Lattice Boltzmann Simulation of Fluid Flow Characteristics in a Rock Micro-Fracture Based on the Pseudo-Potential Model

Abstract

Slip boundary has an important influence on fluid flow, which is non-negligible in rock micro-fractures. In this paper, an improved pseudo-potential multi-relaxation-time (MRT) lattice Boltzmann method (LBM), which can achieve a large density ratio, is introduced to simulate the fluid flow in a micro-fracture. The model is tested to satisfy thermodynamic consistency and simulate Poiseuille flow in the case of large liquid-gas density ratio. The slip length is used as an index for evaluating the flow characteristics, and the effects of wall wettability, micro-fracture width, driving pressure and liquid-gas density ratio on the slip length are discussed. The results demonstrate that the slip length increases significantly with the increase of the wall contact angle in rock micro-fracture. And the liquid-gas density ratio has an important impact on the slip length, especially for the hydrophobic wall. Moreover, under the laminar flow regime the driving pressure and the micro-fracture width has little effect on the slip length.

Recent Advances in Flow and Transport Properties of Unconventional Reservoirs

“…By introducing an improved pseudopotential multirelaxation-time lattice Boltzmann method, Wang et al [12] simulated the fluid flow in a microfracture. The effects of contact angles, driving pressure, and the liquid-gas density ratio on the slip length were discussed.…”

Study on Seepage Simulation of High Pressure Grouting in Microfractured Rock Mass

“…With large deformation and continuous rheology of the surrounding rock, fractures in the rock mass are prone to squeezing and closing. A large number of underdeveloped and closed low-permeability microfractures exist in the surrounding rock [15][16][17]. Owing to the small fracture opening, cement particles cannot enter the microfractures, resulting in poor grouting and support effects as well as failure to achieve the expected reinforcement [18].…”