Components of Paraffin-Base and Naphthenic-Base Crude Oil and Their Effects on Interfacial Performance

The saturate, aromatics, resin and asphaltene components of paraffin-base (PB) and naphthenic-base (HB) crude oil are separated by chromatographic column. The acidic components of crude oil are extracted by compounded polar solvents and identified by methyl esterification of diazomethane. The acidic components before and after asphaltene removal are investigated by gas chromatography-mass spectrometer. The effect of four fractions in simulated oil on interfacial activity is discussed. The results show PB is rich in naphthalene series and tri-aromatic steroids, and HB has a high content of phenanthrene series, chrysene series and methylpyrene, besides higher content of naphthalene series. The long carbon chain acids in HB oil decrease significantly by asphaltenes removal, confirming the presence of heavy oil acids in asphaltene. A little amount of saturates and aromatics in simulated oil can reduce the interfacial tension (IFT). When the content of asphaltenes of simulated oil is increased, IFT is initially decreased and finally increased because of stability of asphaltenes. When resin is increased, IFT is initially increased and then decreased. Simulated oil containing the resin from naphthenic-base oil is more sensitive to alkali than that of paraffin-base resin, which can reduce the IFT between oil and water at a larger range.