A study on the application of scaling equation for asphaltene precipitation

The scaling equation proposed by Rassamdana et al. [H. Rassamdana, B. Dabir, M. Nematy, M. Farhani, M. Sahimi, AIChE J. 42 (1996) 10–22; H. Rassamdana, M. Sahimi, AIChE J. 42 (1996) 3318–3332.] is an attractive tool for modeling asphaltene precipitation, as it is simple and the properties of complex asphaltenes are not involved. In this work, the universality of exponents Z and Z′ in the scaling equation has been examined. The results show that Z′ can be taken as a universal constant (Z′=−2), while Z depends on oil composition but is independent of the specific precipitant (n-alkane) used. For the oils studied, the optimum value of exponent Z is in the range of 0.10≤Z≤0.50. The predictive capability of the scaling equation has been checked by comparison with literature precipitation data, and further extended to the prediction of the onset of asphaltene deposition and asphaltene precipitation in the gas-injected crude oils.