水泥环弹性模量和泊松比与地层性质匹配关系研究

Research on Matching Cement's Elastic Modulus and Poisson's Ratio with Formation Lithology

针对现有文献在固井水泥环对套管载荷影响的研究中存在片面性的现状,以套管和水泥环受力优化为目标,采用有限元方法系统分析了水泥环弹性模量和泊松比与井场周围不同地层的匹配关系。通过实例分析与讨论,分别研究了均匀地应力和非均匀地应力条件下水泥环性质对套管强度的影响规律,提出了改善套管受力状况不应以牺牲水泥环为代价的原则。通过数据和实例分析表明:如果能根据井场周围不同性质的地层优选水泥环弹性模量和泊松比则可大大改善套管受力状况;而且,不论地层参数如何,理想固井水泥环应该是高强度、低刚度、小泊松比。

Considering the limitation of current researches which investigates the impact of cement sheath on casing load, for the purpose of optimizing the load on casing and cement, the matching of cement＇s elastic modulus and Poisson＇s ratio with formation lithology around the wellbore was analyzed using finite element method. The impact of cement sheath property on casing collapse strength was investigated under uniform and non-uniform formation stress. It points out that the improvement in the casing stress conditions should not impact on the cement sheath. It shows that if the cements modulus of elasticity and Poisson＇s ratio can be optimized according to the formation lithology, then casing stress can be greatly improved. The ideal cement should have high strength, low stiffness and low Poisson＇s ratio regardless of formation.