鄂尔多斯盆地合水地区三叠系长7段页岩油储层特征及主控因素  

Characteristics and main controlling factors of shale oil reservoirs of Triassic Chang 7 member in Heshui area,Ordos Basin

作　　者：肖玲 陈曦 雷宁 易涛 郭文杰 XIAO Ling;CHEN Xi;LEI Ning;YI Tao;GUOWenjie(School of Earth Science and Engineering,Xi’an Shiyou University,Xi’an 710065,China;Shaanxi Provincial Key Laboratory of Oil and Gas Accumulation Geology,Xi’an 710065,China;No.12 Oil Production Plant,PetroChina Changqing Oilfield Company,Qingyang 745400,Gansu,China;No.2 Oil Production Plant,PetroChina Changqing Oilfield Company,Qingyang 745100,Gansu,China)

机构地区：[1]西安石油大学地球科学与工程学院,西安710065 [2]陕西省油气成藏地质学重点实验室,西安710065 [3]中国石油长庆油田公司第十二采油厂,甘肃庆阳745400 [4]中国石油长庆油田公司第二采油厂,甘肃庆阳745100

出　　处：《岩性油气藏》2023年第2期80-93,共14页Lithologic Reservoirs

基　　金：国家科技重大专项“CO_(2)捕集、驱油与埋存技术示范工程”(编号:2016ZX05056);西安石油大学研究生创新与实践能力培养计划“鄂尔多斯盆地陇东地区长9—长8油层组沉积环境特征及构造指示意义”(编号:YCS22112048)联合资助。

摘　　要：鄂尔多斯盆地合水地区是长庆油田页岩油勘探开发的重点区块。根据铸体薄片、物性分析、扫描电镜、高压压汞及核磁共振等测试分析结果,对鄂尔多斯盆地合水地区三叠系长7段页岩油储层特征及其主控因素进行了研究。研究结果表明:(1)合水地区长7段页岩油储层主要为一套灰黑—黑色细—粉砂岩,以岩屑长石砂岩为主,填隙物的体积分数平均为16.71%。岩石物性较差,平均孔隙度为8.15%,平均渗透率为0.102 mD,为超低孔—特低孔、超低渗型储层。(2)研究区孔隙类型以长石溶孔和残余粒间孔为主,以亚微米孔(直径为0.1~1.0μm)含量最多,占总孔隙数量的75.56%,纳米孔隙(直径小于0.1μm)数量次之,占总孔隙数量的17.94%。孔喉类型较复杂,溶蚀成因的管束状喉道及压实成因的片状、弯片状喉道为储层主要的喉道类型。(3)沉积作用、成岩作用及构造作用共同控制了研究区长7段页岩油储层的质量和分布。沉积作用为储层提供了物质基础,储层主要形成于深水重力流沉积环境,可分为砂质碎屑流砂体和浊流砂体等2种类型。中等—强压实强度的压实作用和胶结作用降低了储层物性,溶蚀作用对于改善储层物性具有一定的积极作用,构造作用形成的裂缝提高了储层的渗流能力,并对后期的储层压裂改造具有重要意义。Heshui area in Ordos Basin is the main zone for the exploration and development of shale oil in Changqing Oilfield.Based on the data of cast thin section,physical property analysis,scanning electron microscopy,high-pressure mercury compression and nuclear magnetic resonance,the characteristics and main controlling factors of shale oil reservoirs of Triassic Chang 7 member in Heshui area of Ordos Basin were analyzed.The results show that:(1)The shale oil reservoir of Chang 7 member in Heshui area is mainly a set of dark gray-black fine siltstone,mainly lithic arkose,and the average volume fraction of fillings is 16.71%.The rock physical properties are poor,with an average porosity of 8.15%and an average permeability of 0.102 m D.It is an ultra-low porosity,extra-low porosity and ultra-low permeability reservoir.(2)The reservoir pores in the study area are mainly feldspar dissolved pores and residual intergranular pores.Sub-micron pores(0.1-1.0μm)are the main reservoir space,accounting for 75.56%of the total pores,followed by nano pores(with diameter less than 0.1μm),accounting for 17.94%of the total pores.The throat type is relatively complex,and the tube-shaped throats caused by dissolution and the flake and curved flake throats caused by compaction are the main throat types of the reservoir.(3)Sedimentation,diagenesis and tectonism jointly control the quality and distribution of shale oil reservoir of Chang 7 member in the study area.Sedimentation provides the material basis for the reservoir.The reservoir is mainly formed in the deep-water gravity flow sedimentary environment,which can be divided into two types:sandy clastic flow sand bodies and turbidite sand bodies.The medium-strong compaction and cementation reduce the physical properties of the reservoir.The dissolution has a certain positive effect on improving the physical properties of the reservoir.The fractures formed by tectonism improve the percolation capacity of the reservoir and are of great significance for the later fracturing and reconstructi

关 键 词：页岩油储层 亚微米孔 孔隙结构 砂质碎屑流砂体 浊流砂体 成岩作用 长7段 三叠系 合水地区 鄂尔多斯盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]