The effect of anisotropic dispersion on the convective mixing in long‐term CO₂ storage in saline aquifers

Abstract

in Wiley Online Library (wileyonlinelibrary.com).Carbon dioxide storage in deep saline aquifers is considered a possible option to bring greenhouse gas emissions under control. The understanding of the underlying mechanisms, such as convective mixing and associated mechanisms, affecting this mixing may have an impact on the long-term sequestration process in deep saline aquifers. One of the significant aspects of the flow of miscible species in porous media is velocity dependent dispersion. The effect of dispersion on dissolution of carbon dioxide (CO 2 ) into brine is investigated by full nonlinear numerical simulations. This study reveals that dispersion may dramatically change the trend of CO 2 dissolution into brine. It was found that the dissolution of CO 2 increases as dispersion strength increases. The mixing pattern also shows three different mechanisms: diffusion, convection, and a highly nonlinear interaction mechanism. However, the medium dispersivity ratios were found to slightly affect the mixing, while having an impact on the fingering pattern.

Modeling Pathways and Stages of CO2 Storage

“…Three adjacent fingers of similar size arrange themselves to a pattern, showing only three major fingers. Such behaviour was also observed by Gesmat et al [26]. In this simulation the c=0.1 contour has not reached the base yet.…”

“…For the consideration of temperature effects in the borehole see Sponagle et al [23]. Double diffusive effects, arising from coupled mass and heat transport, are studied by Bouzgarrou et al [24] and Islam et al [25].The effects of anisotropic dispersion are examined by Ghesmat et al [26], as well as by Musuuza et al [27,28]. In this paper inhomogenities are taken into account, as they trigger convective motions.…”

Characterizing the Dissolution Rate of CO2-Brine in Porous Media under Gaseous and Supercritical Conditions

“…High contact between the injected brine and the CO 2 surface (i.e., low bypassing) resulted in a greater CO 2 dissolution rate (shown in Figure 2 R3). Particularly for supercritical CO 2 under larger buoyancy forces, the faster growth of perturbations existed over time, which can provoke a more complicated structure of fingers and also more CO 2 dissolution into brine [17]. In contrast, the CO 2 bubbles located parallel to the flow direction led to more bypass trapping and lower average effluent concentrations [26].…”

“…Meanwhile, higher diffusivity generally supports solubility trapping [16]. When the CO 2 -brine system is strongly dispersive, more CO 2 will dissolve into the brine, and the dissolution process will be accelerated [17]. As the CO 2 solubility is enhanced under a supercritical state, it is expected that increasing pressure in deeper aquifers can greatly promote the solubility of CO 2 in aqueous solution [18].…”

A short review on porous media convection

“…Recent studies by [70][71][72][73][74][75][76][77][78][79][80] indicate that at large Ra hydrodynamic dispersion significantly affects the flow pattern and transport of convection in porous media. Although most of the studies agree that hydrodynamic dispersion coarsens the convective pattern, [71,72] show that the hydrodynamic dispersion enhances the convective mixing, while the laboratory experiments by [75,77] reveal that it reduces the increase of convective flux with increasing permeability.…”