长封固段固井套管热应力分析

对于长封固段固井所用套管，由于井眼温度场的作用，使得固井温度平衡后产生一定的热应力。根据固井过程中及固井结束后井眼温度场变化，利用热弹性力学理论，推导了描述固井前后套管柱热应力的公式，并以此为基础建立了考虑热应力作用的套管柱安全系数计算新方法。研究发现：在热应力作用下套管柱抗拉、抗外挤安全系数有所降低，更易使套管产生破坏；使用常规套管安全系数计算方法设计长封固段套管柱有可能导致套管柱产生强度破坏。

Analysis of the Thermal Stress of Casing for Long Section Cementation

Thermal stress of casing for long section cementation yields because of the temperature change of casing before and after cementation. According to the distribution of the temperature field, using the related thermoelasticity theory, the thermal stress formulation is derived, and a new method of calculating the thermal stress and the safety coefficient of casing is presented. According to the research, the safety coefficient of casing descends under the effect of thermal stress, which makes the casing fail easier. The casing for long section cementation designed by conventional method may fail under the effect of thermal stress.