FAST CRUDE-OIL HEAVY-COMPONENT CHARACTERIZATION USING COMBINATION OF ASTM, HPLC, AND GPC METHODS

Leontaritis, K.J. and Mansoori, G.A., 1989. Fast crude-oil heavy-component characterization using combination of ASTM, HPLC, and GPC methods. J. Pet. Sci. Eng., 2: 1-12. Resins and asphaltenes are considered important culprits of the asphaltene deposition problem and understanding their phase behavior is crucial to its solution. Predictive models of asphaltene deposition would normally require as input a minimum number of physical, chemical, and thermodynamic properties of the resins and asphaltenes. The main objective of the paper is to propose an improved technique for quick determination of the resin (i.e., asphaltene peptizing agent) content of a hydrocarbon mixture that simultaneously separates the resins for further analysis. The technique is a combination of ASTM standard and HPLC methods. The results of this technique were checked satisfactorily against those of another equivalent conventional method, which is more time consuming and less reproducible. Furthermore, molecular size distributions of asphaltenes and resins were determined for two crude oils of widely different asphaltene and resin content and place of origin using GPC. A relationship between the asphaltene-number average molecular weight (relative to polystyrene) and the flocculant paraffin carbon number is suggested.