非均匀地应力下蠕变地层套管的载荷分布

地层蠕变效应是引起套管损坏的主要原因之一,在非均匀地应力下,如何计算蠕变地层作用于套管上的最终稳定载荷是一个非常困难的问题.将套管看成弹性体,把地层视为无穷大的粘弹性体,建立了非均匀地应力条件下蠕变地层的开尔文模型本构方程,运用应力分析法和拉普拉斯变换法,求解出非均匀地应力条件下蠕变地层套管的载荷,并分析了套管载荷的分布.结果表明,当套管刚度较大时,经过足够长的时间,套管载荷趋于一个稳定的最大载荷分布,且其值接近于完全弹性解.

Casing loads distribution with non-uniform in-situ stresses in creep stratum

The casing loads in creep stratum under non-uniform in-situ stresses were studied, which is one of the main factors to damage casing. It is very. hard to calculate the finally steady casing loads under non-uniform in-situ stresses in creep stratum. The casing was taken as tile elastic foundation and the stratum as infinite viscoelastic foundation, and then a Kelvin model was built to analyze the casing loads under non-uniform in-situ stresses in creep stratum. By stress analytical method and Laplace transform method, the distribution rules of casing loads under non-uniform in-sitn stresses in creep stratum were studied. Based on the viscoelastic theory, the formulas to calculate casing stresses were obtained. The results show that if the stiffness is big enough, the casing loads will go to a stable and maximal loads distribution, and the value will approach the elastic solution with sufficient time duration.