Dimethyl Ether-Enhanced Co2 Flooding for Improved Heavy Oil Recovery and Geological Co2 Sequestration

Abstract

The viscosity fingering effect of CO2 during heavy oil extraction leads to low recovery rates. Using cosolvents enhances CO2 solubility in heavy oil, reducing viscosity and improving production efficiency. This study introduces dimethyl ether (DME) as an innovative cosolvent to enhance CO2 flooding, aiming to improve heavy oil recovery and facilitate geological sequestration of CO2. A thermodynamic phase equilibrium model was developed to investigate the phase behavior of the heavy oil-CO2-DME system, focusing on DME's influence on CO2 solubility. Numerical simulations compared DME-enhanced CO2 flooding with conventional methods, assessing DME's impact on CO2 sequestration rates in reservoirs. Results show that DME promotes a single-phase state, enhancing CO2 solubility and lowering interfacial tension between oil and gas phases. This leads to more efficient heavy oil recovery. Under similar pressure conditions, DME-assisted flooding achieves a higher CO2 sequestration rate than conventional flooding, reinforcing pore-scale trapping and contributing to CO2 sequestration in heavy oil formations.

Keywords: Dimethyl ether, Phase equilibrium, solubility, CO2 sequestration, dissolution trapping