摘要：Heavy oil is an important oil resource. The main development method is thermal exploitation—steam stimulation. Drastic variation in temperature will result in thermally induced micro-gaps in the first interface during steam stimulation. The existence of micro-gaps will cause steam channeling in the hole and difficulty in engineering logging interpretation. According to the stress of casing string of thermal production wells and thermal injection model, the mechanical model of casing string of thermal production wells is divided into four intervals for further analysis, including the wellhead movement extension interval, the extension and compression movement interval between low-temperature zones, the packer movement interval, and the extension and compression movement interval between perforation sections. For different casing string intervals, two types of mathematical models of first interface micro-gap width are established. In order to comprehensively evaluate the micro-gaps, the mathematical model comprehensively evaluating cement sheath micro-gaps is established through superposition and geometric mean of two models. The models can be used to calculate the first interface micro-gap width of different intervals. In addition, the tri-strata axial symmetric finite element model of first interface with micro-gap is established, and the variation in temperature field, stress field, and width of micro-gap interval of wellbore is analyzed, which provides the theoretical basis for evaluation of micro-gaps.
关键词：Thermal production well; finite element; first interface; micro-gap; mathematical model
