The Influence of Temperature Gradient on the Convective Mixing Phenomena of Geologic Sequestration of CO2

Abstract

Geological sequestration of CO2 as an effective measure of greenhouse gas emission reduction has seized the attention of many governments and scientists. But few studies concern the effect of temperature field on the CO2 convective mixing process. In fact, the temperature gradient almost exists anywhere in the underground, especially the saline aquifer where the temperature increases with soil depth. A numerical model is developed to simulate the heat and mass transfer in the saline aquifer. The effect of initial temperature field on convective mixing flow is presented in this paper. Boussinesq approximation is used to simplify the governing equations. High accuracy compact difference schemes and Runge-Kutta methods are used to simulate the temperature field and CO2 concentration field. Meanwhile a fourth-order precision iterative algorithm is adopted to solve the pressure Poisson equation. Numerical simulation results show that the effects of temperature field are: accelerating the occurrence of convection, strengthening the convective effect and accelerating the CO2 dissolve.