低渗透砂岩储层压驱裂缝起裂及扩展特征实验研究  

Experimental study on fracture initiation and propagation characteristics caused by pressure drive in low-permeability sandstone reservoirs

作　　者：孙强[1,2] 张翼飞 于春磊 孙志刚[1,2] 曹虎 杨丽红[4] SUN Qiang;ZHANG Yifei;YU Chunlei;SUN Zhigang;CAO Hu;YANG Lihong(Exploration and Development Research Institute,Shengli Oilfield Company,SINOPEC,Dongying City,Shandong Province,257015,China;Shandong Key Laboratory of Unconventional Oil and Gas Exploration and Development(Preparation),Dongying City,Shandong Province,257015,China;China University of Petroleum(Beijing),Beijing City,102299,China;The First Oil Production Plant of North China Oilfield Branch,SINOPEC,Renqiu City,Hebei Province,062550,China)

机构地区：[1]中国石化胜利油田分公司勘探开发研究院,山东东营257015 [2]山东省非常规油气勘探开发重点实验室(筹),山东东营257015 [3]中国石油大学(北京),北京102299 [4]中国石化华北油田分公司第一采油厂,河北任丘062550

出　　处：《油气地质与采收率》2024年第6期160-167,共8页Petroleum Geology and Recovery Efficiency

基　　金：中国石化科技攻关项目“压驱开发机理及数值模拟方法研究”(P21072-1)。

摘　　要：针对水驱低渗透油藏地层能量补充困难、“注不进、采不出”的问题,胜利油田结合提液稳产技术需求,形成了针对低渗透油藏的压驱注水技术。压驱通过高压注水有效提高了水驱注水总量,矿场试验表明压驱过程中储层形成了一定规模的裂缝,但压驱破裂压力及裂缝扩展规律尚不明确。为了优化矿场施工参数,采用天然砂岩和真三轴水力压裂平台开展5组压驱与压裂物理模拟实验,研究注入排量对压驱破裂压力和裂缝形态的影响,分析注入方式对裂缝形态的影响,并利用多孔弹性理论分析其成因。结果表明:压驱过程同时存在明显的起裂压力和破裂压力,裂缝发育呈现弹性变形、微破裂和失稳破裂3个阶段。随着注入排量升高,起裂压力基本不变,破裂压力逐渐降低。H-F模型可用于预测起裂压力,H-W模型可用于预测破裂压力的上限。压驱裂缝扩展方向受岩石非均质性的影响较大,非均质性通过影响井眼附近的孔隙压力场,进而改变应力场,使裂缝扩展方向不再垂直于最小地应力。定排量注入时,分支缝与主裂缝夹角大,形成鱼骨状裂缝;变排量注入时,分支缝与主裂缝近平行,在主裂缝两侧形成裂缝带。In view of the difficulties in formation energy replenishment and failed injection and production by water drive in lowpermeability reservoirs,Shengli Oilfield proposed a water injection technology based on pressure drive for low-permeability reservoirs according to the technical requirements for increasing liquid production and stable oil production in the oilfield.Pressure drive could effectively increase the water injection volume through high-pressure water injection.Field tests showed that a certain scale of fractures was formed in the reservoir during the pressure drive.However,the breakdown pressure and fracture propagation law caused by pressure drive were still unclear.Five pressure drive experiments were carried out using natural sandstone and true triaxial hydraulic fracturing platforms to optimize field construction parameters.The influence of injection rate on breakdown pressure and fracture geometry caused by pressure drive was studied,and that of injection modes on fracture geometry was analyzed.The causes were analyzed using the porous elasticity theory.The experimental results showed that there are both obvious fracture initiation pressure and breakdown pressure during the pressure drive.Fracture development presents three stages:elastic deformation,microfracture development,and instability failure.The fracture initiation pressure is basically unchanged,and the breakdown pressure gradually decreases with the increase in injection rate.The H-F model can be used to predict the fracture initiation pressure,and the H-W model can be used to predict the upper limit of the breakdown pressure.The direction of fracture propagation caused by pressure drive is greatly affected by rock heterogeneity,which affects the pore pressure field near the wellbore and thereby changes the stress field so that the fracture propagation is no longer perpendicular to the minimum geostress.The angles between the branch fracture and the main fracture are large during injection with a constant rate,forming a fishbone-like fra

关 键 词：压驱 低渗透储层 孔隙压力场 起裂压力 裂缝扩展 

分 类 号：TE348[石油与天然气工程—油气田开发工程]