Cyclic hot solvent injection: An advantageous injection method compared with mixture solvent in the solvent based heavy oil mining process

Abstract As a significant carbon-based fuel resource, heavy oil requires feasible oil extraction method to increase the production efficiency. Cyclic solvent injection (CSI) method is acknowledged as an effective heavy oil recovery method due to the relatively high oil production rate. In this study, mixture solvent-based CSI method and cyclic hot solvent injection (CHSI) method have been experimentally and numerically compared with each other to optimize the recovery approach for heavy oil mining process. For both methods, the initial reservoir pressure remains constant as 1860 kPa while the injection scheme is different. Experimental results demonstrate that 55℃ pure C 3 H 8 -based CHSI method is superior to mixture solvent (54% mol CO 2 and 46% mol C 3 H 8 ) method since the recovery factor of the CHSI method is 52.8% with longer highly productive period, while the recovery factor of the mixture solvent method is 28.9%. In the CHSI case, solvent chamber tends to expand and yield extra oil production because of the gas flooding effect, while the solvent chamber remains fixed in the mixture solvent case restricting solvent diffusion effect. The simulation study discovers that comparing with mixture solvent process, the CHSI process has demonstrated greater oil production potential due to higher mass transfer efficiency and stronger characteristics of foamy oil flow and solution gas drive. Besides, the solvent preparation method of the CHSI test presents a novel approach for preparing high temperature gas. In addition, this study shows the promising economic potential of the CHSI method through Net Present Value (NPV) calculation.