APPLYING A NOVEL STEAM AND CARGON DIOXIDE COMBINATION PROCESS IN HEAVY OIL AND TAR SAND RESERVOIRS

THE UNITED STATES HAS A LARGE NATURAL RESOURCE OF HEAVY OIL DEPOSITS RANGING FROM 85 TO 100 BILLION BARRELS. THE LARGEST OF THESE ARE IN CALIFORNIA AND ALASKA. TODAY OVER 80 PERCENT OF THE OIL FROM ENHANCED OIL RECOVERY (EOR) RESULTS FROM STEAMFLOODING TECHNIQUES IN THESE LOW GRAVITY, HIGH VISCOSITY, OILCONTAINING RESERVOIRS. MOST OF THE COMMERCIAL PROJECTS ARE IN CALIFORNIA. THEY USE BOTH THE CONVENTIONAL STEAM DRIVE AND CYCLIC STEAM STIMULATION, AND THE MECHANISM OF VISCOSITY REDUCTION BY HEATING DOMINATES THE PROCESS. ANOTHER EOR TECHNIQUE FOR HEAVY OIL RESERVOIRS, AND ONE RECEIVING MORE EXTENSIVE RESEARCH AND GAINING WIDER ACCEPTANCE, IS THE USE OF CO(2) IN IMMISCIBLE FLOODING. THIS CO(2) METHOD ALSO FEATURES VISCOSITY REDUCTION AS THE PRIMARY MECHANISM FOR MOBILIZING THE HEAVY OIL. THIS PHASE I PROJECT COMBINES THE BEST HEAVY OIL RECOVERY METHODS IN A FIELD TEST FOR THE FIRST TIME. TWO WELLS, PRODUCING FROM A HEAVY OIL RESERVOIR, WILL BE GIVEN COMBINATION TREATMENTS WITH STEAM AND CO(2). INTERSPERSED IN EACH TREATMENT WILL BE AQUEOUS SLUGS OF FOAMING SURFACTANT/GELLED POLYMER. THIS CONCEPT HAS THE BENEFICIAL EFFECTS OF STEAM, CO(2), AND THE FOAM SURFACTANT/GELLED POLYMER FOR IMPROVING OVERALL CONFORMANCE. IN THESE TESTS A NEW THERMALLY STABLE WATER-SOLUBLE POLYMER WILL BE GELLED IN SITU WITH AN ORGANIC CROSSLINKING SYSTEM.