2-DIMENSIONAL SOLUBILITY PARAMETER MAPPING OF HEAVY OILS

The solubility and insolubility of heavy oils and their fractions in d ilute mixtures with various solvents were used to characterize heavy o il interactions. A two-dimensional solubility parameter, developed for the selection of solvents for organic polymers, was found to group al l the solvents for each heavy oil fraction in polygon areas when the c omplexing solubility parameter component was plotted against the field force solubility parameter component. All fractions of Cold Lake vacu um residua, except for the saturate fraction, form concentric solubili ty areas. Therefore, in going in the direction of decreasing aromatici ty from coke to asphaltenes to resins to aromatics, all solvents for t he previous fraction in the series are also solvents for all subsequen t fractions in the series. As a result, asphaltenes can be precipitate d, but not extracted, from heavy oils. This is attributed to the inter action among polynuclear aromatics being the dominate interaction in p etroleum that causes insolubility in hydrocarbon liquids. However, the paraffinic chains on the same petroleum molecules limit their solubil ity in highly complexing liquids. In contrast, even vacuum gas oils fr om the Exxon Donor Solvent coal liquefaction process are insoluble in aromatic liquids but soluble in moderately complexing liquids because of hydrogen bonding, resulting from oxygen functionality. Hydrotreatin g of these coal derived vacuum gas oils reduces their oxygen functiona lity and increases their solubility areas so that they become compatib le with petroleum liquids.