Numerical simulation of reactive barrier emplacement to control CO2 migration

Abstract

Long-term storage of anthropogenic CO2 in the subsurface generally requires that caprock formations will serve as physical barriers to upward migration of CO2. As a result, geological carbon storage (GCS) projects require reliable techniques to monitor for newly formed leaks, and the ability to rapidly deploy mitigation measures should leakage occur. Here, we develop a two-dimensional reactive transport simulation to analyse the hydrogeochemical characteristics of a newly formed CO2 leak entering an overlying reservoir and emplacement of a hypothetical pH dependent sealant in the vicinity of the leak. Simulations are conducted using the TOUGHREACT multi-component reactive transport code, focusing on the comparatively short time period of days to months following formation of the leak. The simulations are used to evaluate (1) geochemical shifts in formation water indicative of the leak, (2) hydrodynamics of pumping wells in the vicinity of the leak, and (3) delivery of a sealant to the leak through an adjacent well bore.