CO2-monoethanolamine-induced oil swelling and viscosity reduction for enhanced oil recovery

Abstract

The present study utilizes a microfluidic approach to investigate the effect of monoethanolamine (MEA) on increasing CO2 solubility in a light crude oil for low pressure immiscible enhanced oil recovery (EOR) operations. The CO2 microbubble area reduction over time was measured at varying MEA concentrations in oil to quantitatively estimate the effect of MEA on CO2 solubility, and as a result, its effect on gas-induced oil swelling and oil viscosity reduction. The maximum CO2 dissolution in 0.1% (v/v) MEA and 2% (v/v) MEA in oil was observed to be 77% and 86% dissolution, respectively. In addition, minor increases in CO2 dissolution rate were observed in 2% (v/v) MEA with oil when compared with 1% (v/v) MEA with oil and the control (pure oil). Furthermore, in order to test the feasibility of MEA employment in actual EOR operations, a series of immiscible CO2 flooding experiments were performed in a porous media to simulate an actual oil reservoir. In CO2 flooding experiments, the cumulative oil recovery efficiency was increased by 4% and 22% with 5% (v/v) MEA and 10% (v/v) MEA, respectively, due to the reduction of oil viscosity by CO2 dissolution. Unique phenomena such as trapping, displacement, re-filling, and drifting of oil blobs were observed during CO2 flooding. The MEA's strong effect on CO2 solubility, and as a result, its effect on various oil properties, indicates a potential for improving the recovery factor and reducing the cost of EOR operations.