Youngsoo Lee

The effect of capillary-trapped CO2 on oil recovery and CO2 sequestration during the WAG process

ABSTRACT This study investigated capillary-trapped CO2 depending on the consideration of hysteresis effect in relative permeability for various water-alternation-gas (WAG) operating conditions to ascertain the oil production process. From the simulation results of CO2 WAG flooding method, the trapped CO2 led to prevent water-flow, in which CO2 acts as a gas blocker near the well. It caused the injection pressure increase during water injection period. As the trapped CO2 in pores increased, the reservoir pressure was also increased and maintained above minimum miscibility pressure (MMP). Ultimately, it was concluded that the reservoir was kept under miscible conditions throughout WAG process, reducing residual oil and increasing oil recovery.

Regional CO2 solubility trapping potential of a deep saline aquifer in Pohang basin, Korea

This paper presents regional CO2 solubility trapping potential for stable CO2 storage as immobile phase and decomposed form while CO2 migrates through flow pathways characterized by the geological structure of an aquifer in Pohang basin, SE offshore Korea. The saline aquifer in Pohang basin has been selected as a target formation for geologic carbon storage due to favorable geologic structures and sedimentary strata defined through seismic survey. The aquifer is confined by southeast and northwest faults, and structure is unconfined and sloping toward the northeast direction. The main target within the aquifer to store CO2 contains west plunging anticlines. In order to enlarge contact area of CO2 with brine and improve injectivity, the CO2 injector is located on marginal anticlines or small synclines. This structure may significantly affect CO2 flow dynamics through upward migration pathways within the aquifer. We, in this area, provide estimates for CO2 solubility trapping affected by dynamic CO2 migration pathways and present different types of CO2 trapping potentials. The numerical results based on thermodynamic equilibrium equation provide regional CO2 solubility trapping potential which has a linear relationship with brine salinity. We suggest that dynamic migration pathways resulting from geological structure are significantly important to increase CO2 solubility trapping potential in geological storage of CO2.