潜江凹陷潜江组盐间细粒岩沉积特征及其对页岩含油性的控制  

Sedimentary characteristics of intersalt fine-grained sedimentary rocks and their control on oil-bearing ability of shales in the Qianjiang Formation,Qianjiang Sag

作　　者：陈晨 姜在兴[1] 孔祥鑫[1] 吴世强[2] 陈凤玲[2] 杨叶芃[1] CHEN Chen;JIANG Zaixing;KONG Xiangxin;WU Shiqiang;CHEN Fengling;YANG Yepeng(School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China;Research Institute of Exploration and Development,Jianghan Oilfield Company,SINOPEC,Wuhan 430223,China)

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]中国石化江汉油田分公司勘探开发研究院,湖北武汉430223

出　　处：《地学前缘》2021年第5期421-435,共15页Earth Science Frontiers

基　　金：国家科技重大专项(2017ZX05009-002);国家自然科学基金面上项目(41772090)。

摘　　要：江汉盆地是我国典型的内陆盐湖盆地,位于其中部的潜江凹陷发育盐间细粒沉积,近期油气勘探取得突破。为研究其沉积特征及其对页岩含油性的控制,本文基于岩心和多种测试方法将盐间细粒沉积划分出8种岩相,分别是含灰泥质云岩、云质混合细粒岩、泥质混合细粒岩、灰质混合细粒岩、灰质泥岩/泥岩、云质泥岩、硫酸盐质混合细粒岩和云质/泥质钙芒硝岩。岩相组合有A和B两种:A类岩相组合为含灰泥质云岩、云质混合细粒岩和泥质混合细粒岩,夹少量灰质混合细粒岩、云质泥岩、硫酸盐质混合细粒岩和云质/泥质钙芒硝岩;B类岩相组合为云质泥岩、硫酸盐质混合细粒岩、云质/泥质钙芒硝岩,夹少量灰质泥岩/泥岩和泥质混合细粒岩。A类岩相组合富集碳酸盐质矿物且有机质含量高,岩心上表现为灰黑色泥质岩(泥质混合细粒岩和灰质混合细粒岩)与黄褐色云质岩(含灰泥质云岩和云质混合细粒岩)频繁更替,其中夹有白色硫酸盐质岩,呈透镜体状或层状产出,说明当时环境的盐度较低,镜下纹层大部分呈较为连续的微波状或水平状。其沉积特征反映了A类岩相组合的形成环境为还原性较好、盐度较低的深水区。B类岩相组合硫酸盐矿物含量和有机质含量较低,岩心上表现为白色高硫酸盐质岩夹有黑色泥质层或黄褐色云质层,镜下观察为呈菱形片状钙芒硝,常见穿插双晶,可见明显的粒序变化,云质含量高的薄片镜下为无纹层特征。其沉积特征反映了B类岩相组合形成环境为还原性较弱、盐度较高的较浅水域。本研究将V/(V+Ni)、(S1+S2)/TOC、Sr/Ba和Ga/C31H指数等地化参数与岩相特征相结合,进一步佐证了上述观点,并且补充说明了A类岩相组合形成于气候湿润的环境,而B类岩相组合形成环境较为干旱,且将盐间沉积划分为B、A、B三个阶段,对其进行了沉积模式的研究。结果表The Jianghan Basin is a typical inland salt lake basin in China.The Qianjiang Sag,in the middle of the basin,developed intersalt petroliferous fine-grained sedimentary rocks,and it has seen a recent breakthrough in oil and gas exploration.In order to study its sedimentary characteristics and depositional control,eight kinds of lithofacies are identified in the sedimentary rocks using core and various tests:calcite-bearing argillaceous dolomite,dolomite,argillite or calcite mixed fine-grained sedimentary rocks,calcareous mudstone/mudstone,dolomitic mudstone,sulfate mixed fine-grained rock,and dolomitic/argillaceous glauberite.In addition,two lithofacies associations,types A and B,are identified.The type A association contains calcite-bearing argillaceous dolomite,dolomite or argillite mixed fine-grained sedimentary rocks,with small amounts of calcite mixed fine-grained sedimentary rocks,dolomitic mudstone,sulfate mixed fine-grained rock,and dolomitic/argillaceous glauberite.The type B association involves dolomitic mudstone,sulfate mixed fine-grained rock dolomitic/argillaceous glauberite,small amounts of calcareous mudstone/mudstone and argillite mixed fine-grained sedimentary rocks.The type A lithofacies association is rich in carbonate and organic matter;its cores are gray-black argillaceous rocks(argillite and calcite mixed fine-grained sedimentary rocks)and yellow-brown dolomitic rocks(calcitebearing argillaceous dolomite and dolomite mixed fine-grained sedimentary rocks)frequently interchanging,with white sulfate rocks interspersed in the form of lenses or layers,indicating the environmental salinity at that time was relatively low.Laminates under the microscope mostly show continuous fine wave or aligned horizontally.The sedimentary characteristics show the type A association is formed in a reductive and low salinity deep water environment.The type B lithofacies association,on the other hand,is rich in sulfate and has low organic matter content;its cores are white high sulfate rocks with black argillaceous

关 键 词：细粒沉积 沉积特征 岩相 沉积模式 潜江凹陷 

分 类 号：P618.13[天文地球—矿床学]