Characterization of Sodium Emulsion Soaps Formed from Production Fluids of Kutei Basin, Indonesia

Crude oils, produced waters, and emulsions retrieved from the Kutei Basin of Indonesia have been examined by a variety of analytical techniques to understand soap-formation mechanisms and origins of reactants. Crude oils contain long-chain, n-alkanoic or slightly branched monocarboxylic acids, which primarily have a land-plant origin. Although the crude oils may contain up >1000 ppmw of carboxylic acids, the total acid number (TAN) is anomalously low (∼0.5 mg KOH/g, on average). Traces of mononaphthenic, bicyclonaphthenic, alkyl benzoic, diprotic, and tetraprotic acids are detected in some Kutei Basin oils. The oils and acids therein are significantly different from oils that have a marine algal origin, which, in certain areas of the world, contain high TAN values and concentrations of naphthenic acids synthesized by microbial biodegradation. The naphthenic acids combine with calcium in produced waters to form calcium naphthenates. Produced waters are enriched in sodium bicarbonate (NaHCO3), as a result of the decarboxylation of volatile fatty acids. When the pH of produced water exceeds a value of ∼6.2, NaHCO3 reacts with the carboxylic acids in a saponification-like reaction to form interfacial sodium carboxylate soap emulsions. These emulsions may be stabilized by formation flour (reservoir formation of fine particulates of rock, such as quartz sand, silts, and aluminum silicate clays (for example, allophanes)), scale/corrosion debris, and high-molecular-weight acids. The Kutei Basin soap emulsions are resolved by heating and treatment with relatively high dosages of acid demulsifiers.