Enzymatic Generation of Oil-displacing Systems

The main method for the development of low-temperature reservoirs on viscosity oil deposits – thermal-steam stimulation. To improve oil recovery from low-temperature reservoirs we have developed and apply combined technologies based on steam injection into a reservoir followed by the injection of oil-displacing compositions based on surface-active substances. Besides surfactants such oil-displacing compositions contain nitrogen compounds including carbamide. At a high reservoir temperature carbamide is subjected to hydrolysis to yield СО2 and ammonia. Dissolving in water СО2 decreases oil viscosity and ammonia forms an alkaline buffer system with рН=9.0 10.0. It improves detergency of the system thereby improves oil recovery. To improve oil recovery from low-temperature reservoirs without thermal treatment we have developed a combined physicochemical and microbiological method based on simultaneous injections of the solution of oil-displacing system and urease enzyme catalyzing carbamide hydrolysis with the release of ammonia and СО2. Thus the effective oil-displacing system is generated in situ; it is capable to increase the oil-displacement factor of low-temperature oil deposit without thermal stimulation.