Molecular-Thermodynamic Framework for Asphaltene-Oil Equilibria
نویسندگان
چکیده
Asphaltene precipitation is a perennial problem in producing and rejming crude oils. To avoid precipitation, it is usefid to know the solubility of asphaltenes in petroleum liquids as a function of temperature, pressure and liquid-phase composition In the novel molecular-thermodynamic flamework presented here, both asphaltenes and resins are represented by pseudo-pure components while all other components in the solution are represented by a continuous medium that a$Gects interactions among asphaltene and resin particles. The eflect of the medium on asphaltene-asphalten< resin-asphaltene, resin-resin pair interactions is taken into account through its density and dispersion-force properties. To obtain expressions for the chemical potential of asphaltene and for the osmotic pressure of an asphaltene-containing solution, the SAFT model is used in the framework of McMillan-Mayer theory, which considers hard-sphere repulsue, association and dispersion-force interactions. By assuming that asphaltene precipitation is a liquid-liquid equilibrium process, a variety of experimental observations can be explained, including effects of temperature, pressure, and composition on the phase behat+ ior of asphaltene-containing fluids. For practical quantitative applications, the model outlined here requires molecular parameters that must be estimated from a few qerimental data.
منابع مشابه
Molecular Thermodynamics of Asphaltene Precipitation in Reservoir Fluids
A pre®iously described molecular-thermodynamic framework, based on colloid theory, is used to correlate experimental asphaltene-precipitation data at high-temperature and pressure conditions. In this framework, asphaltenes and resins are represented by pseudopure components, and all other components in a crude oil are presented by a continuous medium that affects ®an der Waals attractions among...
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