Improved oil recovery by application of vibro-energy to waterflooded sandstones

The final oil recovery of reservoirs after waterflooding usually does not exceed 50%. Therefore, the problem of additional oil production in water-flooded oilfields, or after depletion, is of major importance. A method of enhanced oil recovery based on the use of powerful surface-based vibro-seismic sources is discussed here, and results of laboratory tests and their application at several oilfields in Russia and in other states formed from the former USSR are presented. In laboratory experiments, natural core samples and synthetic sandpacks were used. The rate of displacement of oil by water in the presence of applied vibro-energy was studied and compared to the displacement rate in the absence of vibrations. Dependence of relative permeability to oil and to water on application of vibro-energy was analyzed. Effect of vibro-energy on residual oil saturation in the porous medium was also studied. It was shown that the rate of oil displacement increases and the percentage of residual oil decreases if vibro-energy is applied to the porous medium containing oil. Another important phenomenon studied in the synthetic porous models is the increase in the rate of degassing due to applied vibration energy. Results of both laboratory and pilot-field testing of the proposed enhanced oil recovery method showed an increase in both oil recovery and the producing oil/water ratio. This proposed vibro-seismic methodology will serve as an additional tool for increasing oil recovery, possibly in conjunction with application of direct electric current, chemical floods, and other processes.