A New Scaling Equation for Modeling of Asphaltene Precipitation

Abstract

Abstract The amount of asphaltene precipitated is a crucial factor in determining the degree of permeability impairment of the reservoir rocks. It is useful to know how much asphaltene precipitates as a function of temperature, pressure and liquid phase composition. The objective of this work is to present a simple and accurate mathematical model, capable of predicting the amount of asphaltene precipitated at a given operating condition. Extensive new experimental data for the amount of asphaltene precipitated in an Iranian crude oil has been determined with various solvents and at different temperatures and dilution ratios. All experiments were carried out at atmospheric pressure. The experimental data obtained in this study were used to examine the scaling equations proposed by Rassamdana et al. [1,2]. We introduced a modified version of their proposed scaling equation. Our observation showed that the results obtained from the present scaling equation are in good agreement with experimental data at low value of dilution ratios. The properties of complex asphaltenes are not considered in this simple model. We strongly recommend this model for laboratory experiments and core flood tests which are often performed at atmospheric pressure and practically at low value of dilution ratios. Introduction Asphaltene precipitation is one of the most common problems in both oil recovery and refinery processes. In oil recovery, especially in gas injection, formation of asphaltene aggregation, following their deposition causes blocking in the reservoir. This makes the remedial process costly and sometimes uneconomical. Unfortunately, there is no predictive model for asphaltene problem treatment. Hence it is necessary to predict the onset of asphaltene precipitation, as a pre-emptive measure. The major questions in facing such problems are " When" and " How much" heavy organic compounds will precipitate in operational condition. Over the years, many researchers have tried to find the answer. They introduced experimental procedures or even analytical models, but a fully satisfactory interpretation is still lacking. The problem is very difficult mainly because of the fuzzy nature of asphaltene and the large number of parameters affecting precipitation.