水平井内套管柱下入过程的数值模拟

Numerical simulation of the running process of the casing string in horizontal wells

利用有限元软件建立了水平井中弯曲井眼段套管柱下入的力学模型,动态模拟了水平井眼造斜段内套管柱的下入过程,并对套管柱在下入过程中的受力情况进行了分析。结果表明,套管柱进入弯曲段后,最大等效应力首先发生在套管柱的底部,随着套管柱下入深度的增加,套管上的等效应力值不断变化,同时套管柱在下入过程中会发生塑性变形。下入过程中,由于套管的弯曲和阻力作用会促使套管与井壁呈交错接触状态。大曲率井眼中管柱下井所需的下入力比小曲率井中所需的下入力要大,这与实际的管柱下入过程相吻合。井眼的摩阻条件对套管的安全下入有较大影响,光滑的井眼条件产生的摩阻力更小,更加有利于套管柱的下入。

The finite element software was applied to establish the mechanical model of the running process of the casing string in the bending-hole section of the horizontal well.The running process of the casing string in the whipstocking section was simulated dynamically,and the force condition of the casing string was analyzed.The result shows that,when the string runs into the bending section,the maximum equivalent stress first occurs at the string bottom.As the string runs deeper,the equivalent stress value on casing constantly varies.Meanwhile,the string will undergo a plastic deformation in the running process in which casing and well-wall have an alternating contact due to casing bending and resistance.The running force required by the string in boreholes of great curvature is larger than that of small-curvature boreholes,which is in agreement with the actual string running process.The friction resistance condition of the borehole has great effect on the safe running of casing.The smooth borehole condition produces smaller friction resistance and is more favorable to the running of the casing string.