Relationship Between Electrical Properties and Sedimentary Environment of the Longmaxi Formation Shale,Southern Sichuan  

作　　者：YANG Kai ZHANG Bing WANG Xuben HE Lanfang YANG Hongyu WANG Pengwan TANG Jialin DENG Jixin ZHANG Cong 

机构地区：[1]Earth Exploration and Information Technology Key Laboratory of Ministry of Education,Chengdu University of Technology,Chengdu 610059,China [2]State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China [3]Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [4]PetroChina Hangzhou Institute of Petroleum Geology,Hangzhou 310023,China [5]China Geological Survey,the Key Laboratory of Unconventional Petroleum Geology,Beijing 100083,China

出　　处：《Acta Geologica Sinica(English Edition)》2020年第5期1531-1546,共16页地质学报（英文版）

基　　金：financially supported by the National Natural Science Foundation(Grant No.41502111,Grant No.91755215 and Grant No.U1262206);the Unconventional Oil and Gas Geology Key Laboratory of China Geological Survey(DD20160170)。

摘　　要：The Lower Silurian Longmaxi Formation in the south of Sichuan is a key player in the exploration and development of shale gas in China.Due to a highly complex topographic area,electromagnetic methods(EM)become important exploration means in this area.Many studies have been conducted on the shale mineral composition and electrical properties of shale,however,the correlation between sedimentary environments and the electrical properties of shale remain poorly understood.The electrical properties and sedimentary environment of the organic-rich shale of the Longmaxi Formation have been studied by means of X-ray diffraction,organic geochemistry,scanning electron microscopy and complex resistivity measurements.The discovered high quartz content of the Longmaxi Formation shale results in low resistivity.Deep-water shelf biogenic quartz contributes lower resistivity more than that of shallow-water terrigenous quartz.The deep-water anoxic and organic sedimentary environment led to major enrichment of pyrite,leading to a high polarization effect in shale.We present the correlation between the lithofacies types and electrical properties of Longmaxi Formation.The mixed siliceous shale lithofacies is the most favorable among the three lithofacies,which is characterized by high total organic carbon(TOC)content,high brittleness mineral content,high polarization and low resistivity("three high and one low").This feature is an effective identification of shale gas reservoirs by electromagnetic prospecting.Our study can provide constraints on electrical parameters of rocks for electromagnetic"sweet spot"exploration of shale gas,and so this has important geological significance to shale gas exploration and development.

关 键 词：shale gas exploration QUARTZ total organic carbon lithofacies electromagnetic method Sichuan basin 

分 类 号：P618.13[天文地球—矿床学]