Empirical modeling of naphthenic acids precipitation in an idealized system using response surface methodology: impact of factor interactions

Abstract

Several factors are recognized to affect the precipitation of naphthenic acids from oil; however, their interactions have not been thoroughly assessed. This study uniquely investigated the interactions among six factors affecting naphthenate precipitation from a model oil using Box-Behnken design. The findings indicate an independent quadratic effect of calcium concentration. A notable positive interaction was observed between pH and water cut, while naphthenic acid concentration exhibited substantial negative interactions with pH and water cut, respectively. Optimization revealed low naphthenate precipitation at high naphthenic acid concentrations, suggesting a role for low molecular weight acids in pH regulation. Thus, pH modulation using low molecular weight acids remains a key strategy for preventing naphthenate deposition.