Modeling of co-precipitation of resin and asphaltene in crude oil by association equation of state

Resin content is an effective parameter which has adverse effect on precipitation of asphaltene in crude oil. Fluctuations in temperature, pressure or oil composition disturbs chemical equilibrium in reservoir which results in co-precipitation of resin and asphaltene. In this work co-precipitation of resin and asphaltene has been modeled using an association equation of state (AEOS) where asphaltene and resin are considered as associate components of oil. According to association fluid theory, total compressibility factor is assumed to be sum of physical and chemical compressibility factors. Liquid – liquid and liquid – vapor equilibrium calculations are accomplished with the assumption that asphaltene and resin do not contribute in vapor phase. The comparison of experimental asphaltene precipitation with the ones obtained from developed model, proves acceptability of the proposed model.

Keywords:

Asphaltene , resin , association equation of state , chemical compressibility factor , coprecipitation