Characterization of the isolated wetting crude oil components with infrared spectroscopy

To improve the understanding of wettability, especially the influence of different crude oil colloids, wetting experiments on quartz sand and kaolin were performed with an asphaltene rich oil. A two-step procedure was developed to investigate the wetting behavior. In the first step, those crude oil components were extracted, which preferentially wet solid surfaces. The extracted crude oil components were characterized in a second step. The composition of the fractions extracted with different solvents are different. The acetone fractions extracted from quartz sand are rich in compounds containing nitrogen, whereas the compounds containing sulphur predominate in the chloroform fraction extracted from quartz sand. IR spectroscopy of the extracted fractions shows that carbonyl compounds are abundant in the methanol/chloroform and acetone/chloroform fractions extracted from quartz sand. The chloroform fraction is poor in carbonyl group-containing compounds. In agreement with elemental analysis, a strong signal for C-N groups in the IR spectra is found for acetone/chloroform and methanol/chloroform fractions, extracted from the quartz sand system. On the other hand, a significant, strong IR-peak representing S=O containing components is observed in the acetone and acetone/chloroform fractions, extracted from quartz sand. (C) 1999 Elsevier Science B.V. All rights reserved.