Study On Thermal-structure Coupling Stress Field Of Steam Injection Casing

There are many casing damage problems in steam injection wells of heavy oil, the causes of casing damage are manifold, high temperature is one of the most important influence factor. Using the finite element analysis technology, This paper have studied casing thermal-structure coupling stress distribution of steam injection wells and the influence of temperature, steam injection pressure, residual stress on casing damage, then put forward prevention measures and suggestions according to the results of the analysis.The research content of this article is divided into the following points:1. through collecting the data, this paper maked an induction and analysis on the current research status of steam injection wells casing at home and abroad, and maked an analysis of steam injection wells casing damage mechanism and the impact of various geologic and engineering factors on the casing damage;2. this paper maked the analysis of load stress for the conventional casing string and the triaxial calculated model of thermal stress for steam injection wells casing string;3. this paper also maked an analysis of various existing casing damage mechanics model for steam injection wells, among them the true three-dimensional casing-cement ring-rock system mechanics model can simulate the real stress and deformation of casing;4. using ANSYS software, this paper have developed a APDL program of steam injection wells casing true three-dimensional casing-cement ring-rock system for heat-structure coupling finite element analysis, first maked a analysis of the plane model and true three-dimensional model of casing-cement ring-rock system, finally maked an analysis of the influence of various parameters on the stress distribution of casing string;5. through the analysis of residual stress on steam injection wells casing, this paper have studied the mechanism of residual stress and the calculated model of casing residual stress in multiple circular, using the finite element to make the simulation analysis and compare residual stress of different casing types in multiple loop;6. through the above analysis this paper have put forward some prevention measures and suggestions of steam injection wells casing.The article used the true three-dimensional casing-cement ring-rock system to make the finite element simulation analysis of thermal-structure coupling for steam injection wells casing with taking into account the high temperature as well as the non-uniform ground stress and the form of geological structure, reflected the actual stress of the casing, and provided a new research method for the study of steam injection wells casing damage.