High pressure and high-temperature study of CO_2 saturated-water injection for improving oil displacement; mechanistic and application study

摘要

Carbonated Water Injection (CWI) as an enhanced oil recovery method is considered a suitable method for recovering oil from mature fields. In this study, we investigated the effect of carbonated water injection (CWI) on enhanced oil recovery (EOR) in an offshore light oil reservoir. Newfoundland and Labrador's oil and gas industry is based on offshore fields. The challenge facing Newfoundland offshore fields, being 310-350 km off the coast, is the "availability of injection gas required for EOR." In this study, the effect of water flooding and CWI on oil recovery, in the vertically oriented pore and core scales were experimentally investigated. We performed all the core flooding experiments at local reservoir conditions of 4500 psi (31 MPa) and 185 degrees F (85 degrees C). Water flooding, secondary and tertiary CWI, and CO2 water alternating gas (CO2-WAG) processes were simulated to evaluate the results of gravity stable-vertical core flooding experiments at reservoir conditions. A core model was built using WinProp and GEM-CMG compositional software. In seawater flooding, the breakthrough occurred at 0.39 PV resulting with a recovery factor of 47.1% compared to 0.45 PV with a recovery factor of 50.4% in secondary CWI. Seawater flooding resulted in 59.4% ultimate recovery factor compared to 74.8% in secondary CWI, 64.2% in tertiary CWI, and 66.4% in CO2-WAG (8 PV). The results indicate that CWI is an effective oil recovery method at the core scale under typical offshore Newfoundland reservoir conditions, especially if used in place of water flooding.