Studies On The Effects Of Weak Base On The Performance Of ASP Flooding

The effects of weak base (sodium carbonate) on the performance of ASP flooding system were studied through experiments, and then they were compared with the strong base (sodium hydroxide) ASP flooding system.Weak base ASP system compared with strong base ASP system, the interfacial tension of weak base ASP system is lower than that of strong base ASP system under the same level. Apparent viscosity stability of weak base ASP system is better than that of strong base ASP system. The effect of weak base on the rheology and viscoelasticity of ASP system is less than that of strong base. Oil water volume ratio and weak or strong base affects the emulsification ability of ASP flooding system. The emulsification ability of weak base ASP flooding system is weaker than that of strong base ASP flooding system under the same base concentration and oil water volume ratio.For different kinds of minerals, adsorption rules of weak base and strong base, surfactant and polymer in ASP flooding systems were studied. The effects of interfacial tension and emulsification on the partition coefficient of surfactant in oil and water phase were studied for the first time. And transmission rules of weak base or strong base, surfactant and polymer of ASP flooding systems in the porous media under oil and water phase, and some related analysis were carried through.Micromechanism for weak base ASP flooding system starting up residual oil after water flooding was also studied. At first, the residual oil was emulsified by weak base ASP flooding system and was cut into smaller oil droplets which were carried and transported in the form of oil in water emulsion. Finally, they were displaced out. That oil droplets were stretched into lines was also observed in strong base ASP flooding system. Strong base ASP flooding system displaces more residual oil than weak base ASP flooding system.Displacing oil efficiency experiments show that the higher the base concentration is, the higher the displacing oil efficiency is. At a certain base concentration, displacing oil efficiency of strong base ASP flooding system is bigger than that of weak base ASP flooding system. Since the extent of enhanced oil recovery is a result of the comprehensive function of interfacial tension, viscosity, viscoelastcity and emulsification, though low interfacial tension is available for enhanced oil recovery, it is not the key factor for determining oil recovery but emulsification determines the extent of oil recovery.