陆相页岩油储层水力压裂裂缝形态的试验  

Experimental Study on Fractures Morphology of Hydraulic Fracturing in Continental Shale Oil Reservoir

作　　者：宁文祥 何柏[1,2,3] 李凤霞 谢凌志[1,2,3] 史爱萍[4] 何强 NING Wen-xiang;HE Bo;LI Feng-xia;XIE Ling-zhi;SHI Ai-ping;HE Qiang(College of Architecture and Environment, Sichuan University, Chengdu 610065, China;State Key Laboratory of Hydraulic and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China;Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610207, China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Petroleum Exploration and Production Research Institute, China Petroleum & Chemical Corporation, Beijing 100083, China)

机构地区：[1]四川大学建筑与环境学院,成都610065 [2]四川大学建筑与环境学院水力学与山区河流开发保护国家重点实验室,成都610065 [3]四川大学新能源与低碳技术研究院,成都610207 [4]中国石化石油勘探开发研究院页岩油气富集机理与有效开发国家重点实验室,北京100083

出　　处：《科学技术与工程》2021年第18期7505-7512,共8页Science Technology and Engineering

基　　金：国家科技重大专项(2017ZX05049-006-007);国家自然科学基金(11872258);四川省国际科技创新合作/港澳台科技创新合作项目(2019YFH0121)。

摘　　要：水力压裂技术是在页岩油气藏中建立人工裂缝网络的一种重要方法,但由于各储层地质条件的差异性以及页岩具有的强非均质性,使得水力压裂裂缝形态十分复杂。为了了解长7陆相页岩油储层页岩水力压裂裂缝网络的形成机理,将室内真三轴水力压裂试验与基于计算机断层扫描的3D可视化模型相结合,初步探讨了水平应力差异系数、压裂液黏度和天然不连续面对岩样水力压裂裂缝形态的影响。结果表明:页岩水力压裂裂缝形态按照复杂程度可以分为三类,即单一裂缝,鱼骨状裂缝和网状裂缝;低水平应力差异系数和低黏度压裂液有利于形成复杂的裂缝网络,较为合理的条件为水平应力差异系数为0~0.53,且压裂液黏度为0~17.1 mPa·s,在此条件下易形成鱼骨状裂缝或网状裂缝;此外,平行于层理面的天然不连续面有利于形成复杂裂缝网络,但是过多的天然不连续面开启是不利于主水力裂缝的形成和扩展。The hydraulic fracturing technique has been an indispensable approach to creating artificial fracture networks in shale oil/gas reservoirs.However,due to the difference of geological conditions of different reservoirs and the strong heterogeneity of shale,the fracture morphology of hydraulic fracturing is very complex.To gain a better understanding of the formation mechanism of hydraulic fracture networks in the Chang 7 continental shale oil reservoir,physical true triaxial experiments of hydraulic fracturing were carried out at the laboratory scale.Accordingly,the hydraulic factures in the continental shale samples were obtained by computed tomography-based 3D visualization.Afterwards,the influence of horizontal stress,fluid viscosity and natural discontinuities on the morphology of hydraulic fractures is systematically discussed.The test results showed that the fracture morphology of hydraulic fracturing in shale can be divided into three types according to the degree of complexity:single fractures,fishbone fractures and network fractures.A smaller horizontal stress difference coefficient and lower fluid viscosity make it easier to form a complex fracture network.The reasonable condition is that the horizontal stress difference coefficient is 0~0.53 and the viscosity of fracturing fluid is 0~17.1 mPa·s.Under this condition,it is easy to form fishbone fracture and network fracture.In addition,discontinuities along the bedding direction are beneficial to form a fracture network.Too many discontinuities are not conducive to the formation and extension of a main hydraulic fracture.

关 键 词：页岩油 水力压裂 计算机断层扫描 3D可视化 裂缝形态 

分 类 号：TE348[石油与天然气工程—油气田开发工程]