2018/01/08 by Baole Wen, Wen, Baole, Daria Ahkbari +5
Engineering · Environmental Science · #CO2 Sequestration and Geologic Interactions #Enhanced Oil Recovery Techniques #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Methane Hydrates and Related Phenomena
paper · pdf · doi:10.48550/arxiv.1801.02537
openalex publication_date 2018/01/08 · openalex created_date 2018/01/26 · openalex updated_date 2026/07/28
Motivated by geological carbon dioxide (CO2) storage, many recent studies have investigated the fluid dynamics of solutal convection in porous media. Here we study the convective dissolution of CO2 in a closed system, where the pressure in the gas declines as convection proceeds. This introduces a negative feedback that reduces the convective dissolution rate even before the brine becomes saturated. We analyse the case of an ideal gas with a solubility given by Henry's law, in the limits of very low and very high Rayleigh numbers. The equilibrium state in this system is determined by the dimensionless dissolution capacity, Π, which gives the fraction of the gas that can be dissolved into the underlying brine. Analytic approximations of the pure diffusion problem with Π>0, show that the diffusive base state is no longer self-similar and that diffusive mass transfer declines rapidly with time. Direct numerical simulations at high Rayleigh numbers show that no constant flux regime exists for Π> 0; nevertheless, the quantity F/Cs2 remains constant, where F is the dissolution flux and Cs is the dissolved concentration at the top of the domain. Simple mathematical models are developed to predict the evolution of Cs and F for high-Rayleigh-number convection in a closed system. The negative feedback that limits convection in closed systems may explain the persistence of natural CO2 accumulations over millennial timescales.