Naphthenate Soap Formation Analysis Under Laboratory Conditions.

A.G.Shepherd ¹; R.E.Westacott ¹; K.Sorbie ¹; M.Turner ²; C.Smith ² .

1 =  Heriot-Watt University, Edinburgh; UK. 2 = Oil Plus, Newbury, UK.

Static bottle tests were performed on model naphthenic acid solutions, extracts obtained from calcium naphthenate soaps and their original crude oils. The objectives of these tests were to examine the factors influencing the deposition of the soaps under a set of controlled laboratory conditions. The variables examined were: effect of aqueous phase ions and initial pH of the aqueous phase. When a deposit was formed (typically at the oil-water interface), it was separated from solution by filtration and analysed using x-ray diffraction XRD and energy dispersive x-ray/environmental scanning electron microscopy EDAX/ESEM and transmission microscopy. The results show correspondence between model solution behaviour and soap extract results, namely the dependency of the precise ionic composition and initial pH for deposition. The influence of naphthenic acid concentration is highlighted by differences between crude oils and extract solutions.