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

Abstract

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.

Keywords:

• Asphaltenes
• Kuwaiti oil fields
• resins
• water-oil emulsions
• waxes

Acknowledgments

This project has been financially supported by Kuwait Foundation for Advancement of Sciences, Grant No. KFAS 2000-09-02, “Role of asphaltene, reins, and wax in the stability of water/oil emulsions in Kuwaiti crudes.” Special thanks go to the Research Administration at Kuwait University for administrating the project, providing assistance in manpower and equipments. The authors also thanks Kuwait Oil Company (KOC) for providing emulsion samples used in this research project. A. M. E. thanks the Department of Chemical and Petroleum Engineering, University of Calgary for providing computing and other research facilities during his sabbatical leave.