论文标题

局部嵌入式离散断裂模型(LEDFM)

Local Embedded Discrete Fracture Model (LEDFM)

论文作者

Losapio, Davide, Scotti, Anna

论文摘要

裂缝多孔培养基中流量的研究是许多地球科学应用的关键要素,例如储层管理和地热能生产。这些高度异构和几何复杂系统的建模和模拟需要采用非标准数值方案。嵌入式离散断裂模型(EDFM)是一种说明裂缝和常规网格的裂缝的简单有效方法,但它具有某些局限性:它假设骨折周围有线性压力分布,这仅能远离尖端和骨折相互作用,并且仅用于高度可传输的分裂。在本文中,我们提出了EDFM的改进,旨在克服这些限制,以计算裂缝和周围多孔介质之间的改善耦合,a)放松线性压力分布假设,b)考虑不可渗透的裂缝修饰近乎骨折的透射性。这些结果是通过使用精细的符合网格解决不同类型的局部问题并计算新的透射性(对于裂缝与周围多孔培养基之间的连接以及通过裂缝附近的多孔培养基本身的连接)来实现这些结果。此类局部问题是由于文献中存在的数值升级技术的启发。新方法称为局部嵌入式离散断裂模型(LEDFM),从几个数值测试获得的结果证实了上述改进。

The study of flow in fractured porous media is a key ingredient for many geoscience applications, such as reservoir management and geothermal energy production. Modelling and simulation of these highly heterogeneous and geometrically complex systems require the adoption of non-standard numerical schemes. The Embedded Discrete Fracture Model (EDFM) is a simple and effective way to account for fractures with coarse and regular grids, but it suffers from some limitations: it assumes a linear pressure distribution around fractures, which holds true only far from the tips and fracture intersections, and it can be employed for highly permeable fractures only. In this paper we propose an improvement of EDFM which aims at overcoming these limitations computing an improved coupling between fractures and the surrounding porous medium by a) relaxing the linear pressure distribution assumption, b) accounting for impermeable fractures modifying near-fracture transmissibilities. These results are achieved by solving different types of local problems with a fine conforming grid, and computing new transmissibilities (for connections between fractures and the surrounding porous medium and those through the porous medium itself near to the fractures). Such local problems are inspired from numerical upscaling techniques present in the literature. The new method is called Local Embedded Discrete Fracture Model (LEDFM) and the results obtained from several numerical tests confirm the aforementioned improvements.

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