A thermodynamic micellization model for asphaltene precipitation: Part 1: Micellar size and growth
Asphaltene precipitation is a serious problem in the production of some petroleum reservoirs. A thermodynamic predictive model is a challenge and currently does not exist. Published models do not yet represent a realistic picture of asphaltenes in the crude. A large number of recent experimental studies have shown that asphaltenes aggregate in the crude to form micelles. The size of the micelle changes due to changes in composition and temperature. In this study, we present a simple thermodynamic micellization model to describe asphaltene aggregation in crude mixtures. The asphaltene molecules are assumed to form the micellar core and the resin molecules adsorb onto the core surface to stabilize the micelle. The asphaltene and resin molecules in a micelle are in equilibrium with the asphaltene and resin monomers in the bulk crude. The principle of the minimization of Gibbs free energy is used to determine the micellar structure and concentration. The predicted micellar size and growth when the crude is diluted with normal alkanes are in line with experimental observations. The predicted effects of temperature and pressure on the micellar size are also in agreement with data. The expression for the micellar concentration in our simple approach is the same as the published expression based on the multiple chemical equilibrium principle.
- OSTI ID:
- 468156
- Report Number(s):
- CONF-961003--
- Country of Publication:
- United States
- Language:
- English
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