热采抗高温水泥石力学完整性研究  

Study on Mechanical Integrity of High Temperature Cement in Thermal Recovery Well

作　　者：陈毅 刘海龙[1,2] 张羽臣 贾立新 谢涛 Chen Yi;Liu Hailong;Zhang Yuchen;Jia Lixin;Xie Tao(CNOOC Tianjin Company;State Key Laboratory of Offshore Oil Exploitation)

机构地区：[1]中海石油(中国)有限公司天津分公司 [2]海洋石油高效开发国家重点实验室

出　　处：《石油机械》2018年第11期23-29,共7页China Petroleum Machinery

基　　金："十二五"国家科技重大专项"海上稠油油田高效开发示范工程"(2011ZX05057)

摘　　要：热采井固井水泥浆要在低温下实现迅速凝结,防止环空窜流,形成封闭完整性的水泥环,同时要具有抗高温强度衰减性能。为了研究热采抗高温水泥石的力学完整性,以水泥环完全固结之后的套管-水泥环-地层系统为研究对象,建立了组合体力学分析模型,推导了考虑温度效应的总应力分布解析解,提出了水泥环失效的判别准则,对热采井水泥环进行了评价试验,分析了地应力非均匀系数、水泥环弹性模量及热膨胀系数对组合体周向应力的影响。分析结果表明:以硅粉、低密惰性材料P69等构建的水泥石体系C可有效防止水泥石高温下的强度过度下降;组合体周向应力在径向上呈现"Z"形跳跃特性,第1界面处周向应力随地应力非均匀程度和水泥环弹性模量的升高、水泥环热膨胀系数的减小而降低,产生拉伸破坏的风险增大。所得结论可为稠油热采井的固井工艺设计提供指导。The cementing slurry for thermal recovery well is expected to cement at low temperature to prevent channeling in the annulus to form cement sheath with high-temperature strength attenuation resistance.Taking the casing-cement sheath-formation system as study object,the mechanical analysis model of the combined unit is established.The analytical solution of the total stress distribution considering the temperature effect is derived.The criterion for the failure of the cement sheath is proposed.The cement sheath in thermal recovery well was evaluated to analyze the influence of the non-uniformity coefficient of in-situ stress,the elastic modulus of the cement sheath and the thermal expansion coefficient on the circumferential stress of the combined unit.The analysis results show that the cement system C constructed with silicon powder,low-density inert material P69,new dispersant and new hardening accelerator can effectively prevent the excessive decrease of strength of cement stone at high temperature.The circumferential stress of the composite unit shows a Z-shaped jump in the radial direction.The circumferential stress at the first interface decreases with the increase of non-uniformity of the in-situ stress and elastic modulus of the cement sheath,and with the decrease of the thermal expansion coefficient of the cement sheath,resulting increased risk of tensile failure.The study could provide guidance for the cementing process design for heavy oil thermal recovery wells.

关 键 词：热采井 固井 水泥石 温度效应 周向应力 应力解析解 

分 类 号：TE21[石油与天然气工程—油气井工程]