A validation analysis of a reactive transport tool for predicting permeability and storage capacity changes resulting from CO2-brine-mineral reaction in carbonate reservoirs

摘要: Carbonate reservoirs are an attractive target for subsurface CO2 storage because reaction and dissolution of carbonate minerals (eg, calcite, dolomite) by CO2-acidified brine can alter pore space distributions, leading to changes in permeability and potential increases in storage capacity. Better prediction of the extent and timescale of these changes should result in improved estimates of CO2 storage capacity and lowered risks for reservoir management. Our past work (Carroll et al., 2013; Hao et al., 2013; Smith et al., 2013) has focused on the development of a continuum-scale reactive transport model for predicting the evolution of porosity and permeability during CO2-fluid-rock reaction, based on refinement and comparison with sixteen core-flooding experiments conducted on samples sourced from two different reservoirs. We employ two primary model parameters to describe mineral reactivity and permeability evolution: the kinetic rate constant for carbonate mineral reaction, k; and an exponential parameter, n, relating porosity and permeability, and have defined the expected range of both input values in Smith et al.(2017). Here we seek to validate the use of this continuumscale model and these parameter values against experimental data collected from samples obtained from a third carbonate reservoir (Duperow Formation, Montana, USA).Five core samples of variable initial permeability were reacted with CO2-acidified brine at relevant reservoir pressure and temperature conditions, and non-destructively imaged using X-ray computed tomography to quantify mineral and void volume changes as a result of reaction. We compare the extent …