Pore-scale study of miscible density instability with viscosity contrast in porous media
Pore-scale study of miscible density instability with viscosity contrast in porous media
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DOI：
10.1063/5.0161872
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发表时间：
2023-09
影响因子：
4.6
通讯作者：
Jin Chen;Geng Wang;Junyu Yang;Timan Lei;K. H. Luo
中科院分区：
文献类型：
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作者：
Jin Chen;Geng Wang;Junyu Yang;Timan Lei;K. H. Luo
可混溶流体在多孔介质中的传输是一种普遍存在的现象，发生在各种自然和工业环境中。然而，这种基本现象通常与界面不稳定性（例如，粘性/密度指进），这还有待彻底研究。本文采用多重弛豫时间格子Boltzmann方法，在孔隙尺度上研究了密度差（Rayleigh数Ra）、粘度差（R）和注入速度（Utop）共存的多孔介质中两种可混溶流体之间的驱替问题。进行参数研究以评估Ra、R和Utop对流动稳定性的影响。当Ra一定时，R或Utop的增大会抑制密度指进。因此，在较大的Utop和中等的R下，密度指进完全稳定，流动遵循稳定的模式。此外，当R和Utop都增长到足够高的水平时，它们可以共同触发粘性指进。此外，Ra的增加对密度指进和粘性指进都有增强作用。最后，通过定量分析指进长度（lm）和指进传播时间（te），五种不同的流动模式分为粘度抑制（I），粘度增强（II），粘度不稳定（III），位移抑制（IV）和稳定（V）的制度。在由Ra、R和Utop构成的三维参数空间中，根据lm和te确定五种状态的参数范围。这些研究结果具有重要的价值，提供指导，通过选择适当的操作条件来控制流动稳定性。
The transport of miscible fluids in porous media is a prevalent phenomenon that occurs in various natural and industrial contexts. However, this fundamental phenomenon is usually coupled with interface instabilities (e.g., viscous/density fingering), which has yet to be thoroughly investigated. In this paper, a multiple-relaxation-time lattice Boltzmann method is applied to study the displacement between two miscible fluids in porous media at the pore scale, with the coexistence of density difference (Rayleigh number Ra), viscosity contrast (R), and injection velocity (Utop). A parametric study is conducted to evaluate the impact of Ra, R, and Utop on the flow stability. For a fixed Ra that can trigger density fingering, the increase in R or Utop is found to suppress density fingering. Consequently, under a large Utop and a moderate R, the density fingering is fully stabilized and the flow follows a stabile pattern. Furthermore, as both R and Utop grow to a sufficiently high level, they can jointly trigger viscous fingering. In addition, the increasing Ra shows an enhancing effect on both density fingering and viscous fingering. Finally, by quantitatively analyzing the fingering length (lm) and the fingering propagation time (te), five different flow patterns are classified as viscosity-suppressed (I), viscosity-enhanced (II), viscosity-unstable (III), displacement-suppressed (IV), and stable (V) regimes. In a three-dimensional parameter space spanned by Ra, R, and Utop, the parameter ranges of the five regimes are determined according to lm and te. These findings hold a significant value in providing guidance for controlling the flow stability by selecting appropriate operating conditions.