1. Pore-scale insight into the effect of porous walls on fluid flow in rough-walled fractures.
- Author
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Li, Changdong, Zhu, Yinbin, Zhou, Jia-Qing, Xiang, Linyu, Jiang, Xihui, and Zhu, Wenyu
- Subjects
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FLUID flow , *ROCK deformation , *FRACTURING fluids , *HYDRAULIC fracturing , *REGRESSION analysis , *POROSITY , *HYDRAULIC conductivity - Abstract
• Impacts of wall porosity on fracture flow were systematically investigated at pore scale. • Mechanisms governing direction and magnitude of fluid exchange at the fracture-matrix interface were elucidated. • Flux contributions of porous walls to fracture outlet and fracture-matrix interface were functionalized by wall porosity. • Influence of porous walls cannot be equivalently represented by applying slip boundary conditions. This study investigates the influence of porous walls on fluid flow behavior in single rough-walled fractures. A series of direct numerical simulations (DNS) were conducted to examine fluid flow through rough-walled fractures surrounded by porous walls under various hydraulic gradients. The simulation results clearly demonstrate the progressively significant impact of porous walls on flow characteristics as porosity increases. Regression analyses indicate that the Forchheimer's law, which characterizes the nonlinear flow of rock fractures, remains valid in the presence of porous walls. Moreover, increased porosity enhances fluid exchange and leads to an increased ability for single fractures to transmit fluid. Two double-parameter equations were established to quantitatively characterize the effects of porous walls on hydraulic conductivity of the fracture and fluid exchange between porous walls and the fracture. Further analysis revealed that the angle between the fracture profile and main flow direction profoundly influences the inflow/outflow exchange between the fracture and its adjacent porous walls. Moreover, the pore-scale results indicate that it is unreasonable to equate the effect of porous walls with slip boundaries as suggested in previous studies. The results and findings of this study deepen our understanding of flow behavior at the interface between the rough-walled fracture and adjacent porous walls, and they serve as a basis for accurately simulating large-scale fracture networks that consider the hydraulic contribution of fracture walls. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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