Research On Surfactant Flooding Technique For Heavy Oil

Surfactant with perfact emulsification is a key factor to chemical flooding to enhance sweep efficiency and displacement efficiency. Emulsion stability and emulsion rate are two important characters of emulsification, but emulsion rate and contribution of emulsion to recovery is not clear. For the sake of resolving the problem, the mechanism of emulsification and the role of emulsification to enhance oil recovery was revealed considering emulsion stability and emulsion rate on the base of experiments and theoretical analysis. These results benefit the design of displacing surfactants with high efficiency.The concept of emulsion rate was proposed to characterize the ablility of emulsification for the fist time.In order to measure the emulsion rate , An equipment has been designed ,and its applications was suggested. Such factors as temperature, concentration of surfactant, water quality and viscosity of water phase , which affect emulsion stability and emulsion rate, were investigated. The heavy oil was separated to saturation component, aromatic component, resin and asphaltene by polar separation to investigate the crucial component for emulsion rate. It shows that resin and asphaltene to be with capability to enlarge emulsion rate. The relationship between molecular structure of surfactant and emulsion rate were developed based on experiments and some rules were obtained. There is some correspondence in length of lipophilic group, number of EO to emulsion rate. Surfactant with branched chain specializes in emulsion rate.Higher emulsion stability and emulsion rate can be acquired if dynamic interfacial is decreased, while there are no correspondence between dynamic interfacial and emulsion stability, emulsion stability and emulsion rate because of some other influence. The starting value of dynamic interfacial tension (within 1~2 min) is vital to emulsion rate of all. Emulsion rate is determined by hydrophilic-lipophilic equilibration of membrane formed by surfactant in water-oil interface, the more close to equilibration, the lower interfacial energy and the more great emulsion rate could be acquired.It is proposed according to displacement experiments that the displacement efficiency is determined by emulsion rate , emulsion stability is key to sweep efficiency, higher sweep efficiency would be gotten if emulsion stability are reduced properly.