CO₂ and miscible gas injection for enhanced recovery of Schrader Bluff heavy oil

The performance of CO₂ injection and miscible water alternating gas (WAG) processes for enhanced recovery of Schrader Bluff heavy oil was studied experimentally. Slim tube experiments revealed that CO₂ was immiscible with the Schrader Bluff oil at reservoir conditions. Coreflood experiments in a 4 ft long sandpacks were conducted using CO₂, and a mixture of 50% Prudhoe Bay gas (PBG) and 50% natural gas liquids (NGL) as the solvents to study the effects of slug size and WAG ratio on displacement of Schrader Bluff oil at reservoir conditions. There was no significant improvement in the incremental oil recovery (IOR) for PBG/NGL slug sizes larger than an optimum value. CO₂ has the highest IOR per unit slug size although it was immiscible with the oil.