Solid deposition is one of the most serious problems that arise in oil production. Well and oil pipeline clogging can lead to operational delays and result in very significant cost elevations. The tendency of certain oils to flocculate and form deposits is attributed to asphaltenes and their respective molecular interactions. Asphaltenes are dark brown to black solids and are defined as being soluble in toluene and insoluble in heptane. We have recently developed a fractionation procedure that is faster than the traditional IP 143 method and requires less sample and heating and no aromatic solvents. Asphaltene samples were extracted from two Colombian crude oils (C1 and C2) and fractionated by new method based on solvent blends, NP1 and NP2. Constituents were monitored by Hydrogen Nuclear Magnetic Resonance (1H-NMR).This extraction technique employs a naphthenic solvent, (N), in combination with two paraffinic solvents referred to as P1 (n-pentane) and P2 (n-heptane). In a typical procedure, a corresponding amount of sample is added to a 250ml extractor with the specific solvent blend, and left under magnetic stirring for two hours at room temperature. At the end of this period, the insoluble fraction (asphaltene) is filtered under vacuum and dried in an oven at 80�C. As expected, the percentage of asphaltenes extracted by the NP1 technique was higher than that obtained by the NP2 technique. Even when varying the type of paraffin solvent, the constituents extracted revealed very similar total percentages of saturated and aromatic hydrogens however the proportions of.different types hydrogen may vary considerably. Thus the method may provide additional information on the types of hydrogens that are present.

Fractionation by solvent blends and characterization by NMR of asphaltenes from Colombian crude oils

248th National Meeting (2014)

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