断面有效正应力对断层侧向封闭能力的控制作用  

Control of Effective Normal Stress on Fault Lateral Sealing Capacity

作　　者：严念斌 王海学[1] 侯嘉怡 姜明明[2] 宋宪强[1] Yan Nianbin;Wang Haixue;Hou Jiayi;Jiang Mingming;Song Xianqiang(Northeast Petroleum University,Daqing,Heilongjiang 163318,China;Peking University,Beijing 100871,China)

机构地区：[1]东北石油大学,黑龙江大庆163318 [2]北京大学,北京100871

出　　处：《特种油气藏》2024年第4期64-70,共7页Special Oil & Gas Reservoirs

基　　金：国家自然科学基金“断层破坏盖层机理及封闭性定量评价”(41972157);“基于环形剪切实验的高孔隙砂岩碎裂变形带主控因素与封闭能力研究”(42302146);黑龙江省普通本科高等学校青年创新人才项目“断层在泥岩盖层段变形机制及垂向封闭有效性定量评价”(UNPYSCT-2020142)。

摘　　要：小位移断层的侧向封闭性决定断层圈闭富集油气的能力,随着油气勘探技术理论的发展,曾被忽略的小位移断层在油气勘探和开发过程中的作用日益突出。为了明确小位移断层的内部结构特征及其对断层侧向封闭性的影响,应用自主研发的高压低速环形剪切装置,以断面有效正应力为变量,对高孔隙度纯净砂岩开展环形剪切物理模拟实验,分析断面有效正应力对断层侧向封闭性的影响。结果表明:断裂在高孔隙纯净砂岩内以碎裂作用机制为主,形成典型的碎裂型断层岩,其渗透率明显降低,是导致同层砂岩对接段侧向封闭的根本原因。在其他因素固定的条件下,断面有效正应力越大,断层岩碎裂程度越大,颗粒直径和孔隙度越小;岩石颗粒的破碎及碎屑基质的填充导致断裂带孔隙度和渗透率明显降低。断面有效正应力是小位移断层侧向封闭能力的主要控制因素,小位移断层具有富集油气的潜力。研究结果对裂陷盆地断块油气藏勘探开发具有重要的指导意义。The lateral sealing of small displacement faults determines the capacity of fault traps to accumulate oil and gas.With the development of oil and gas exploration technology theories,the role of small displacement faults,which were once overlooked,is becoming increasingly prominent in the process of oil and gas exploration and development.To clarify the internal structural characteristics of small displacement faults and the influence on the lateral sealing of faults,a self-developed high-pressure and low-speed circular shear device was applied.Taking the effective normal stress of the cross-section as a variable,it conducts circular shear physical simulation experiments on high porosity pure sandstone to analyze effective normal stress on the lateral sealing of faults.The results show that the fracture mechanism is mainly characterized by fragmentation in high porosity and pure sandstone,forming typical fragmented fault rocks.The significant decrease in permeability is the fundamental reason for the lateral sealing of the joint section of sandstone in the same formation.Under the condition that other factors remain unchanged,the larger the effective normal stress of the cross-section,the greater the degree of fragmentation of the fault rock,and the smaller the particle diameter and porosity;the fracture of rock particles and the filling of detrital matrix lead to a significant decrease in porosity and permeability of the fracture zone.The effective normal stress of the fault section is the main controlling factor of the lateral sealing capacity of the small displacement fault.Small displacement faults have the potential of oil and gas accumulating.The study results have guiding significance for the exploration and development of fault-block oil and gas reservoirs in rift basins.

关 键 词：小位移断层 断面有效正应力 环形剪切 渗透性 侧向封闭性 渤海 

分 类 号：TE121.2[石油与天然气工程—油气勘探]