水泥环周向缺失的热采井井筒热应力耦合分析

Thermal-stress coupling analysis of thermal recovery wells with cement sheath circumferential discontinuity

为研究热采井中水泥环周向局部破坏对套管力学性能的影响,利用ABAQUS软件建立了水泥环圆周方向上不同缺失程度的有限元模型,研究了在蒸汽吞吐过程中,套管应力、位移的变化规律。分析结果表明:由于水泥环周向上的缺失,在井筒中产生的温度分布不均,使得水泥环缺失部分的套管外壁温度和井壁温度低于水泥环完好部分的套管外壁温度和井壁温度;水泥环缺失程度对套管上的等效应力峰值影响较大,随着水泥环周向缺失程度的增大,套管上产生的Von M ises等效应力峰值逐渐减小;水泥环周向缺失程度为30°时,套管径向变形较大,随着水泥环周向缺失程度的增大,套管径向变形随之减小。该分析结果为热采井中的套管损坏机理研究提供了理论依据。

In order to analyze the effect of the local circumferential breakdown of the cement sheath on the casing mechanics properties in thermal recovery wells, the finite element model of cement sheath circumferential discontinuity is established using the ABAQUS program. The variation laws of casing stress and deviation is studied during the process of steam stimulation. The result shows that the borehole temperature fluctuates due to the cement sheath circumferential discontinuity. As a result, the temperature outside the casing - wall and the borehole temperature without cement sheath are lower than that with perfect cement sheath. Cement sheath discontinuity exerts great effect on the equivalent stress peak value. The equivalent stress peak value Von Mises declines as the degree of cement sheath circumferential discontinuity increases. When the cement sheath circumferential discontinuity is 30°, the casing deforms much in the radial direction. It will drop as the degree of cement sheath circumferential discontinuity increases. The analysis provides theoretical basis for the mechanisml research of casing failure in thermal recovery wells.