Low-permeability sedimentary formations, such as tight sandstones, exhibit fluid flow and transport phenomena distinct from those in conventional porous systems due to the dominance of micro- to nanometer-sized pores and variable amounts of boundary slip. The widely used traditional no-slip boundary condition often fails to accurately describe fluid behavior in these formations. A knowledge gap exists in understanding how liquid slip influences fluid dynamics in complex, heterogeneous sedimentary structures, as previous studies have primarily focused on simplified, homogeneous pore geometries. In this study, we investigated the impact of boundary slip on low-Reynolds number fluid dynamics within synthetically designed two-dimensional graded and random pore networks with varying pore-size distributions to account for heterogeneity. Our results showed that velocity variance increased with increasing heterogeneity, following a power-law relationship. The power-law exponents decreased with boundary slip, quantifying how boundary slip mitigated the impact of heterogeneity on velocity variance. We developed a theoretical model to predict asymptotic flow enhancement and derived constitutive relations to estimate the coefficient and maximum flow enhancement (Δ) based on the pore-to-grain size ratio and porosity. Energy dissipation increased with both heterogeneity and boundary slip, which we identified as the primary mechanism contributing to asymptotic flow enhancement. This relationship was illustrated by a 1:1 linear correlation between maximum energy dissipation and maximum flow enhancement, regardless of heterogeneity, indicating that energy dissipation due to boundary slip entirely controls the emerging fluid dynamics. The presented theoretical model and constitutive equations offer practical applications for optimizing fluid dynamics in heterogeneous formations.

中文翻译：

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沉积结构和孔径分布对液体边界滑移引起的渗透率放大和流动增强的影响：孔隙尺度计算研究


由于微米至纳米尺寸的孔隙和不同量的边界滑移占主导地位，低渗透性沉积地层（例如致密砂岩）表现出与传统多孔系统不同的流体流动和传输现象。广泛使用的传统无滑移边界条件通常无法准确描述这些地层中的流体行为。在理解液体滑移如何影响复杂、非均质沉积结构中的流体动力学方面存在知识差距，因为之前的研究主要集中在简化、均质的孔隙几何形状上。在这项研究中，我们研究了边界滑移对综合设计的二维分级和随机孔隙网络中低雷诺数流体动力学的影响，这些孔隙网络具有不同的孔径分布，以解释不均匀性。我们的结果表明，速度方差随着异质性的增加而增加，遵循幂律关系。幂律指数随着边界滑移而减小，量化边界滑移如何减轻不均匀性对速度方差的影响。我们开发了一个理论模型来预测渐近流动增强，并导出了本构关系，以根据孔与颗粒尺寸比和孔隙率来估计系数和最大流动增强（Δ）。能量耗散随着异质性和边界滑移的增加而增加，我们将其确定为有助于渐近流动增强的主要机制。无论异质性如何，最大能量耗散和最大流量增强之间的 1:1 线性相关性说明了这种关系，表明边界滑移引起的能量耗散完全控制了新兴的流体动力学。 所提出的理论模型和本构方程为优化非均质地层中的流体动力学提供了实际应用。