Numerical simulation of porosity and permeability evolution of Mount Simon sandstone under geological carbon sequestration conditions

Abstract

A numerical model was developed with the use of reactive transport code CrunchFlow to estimate porosity, permeability and mineral composition changes of Mount Simon sandstone under typical geological carbon sequestration conditions (P=23.8MPa and T=85°C). The model predicted a permeability decrease from 1.60mD to 1.02mD for the Mount Simon sandstone sample in a static batch reactor after 180days of exposure to CO2-saturated brine, which is consistent with measured permeability results. Model-predicted solution chemistry results were also consistent with laboratory-measured solution chemistry data. SiO2 (am) was the primary mineral that causes permeability decrease, followed by kaolinite. Both SiO2 (am) formation and kaolinite formation were attributed to the dissolution of quartz and feldspar. This study shows that the formation of SiO2 (am) and kaolinite in the pore space of host rock is possible under typical CO2 sequestration conditions. SiO2 (am) and kaolinite precipitation at the CO2 plume extent could reduce the permeability of host rock and improve lateral containment of free-phase CO2, contributing to overall security of CO2 storage.