玛北地区风城组页岩储层构造裂缝有效性评价及其油气地质意义  

Evaluation of the effectiveness of tectonic fractures in shale reservoirs of Fengcheng Formation in Mabei area and its geological significance for oil and gas

作　　者：曹峰 何建华 邓虎成[1,3] 李可赛 解馨慧 王伟[5] 毛金昕 孙佳琦 CAO Feng;HE Jianhua;DENG Hucheng;LI Kesai;XIE Xinhui;WANG Wei;MAO Jinxin;SUN Jiaqi(College of Energy(College of Modern Shale Gas Industry),Chengdu University of Technology,Chengdu,Sichuan 610059,China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development,Beijing 102206,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu,Sichuan 610059,China;School of Geophysics,Chengdu University of Technology,Chengdu,Sichuan 610059,China;Research Institute of Petroleum Exploration and Development,Xinjiang Oilfield Company of Petro China,Karamay,Xinjiang 834000,China)

机构地区：[1]成都理工大学能源学院(页岩气现代产业学院),四川成都610059 [2]页岩油气富集机理与高效开发全国重点实验室,北京102206 [3]成都理工大学油气藏地质及开发工程全国重点实验室,四川成都610059 [4]成都理工大学地球物理学院,四川成都610059 [5]中国石油新疆油田分公司勘探开发研究院,新疆克拉玛依834000

出　　处：《中国矿业大学学报》2024年第6期1198-1217,共20页Journal of China University of Mining & Technology

基　　金：国家自然科学基金面上项目(42072182);四川省科技厅青年科学基金项目(2023NSFSC076,24NSFSC4997);页岩油气富集机理与高效开发全国重点实验室开放基金联合资助项目(P24181)。

摘　　要：页岩油储层天然裂缝有效性不仅对页岩油的高效富集具有重要影响,也对储层渗流能力与后期造缝成网具有明显的控制作用,而目前针对页岩油储层天然裂缝力学有效性研究相对薄弱.本文以玛北地区风城组页岩油储层构造裂缝为例,利用岩心、薄片及测井资料,并结合裂缝面三维激光扫描、CT扫描及含裂缝的应力敏感性流动试验等,明确了玛北地区风城组构造裂缝的力学类型及发育特征,查明了构造裂缝力学有效性的主控因素,分析了不同力学类型裂缝对页岩油富集高产的影响.结果表明:构造裂缝可分为三类,分别为以NNW和NNE向为主且多为高角度的斜交剪切裂缝;无优势组系的顺层滑移剪切裂缝;以及NW向为主的垂直张裂缝,其中斜交剪切裂缝的纵向延伸规模最大.构造裂缝的现今力学有效性主要受控因素包括了应力方向调整、缝面正应力大小、裂缝应力敏感性及岩相组合结构4个方面,NNW向及NNE向高角度斜交剪切裂缝分别受到古应力场及现今应力场方向影响使得充填弱、缝面正应力小且纵向连通程度较高;并且斜交剪切裂缝还具有缝面粗糙度低(裂缝面高度均方根h_(RMS)=2.379 mm)及低应力敏感性(K_(φ)=0.038 MPa^(-1))的特点.故其力学有效性最好,储渗能力较好,压裂后容易剪切活化并与人工裂缝形成复杂缝网,对后期页岩油高产控制明显.另外,含云粉砂质页岩岩相结构内发育的裂缝网络连通性最高(裂缝平均连接数C_(L)=4.97,裂缝分支平均连接数C_(B)=1.69),且较厚的岩石力学层会对裂缝纵向连通性产生抑制作用.The effectiveness of natural fractures in shale oil reservoirs not only significantly influences the efficient enrichment of shale oil but also greatly affects the permeability of the reservoir and the formation of the fracture network.However,current research on the mechanical effectiveness of natural fractures in shale oil reservoirs is relatively limited.Based on cores and thin-sections observation,and logging,and also combined with three-dimensional laser scanning of fracture surfaces,CT scanning,and stress-sensitive flow experiments of the fracture-containing samples,the mechanical genesis types and developmental characteristics of the tectonic fractures in the study area in shale oil reservoirs of the Fengcheng Formation in the Mabei area were firstly presented.And thus,the main controlling factors of the mechanical effectiveness of the tectonic fractures were studied,and finally the influence of different mechanical types of the fractures on the enrichment and high production of shale oil were confirmed.The results indicate that the tectonic fractures can be categorized into three groups:oblique shear fractures predominantly in the NNW and NNE directions with a high angle;bedding slip shear fractures without a dominant strike;and vertical tensile fractures mainly with a strike of NW direction.Among these,the oblique shear fractures show the greatest longitudinal extension.The current mechanical effectiveness of tectonic fractures is primarily influenced by four factors:adjustment of in-situ stress orientation,the magnitude of normal stress at the fracture surface,fracture stress sensitivity,and the structure of lithofacies assembles.NNW and NNE oriented high-angle oblique shear fractures are influenced by the orientations of paleo-stress and present in-situ stress fields,respectively.This results in weak filling,low normal stresses on the fracture surface,and a high degree of longitudinal connectivity.Additionally,the oblique shear fractures are characterized by a low roughness of the fracture surface(Root

关 键 词：玛北地区 风城组 构造裂缝 力学有效性 页岩油开发 

分 类 号：P618.13[天文地球—矿床学]