Enhanced Heavy Oil Recovery on Depleted Long Core System by CH4 and CO2
Shi, R. and Kantzas, A.
SPE/PS/CHOA 117679, presented at the 2008 SPE International thermal Operations and Heavy Oil Symposium held in Calgary, Alberta, Canada, October 20-23, 2008.
This paper describes a laboratory study of potential post-cold production strategies for heavy oil reservoirs. The tests were conducted on two primarily depleted long core systems (glassbeads core and sandpack core). The glassbeads core is 18.2 m in length with higher permeability (11.8 Darcy) and the sandpack core is 18.5 m long with lower permeability (1.9 Darcy). Both core systems were recharged by CH4 injection followed by a depletion step similar to the cold production experiment. Both cores were then exposed to a single cycle of CO2 injection, soaking and production. This work aims at further understanding the heavy oil solution gas drive mechanism. Furthermore, the study aims at assessing methane and carbon dioxide recharging as a potential recovery method for heavy oil reservoirs, and at establishing a base line for comparison against each other. Results of this study indicate that CH4 and CO2 recharge processes give an additional 8% and 9% OOIP recovery for the glassbeads core and the sandpack core, respectively. Since the cold production for the glassbeads core (22.2% OOIP) was high, the low recharge recoveries may be pessimistic. However, for the sandpack core, the recharge recovery appears more optimistic with almost similar recovery to that of cold production (about 10.2% OOIP).