考虑水力耦合的射孔围岩水力压裂破裂数值模拟方法

以多孔介质流体渗流和围岩应力耦合理论为基础,提出一种基于有限容积法(FVM)的水力耦合作用下射孔围岩水力压裂破裂数值模拟方法。首先,考虑初始地应力和流体渗流对射孔围岩的影响,运用坐标转换和叠加原理得到围岩应力分布。其次,考虑围岩渗透率和孔隙度的应力敏感性,通过渗流力学分析确定射孔围岩的流体压力。最后,探讨水力压裂射孔围岩破裂准则的基础上,构建考虑水力耦合的射孔围岩水力压裂力学模型,并基于有限容积法对渗流方程和应力方程予以离散,提出水力耦合作用下射孔围岩水力压裂破裂数值模拟方法。该方法实现了流体渗流与围岩应力的耦合,可精确求解水力耦合作用下射孔围岩水力压裂破裂压力和破裂时间,亦能对流体压力和围岩渗透率演化予以准确描述。相关成果丰富了水力压裂破裂机理的研究,亦可对实际工程设计提供重要的参考。

Calculating minimum perforating depth with consideration of plastic deformation around well-hole

In order to obtain the perforation depth, the three zones with different permeability because of plastic deformation and fluid invasion were studied based on related theories. The study shows that the calculation of perforation depth should take account of not only damaged zone, but also plastic zone, because the plastic zone has much lower permeability. The required minimum perforation depth was obtained by making the solution of elastic/plastic equations, and the factors affecting perforation depth were analyzed accordingly.