Efficient use of oil in water macroemulsions as enhanced oil recovery agents

To obtain some insights into the transport of macroemulsions prepared outside of the reservoir for oil recovery through porous media, laboratory experiments were run by injecting different formulations of diluted oil in water emulsions through sandstone cores. Emulsions, whose disperse phase was 70%, were stable for one year. Mathematical model parameters were fitted with data from emulsion transport experiments. According to this model, it is enough to inject 0.1 pore volume of emulsion slug for its adequate transportation through porous media. Oil displacement tests were carried out as part of a secondary recovery process, followed by the injection of an emulsion slug, and then again by water flooding to obtain additional oil recovery up to 23.5%. At the same concentration, emulsions based on a hydrophobic compound were more effective than emulsions prepared from crude oil, obtaining a difference of cumulative residual oil recovery of around 12%. The injection of an emulsion slug at 1wt.% of concentration and 0.1 pore volume after waterflooding is both a promising alternative and technically viable additional recovery method. Emulsions were stable for a long time and easyly diluted with water, which can be very useful in mature oilfields.