摘要
砾岩储层普遍具有低孔低渗、非均质性强等特点,地层起裂以及裂缝扩展难以控制,极大影响了砾岩储层的压裂改造效果。为了搞清砾岩储层水力压裂裂缝的形成机制,针对国内典型砾岩储层,采用数值模拟方法研究了砾岩储层裂缝的扩展规律及主要控制因素。结果表明:强度高、尺寸大的砾石对裂缝的阻碍作用较为明显,破裂压力随着砾石的强度和粒径的增大而增大;低胶结强度比有利于砾石对水力裂缝的“吸引”,进而形成曲折的裂缝延伸路径;水平应力差对裂缝延伸方向起主导作用,随着最小水平主应力的减小,地层起裂难度降低;通过随机森林对影响压裂缝扩展因素的重要程度进行分析,认为胶结强度比和水平应力差为影响压裂缝扩展的主要因素。研究成果为砾岩储层压裂的选层提供了理论依据。
Conglomerate reservoirs generally have characteristics of low porosity,low permeability and high heterogeneity.Fracture initiation in formation and fracture propagation are difficult to control,much affecting the fracturing effect of conglomerate reservoirs.In order to understand the formation mechanism of hydraulic fractures in conglomerate reservoirs,the propagation law and main controlling factors of fractures in conglomerate reservoirs are studied by numerical simulation method for typical domestic conglomerate reservoirs.The results show that highstrength and large-size gravel has obvious hindering effect on fractures,and fracture pressure increases with the increase of strength and particle size of gravel.Low cementing strength ratio is favorable for“attraction”of conglomerate for hydraulic fractures,thus forming tortuous fracture extension path.Horizontal stress difference plays dominant role in fracture extension orientation,and with the decrease of minimum horizontal principal stress,the difficulty of fracture initiation decreases.The importance of the factors affecting fractures propagation is analyzed by random forest,and it is considered that cementing strength ratio and horizontal stress difference are the main factors affecting fractures propagation.The research provides theoretical basis for selection of fracturing layers in conglomerate reservoirs.
作者
张家伟
刘向君
熊健
梁利喜
张文
张旭
ZHANG Jiawei;LIU Xiangjun;XIONG Jian;LIANG Lixi;ZHANG Wen;ZHANG Xu(Petroleum Engineering School,Southwest Petroleum University,Chengdu 610500,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu 610500,China;West-to-East Gas Transmission Subei Gas Transmission Branch,Nantong 226363,China)
出处
《大庆石油地质与开发》
CAS
北大核心
2023年第3期48-57,共10页
Petroleum Geology & Oilfield Development in Daqing
基金
西南石油大学青年科技创新团队项目“非常规地层岩石物理”(2018CXTD13)。
关键词
砾岩
离散元
水力压裂
胶结强度比
数值模拟
扩展规律
主控因素
conglomerate
discrete element
hydraulic fracturing
cementing strength ratio
numerical simulation
propagation law
main controlling factor
