Research On Flow And Heat Transfer Characteristics Of Gas In Porous Media Through Numerical Simulation

Porous media are found in all areas of production and life,which constitutes the entire biosphere of human life and the scholars have conducted extensive research on the behavioral characteristics of porous media for a long time.The shale is one of the typical natural porous media.The process of shale gas migration and flow in shale is essentially the energy and mass transfer process of shale gas in the shale porous media.There are random and disordered micro-nano scale pores or artificial macro-scale flow space fractures in the shale.The development process of shale gas involves many problems such as multi-scale effects and fluid-solid coupling,which makes the flow and heat transfer of shale gas becomes very complicated.There is great relationship between the flow and heat transfer capabilities of porous media and the complex structures of porous media,which making people not fully aware of the heat transfer and flow rules in shale porous media.Therefore,research on the flow and heat transfer characteristics of shale gas from the macro and micro perspectives become very important for us to comprehensive understanding of the flow and heat transfer process of shale gas in rock formations,and which will provide us the necessary theoretical support and technical guarantee for the development of shale gas.Firstly,research on the micro-characteristics of the flow and heat transfer of shale gas in a single sudden expansion and continuous expansion channel using the dual distribution model in the thermal lattice Boltzmann model combined with Matlab programming software.The results show that the fluid velocity and temperature gradient on the centerline in the continuously expanding channel are larger than in the single sudden expansion channel.As for the single sudden expansion channel,its cross-section expansion coefficient and Knudsen number have a greater impact on the heat transfer characteristics of gas flow,and the larger the section expansion coefficient,the more difficult to develop shale gas reservoirs.Secondly,research on the flow and heat transfer characteristics of shale gas in parallel connected channels through the CFD numerical simulation software,and to explore the characteristics of flow and heat transfer in the channels under varying angles.The research shows that with the increase of the deflection angle of the communication channel,the gas velocity in the channel is continuously decreasing,and the average temperature is slowly increasing.Studying the flow and heat transfer characteristics of rock gas in shale pores under typicalβ=30°at different flow pressure,and the results show that as the pressure difference gradually increases,the average gas flow rate increases,while the relatively high temperature region gradually decreases,and the temperature in local areas changes drastically due to disturbance.Finally,studying the flow and heat transfer characteristics of gas in random porous media based on the CFD numerical simulation method,and analyzing the effects of different porosities and thermal conductivity of solid frameworks on the thermal conductivity of porous media.It is found that as the porosity increases,the effective thermal conductivityλ_eff does not simply decrease linearly.When the thermal conductivity of the solid phase skeleton is large,the temperature distribution inside the porous medium becomes more uniform and the temperature gradient is small.Investigate the effect of pressure difference and porosity of porous media on its internal flow and heat transfer characteristics with consideration of flow heat transfer,the results show that the flow velocity of the fluid tends to increase linearly and monotonically as the pressure difference increases,the average flow velocity and average temperature of porous media are gradually increasing with the increase of porosity.In short,we have a better understanding of the flow and heat transfer characteristics of shale gas in shale porous media through the study of fluid flow and heat transfer processes in different structural channels of porous media under different technological conditions,and which making there are certain reference significance in development and enhanced oil recovery.