固井水泥环性质和厚度对套管承载能力的影响研究

Study on Effects of Cement Sheath Quality(Characteristics and Thickness) on the Load-bearing Capacity of Casing

油气井固井注水泥作业主要目的就是要形成质量较好的水泥环,起到支撑及保护套管的作用。但在钻井和开发过程中,水泥环会受到多种不利载荷的影响,如温度应力、地层岩石围压、套管内压力等,使水泥环不能起到有效保护套管的作用。本文以某口井作为研究对象,根据弹性力学的相关理论并结合有限元方法,通过建立有限元模型,利用和操作有限元分析软件ANSYS,系统的研究了水泥环性质、厚度,对套管的承载能力的影响规律,并根据以上情况提出了相应的措施,用于指导现场工程实践。

The aim of cementing in the wellbore is to get good quality cement sheath between the wellbore and the casing to protect and sustain the casing. But during the process of development and drilling, the cement sheath will bear many kinds of loads, such as temperature stress, confining pressure of rock, casing pressure and so on, which can cause the cement sheath not protect the casing effectively. In this paper, taking one well as the research object, on the basis of correlated theories of elastic mechanics, the finite element model was established. The ANSYS program was used to study the influencing tendencies of cement sheath quality （characteristics and thickness） on casing retaining capacity. At last, some suitable measures were put forward according to these complex situations to guide the engineering practice.