The mechanism, reaction kinetics, and rate equation of the naphthenate soap precipitation are determined by means of experimental and theoretical investigations. Such information may be important for controlling and minimizing the well productivity loss by naphthenate soap precipitation in petroleum reservoirs. This was accomplished by three means: a) Static bottle tests were conducted to determine the precipitation rate at various pH and temperature conditions, b) particle size growth of the naphthenate soap precipitates was investigated under static conditions to determine the governing growth mechanism, and c) core flow tests were run to determine the effect of the naphthenate soap precipitation on permeability impairment in porous media. The naphthenate soap precipitation rate was correlated with respect to the considered parameters based on a power-law expression. The measured particle size data indicated the growth of particle size with time. Finally, the core flow tests allowed the determination of the impact of the naphthenate soap precipitation in porous media in terms of the permeability impairment and damage ratio. The results of these studies may be instrumental in avoiding or minimizing formation damage problems associated with the naphthenic acid containing petroleum reservoirs.
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