Effects of Crude Oil Composition and Alcohol Augmentation on Transient Interfacial Phenomena in Alkaline-Water/Crude-Oil Systems.

Abstract

The microscopic phenomena which occur at the alkaline-water/crude-oil interface greatly affect the potential for success of the alkaline water flooding process. The propensity of crude oils to emulsify and the ability of the oil to coalesce improves the chance for successful oil bank formation and leads to better recovery efficiency. Interfacial phenomena are affected by interfacial rheological properties and interfacial tensions. This research investigates the interfacial behavior of alkaline-water/crude-oil systems in three parts. In part one, a new method and apparatus are designed for the measurement of interfacial shear viscosity (IFSV). The method is applied to study the effect of oil composition and alcohol augmentation on the IFSV and to correlate IFSV with recovery efficiency. A phenolic, non-surfactant fraction is found to severely increase the oil IFSV. Alkalinity of the water can increase or reduce the oil/water IFSV. Small, polar molecules are shown to affect interfacial structures reducing the IFSV in some cases and increasing it in others. In alcohol augmentation, a developed correlation shows that the alcohol that yields the lowest IFSV results in the best recovery. Part two comprises an investigation of the transient interfacial tensions in the system. The effect of crude oil composition, temperature, and oil viscosity on the IFT transients is determined. It is found that stability of the transients can be diffusion dependent, and that the nature of the acid fraction in the crude is responsible for the rate of loss of acid to the water. In part three the interfacial phenomena are observed microvisually in cryolite porous media. The predominant emulsification mechanism is stringing of oil due to low IFT and flow of the water and subsequent breakup of the strings into emulsion droplets. A chronological description is developed describing the events which lead to alkaline flooding oil recovery. The research improves the understanding of the phenomena which lead to alkaline flooding oil mobilization and displacement and enhances the capacity for future research of interfacial phenomena. The techniques employed will lead to improved screening tests for designing alkaline floods.