页岩裂缝和基质渗透率各向异性特征及影响因素  

Anisotropy and Influencing Factors of Shale Fracture and Matrix Permeability

作　　者：胡辉庭 马勇[1] 张遂安 张凯逊 张海鹏 黄越 HU Hui-ting;MA Yong;ZHANG Sui-an;ZHANG Kai-xun;ZHANG Hai-peng;HUANG Yue(State Key Laboratory of Petroleum Resources&Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;Center International Group Co.,Ltd.,Beijing 100176,China;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]森特士兴集团股份有限公司,北京100176 [3]中国地质科学院地质力学研究所,北京100081

出　　处：《科学技术与工程》2023年第24期10252-10263,共12页Science Technology and Engineering

基　　金：国家自然科学基金(41772202,41802149,42173030);中国石油科技创新基金研究项目(2018D-5007-0102)。

摘　　要：页岩裂缝渗透率是控制页岩气富集高产的关键参数,而页岩基质渗透率决定了页岩气的稳产和经济开发,研究页岩裂缝和基质渗透率的各向异性特征对于保障页岩气的长期产量尤为重要。以渝东南地区海相页岩为研究对象,探究了页岩裂缝和基质渗透率各向异性特征及其影响因素。基于微计算机断层扫描技术(micro computed tomography,micro-CT)、高压压汞手段分析了页岩裂缝特征并区分了页岩裂缝与基质,利用立方体样品以及3D打印岩心夹持器技术测定了地层压力条件下页岩三轴方向的渗透率,采用定性观察、定量分析和数字岩心等方法揭示了页岩裂缝和基质渗透率各向异性与孔隙结构特征的关系。研究表明:页岩基质渗透率主要受岩石的微观结构控制,而页岩裂缝渗透率主要由裂缝形态和特征决定;微裂缝的存在增大了水平与垂直方向裂缝渗透率的差异性,但对水平方向间裂缝渗透率的比值影响较小甚至有所降低;水平方向上矿物和有机质呈层排列易形成连通的孔隙微裂缝网络,增大了页岩平行层理方向上的基质渗透率,使其比其垂直层理方向高出1~2个数量级;砂质条带和砂质纹层使得页岩水平方向上的基质渗透率差异性增强,而且页岩3个方向的基质渗透率与孔隙的比表面积、孔隙体积以及平均孔径具有较好的正相关性,页岩微孔和介孔越发育,页岩的基质渗透率越高。研究成果对进一步认识页岩非均质性的理论问题及其影响具有重要意义,可指导页岩气勘探开发并为页岩气经济开采提供依据。Shale fracture permeability is a key parameter to control the enrichment and high yield of shale gas,and shale matrix permeability determines the stable and economic production of shale gas.It is particularly important to study the anisotropy characteristics of shale fracture and matrix permeability to ensure the long-term production of shale gas.Taking Marine shale in southeastern Chongqing as the research object,the influencing factors of shale fracture and matrix permeability anisotropy were explored.By means of micro computed tomography(micro-CT) and high-pressure mercury injection,the characteristics of shale fractures were analyzed and the shale fractures and matrix were distinguished.The triaxial permeability of shale under formation pressure was measured using cubic samples and 3D printed polymer membrane technology.The relationship between permeability anisotropy of shale fractures and matrix and characteristics of pore structure was revealed by qualitative observation,quantitative analysis and digital core.The results show that shale matrix permeability is mainly controlled by shale microstructure,while shale fracture permeability is mainly determined by fracture morphology and characteristics.The existence of microfractures increases the difference of fracture permeability between horizontal and vertical directions,but has little effect on the ratio of horizontal fracture permeability directions or even decreases.In the horizontal direction,minerals and organic matter are arranged in layers,which are easy to form a connected pore microfracture network,and increase the matrix permeability in the parallel bedding direction of shale,making it 1~2 orders of magnitude higher than that in the vertical bedding direction.The difference of matrix permeability in horizontal direction is enhanced by sandy bands and laminaries.Moreover,the matrix permeability in the three directions of shale has a positive correlation with the pore specific surface area,pore volume and average pore size,and the more developed micr

关 键 词：海相页岩 裂缝渗透率 基质渗透率 各向异性 孔隙结构特征 影响因素 

分 类 号：TE122[石油与天然气工程—油气勘探]