基于ANSYS的油井套管可靠性分析与数值模拟

Reliability analysis and numerical simulation of casing in oil wells based on ANSYS

鉴于油气井套管柱的安全可靠性问题,通过对套管、水泥环及地层岩石的几何尺寸和力学性能以及套管载荷的随机性分析,提出了以概率论为基础的套管可靠性分析这一概念。运用ANSYS软件平台建立了"套管—水泥环—岩石"三层结构的三维有限元模型,并结合基于Monte-Carlo的Latin Hypercube随机模拟方法构建了套管的可靠性计算模型。分析了各种影响因素的随机性对套管可靠性的影响规律,并对实际工程中的套管进行了可靠性计算。研究结果表明,各因素的随机性能够降低套管的可靠性,但各因素的随机性对套管可靠性的影响情况存在较大差异。对于明显降低套管可靠性的影响因素,需要严格控制其随机性。

Aiming at the problem of safety and reliability of casing string of oil and gas wells, the randomness of geometric dimensions and mechanical properties of casing, cement ring and rock were discussed. The reliability analysis of casing based on probability theory is defined. The three-dimensional finite element model of three-layer structure of casing cement ring and rock was founded. The reliability model of casing was established by means of Latin Hypercube random simulation method based on Monte-Carlo method. The influences of the randomness of every factors on the randomness of casing reliability were analyzed. The reliability of casing in factual engineering was worked out. Results of the research indicate that the randomness of every factors can reduce the reliability of casing, but the influences of the randomness of every factors on the randomness of casing reliability are different. The randomness of the factors that reduce the reliability of casing markedly must be controlled strictly.