Techbits: Naphthenate Deposits, Emulsions Highlighted in Technology Workshop
- _ JPT staff (_)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- July 2008
- Document Type
- Journal Paper
- 30 - 31
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Pau, France was the scene for a recent SPE Applied Technology Workshop (ATW) titled “Managing Naphthenates and Soap Emulsions.” From 10–13 March 2008, more than 70 attendees discussed the flow assurance challenges that naphthenate deposition presents, as well as the current state of the art in mitigating their formation in the field.
Colin Smith, senior consultant with Maxoil Solutions and ATW Committee Member, opened the workshop with a scene-setting discussion on the fundamentals of naphthenate sludge and emulsion formation. If left unchecked, naphthenate deposits may cause fouling or plugging of production equipment such as flowlines and separators, and the formation of stable emulsions may prevent efficient oil/water separation, increasing separator residence times. The problem is more common than the industry might think, according to Smith; naphthenate deposits are present in 10% or more of North Sea crudes, while 30% of southeast Asian crudes and 20% of west African crudes demonstrate soap emulsion or sludge problems. Smith mentioned that naphthenates were first clearly identified in oilfields in the 1960s, but research and development (R&D) efforts began in earnest in the mid-1990s.
The first session of the workshop highlighted the fundamentals. Johan Sjoblom, Professor at the Norwegian University of Science and Technology (NTNU), examined the current understanding of the different types of acids in a crude oil that can lead to naphthenate formation and sludge or emulsion problems. Monoacids (those acids with one carboxyl [COOH] group) tend to stabilize emulsions and concentrate in the oil phase or sludges, while tetracids (those with four COOH groups) can stabilize oil/water emulsions and tend to react with metallic ions such as calcium (Ca2+) to form deposits that harden irreversibly.
Christian Hurtevent, an expert in physical chemistry and deposits with Total, discussed his company’s experience with emulsion formation based on oil density and acid type. In general, Total has observed biodegradation and deposit problems in problem crudes with lower API values (<30), while higher API problem crudes tend to demonstrate emulsion stability challenges. The company has used an ultrasonic scanner to evaluate emulsion phase behavior, which has suggested how various naphthenic salts aggregate in a crude oil/water mixture.
Ingemar Uneback, Application Development Manager for Akzo Nobel, proposed how derivatives of naphthenic mono acids could be extracted from crude oil and used as favorable starting blocks in chemical synthesis. In the formation of surfactants, for example, several monoacids demonstrate excellent surface active properties, low viscosity, good oxidative stability, and favorable biodegradability for environmentally sensitive applications. Uneback stated that Akzo Nobel has begun testing naphthenic monoacids as surfactants with promising results for potential application in fuels, agrochemicals, oilfield process chemicals, and asphalts.
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