Impacts of dynamic capillary pressure effects in supercritical CO2-Water flow: Experiments and numerical simulations

Abstract

Contrary to report that dynamic capillary pressure effect was insignificant in the supercritical CO2-water (scCO2-water) flow system, this work found the effect to be considerable in the displacement of water or brine by injected scCO2in the geological carbon sequestration, especially prior to the attainment of equilibrium in the system.Series of controlled laboratory scale experimental measurements and numerical simulations of the dynamic capillary pressure effect and its magnitude (dynamic coefficient, τ ) for supercritical CO2-water(scCO2-water) system are reported inunconsolidated silica sand. Novel measurement technique has been developed to achieve this purpose, by applying the concept of two-phase flow system in the context of geological carbon sequestration. This work considers the injection of scCO2 into storage aquifer as a two-phase flow system, where the CO2 displaces the resident fluid (brine or water). Using a high-pressure and high-temperature experimental rig, capillary pressure-saturation relationships (P c -S) for this flow system and the saturation rate dependencies of theP c -S relationships (quantified by dynamic coefficient, τ ), known as dynamic capillary pressure effect were determined. This τ was previously unreported for scCO2-water system. In scCO2water flow system, τ ranges from 2 x10 5 to 6 x10 5 Pa s at high water saturation and 1.3 x 10 6 to 8 x10 6 Pa saround the irreducible saturation. τ increases with rising temperature but decreases with increase in porous medium permeability.Numerically determined τ -S relationships compare well with the corresponding experimental results for wide range of water saturation.The implication was that Page 2 of 36 water saturation of the porous media will be considerably underestimated, if the dynamic capillary pressure effectwas ignored in the characterization of the scCO2water flow system , i.e., if only equilibrium Pcrelationship was used.

Physico-chemical and dielectric parameters for the monitoring of carbon sequestration in basalt and silica media

“…Carbon capture and sequestration (CCS) is a promising approach for reducing atmospheric CO2 emission (Abidoye and Das, 2020;Kim et al, 2018;Terzi et al, 2014). The process starts with the capture of CO2 primarily from power plants, transport through pipeline or ships and injection into a geological formation (Rabiu et al, 2017b;Myer, 2011).…”

“…Salinity is less 2 important in basalt rock but, its consideration is essential in saline aquifers typically composed of silica sand. Injection of CO2 into saline aquifer has been considered as a two-phase flow process because the injected CO2 (non-wetting phase) displaces the resident brine water (wetting phase) during the drainage process (Abidoye and Das, 2020;Ajayi et al, 2019;Cao et al, 2020). On the other hand, when the injection of CO2 stops, the resident brine water (wetting phase) tends to displace the CO2 (non-wetting phase) during an imbibition process (Ajayi et al, 2019;Cao et al, 2020).…”