A Laboratory and Numerical Simulation Study of Co-optimizing CO2 Storage and CO2 EOR

Abstract

This paper presents experimental observations that delineate co-optimization of CO2 EOR and storage. Pure supercritical CO2 was injected into a homogeneous, outcrop sandstone under various miscibility conditions. A mixture of hexane and decane was used for the oil phase. Three experiments were run at 70°C and different pressures (1,300, 1,700 and 2,100 psi). Each pressure was determined using a PVT simulator to create immiscible, near-miscible and miscible displacements. Oil recovery, differential pressure and compositions were recorded during experiments. A co-optimization function for CO2 storage and incremental oil was defined and calculated using the measured data for each experiment. A compositional simulator was then used to examine gravity effects on displacements and derive relative permeabilities. Experimental observations demonstrate that an almost similar oil recovery was achieved during miscible and near-miscible displacements whereas about 18% less recovery was recorded in the immiscible displacement. More decane was recovered in the miscible and near-miscible displacements than the immiscible displacement. The co-optimization function suggests that the CO2 storage efficiency was highest in the near-miscible displacement and that the near-miscible displacement displayed the best performance for coupling CO2 EOR and storage. Numerical simulations show that, even on the laboratory scale, there were significant gravity effects in the near-miscible and miscible displacements. It was revealed that the near-miscible and miscible recoveries depend strongly on the end-point CO2 relative permeability which increased with miscibility.

Current situation of carbon dioxide capture, storage, and enhanced oil recovery in the oil and gas industry

“…In an experiment Kamali et al examined the oil recovery rate and storage efficiency of pure supercritical CO 2 under different miscible conditions of a geological sample pore volume (PV) CO 2 injection capacity. Their results showed that CO 2 injection under miscible and near‐miscible conditions can improve the ultimate oil recovery by about 18 % compared to the immiscible injection (Figure ).…”

“…Comparison for oil recovery profiles of immiscible, near‐miscible, and miscible displacement at different pore volume CO 2 injection (Kamali et al).…”