基于组合体力学模型的固井水泥石封隔能力分析

为探究水力压裂过程中水泥石封隔失效的内在机理，建立了一套基于套管-水泥石-地层组合体弹塑性力学模型的水泥石封隔能力失效分析方法，并通过数值模拟和实验分别验证了力学模型和分析方法的可靠性.然后借助等效应力与屈服强度、应变与材料极限伸长率的对比，绘制了水泥石封隔能力图版.研究表明:水泥石弹性模量对水泥石封隔能力影响存在最优区间，在本文研究条件下，水泥石弹性模量在6~9.7GPa之间有利于保持水泥石封隔能力.研究结果可为不同地区页岩气水平井固井水泥参数选择提供参考.

Sealing Capacity Analysis of Cement Sheath Based on Combined Mechanical Model

In order to explore the mechanism of cement sheath sealing failure during hydraulic fracturing， a failure analysis method of cement sheath sealing capacity based on combined casing-cement-formation elastic-plastic mechanical model was established. The reliability of the mechanical model and analysis method was verified by numerical simulation and experimental data. With the comparison of equivalent stress and yield strength， strain and ultimate elongation of the material， the cement sheath sealing capacity chart was drawn. The research shows that there is an optimal range for the influence of the elastic modulus of the cement sheath on its sealing capacity. Under the conditions presented in this paper， the elastic modulus of the cement sheath between 6 and 9.7GPa is beneficial to maintain its sealing capacity. This study can provide a reference for the cement parameters selection in horizontal well in different shale formations.