MOBILIZING COMPOSITION FOR USE IN GRAVITY DRAINAGE PROCESS FOR RECOVERING VISCOUS OIL AND START-UP COMPOSITION FOR USE IN A START-UP PHASE OF A PROCESS FOR RECOVERING VISCOUS OIL FROM AN UNDERGROUND RESERVOIR

摘要

Generally, described herein is a mobilizing composition for use in a gravity drainage process for recovering viscous oil from an underground reservoir. The mobilizing composition may comprise (i) 75-98 vol. % diluting agent; (ii) 2-25 vol. % steam having a steam quality of at least 5%; and (iii) 0-5 vol. % accelerating agent for accelerating penetration of the diluting agent into the viscous oil. Also generally described herein is a start-up composition for use in a start-up phase of a process for recovering viscous oil from an underground reservoir. The start-up composition comprises (i) 74.9-97.9 vol. % diluting agent; (ii) 2-25 vol. % steam having a steam quality of at least 5%; and (iii) 0.1-5 vol. % accelerating agent for accelerating penetration of the diluting agent into the viscous oil.