基于粘土吸水膨胀地层的套管柱设计

发布时间：2018-08-28 20:54

【摘要】：套管柱强度分析及设计是钻井设计的关键技术,是关系到钻井成本、油气井连续稳定生产的重要因素。目前,随着油气田勘探和开发技术的发展,套管深度的增加,套管下入层次的增多,套管的受力和变形越来越复杂,这就对套管设计提出了更高的要求。本文针对粘土吸水膨胀地层这种特殊的地质条件,结合胜利坨142区块的套管损坏情况,围绕套管柱外部载荷、套管的三轴强度设计理论、套管非均载荷下的承载能力有限元仿真等内容展开研究。本文首先分析了套管柱承受的外部载荷,根据总结的计算方法求出套管的有效内压力、有效外挤压力及有效轴向力,为得到套管的双轴强度和三轴强度及进行强度校核打下了基础。然后推导了套管的双轴强度和三轴强度计算公式,在进行套管柱设计时首先按照抗挤强度选择套管型号,然后再通过抗内压强度和抗拉强度对套管强度进行校核,如果抗内压或抗拉强度不满足设计要求,需要重新选择套管进行抗内压强度设计,直到选出符合要求的套管为止。接着采用APDL语言建立了套管的参数化模型,设置非线性相关参数,通过改变套管的壁厚,钢级及加载长度,利用ANSYS有限元分析软件的屈曲分析模块对套管的承载能力进行仿真,针对套管的不同工况,得到承载能力随套管径向变形的变化曲线和套管的屈曲载荷,获得非均载荷下套管的承载能力降低百分比,分析粘土吸水膨胀地层套管承载能力的变化规律。最后,给出了求解套管柱下入长度的算法并利用VB软件开发了粘土吸水膨胀地层套管柱设计系统,该软件具有界面友好,操作简单,数据管理全面,调用ANSYS软件,直接输出设计报告和强度曲线的功能。可以为钻井设计工程师进行套管柱设计提供可靠的理论依据和有力的技术支持,对减少套管设计周期具有重要意义。
[Abstract]:The strength analysis and design of casing string is a key technology in drilling design and an important factor related to drilling cost and continuous and stable production of oil and gas wells. At present, with the development of exploration and development technology in oil and gas fields, the depth of casing increases, the casing level increases, and the stress and deformation of casing become more and more complex, which puts forward higher requirements for casing design. In this paper, according to the special geological conditions of clay water absorption and swelling formation, combined with the casing damage in Shengtuo 142 block, the theory of triaxial strength design of casing around the external load of casing string and casing is discussed in this paper. The finite element simulation of bearing capacity of casing under non-uniform load is studied. In this paper, the external load of casing string is analyzed, and the effective internal pressure, effective external extrusion pressure and effective axial force are calculated according to the calculation method. It lays a foundation for obtaining the biaxial strength and triaxial strength of casing and for strength checking. Then, the calculation formulas of biaxial and triaxial strength of casing are derived. The casing type is selected according to the strength of the casing string first, and then the strength of the casing is checked through the strength of internal pressure and tensile strength. If the internal pressure or tensile strength does not meet the design requirements, the casing shall be re-selected for the internal pressure strength design until the required casing is selected. Then the parametric model of casing is established by APDL language, and the nonlinear parameters are set up. By changing the wall thickness, steel grade and loading length of casing, the buckling analysis module of ANSYS finite element analysis software is used to simulate the bearing capacity of casing. According to the different working conditions of casing, the curve of bearing capacity with casing radial deformation and the buckling load of casing are obtained, and the percentage of casing bearing capacity under non-uniform load is obtained. The variation law of casing bearing capacity in clay water-absorbing and expanding formation is analyzed. Finally, an algorithm for calculating the length of casing string is given, and a casing string design system is developed by using VB software. The software has the advantages of friendly interface, simple operation, comprehensive data management, and the transfer of ANSYS software. Direct output design report and strength curve function. It can provide reliable theoretical basis and powerful technical support for casing string design of drilling design engineers. It is of great significance to reduce casing design cycle.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE931.2

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