A COLLOIDAL MODEL FOR ASPHALTENE FLOCCULATION FROM PETROLEUM FLUIDS

The need to understand the nature of asphaltenes and asphalts and their role in the production, transportation and processing of crude oil is wellrecognized internationally, as manifested by the current activities in the petroleum industry towards exploration, drilling, production and processing of heavier oils (higher in asphaltene content). Asphaltene deposition during oil production and processing ranks as one of the costliest technical problems the petroleum industry currently faces. In the present report, a colloidal model has been developed, capable of predicting the onset of flocculation of colloidal asphaltene in oil mixtures, due to either changes in composition (i.e., solvent addition) or electrical phenomena (i.e., streaming potential generation due to flow of asphallenes containing oil in conduits or porous media). For oil mixtures from which flocculation is caused simply by flow, the model can make predictions as to the velocity ranges where colloidal asphaltene flocculation can be avoided. This could have a significant impact on allowed reservoir drawdown rates, well spacing and tubing design. The present model is a part of a comprehensive asphaltene FRACTAL aggregation model (ASPHRAC) being developed at the University of Illinois.