Study on the Re-emulsification Process of Water in Heavy Oil Emulsion with Addition of Water-Soluble Viscosity Reducer Solution

The emulsification of heavy oil and water into a W/O emulsion would increase the viscosity of the W/O emulsion and reduce the mobility of heavy oil. As we know, addition of a viscosity reducer such as water-soluble surfactants could change the status of emulsion and improve the mobility of heavy oil. Although up to 90% viscosity reduction could be achieved in laboratory experiments, field improvement of the heavy oil recovery is not satisfactory with addition of a viscosity reducer. Actually, it is related to the difference of the mixing process of water-soluble viscosity reducer, water, and heavy oil between lab experiments and subsurface flow in the formation. The viscosity of heavy oil is significantly affected by the temperature and emulsification. As for the heavy oil sampled from Bohai Oilfield, its viscosity decreases by 95% when the temperature increases from 50 to 100 °C. At 50 °C, the viscosity of the W/O emulsion with 70% water content is up to 21.05 times that of the dehydrated heavy oil. In t...