基于数字岩心的致密砂岩储层孔隙结构与渗流机理  

Flow mechanism and pore structures of tight sandstone based on digital core analysis

作　　者：汪新光 郇金来 彭小东 张冲 袁雯 王寅 WANG Xinguang;HUAN Jinlai;PENG Xiaodong;ZHANG Chong;YUAN Wen;WANG Yin(Zhanjiang Branch of CNOOC Ltd.,Zhanjiang City,Guangdong Province,524057,China;Colchis PetroConsulting Ltd.,Beijing City,100176,China)

机构地区：[1]中海石油(中国)有限公司湛江分公司,广东湛江524057 [2]科吉思石油技术咨询(北京)有限公司,北京100176

出　　处：《油气地质与采收率》2022年第6期22-30,共9页Petroleum Geology and Recovery Efficiency

基　　金：国家科技重大专项“莺琼盆地高温高压天然气富集规律与勘探开发关键技术”(2016ZX05024-005);中海油重大科技项目“南海西部高温高压气藏勘探开发技术及勘探新领域研究”(CNOOC-KJ135ZDXM38ZJ02)。

摘　　要：针对致密砂岩储层微观孔隙结构复杂导致孔隙空间展布和渗流机理认识不清的问题,以莺歌海盆地乐东10区高温高压特低渗透致密砂岩储层为例,利用三维高精度Micro-CT扫描、纳米级电镜扫描等图像分析技术对致密砂岩储层的孔隙空间展布规律进行定量表征,建立基于数字岩心的双尺度三维孔隙结构模型,并基于双尺度孔隙耦合渗流模拟方法确定致密砂岩储层渗流机理。研究结果表明:①乐东10区致密砂岩储层主要发育3种尺度范围的孔隙,孔隙半径分别为0.070~3,3~40,40~300μm;②在以长石溶孔、岩屑粒间孔为主的微孔隙尺度下,孔隙与喉道半径差异较小,渗流空间以微孔隙和喉道构成,表现为小孔小喉渗流模式,在气水两相渗流过程中水相渗透率下降快;③在由较大粒间溶孔、铸模孔与次级尺度孔隙共同组成的双尺度孔隙结构模型中,呈大孔小喉渗流模式,水相渗透率下降较缓。The complex micropore structures of tight sandstone reservoirs leads to an unclear understanding of pore space distribution and flow mechanism.Accordingly,taking the high-temperature,high-pressure,and ultra-low permeability tight sandstone reservoir at Ledong 10 area in Yinggehai Basin as an example,the pore space characteristicss of tight sand⁃stone reservoirs with image analysis techniques such as 3D high-precision micro CT scanning and nano electron micro⁃scope scanning were quantitatively characterized in this paper.A two-scale 3D pore structure model based on digital cores was constructed and the flow mechanism of tight sandstone reservoirs based on the two-scale pore coupling flow simulation was determined.The results show as following:①The tight sandstone reservoir at Ledong10 area mainly develops three scale ranges of pores,which are respectively 0.070-3μm,3-40μm,and 40-300μm.②In the micropore scale dominated by feldspar dissolved pores and rock debris intergranular pores,the difference between pore and throat radius is small.The flow space is composed of micropores and throats,which are characterized by small pores and small throats.The water phase permeability decreases rapidly in the process of gas-water two-phase flow.③In the two-scale pore structure model composed of large intergranular dissolved pores,mold pores,and secondary scale pores,the flow model presents the charac⁃teristics of large pores and small throat,and the water phase permeability decreases slowly.

关 键 词：高温高压 致密砂岩 数字岩心 孔隙结构模型 渗流机理 

分 类 号：TE122.23[石油与天然气工程—油气勘探]