Recovery of petroleum from viscous petroleum containing formations including tar sand deposits

Claim 1

IN A METHOD OF RECOVERING VISCOUS PETROLEUM INCLUDING BITUMEN FROM A SUBTERRANEAN, VISCOUS PETROLEUM-CONTAINING FORMATION INCLUDING TAR SAND DEPOSITS, SAID FORMATION BEING PENETRATED BY AT LEAST TWO SPACED APART WELLS, AT LEAST ONE OF WHICH IS AN INJECTION WELL AND AT LEAST ONE OF WHICH IS A PRODUCTION WELL IN FLUID COMMUNICATION WITH THE LOWER PORTION OF THE FORMATION, SAID PROCESS BEING OF THE TYPE WHEREIN A FLUID IS INJECTED VIA SAID INJECTION WELL INTO THE PETROLEUM FORMATION FOR THE PURPOSE OF INCREASING THE MOBILITY OF THE PETROLEUM CONTAINED THEREIN, WHEREIN THE IMPROVEMENT FOR REMOVING IMMOBILE HYDROCARBON DEPOSITS FROM THE FORMATION IN THE VICINITY OF THE PRODUCTION WELL, WHICH DEPOSITS ARE OBSTRUCTING THE FLOW OF PETROLEUM MOBILIZED BY THE FLUID INJECTED INTO THE FORMATION VIA THE INJECTION WELL ARE OBSTRUCTING THE FLOW OF PETROLEUM INTO THE PRODUCTION WELL COMPRISES: A. PROVIDING A LIQUID INJECTION FLOW PATH FROM THE SURFACE SEPARATE FROM THE PRODUCTION FLOW PATH OF THE PRODUCTION WELL AND ADJACENT THERETO, SAID INJECTION MEANS BEING IN FLUID COMMUNICATION WITH THE UPPER PORTION OF THE VISCOUS PETROLEUMCONTAINING FORMATION NEAR THE PRODUCTION WELL, B. INJECTING AN AQUEOUS HEATING LIQUID INTO THE UPPER PORTION OF THE VISCOUS PETROLEUM-CONTAINING FORMATION IN THE VICINITY OF THE PRODDUCTION WELL AT A PRESURE LESS THAN THE PRESSURE AT WHICH FLUID IS INJECTED INTO THE INJECTION WELL TO MOBILEZIE VISCOUS PETROLEUM, SAID HEATING LIQUID BEING INJECTED VIA SAID LIQUID INJECTION FLOW PATH ADJACENT THE PRODUCTION WELL, SAID LIQUID BEING CAPABLE OF INCREASING THE MOBILITY OF THE IMMOBILE HYDROCARBON MATERIALS IN THE VICINITY OF THE PRODUCTION WELLBORE, AND C. RECOVERING THE INJECTED AQUEOUS HEATING LIQUID, MOBILIZING FLUID AND FORMATION PETROLEUM FROM THE LOWER PORTION OF THE FORMATION VIA THE PRODUCTION WELL.