Effects of electroosmosis and viscosity ratio on waterflooding performance

The effect of electroosmosis on waterflooding performance was examined and compared to the effect of improving viscosity ratio. Experiments were conducted using a model representing one quarter of a five-spot waterflood pattern. Arabian crude oil with a viscosity of 61.8 cP was used as the displaced fluid in one set of experiments. A second set of experiments utilized kerosene (2.5 cP viscosity) instead of crude oil to show the effect of viscosity ratio improvement. Water with 30000 ppm NaCl was used as the displacing fluid for all of the experiments. A direct electrical potential gradient was applied between the injection and production wells (with the injector being the cathode) to examine the effect of electroosmosis. It was found that electroosmosis increases oil production and reduces the produced water-oil ratio. The effect was more appreciable after water breakthrough and is comparable to the effect of improving the viscosity ratio of the system.