Pore-scale study on miscible thermal displacing process in porous media using lattice Boltzmann method

A pore-scale investigation for a miscible thermal displacing process in porous media is performed in the present work using the lattice Boltzmann method. Particularly, the effects of viscous expansion coefficient beta(T) and Lewis number Le on the displacing patterns and the residual rate sigma are investigated. The numerical results show that the thermal displacement in porous media can be divided into four modes, i. e., one dominant displacement, conical displacement, local ramified displacement, and compact displacement. The prediction of the displacing modes for different values of beta(T) and Le is summarized. Quantities analysis for characterizing thermal displacement indicates that sigma in all simulation cases increases with beta(T) , but the evolution trends of the residual rate for different Le are different. When beta(T) > 0, the residual rate sigma decreases with the increasing Le, while for the cases with beta(T) < 0, the opposite is true. Furthermore, we found that sigma changes obviously in the range of Le 1/4 1-10, indicating that the thermal displacement mode can be easily changed by adjusting the thermal conductivity of the fluid to achieve different Lewis numbers of the system, thereby improving the displacement efficiency and displacement rate.

Automated summary

A pore-scale investigation using the lattice Boltzmann method was carried out to study the miscible thermal displacing process in porous media. The effects of viscous expansion coefficient beta(T) and Lewis number Le on the displacing patterns and the residual rate sigma were examined. The results showed four displacement modes in porous media: dominant displacement, conical displacement, local ramified displacement, and compact displacement. The quantity analysis revealed that sigma increased with beta(T) in all cases, but the evolution trends of the residual rate varied for different Le values. It was also found that adjusting the thermal conductivity of the fluid to achieve different Lewis numbers could change the thermal displacement mode, thereby improving displacement efficiency and rate.