Journal Article

Empirical Modeling of the Precipitation Formation of Naphthenic Acid in An Idealized System

Abstract

The tendency of naphthenic acids to precipitate out of solution when in contact with the metal ions present in the formation water, present a formidable challenge for the petroleum industry. In this study, empirical modeling of naphthenic acid precipitation in idealized system was investigated. Response surface design based on Box-Behnken statistical design was used for the analysis. The result of the analysis revealed that the relative amount of naphthenate precipitate formed increases with increase in naphthenic acid concentration, calcium ion concentration, pH of formation water and percent water cut, as indices have significant effect on the formation of the precipitate. The predicted yield values for the options by the optimizer were1.62%, 2.86% and 7.94% and validated values obtained empirically are 2.05±0.16, 3.36±0.24 and 8.80±0.14 respectively. These values were quite close of less than 1% differences for all the solutions predicted by the optimizer, this indicates that the model developed were well fitted and highly reliable. Validated yield of 2.05±0.16 under the optimal condition given in solution was the best option for the minimizing the naphthenate precipitate. In general, the observed effects of the factors suggest that precipitation of the naphthenic acid can be minimized with acidic formation water that contains relatively low concentration of calcium ions concentration particularly when the concentration of the naphthenic acid in the crude oil is as low as possible.

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