Simulation On Non-Darcy Flow Phenomena Through Tight Porous Media By Using Lattice Boltzmann Method

Non-Darcy flow is an important branch of flow in porous media. It plays a crucial role in the development of energy, chemical industry, material, life sciences and medical science. But the physical mechanism of nonlinear is limited to be cognitive due to the complexity of itself. When researching non-Darcy flow, traditional experimentation and resolution would encounter a difficult owing to the complexity inherent in porous media.Lattice Boltzmann method (LBM) is a new method of computational fluid dynamics, it has the advantage of depicting the interaction between different phases because of its microcosmic characteristic. Because the generalized lattice Boltzmann equation (GLBE) model proposed by Guo only depends on porous media statistical parameters, such as viscosity, porosity, permeability but no micro structure. GLBE model can be used in non-Darcy flow in porous media.In order to prove the feasibility of the LBM in the fluid simulation, a single relaxation time model was constructed and was used to simulate the cavity and poiseuille flows. On the base of porous media model, a GLBE model was built and validated through the simulation of Newton fluid flow in porous media. The flow characteristics within low pressure shows deviating off the linear relationship of Darcy law while gas flows at low velocity in a tight porous media, which presents non-Darcy phenomena. The influence of gas and the porous media characteristics on gas flow Klinkenberg effect is studied by using lattice Boltzmann method. Finally, through using the LBM, the flowage of power law Non-Newtonian fluid on porous media is simulated, flow state of Newtonian on tight porous media is analyzed, and the influence of Non-Darcy phenomena from pressure gradient and power law index is researched。The results show that the smaller the gas viscosity, net confining pressure, permeability and porosity in low pressure gradient grade, the bigger the distance between nonlinear critical point and pressure gradient. This indicates that the difference between Darcy phenomena linear relation and them is obvious. It identifies that Klinkenberg effect cannot be neglected within low permeability and low voltage. In particular there exists an influence of gas viscosity and porosity on Klinkenberg effect. Relation between gas seepage flow rate and pressure gradient is in line of Darcy phenomena, when net confining pressure or permeability is big enough. When power-law fluid is seepage, the flow curve displays Non-Darcy phenomenon. The bigger the power law index, the larger the departure grade to Darcy law.