Demulsifier in Injected Water for Improved Recovery of Crudes That Form Water/Oil Emulsions

Abstract

Summary Waterflooding for oil displacement becomes a challenge when water-in-oil (W/O) emulsion forms upon contact of injected water with oil in the porous media. We have recently reported very-high pressure drops and high pressure fluctuations for a number of crudes in waterflooding. In this work, we address the challenge by adding a small amount of a demulsifier in the injected water. The stability of W/O emulsion is affected by many factors, including oil chemistry, brine chemistry, and temperature. We find that the W/O emulsion formation may correlate closely to the low total acid number (TAN). In this work, we report the effectiveness of a demulsifier in significant reduction of pressure drop and elimination of pressure-drop fluctuations. The demulsifier can be dispersed in brine or water, and can be carried by injection fluid as an additive for improved oil recovery. Both micromodel observations and coreflooding results show that W/O-emulsion formation is avoided when 100 ppm demulsifier is injected in the carrier brine. Results also show that there is an increase in oil recovery.