Impact of elastic parameters of cement ring on structural integrity of casing-cement ring-strata cementing combination

In the process of the oil and gas well operations such as casing pressure test, fracturing, etc., casing-cement ring- strata cementing combination will have stress and deformation response. Under the condition of high load, the cement ring body damage, cementing interface tear, and other forms of structural failure may occur, which may make the effect of cement ring sealing worsen. The casing-cement ring-strata cementing combination finite element mechanics model was established by using the mechanics theory and finite element theory in the paper. The impact of elastic parameters of cement on the casing-cement ring- strata cementing combination structural integrity was analyzed. The results showed that, when the elastic modulus of cement ring was smaller, the deformability was better, and cement stone was more difficult to be hardness crushed after load, while the tear resistance was better after unload; The smaller the poisson ratio was, the harder the cement was to be crushed under the geological conditions of high in-situ stress. The larger the poisson ratio was, the harder the cementation interface was to be tore under the geological conditions of low in-situ stress. The optimization of cement ring elastic perameters should be based on specific circumstances such as cementing well depth in the comprehensive consideration of loading and unloading methods in engineering designing.