王典, 李军, 连威, 刘献博, 张俊成, 郭少坤. CO2封存井筒密封性及强化方法[J]. 华南师范大学学报(自然科学版), 2024, 56(1): 1-8. doi: 10.6054/j.jscnun.2024001
引用本文: 王典, 李军, 连威, 刘献博, 张俊成, 郭少坤. CO2封存井筒密封性及强化方法[J]. 华南师范大学学报(自然科学版), 2024, 56(1): 1-8. doi: 10.6054/j.jscnun.2024001
WANG Dian, LI Jun, LIAN Wei, LIU Xianbo, ZHANG Juncheng, GUO Shaokun. CO2 Sequestration Wellbore Sealing and Enhancement Method[J]. Journal of South China Normal University (Natural Science Edition), 2024, 56(1): 1-8. doi: 10.6054/j.jscnun.2024001
Citation: WANG Dian, LI Jun, LIAN Wei, LIU Xianbo, ZHANG Juncheng, GUO Shaokun. CO2 Sequestration Wellbore Sealing and Enhancement Method[J]. Journal of South China Normal University (Natural Science Edition), 2024, 56(1): 1-8. doi: 10.6054/j.jscnun.2024001

CO2封存井筒密封性及强化方法

CO2 Sequestration Wellbore Sealing and Enhancement Method

  • 摘要: 考虑CO2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CO2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。

     

    Abstract: Considering the service environment of the CO2 sequestration wellbore, a wellbore model containing a cement corrosion layer was developed. Based on the finite element method, the development process of micro-annulus 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 proposed. The simulation results show that the supercritical CO2 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.

     

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