Effect of Inorganic Solids, Wax to Asphaltene Ratio, and Water Cut on the Stability of Water-in-Crude Oil Emulsions

The formation of stable water-in-crude oil emulsions during petroleum production and refinery may create sever and costly separation problems. It is very important to understand the mechanism and factors contributing to the formation and stabilization of such emulsions for both great economic and environmental development. This article investigates some of the factors controlling the stability of water-in-crude oil emulsions formed in Burgan oil field in Kuwait. Water-in-crude oil emulsion samples collected from Burgan oil filed have been used to separate asphaltenes, resins, waxes, and crude oil fractions. These fractions were used to prepare emulsion samples to study the effect of solid particles (Fe3O4) on the stability of emulsions samples. Results indicate that high solid content lead to higher degree of emulsion stability. Stability of emulsion samples under various waxes to asphaltenes (W/A) ratios have also been tested. These tests showed that at low W/A content, the emulsions were very stable. While at a wax to asphaltene ratio above 1 to 1, the addition of wax reduced emulsion stability. Stability of emulsion samples with varying amount of water cut has also been investigated. Results indicated that stability and hence viscosity of emulsion increases as a function of increasing the water cut until it reaches the inversion point where a sharp decline in viscosity takes place. This inversion point was found to be approximately at 50% water cut for the crude oils considered in this study.