鄂尔多斯盆地中奥陶统乌拉力克组海相页岩岩相类型及优质储层发育特征  

Lithofacies types and high-quality reservoir development characteristics of marine shale in the Middle Ordovician Wulalike Formation,Ordos Basin

作　　者：于洲 黄正良[2] 李维岭 李靖[3] 曹斌风 吴东旭 胡琮 吴兴宁 朱文博 YU Zhou;HUANG Zhengliang;LI Weiling;LI Jing;CAO Binfeng;WU Dongxu;HU Cong;WU Xingning;ZHU Wenbo(PetroChina Hangzhou Research Institute of Geology,Hangzhou,Zhejiang 310023,China;Research Institute of Exploration and De-velopment,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;Exploration Department,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;Northwest University,Xi'an,Shaanxi 710127,China)

机构地区：[1]中国石油杭州地质研究院 [2]中国石油长庆油田公司勘探开发研究院 [3]中国石油长庆油田公司勘探事业部 [4]西北大学

出　　处：《天然气工业》2023年第3期23-33,共11页Natural Gas Industry

基　　金：中国石油天然气股份有限公司“十四五”前瞻性基础性重大科技项目“鄂尔多斯盆地西缘海相页岩气资源潜力与富集分布规律研究”(编号:2021DJ1904);中国石油长庆油田公司重大科技专项“鄂尔多斯盆地中元古界—奥陶系构造沉积演化、成源机制与勘探新领域”(编号:ZDZX2021)。

摘　　要：近期,鄂尔多斯盆地西缘中奥陶统乌拉力克组海相页岩获得页岩油气勘探重大突破,成为该盆地油气勘探开发的新领域,但乌拉力克组岩相类型及优质岩相分布特征不够清晰,制约了该层系下一步页岩油气的勘探开发。为此,基于岩石薄片、X射线衍射、扫描电镜和有机地球化学分析等资料,对乌拉力克组海相页岩开展了岩相类型划分,分析了不同岩相储层发育特征,明确了优质岩相的主控因素并预测了优质海相页岩储层的发育区。研究结果表明:(1)乌拉力克组主要发育富有机质硅质页岩、含有机质硅质页岩、贫有机质钙质页岩、富有机质混合页岩、含有机质混合页岩和贫有机质混合页岩6类页岩岩相;(2)乌拉力克组页岩储集空间主要为粒间孔和微裂缝,含少量黄铁矿晶间孔、有机质孔和粒内溶孔;(3)富有机质硅质页岩、含有机质硅质页岩、富有机质混合页岩、含有机质混合页岩、贫有机质混合页岩和贫有机质钙质页岩的平均孔隙度分别为2.31%、1.57%、1.07%、1.09%、0.66%和0.62%。结论认为,富有机质硅质页岩、含有机质硅质页岩和富有机质混合页岩总有机碳含量和脆性指数较高,储集物性及含气性较好,是乌拉力克组优质岩相,位于坳陷区的乌三段和乌二段下部是优质岩相的发育部位,该研究成果对于该区页岩油气勘探选区、有利目标评价以及丰富我国海相页岩气理论认识与实际勘探具有重要意义。Recently,a great breakthrough in shale oil and gas exploration has been achieved in the marine shale of Wulalike Formation of Middle Ordovician along the western margin of the Ordos Basin,which has become a new field of oil and gas exploration and development in this basin.However,the lithofacies types and high-quality lithofacies distribution characteristics of the Wulalike Formation are not clarified yet,which restricts the next step in shale oil and gas exploration and development in this formation.Based on rock thin section,X-ray diffraction,SEM and organic geochemical analysis data,this paper classifies the lithofacies types of the Wulalike Formation marine shale.Then,the development characteristics of different lithofacies reservoirs are analyzed.Finally,the main control factors of high-quality lithofacies are determined,and the development zones of high-quality marine shale reservoir are predicted.And the following research results are obtained.First,the Wulalike Formation mainly develops 6 types of shale lithofacies,including organic rich siliceous shale,organic bearing siliceous shale,organic poor calcareous shale,organic rich mixed shale,organic bearing mixed shale and organic poor mixed shale.Second,the reservoir space in the Wulalike Formation shale is acted mainly by intergranular pores and microfractures,with a small number of pyrite intercrystalline pores,organic matter pores and intragranular dissolved pores.Third,the average porosity of organic rich siliceous shale,organic bearing siliceous shale,organic rich mixed shale,organic bearing mixed shale,organic poor mixed shale,and organic poor calcareous shale are 2.31%,1.57%,1.07%,1.09%,0.66%and 0.62%,respectively.In conclusion,organic rich siliceous shale,organic bearing siliceous shale and organic rich mixed shale have higher TOC and brittleness index and better reservoir physical property and gas bearing property,and they are the high-quality lithofacies of Wulalike Formation.The third Member of Wulalike Formation and the lower part of the second

关 键 词：鄂尔多斯盆地 下奥陶统 乌拉力克组 页岩岩相 储集空间 优质岩相 

分 类 号：P618.13[天文地球—矿床学]