The simplified view of two-phase flow, such as oil and gas, in a fracture is often assumed to occur in a stratified behavior. However, recent studies and production practices have revealed that two-phase flow in fractures exhibits diverse flow patterns. This paper investigates the control of the fracture aperture, fluids viscosity, and wettability on two-phase flow in a 2D cross section of a 3D Berea fracture. Lattice Boltzmann Method (LBM) simulations are used to model the impact of these properties on relative permeability curves. Notably, in strongly wet fractures, two distinct permeability regimes emerge. High aperture values exhibit behavior resembling parallel planes, while low aperture values lead to a linear decrease in permeability due to fluid interactions between fracture surfaces. Conversely, anomalous behavior of the relative permeability curves is identified in weakly wet fractures within specific aperture ranges. This behavior is associated with the occurrence of specific flow patterns within the fracture. Results also emphasize that changes in viscosity ratio do not affect the presence or the saturation range of the anomalous behavior but do influence its intensity for each fluid. Comparisons with Poiseuille profile equations reveal the limited impact of the fracture roughness. These findings enhance our understanding of the interactions between aperture, viscosity, and wettability and how they control the shape of the relative permeability curves. These curves are pivotal parameters for the continuum scale modeling (reservoir models) in oil and gas application, for instance.

中文翻译：

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对强湿和弱湿天然裂缝相对渗透率的孔隙尺度洞察：格子玻尔兹曼方法二维模拟研究


裂缝中两相流（例如石油和天然气）的简化视图通常被认为以分层行为发生。然而，最近的研究和生产实践表明，裂缝中的两相流表现出不同的流动模式。本文研究了裂缝孔径、流体粘度和润湿性对 3D Berea 裂缝的 2D 横截面中两相流的控制。格子玻尔兹曼方法 (LBM) 模拟用于模拟这些特性对相对渗透率曲线的影响。值得注意的是，在强湿裂缝中，出现了两种不同的渗透率状态。高孔径值表现出类似于平行平面的行为，而低孔径值则由于裂缝表面之间的流体相互作用而导致渗透率线性下降。相反，在特定孔径范围内的弱湿裂缝中发现了相对渗透率曲线的异常行为。这种行为与裂缝内特定流动模式的发生有关。结果还强调，粘度比的变化不会影响异常行为的存在或饱和范围，但会影响每种流体的强度。与泊肃叶轮廓方程的比较揭示了断裂粗糙度的影响有限。这些发现增强了我们对孔径、粘度和润湿性之间相互作用以及它们如何控制相对渗透率曲线形状的理解。例如，这些曲线是石油和天然气应用中连续尺度建模（储层模型）的关键参数。