页岩油水平井体积压裂期水泥环失效机理研究  

Study on Cement Sheath Failure Mechanism for Stimulated Reservoir Volume in Shale Oil Horizontal Wells

作　　者：徐新纽 赵保忠 黄鸿 魏瑞华 曹光福 杨虎 周鹏高[3] Xu Xinniu;Zhao Baozhong;Huang Hong;Wei Ruihua;Cao Guangfu;Yang Hu;Zhou Penggao(Exploration Department,PetroChina Xinjiang Oilfield Company;China University of Petroleum(Beijing)at Karamay;Karamay Vocational&Technical College)

机构地区：[1]中国石油新疆油田分公司勘探事业部 [2]中国石油大学(北京)克拉玛依校区 [3]克拉玛依职业技术学院

出　　处：《石油机械》2022年第11期73-80,共8页China Petroleum Machinery

基　　金：国家科技重大专项“准噶尔盆地致密油开发示范工程”(2017ZX05070);中国石油集团科技专项“页岩油优快钻完井关键技术研究与应用”(2019E-2605)。

摘　　要：目前页岩油开发多采用长段水平井的体积压裂增产开发方式。针对水平井油气藏,为了研究体积压裂和返排期间的周期载荷作用对水泥环密封性的影响以及水泥石力学性能的具体要求,依据页岩油水平井压裂特点和井筒条件,构建了均匀地应力场的套管-水泥环-井壁组合体完整性力学模型。将水泥环的应力状态及其力学参数测试数据代入强度破坏准则中,以判断水泥环是否失效以及其失效形态。同时结合吉木萨尔页岩油的地应力、压力和温度等参数,开展了典型井油层固井水泥石的力学参数测试,以及压裂-返排期水平段水泥环力学破坏极限模拟。研究结果表明:压裂液返排过程中,套管内流体压力减小,套管收缩,可能导致套管-水泥环之间产生微间隙;水平井段固井水泥环的主要失效形式为压裂期的径向压缩或周向拉伸破坏,以及返排期的微间隙胶结失效;返排期水泥环微间隙胶结失效的主要影响因素为井筒内外压差和水泥石的弹性模量。研究结果可为水泥浆材料配比和储层改造工程参数的优化提供科学依据。At present,shale oil development mostly adopts stimulated reservoir volume of long horizontal wells for reservoir stimulation.For horizontal well development in oil and gas reservoirs,in order to study the effect of cyclic loading during stimulated reservoir volume and flowback on the sealing performance of cement sheath and clarify the requirements of mechanical properties of cement,according to the fracturing characteristics of shale oil horizontal wells and wellbore conditions,the integrity mechanical model of casing-cement sheath-wellbore combination with uniform in-situ stress field was established.Test data of stress state and mechanical parameters of cement sheath were substituted into the strength failure criterion to judge whether the cement sheath fails and its failure form.Meanwhile,combined with the parameters of in-situ stress,pressure and temperature of Jimsar shale oil,the mechanical parameters of cementing cement in typical oil reservoirs were tested and the mechanical failure limit of cement sheath in horizontal interval during fracturing-flowback period was simulated.The results show that during fracturing fluid flowback,the fluid pressure in the casing decreases and the casing shrinks,which may lead to micro-annulus between casing and cement sheath.The main failure forms of cement sheath in horizontal interval are radial compression or circumferential tensile failure in fracturing period and micro-annulus cementation failure in flowback period.The micro-annulus cementation failure of cement sheath in flowback period is mainly influenced by the pressure difference inside and outside the wellbore and the elastic modulus of cement.The research results can provide scientific basis for the optimization of cement slurry material ratio and reservoir stimulation engineering parameters.

关 键 词：页岩油 水平井 体积压裂 水泥环失效 密封性能 胶结强度 微环隙 

分 类 号：TE934[石油与天然气工程—石油机械设备]