Hypothesis

Based on energy balance during two-phase displacement in porous media, it has recently been shown that a thermodynamically consistent contact angle can be determined from micro-tomography images. However, the impact of viscous dissipation on the energy balance has not been fully understood. Furthermore, it is of great importance to determine the spatial distribution of wettability. We use direct numerical simulation to validate the determination of the thermodynamic contact angle both on an entire domain and on a pore-by-pore basis.

Simulations

Two-phase direct numerical simulations are performed on complex 3D porous media with three wettability states: uniformly water-wet, uniformly oil-wet, and non-uniform mixed-wet. Using the simulated fluid configurations, the thermodynamic contact angle is computed, then compared with the input contact angles.

Findings

The impact of viscous dissipation on the energy balance is quantified; it is insignificant for water flooding in water-wet and mixed-wet media, resulting in an accurate estimation of a representative contact angle for the entire domain even if viscous effects are ignored. An increasing trend in the computed thermodynamic contact angle during water injection is shown to be a manifestation of the displacement sequence. Furthermore, the spatial distribution of wettability can be represented by the thermodynamic contact angle computed on a pore-by-pore basis.

中文翻译：

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使用能量平衡来确定孔尺度的润湿性。

假设

基于多孔介质中两相位移过程中的能量平衡，最近表明，可以从显微断层图像确定热力学一致的接触角。但是，粘性耗散对能量平衡的影响尚未完全了解。此外，确定润湿性的空间分布非常重要。我们使用直接数值模拟来验证在整个域和逐孔基础上热力学接触角的确定。

模拟

在具有三种润湿状态的复杂3D多孔介质上执行两阶段直接数值模拟：均匀水湿，均匀油湿和非均匀混合湿。使用模拟的流体配置，计算热力学接触角，然后与输入接触角进行比较。

发现

量化了粘性耗散对能量平衡的影响；对于在水湿介质和混合湿介质中的水驱来说，这是微不足道的，即使忽略了粘性效应，也可以准确估算整个区域的典型接触角。在注水过程中，计算出的热力学接触角的增加趋势显示出位移序列。此外，润湿性的空间分布可以通过基于孔的计算的热力学接触角来表示。