Study On Viscous Coupling Effect Of Multiphase Seepage Considering Gravity Stratification

In the development and exploitation of oil and gas fields,the seepage of fluids in the formation rocks of porous pores,ie porous media,is one of the key physical processes.Studying the seepage law of fluid in porous media is of great significance for improving oil and gas field recovery.Due to the complexity of the pore structure of porous media,traditional nunerical simulation methods such as finite element method,finite volume method,finite difference method,etc.the boundary processing is complicated,the program implementation is difficult,and the lattice Boltzmann method can be very useful as a mesoscopic numerical simulation method.It is a good idea to overcome the difficulties of complex boundary processing and the program is easy to implement,which provides a new idea for seepage simulation in porous media.Based on the above characteristics,based on the lattice Boltzmann phase field model,the two-phase seepage characteristics considering the gravity stratification effect are studied by the lattice Boltzmann method at the pore scale,and the two-phase flow of the two-dimensional porous medium is further studied.The influence mechanism reveals the influence of gravity factors on the viscous coupling effect of multiphase seepage from the perspective of physical mechanism.The main work done in this paper is as follows:(1)The research and development of the lattice Boltzmann method in multiphase flow,and the basic theory and model of the lattice Boltzmann method.(2)A lattice Boltzmann program based on the gravity factor is developed based on the Python language.A random algorithm is used to generate a homogeneous and heterogeneous model of the two-dimensional porous medium with corresponding porosity and the corresponding boundary conditions are applied in the flow field.(3)The reliability of the two-phase flow simulation is verified by the three benchmarks of Hagen-Poisu flow,Rayleigh-Taylor Instabilitya nd contact angle test.The single-hole Hagen-Posu is further studied.Viscous coupling effect in the flow of leaves.The study was then extended to the actual porous media flow.The effects of wettability,viscosity ratio,surface tension,pressure gradient and matrix heterogeneity on the viscous coupling in the porous media flow were evaluated by a series of simulations.(4)A series of LBM numerical simulation comparison studies were carried out by controlling gravity factors to analyze the influence mechanism of gravity stratification on two-phase porous media two-phase flow.