页岩气体积压裂固井界面微环隙产生机理研究  

Research on Micro-gap Generation of Shale Gas Well Cementing Interface during SRV Fracturing

作　　者：范明涛[1] 李军[1] 柳贡慧[1,2] 陈晓欣 Fan Mingtao;Li Jun;Liu Gonghui;Chen Xiaoxin(College of Petroleum Engineering,China University of Petroleum(Beijing);Beijing University of Technology;No.2 Drilling Company,Zhongyuan Petroleum Engineering Company,SINOPEC))

机构地区：[1]中国石油大学(北京)石油与天然气工程学院 [2]北京工业大学 [3]中国石化中原石油工程有限公司钻井二公司

出　　处：《石油机械》2018年第10期78-82,共5页China Petroleum Machinery

基　　金：国家自然科学基金联合基金重点项目"页岩气水平井井筒完整性失效机理与控制方法"(U1762211);国家自然科学基金面上项目"长水平段非均质页岩储层非均匀分簇射孔优化研究"(51674272);国家科技重大专项"复杂结构井分簇射孔完井设计优化新技术"(2017ZX05009)

摘　　要：页岩气体积压裂施工过程中地层性质以及固井质量的变化,可能会导致固井界面微环隙的产生,从而威胁油气井的正常生产。为了准确了解页岩气井施工过程中固井界面微环隙的产生规律,基于分步有限元方法,采用场变量以及生死单元技术构建了考虑固井界面存在微环隙的井筒组合体变形数值模型,分析了水泥浆失重、压裂过程中地应力、地层弹性模量变化以及水泥环性质对固井界面微环隙的影响。研究结果表明:压裂过程中地应力的亏空以及水泥浆的失重提高了微环隙产生的概率。微环隙尺寸随着压裂过程中地层弹性模量的降低有所减小;根据施工环境,适当降低水泥环弹性模量有助于降低固井界面微环隙产生的概率。建立的有限元模型以及研究结果能够为压裂施工作业中油气井环空带压的产生提供理论依据。The changes of formation properties and cementing quality during shale gas SRV fracturing may result in micro-gap at the cementing interface,thus imposing hazard on the production of oil and gas wells.To accurately understand the generation of micro-gap in cementing interface during shale gas well operation,based on the step-by-step finite element method,the numerical model of wellbore assembly deformation considering the micro-gap at cementing interface was established by using field variables and birth and death element technology.The effects of weightlessness of cement slurry,ground stress and stratum elastic modulus change during fracturing,and cement sheath properties on micro-gap of cementing interface were analyzed.The results showed that the reduction of the ground stress and the weightlessness of the cement slurry increase the probability of micro-gap generation during fracturing.The micro-gap size decreases with the decrease of the stratum modulus during the fracturing process.According to the construction environment,properly reduced elastic modulus of the cement sheath can reduce the probability of micro-gap generation at the cementing interface.The established finite element model and the research results could provide theoretical bases for the generation of annulus pressure in oil and gas wells during fracturing operations.

关 键 词：页岩气 微环隙 体积压裂 水泥浆失重 分步有限元 地层性质 

分 类 号：TE934[石油与天然气工程—石油机械设备]