Establishment and Application of Cement Sheath Integrity Risk Evaluation Model for CO2 Flooding Wells

In response to the issue of annular space pressure in CO2 flooding wells, this paper analyzed the cement sheath seal integrity from a life-cycle perspective, taking into account various influencing factors. The evaluation of cement sheath integrity for CO2 flooding well was divided into three parts: cementing quality, ability to withstand temperature and pressure changes, and environmental corrosion strength, and then the cement sheath integrity evaluation index was given, and the weight of each integrity risk factor was determined by analytic hierarchy process. On this basis, the cement sheath integrity risk evaluation model for CO2 flooding wells was established by fuzzy comprehensive evaluation method, and the integrity risk value and risk grade were determined. By using the method above, the cement slurry performance and cementing parameters in CO2 flooding block of Jilin oilfield were optimized, which reduced the failure risk of cement sheath integrity and guaranteed the long-term safe production of injection-production wells.