CO_(2)封存井筒密封性及强化方法  

CO_(2)Sequestration Wellbore Sealing and Enhancement Method

作　　者：王典 李军[1,2] 连威 刘献博 张俊成 郭少坤 WANG Dian;LI Jun;LIAN Wei;LIU Xianbo;ZHANG Juncheng;GUO Shaokun(College of Petroleum Engineering,China University of Petroleum(Beijing),Beijing 102249,China;College of Petroleum,China University of Petroleum-Beijing at Karamay,Karamay 834000,China)

机构地区：[1]中国石油大学(北京)石油工程学院,北京102200 [2]中国石油大学(北京)克拉玛依校区石油学院,克拉玛依834000

出　　处：《华南师范大学学报（自然科学版）》2024年第1期1-8,共8页Journal of South China Normal University(Natural Science Edition)

基　　金：国家自然科学基金联合基金项目(U23B2081);中石油科技创新基金项目(2022DQ02-0605)。

摘　　要：考虑CO_(2)封存井筒的实际服役环境,基于有限元方法建立了含水泥腐蚀层的井筒屏障模型,模拟了水泥塞-地层界面微环隙发育过程,厘清了流体驱动下微环隙扩展机制及主控因素,提出了井筒密封性强化方法。模拟结果表明:超临界CO_(2)聚积会引起水泥胶结面应力改变,当界面处应力由压应力转为拉应力,且应力值高于界面胶结强度时,井筒便会产生微环隙;若水泥腐蚀后腐蚀层刚度、界面胶结强度下降,则井筒密封能力下降;膨胀性添加剂可提高胶结面初始压应力,进而增强井筒密封性。当水泥塞膨胀率为0.5‰时,微环隙扩展压力上升43.7%,微环隙长度下降了42.7%,井筒密封性得到显著增强。Considering the service environment of the CO_(2)sequestration wellbore,a wellbore model containing a cement corrosion layer was developed.Based on the finite element method,the development process of micro-annu⁃lus at the cement plug-formation interface was simulated,the mechanism of micro-annulus expansion and the main controlling factors under the fluid drive were clarified,and the method of wellbore sealing enhancement was pro⁃posed.The simulation results show that the supercritical CO_(2)accumulation will cause a change in the stress at the cement bonding surface.When the stress at the interface changes from compressive to tensile,and the stress value is higher than the bonding strength,micro-annulus will be generated in the wellbore.If the cement stiffness and bonding strength decrease after corrosion,the wellbore sealing decreases;the expansive additive can increase the initial compressive stress of the bonding surface and then enhance the wellbore sealing.When the expansion rate is 0.5‰,the micro-annulus propagation pressure rises by 43.7%,the micro-annulus length decreases by 42.7%,and the wellbore sealing is significantly enhanced.

关 键 词：CO_(2)封存井筒 密封性 微环隙 水泥塞 强化方法 

分 类 号：TE4[石油与天然气工程—油气田开发工程]