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运用有限元软件模拟分析了井筒内压达到预期的25MPa,温度从28℃升高到50℃的极限状态时,套管和下封头等应力的变化情况。结合储气井现场现象建立了井筒工况模型,采用平面四节点等参元划分网格,使实际三维井筒模型简化为平面应变问题加以处理。详细分析温度变化对套管、套管与接箍以及套管与下封头的应力变化。经过计算分析,温度升高使得套管与下封头在充气、储气以及放气过程中的应力增加但处于弹性变化范围内,不过套管在这种长期交变载荷的作用下,可能会产生疲劳破坏。
The finite element software was used to simulate and analyze the changes of stress such as casing and lower head when the internal pressure of wellbore reached the expected 25MPa and the temperature was raised from 28 ℃ to 50 ℃. A wellbore condition model was established based on the field phenomenon in the gas well. The four-grid isoparametric element was used to divide the grid so that the actual three-dimensional wellbore model was simplified to the plane strain problem. Detailed analysis of the temperature changes on the casing, casing and coupling and the casing and the lower head of the stress changes. After the calculation and analysis, the temperature increase makes the casing and the lower head in the inflation, gas storage and deflation process increases the stress but in the elastic range, but the casing in this long-term alternating load may be Fatigue damage.