Characterization of C80 Naphthenic Acid and Its Calcium Naphthenate

Abstract

A C80 naphthenic acid (tetraacid) and its calcium naphthenate have been characterized with respect to their interfacial properties at both the oil/water and the air/water interfaces as well as their thermal properties. Naphthenic acids in crude oils may give rise to different problems in oil production including naphthenate deposition and formation of stable emulsions. This may lead to severe disturbances of regularity and shut‐in in the oil production. The interfacial activity and film properties of the compounds were examined by the oscillating drop method. The calcium naphthenate film was primarily elastic and solid‐like. Measurements on the acid gave similar results, an elastic, solid‐like film was formed, but the effect was less pronounced than for the calcium naphthenate. Langmuir‐Blodgett films of the acid and its naphthenate were deposited on conducting substrates and subsequently analyzed by scanning electron microscopy, SEM. It was found that the pure acid formed crystalline structures in the interfacial film on compression. The calcium naphthenate, on the other hand, form a continuous amorphous film on the substrate.

Keywords:

• Calcium naphthenic
• napthenic acid
• tetraacid
• stable emulsions
• oscillating drop

A.‐M. D. H. would like to acknowledge Statoil ASA and The Norwegian Academy of Science and Letters for the financial support through the VISTA program. Acknowledgement is also extended to the JIP consortium, consisting of AkzoNobel, Baker Petrolite, BP, Champion Technologies, Chevron, Clariant Oil Services, ConocoPhillips, Shell Global Solutions, Statoil ASA, Talisman Energy and Total. A. H. is thanked for discussions and help with the oscillating pendant drop method. H.M. would also like to thank the participants of the project “Electrocoalescence—Criteria for an efficient process in real crude oil systems”: The Research Council of Norway, Vetco Aibel AS, Aker Kvaerner Process Systems AS, Statoil ASA, Norsk Hydro ASA, BP Exploration Operating Company Ltd., Shell Technology Norway AS, and Petrobas.