqiao Formation SICHUAN Basin MUDSTONE LAMINATED MUDSTONE Water condition 

分 类 号：TE[石油与天然气工程]