考虑泥岩软化特性的油藏渗流场与地应力场耦合分析

为研究注水过程中流固耦合作用下套管损坏的力学机理,在传统的Biot方程基础上,考虑储层渗透性随地应力的变化关系及泥岩进水软化的本构关系,建立了注采过程中流体与固体介质的非线性耦合的数学模型;对大型有限元分析软件ABAQUS进行了二次开发,采用全耦合的有限元法对所建立的模型进行求解.对大庆油田南二区某块注水开发过程中,考虑泥岩软化和不考虑泥岩软化两种情况的计算对比表明,泥岩软化对地层特别是井壁附近围岩应力和变形影响很大.本文的研究结果为合理建立油藏注水开发的流固耦合计算模型,预测该地区地层变形、套管损坏等提供了依据.

Coupling effect of the seepage and stress fields in reservoir on casing damage under considering the softening of mudstone

In order to study the mechanic mechanism of casing damage under the coupling effect of reservoir seepage field and stress field,the non-linear fluid—solid coupling mathematical model in water-flooding process is established based on the conventional Biot equation,in which the variation of reservoir permeability with formation stress and the softening of mudstone because of water absorbing are considered.The secondary development of finite element software ABAQUS is carried out,and the modified finite element software is used to solve the model.The calculating results under considering and not considering the softening of mudstone show that the mudstone softening has great effect on the stress and deformation of the formation especially near well-bore.The research result can provide basis for the establishment of the fluid—solid coupling model for reservoir water-injection development and the prediction of formation deformation and casing damage.