模拟水压致裂的二维FDEM-flow方法

水压致裂在非常规天然气开采中被广为采用,对该问题的研究具有重要意义。基于FEM/DEM耦合分析方法,提出解决FEM/DEM方法中流–固耦合问题的理论框架,称之为FDEM-flow方法,并结合贯通节理裂隙网络形成的递归搜索算法,为在二维情形下考虑流–固耦合驱动下的岩体破裂问题提供完整的解决方案,并给出实现流–固耦合的整个计算流程。通过2个含有解析解的裂隙渗流算例,验证本文提出方法求解纯裂隙渗流问题的正确性。最后,通过一个流体驱动下的岩体破裂算例,展现提出的方法在模拟流–固耦合驱动下的岩体破裂问题的巨大潜力,为模拟页岩气开采中的水压致裂问题提供了新途径。

A 2D FDEM-FLOW METHOD FOR SIMULATING HYDRAULIC FRACTURING

Hydraulic fracturing is a commonly-used technique in unconventional gas rupture(such as shale gas) exploration. A theoretical framework，called FDEM-flow method，for analyzing flow-structure interaction was proposed based on FEM/DEM. Combined with the recursive algorithm of searching the fracture network formed，a complete solution was developed to simulate the hydraulic fracturing of rock under the coupled action of fluid and solid in two-dimensional condition. The results from the proposed method agree well with the analytical solutions in two seepage cases，which verifies the correctness of the proposed method. An example of hydraulic fracturing was analyzed. The results demonstrate that the proposed method has a good potential in simulating hydraulic fracturing and that the method might provide a new way to simulate the hydraulic fracturing in the exploitation of shale gas.