High-Pressure Modeling of Asphaltene Precipitation during Oil Depletion Based on the Solid Model

Abstract

Asphaltene precipitation is a complex and serious problem in all sectors of the oil industry because it has a severe and detrimental impact on oil production. Thus, it is crucial to investigate under which conditions asphaltenes precipitate in order to prevent or mitigate the effects. Several approaches have been reported in the literature regarding the modeling of asphaltene precipitation during oil production. The simplest one is the single-component solid model in which the precipitated asphaltene is considered a pure solid and the oil and gas phases are described by a cubic equation of state (EOS). These are the basic assumptions of the Nghiem and Coombe’s model. In this paper, based on this model, we make numerous improvements and simplifications such as reducing the number of parameters to be estimated and considering that the number of asphaltene fractions can vary according to the oil characteristics. The characterization method is performed using the exponential distribution and only the binary interaction parameter is fitted to the experimental oil saturation pressure data. The reference pressure is calculated according to de Boer’s method instead of only extrapolating precipitation depletion experimental data. Furthermore, the solid molar volume is predicted using two correlations from literature, expressed as a function of the molecular weight of the asphaltene. The developed model is capable of calculating the amount of precipitated asphaltene as a function of pressure. Our results indicate that the proposed approach is quite accurate even having a smaller number of parameters to be estimated compared to the original model.