CO2埋存井注入过程中水泥环应力完整性研究

CO2埋存井固井水泥环完整性直接涉及到CO2能否安全、长期有效的进行地质埋存,因此对埋存井水泥环完整性的分析是很有必要的。提出了CO2埋存井水泥环动态应力完整性模型,并分析了温降、地层孔隙压力的变化对水泥环应力完整性的影响。结果表明:温降和孔隙压力的增大均能对水泥环产生轴向诱导拉应力,温降和孔隙压力单独作用时,不足以使水泥环受拉而发生破坏。两者同时作用时,当温降和孔隙压力增加到一定值就会使水泥环发生轴向断裂。产生水平裂纹,所以为了保证水泥环完整性不发生破坏,在注入CO2时,要正确的处理好CO2的注入温度与注入速度的关系。

Research on Cement Sheath Stress Integrity of CO2 Buried Well in the Process of Injection

Cement sheath stress integrity of CO2 buried well directly involves CO2 whether can be safety and long-term effective geological buried or not , therefore the analysis of buried wells cement sheath integrity is very necessary. CO2 buried well cement sheath stress integrity model is rasied, and analyses the effects temperature drop and formation pore pressure change on cement sheath stress integrity.The results show that temperature drop and the increase of pore pressure are able to produce axial induced tensile stress to cement sheath, when temperature drop and pore pressure act separately, it is not enough to make cement sheath damaged for tensile stress;While they both acted , as temperature drop and pore pressure increases to a certain value will make cement sheath produce axial fracture and horizontal crack is appeared, So in order to ensure the integrity of cement sheath , before the injection of CO2, it is important to deal with the relation between injection temperature and injection speed correctly.