Direct Numerical Simulation of Pore Scale Flow and Reactive Transport of CO2 in Porous Media.
Monday, 15 December 2014
Recently, the need to decrease CO2 concentration in the atmosphere has been recognized because of the role of CO2 as a greenhouse gas that contributes to global warming. Carbon Capture and Sequestration (CCS) is one of the most promising long term solutions for the reduction of CO2 in the atmosphere. To this end, injection of CO2 into deep geological formations has been proposed and investigated theoretically and experimentally in the last years. The fracture permeability, an important parameter controlling CO2 migration throughout sequestration, affects the amount of mineralization trapping of CO2 which enhances the long-term CO2 storage. A long-term geochemical modeling of subsurface CO2 storage is carried out in a single fracture to investigate its impact on CO2 transport and storage capacity. We model the fracture by considering flow of CO2 between finite plates. CO2 is initially dissolved in the brine and then precipitates during the geochemical reactions between H2O-CO2 and minerals. We study the physics and the critical time of blockage for a fracture to interpret the results. We employ direct numerical simulation tools and algorithms to simulate incompressible flow along with necessary transport equations that capture the kinetics of relevant chemical reactions. The numerical model is based on a finite difference method using a sequential non-iterative approach. It is found that mineral precipitation has an important effect on reservoir porosity and permeability. The fracture ceases to be a fluid channel because of the precipitation of minerals.