摘要
由于致密砂砾岩具有超低渗透性,不进行水力压裂难以达到经济开采目标。砂砾岩储层的有效开采需要对水力裂缝扩展规律有清晰认识。考虑砂岩或砾岩材料本身的非均质性以及砂岩与砾岩之间的非均质性,提出一种数字图像技术和有限元软件RFPA(Rock Failure Process Analysis)相结合的数值模拟方法。基于该方法的致密砂砾岩压裂的二维数值模拟结果表明,在不同水平地应力差和砾岩强度条件下,水力裂缝可以穿过砾岩或沿砾岩转向扩展。考虑砾岩分布方位、尺寸和轴比,三维数值模型模拟结果表明,水力裂缝能够穿过砾岩,形成一种在常规压裂实验中不容易观察到的环绕扩展模式,也能够像二维数值模型得到的结果那样沿砾岩转向扩展,即不同的砾岩分布方位、尺寸和轴比使水力裂缝扩展遇到砾岩时呈现不同的扩展模式,包括:①直接穿过砾岩;②沿砾岩转向扩展;③环绕扩展;④模式①和②或者②和③同时出现。
It is difficult to obtain profitable production without the application of hydraulic fracturing in tight glutenites because of their ultra-low permeability.Profitable exploitation of glutenites requires a clear understanding of the hydraulic fracture propagation law in these reservoirs. Considering the heterogeneity of sandstone or gravel and the heterogeneity between sandstone and gravels,a numerical method that integrates the digital image processing technique into a numerical software named rock failure process analysis(RFPA)was proposed.Based on the method,two-dimensional simulation results of the fracturing in the tight glutenites indicate that hydraulic fractures can penetrate or deflect along the gravels depending on the conditions of stress differences and gravel strengths. Three-dimensional simulations considering gravel distribution orientation,gravel size and axial ratio reveal that the hydraulic fractures can penetrate gravels,resulting in a bypass fracture which is difficult to be observed in regular lab experiments,or deflect along the gravel which is similar to that observed in two-dimensional simulations. Main propagation modes under various gravel distribution orientation,size and axial ratio are as follows:①penetrate gravels directly;②deflect along the gravels;③bypass the gravels;④combination of① and②,or②and③.
作者
张子麟
陈勇
张全胜
李爱山
张潦源
李明
黄波
ZHANG Zilin;CHEN Yong;ZHANG Quansheng;LI Aishan;ZHANG Liaoyuan;LI Ming;HUANG Bo(Petroleum Engineering Technology Research Institute,Shengli Oilfield Company,SINOPEC,Dongying City,Shandong Province,257000,China)
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2019年第4期132-138,共7页
Petroleum Geology and Recovery Efficiency
基金
国家科技重大专项“渤海湾济阳坳陷致密油开发示范工程”(2017ZX05072)
国际合作与交流项目“基于连续-非连续模型的超临界CO2压裂页岩增透机理研究”(51761135102)
国家自然科学基金项目“软硬间互地层水力压裂裂缝三维延伸机理研究”(51479024)
关键词
致密砂砾岩
水力裂缝
数值模拟
砾岩
扩展
tight glutenite
hydraulic fracture
numerical simulation
gravel
propagation
