Simulation Of Single- And Two-phase Flow In Porous Media By Lattice Boltzmann Methods

The study of fluid flow regularity in reservoir rock is the foundation of increasing for oil production and improvement for recovery,and the important research content in the field of oil development.Flowing in reservoir rock is the flow of oil,gas and water in porous media essentially.Lattice Boltzmann methods have great advantages in simulation of flowing with complex geometrical structure such as porous media,and can explain the fluidic interaction of multicomponent multiphase system at the micro-sizes.The simulation of single-phase flow and double-component double-phase flow in natural porous media using lattice Boltzmann methods is the research focus of this article.After obtaining porous media of digital core with CT scanning technology,we calculated the simulated value of permeability of 2D porous media with BGK model,MRT model and IncBGK model and studied dependence of permeability on viscosity and density of the fluid.Then we did the statistics of micro-parameters such as the pore radius of six digital cores for sandstone,simulated the single-phase flow in 3D porous media,studied the distribution of velocity field and pressure field,computing permeability of 3D porous media and then discussed the influence of different micro-parameters on the simulated value of permeability.Two-phase displacement in a single pore and 2D porous media was simulated using Shan-Chen model,then the fingering phenomenon which is influenced by the pore width and fluidic viscosity was studied and the effect of body force,viscosity and density of fluid on displacement in porous media was analyzed.In the single-phase simulation in 2D porous media,the simulated value of permeability shows dependence on viscosity of fluid for BGK model and IncBGK model,while for the TRT model the result shows inversely.The simulated value of permeability shows dependence on density of fluid for BGK model and TRT model,the result shows inversely for IncBGK model.The average pore radius of six digital cores ranges from 16.28?m to 21.16?m,and simulation error of permeability ranges from 2.4%to 26.9%in the single-phase simulation for six sandstone cores.The simulation error of permeability would be smaller if the value of the average pore radius,the average throat radius,the length of throat and pore vol?me is larger.In the velocity field of single-phase simultion,the flowing velocity is larger where the pore radius is small or the crossed pores join,and in the narrow channel or in the branch the flowing velocity is smaller.In the pressure field of single-phase simultion,pressure is smaller and smaller along the flow direction,which changes a lot where the pore radius is small so the pressure difference changes remarkably.While pressure keeps a constant and does not produce drop along the flow direction in some big pores which connected well or closed pores.In the double-component double-phase simulation,the wetting angle can be calculated correctly with the modified forms of Young's equation.The phase-interface sharpness is increased and the solubility of the fluids within each other is limited while the n?merical difficulties are intensified when the value of G_c is 1.5,while G_c is equal to 1.0 which alleviates some n?merical difficulties and can reduce the compressibility of fluids bedims the interface.Wider pores can increase the fingering length,bigger ratio of viscosity can accelerate the displacement and higher initial velocity can do the both in two-phase displacement in a sinlge pore.Higher diaplacement efficientcy can be reached with bigger displacing force or bigger ratio of viscosity in the two-phase displacement in 2D porous meida.The results of this article could provide some theoretical basis for the study of fluidic flow regularity in reservoir rock and improvement of the recovery efficiency.