Mathematical Model of Asphaltene Deposition During Oil Production

Abstract

Asphaltenes are heavy hydrocarbon molecules that exist naturally in petroleum reservoir fluids. Asphaltene precipitation may occur during pressure depletion or during gas injection processes to improve oil recovery. Inside the reservoir, the precipitated asphaltene can deposit onto the rock surface or remain as a suspended solid in the oil phase. Precipitated asphaltenes are one of the main causes of decreased permeability. A new approach to modeling asphaltene deposition during oil production has been developed. In the model, oil is represented by two hydrocarbon components (‘‘oil’’ and ‘‘asphaltene’’) that do not dissolve in water and the theory of an ideal solution of a binary mixture is used. Closing relations for the mass and momentum conservation equations describing porosity, permeability and mass transfer are constructed using the pore size distribution function and a model of an ideal porous medium consisting of a bundle of capillaries.