橡胶套筒对非均匀地应力下固井水泥环受力的影响分析  

Effect of rubber sleeve on the stress of cement sheath under non-uniform geologic stress

作　　者：王宴滨 曾静 高德利[1] 房军[1] Wang Yanbin;Zeng Jing;Gao Deli;Fang Jun(MOE Key Laboratory of Petroleum Engineering,China University of Petroleum,102249,Beijing,China)

机构地区：[1]中国石油大学(北京)石油工程教育部重点实验室,北京102249

出　　处：《应用力学学报》2020年第4期1731-1736,I0024,共7页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金青年基金(51804321);国家自然科学基金创新研究群体项目(51821092);国家科技重大专项课题(2017ZX05009-003);国家科技重大专项子课题(2017ZX05005005-007);国家重点研发计划课题(2016YFC0303303,2018YFB0605502);中国石油大学(北京)科研基金(00000)。

摘　　要：针对固井水泥环密封失效引起的环空气窜问题,本文提出了在套管外部安装一层橡胶套筒的方案,利用橡胶材料的超弹性能缓解水泥环的受力变形。建立了非均匀地应力和套管内压作用下的套管-橡胶套筒-水泥环-地层力学特性分析的有限元模型,研究了水泥环内壁的受力变形和等效塑性应变,分析了橡胶套筒材料属性对水泥环受力变形的影响。结果表明:当套管内压为90MPa时,无橡胶套筒条件下水泥环内壁的等效塑性应变为5.36×10^-2,套管的最大Von-Mises应力为525.2MPa,有橡胶套筒时(橡胶套筒厚度为6mm)水泥环内壁的等效塑性应变为7.63×10^-5,套管的最大Von-Mises应力为772.8MPa;橡胶套筒大幅缓解了水泥环的塑性变形,但对其受力状态不利;要使橡胶套筒对水泥环的等效塑性应变起到较好的改善作用,其厚度应大于3mm,硬度应大于85。研究结果对环空带压的预防和控制具有参考价值。In order to solve the problem of gas channeling caused by the failure of cement sheath seal, put forward a countermeasure in this paper, where a layer of rubber sleeve is installed outside of the casing. The mechanical characteristics of cement sheath can be improved by the hyper-elasticity of the rubber sleeve. The finite element analysis model of casing-rubber sleeve-cement sheath-formation under the combined action of non-uniform in-situ stress and inner pressure is established. The variations of stress and deformation and the equivalent plastic strain of inner wall of cement sheath are obtained. On this basis, influence of the mechanical properties of the rubber sleeve on stress of cement sheath is studied. Analysis results show that when the thickness of rubber sleeve is 6 mm and the casing inner pressure is 90 MPa, the equivalent plastic deformation of the cement sheath inner wall is 5.36×10^-2, and the maximum Von-Mises stress of the casing is 525.2 MPa if there is no rubber sleeve. However, if there is a rubber sleeve, the equivalent plastic deformation of the cement sheath inner wall is 1.07×10^-4, and the maximum Von-Mises stress of the casing is 772.8 MPa. The rubber sleeve greatly alleviates the plastic deformation of cement, but it is unfavorable to the stress state of the casing. According to the influence analysis of rubber material, in order to improve the equivalent plastic deformation of cement sheath, the thickness of rubber sleeve should be more than 3 mm and the hardness should be more than 85. The results are of reference value for the prevention and control of annular pressure.

关 键 词：井筒完整性 环空带压 弹性橡胶套筒 力学特性 

分 类 号：TE24[石油与天然气工程—油气井工程]