Dispersion Coefficient Inferred from Convection Dynamics of CO2 in Brine Saturated Porous Media

Abstract

Summary Mass transfer rate estimation is an important aspect of the dissolution trapping mechanism analysis during CO2 sequestration in saline aquifers which has been studied extensively in recent years. Based on laboratory experiments or direct numerical simulation tools, scaling relationships have been introduced for the mass transfer rate estimation. However, there are discrepancies between these results. To investigate the discrepancies between experimental and direct numerical simulation results, we carried out a series of experiments to quantify dispersion during CO2 convective mixing, which enabled us to obtain robust scaling relationships. Two brine compositions including sodium chloride (NaCl) and a mixture of NaCl and calcium chloride (CaCl2) are separately considered in two levels with two levels of permeability to encompass the applicable range of the Peclet number (Pe). Furthermore, we conducted a series of high resolution direct numerical simulations to show the applicability of the proposed relationship in simulation. Our analysis of results reveals that a power-law scaling relationship based on the Pe best fits the dispersion values. Furthermore, numerical simulation results show that dispersion has a considerable impact on the pattern and amount of CO2 dissolution in brine.