Optimization of CO2 Sequestration in Reservoirs under Geochemistry and Thermal Effects

Abstract

Abstract Disposal and long-term sequestration of anthropogenic " greenhouse gases" such as CO2 is a proposed approach to reducing global warming. Deep, regional-scale aquifers in sedimentary basins are possible sites for sequestration, given their ubiquitous nature. In order for CO2 to be stored in aquifers responsibly, it is essential to identify key concepts that need to be considered for potential implementation. Ideally, 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 have concerned not just scientific and technical aspects, but practical concerns such as the 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 too 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 in order to investigate the significance of the major parameters on performance of wells in CO2 sequestration under geochemistry and thermal effects. CO2 injection is done for first 25 years. The injector is shut-in thereafter and the fate of CO2 is modeled for the next 225 years. Chemical equilibrium constants are functions of temperature. Trace gas is used. Molecular diffusion of CO2 in water is modeled. Thermal effects due to injection of CO2 at are modeled. 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 in tornado diagrams. It is observed that a robust approach on handling of uncertainties in reservoir are 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.