Optimization of CO2 Sequestration in Aquifers under Geochemistry and Thermal Effects

Abstract

Abstract Disposal and long-term sequestration of anthropogenic "greenhouse gases," such as, CO2 is a proposed approach for reducing global warming. Deep, regional-scale aquifers in sedimentary basins are possible sites for sequestration, given their ubiquitous nature. For Carbon dioxide (CO2) to be stored in aquifers responsibly, it is essential to identify key concepts that need to be considered for potential implementation. Ideally, the injected CO2 will migrate through an aquifer from injection wells to remote storage sites, and remain isolated from the atmosphere for a considerable period of time. Fundamental topics of interest in sequestration research are not just concerned with scientific and technical aspects, but also with practical concerns, such as, economic feasibility of storage, safety, and the maximum possible amount of CO2 storage globally and for specified regions. Thus, it is crucial to have a robust understanding of this important process not only in theory, but in practice as well through illustration with solid examples as in this study. A robust commercial optimization and uncertainty software is coupled with a full-physics commercial simulator that models the phenomenon to investigate the significance of major parameters on performance of wells in CO2 sequestration, under geochemistry and thermal effects. CO2 injection is first done for 25 years then the injector is shut-in and the molecular diffusion of CO2 in water is modelled for the next 225 years. Thermal effects due to injection of CO2 are also modelled. Sensitivity and optimization have been done on major reservoir parameters, such as, fluid and rock properties and well operational parameters, and then significance of each has been illustrated through tornado diagrams. It is observed that a robust approach on handling of uncertainties in the reservoir is as important as management of well operational parameters in the scope of reservoir management. Presence of impact of geochemistry and temperature effects have proven to play an important role in the process. This study provides an in-depth optimization and uncertainty analysis to outline the significance of each major parameter involved in the performance, and CO2 sequestration in aquifers where influence of temperature and geochemistry is present.