RECOVERY OF HEAVY OILS USING VAPORIZED HYDROCARBON SOLVENTS - FURTHERDEVELOPMENT OF THE VAPEX PROCESS

There are extensive deposits of heavy oil in Saskatchewan and Alberta which can only be recovered with low efficiency by conventional method s. Primary recovery in the best of these heavy oil reservoirs can yiel d about 6 percent of the OOIP. Waterflooding can improve the recovery, but only to an extent of 1-2 percent because of the adverse mobility ratio. Thermal recovery processes using steam can be effective, but th ese are uneconomic in many Lloydminster type reservoirs because the de posits are relatively thin and heat losses to the overburden and under burden are excessive. One potential means for overcoming the problem o f heat loss is to make use of vapourized hydrocarbon solvents at their dew point. This paper discusses the results of experiments with Tangl eflags heavy oil and propane carried out in a large. scaled, physical model. It focuses on the area of potential problems encountered with t he use of saturated hydrocarbon vapours as a solvent. In particular. i t addresses the issue of precipitation of asphaltenes which may lead t o reduced permeability and lower production rates. Rates, recoveries, gas to oil ratios and other important parameters will be presented and field performance of the process will be predicted from the data obta ined in the scaled laboratory model.