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页岩气钻井保持泥页岩井壁稳定是关键问题。本文在流-固耦合研究基础上,进一步考虑泥页岩损伤与水化作用的耦合影响,建立了渗流-应力-损伤-水化耦合模型,编制了多场耦合子程序,以ABAQUS软件为平台,实现了泥页岩井壁稳定多场耦合数值模拟。模拟得到了井壁围岩吸水后的破坏规律。本例中,泥页岩水化效应使得损伤增大幅度为+0.41和+0.30,非均匀地应力的作用使得损伤增大幅度为+0.58和+0.47,同时考虑水化效应后围岩损伤范围大幅增加。模拟计算表明泥页岩水化效应的影响不容忽视,该方法能为定量分析泥页岩水化对井壁稳定性的影响提供一种可行途径。
Shale gas drilling is the key issue to maintain the stability of shale lining. Based on the study of fluid-solid coupling, coupled with the coupling between shale damage and hydration, the seepage-stress-damage-hydration coupling model is established and several coupling subroutines are developed. ABAQUS software is used as the platform , The multi-field coupled numerical simulation of shale well wall stability is achieved. The damage law of surrounding rock of wellbore after absorbing water was simulated. In this case, the shale hydration effect makes the damage increase by +0.41 and +0.30, and the effect of non-uniform stress makes the damage increase by +0.58 and +0.47, taking into account the damage range of surrounding rock after hydration effect A substantial increase. The simulation results show that the influence of shale hydration can not be ignored. This method can provide a feasible approach for the quantitative analysis of the influence of shale hydration on the stability of the shaft.