Research and performance evaluation of CO2 solubilization synergist for heavy oil

Abstract

Some heavy oil reservoirs with deep burial depths, low permeabilities, high temperatures and high salinities that cannot be thermally recovered or chemically flooded are treated with the “CO2 + chemical agent” compound huff and puff method, and positive results are achieved. However, there are still problems, and a more efficient compound system needs to be developed. This study first determined the design principles for molecular optimization, selected six chemical systems for two crude oils with two viscosities, and then analyzed and evaluated the viscosity reduction performance, increased CO2 solubility performance, and synergistic viscosity reduction performance to obtain the optimal solubilization synergist formula. The results show that the preferred system has a better effect on BN-1 crude oil. For the BN-1 crude oil, the ZR-1 system can increase the amount of dissolved CO2 by more than 30% under 15 MPa, and the synergistic viscosity reduction rate with CO2 can reach 98% at 10 MPa. Therefore, research on CO2 compound systems can improve the synergistic viscosity reduction effect, reduce the dosage of agents, further reduce the cost and increase the efficiency of viscosity reduction technology.