Dilatancy controlled gas flow is characterized by a series of gas pressure-induced dilatant pathways in which the pathway aperture is a function of the effective stress within the solid matrix. In this paper, a three-dimensional hydro-mechanical model is presented to simulate the gas migration in initially saturated claystone with considerable anisotropy. The governing equations including mass conservation, momentum balance and energy conservation are presented for the unsaturated rock containing three phases, i.e., gas, water and solid grain. The constitutive model is proposed in which two conceptualized fracture sets with nonlinear mechanical behavior and cubic law controlled permeability are inserted, which have a direct effect on the hydro-mechanical behavior of the equivalent continuum. Finally, the developed model is validated against three gas injection tests on initially saturated Callovo–Oxfordian claystone. In general, the model is capable of capturing the main features of dilatancy controlled flow, i.e., anisotropic radial deformation, major gas breakthrough, and mechanical volume dilation of the sample. The proposed model offers additional insight into the relation between gas flow, solid matrix deformation and fracture opening/closure, which helps us get in-depth understanding of this gas transport mechanism.

中文翻译：

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用于模拟各向异性粘土中膨胀控制气流的三维流体力学模型

膨胀控制气流的特征在于一系列气压引起的膨胀路径，其中路径孔径是固体基质内有效应力的函数。在本文中，提出了一个三维流体力学模型来模拟具有相当大各向异性的初始饱和粘土岩中的气体运移。给出了含气、水、固粒三相的非饱和岩石的质量守恒、动量平衡和能量守恒的控制方程。提出了本构模型，其中插入了两个具有非线性力学行为和三次定律控制渗透率的概念化裂缝组，这对等效连续体的流体力学行为有直接影响。最后，开发的模型在最初饱和的 Callovo-Oxfordian 粘土岩上进行了三项注气测试验证。一般而言，该模型能够捕捉剪胀控制流动的主要特征，即样品的各向异性径向变形、主要气体突破和机械体积膨胀。所提出的模型提供了对气体流动、固体基质变形和裂缝打开/关闭之间关系的额外洞察，这有助于我们深入了解这种气体传输机制。