Behavior and Stability of Naphthenic Acid/Naphthenate Stabilized Emulsions. Mixed C80-Tetraacid and Stearic Acid Stabilization

Abstract

Previous studies have focused on monomeric naphthenic acids and their ability to stabilize emulsions, but little has been reported on C80-tetraacids and their ability to function as an emulsifier. In this article, we report on the chemistry of the C80-tetraacids as an emulsion stabilizer and also on the role this acid has in mixed monoacid-tetraacid systems. The study focuses on the type of emulsion formed and the stability of these emulsions with respect to water cut, pH, salinity of the water phase, and type of counterion. Interfacial behavior and the electrostatic properties of the emulsion were studied in order to determine which of the acids were present at the interface and which of the acids gave the largest contribution to the emulsion stability. It was found that C80-tetraacids form only O/W emulsion under the conditions studied. Addition of monoacid to the system did not change the type of emulsion formed. Highest stability was seen for emulsions containing both monoacid and tetraacids. When adding NaCl a phase inversion from O/W to W/O emulsion appeared around a concentration of 2 wt% of NaCl.

Keywords:

• ARN
• C80-tetraacids
• emulsion
• momacid-tetraacis systems
• naphthenic acids

The authors would like to acknowledge Statoil ASA and The Norwegian Academy of Science and Letters for financial support through the VISTA program. Acknowledgments are extended to the JIP consortium, consisting of AkzoNobel, Baker Petrolite, BP, Champion Technologies, Chevron, Clariant Oil Services, ConocoPhillips, Saudi Aramco, Shell Global Solutions, StatoilHydro, Talisman Energy and Total. Finally, Heléne Magnusson is thanked for valuable discussions.