Study On Micro Scale Flow Mechanism Of Shale Gas Based On Lattice Boltzmann Method

As an important unconventional gas resource,shale gas has great potential for development.Shale reservoirs have complex micro-pore structure characteristics.Gas has complex micro-scale flow effects in these pores.The theory of macro-infiltration mechanics based on continuum hypothesis can no longer accurately characterize shale gas flow and requires new development.The simulation method simulates the gas flow in the micro-nanometer pores of shale in order to grasp the flow law of shale gas in the micro-pore,improve the accuracy of gas flow simulation in shale reservoirs,and provide certain efficiency for the development of shale gas reservoirs.Theoretical support.Based on the microscopic flow characteristics of gas in the nano-pores of shale,this paper establishes a micro-scale gas flow model of shale based on the lattice Boltzmann method,quantitatively analyzes the influencing factors of the micro-scale flow of shale gas,and obtains shale by establishing a digital core.Matrix gas flow related physical properties parameters.The main results and understanding obtained from the study are as follows:(1)The research status of the micro-scale flow mechanism of shale gas is summarized,and the physical characteristics and gas flow mechanism of shale reservoir are analyzed.(2)The basic principles of the lattice Boltzmann method are discussed.The commonly used boundary conditions and the program structure of the lattice Boltzmann method are introduced.The lattice Boltzmann model of the micro-scale flow of shale gas is deduced and the boundary conditions are given.(3)The reliability of the lattice Boltzmann method was verified by the classical Poiseuille flow contrast analysis.The influence of pressure and pore size on the flow of shale gas in the nanopores was analyzed,and the conclusion that the pressure energy could enhance the gas flow ability was obtained.The characteristics of the gas flow behavior of the rock gas,each factor has a greater impact on the gas flow in the transition zone.(4)An example study was conducted on the Fuling shale gas field,and the three-dimensional digital core was reconstructed using the OTSU and the MCMC method,and the reconstructed figures were verified by the autocorrelation function and the variogram function.The core can better characterize the physical properties of the actual core.The lattice Boltzmann method was used to calculate the physical properties of the digital core.Compared with the empirical formula,the simulation results had a higher degree of fit and the accuracy of the lattice Boltzmann method for the study of shale gas flow characteristics was verified.