Chemical composition of Pechora Sea crude oil

The physicochemical properties of the Pechora Sea shelf oil and its chemical composition have been studied using the methods of refractometry, titrimetry, viscometry, rheometry and standard methods for the analysis of oil and petroleum products. The fractionation of oil is held at atmospheric pressure, some fractions boiling at the temperature below and above 211 °C have been received. Chemical structural-group composition of oil and its components has been investigated using a Fourier infrared (IR) spectroscopy method. The density of oil has been obtained, it is equal to 24.2 API. The chemical composition analysis shows that water content in the investigated oil sample is about 0.03 % (by weight). The oil sample contains hydrocarbons (including alkanes, naphthenes, arenes) and asphaltenes with resins; their content is equal to 89 and 10 % (by weight) respectively. Alkane content is about 66 %, including alkanes of normal structure - about 37 %. The solidification temperature of oil sample is equal to -43 °C. This low temperature testifies obliquely low content of solid alkanes (paraffin). Bearing in mind the content of asphaltenes with resins we can refer the investigated oil sample to resinous oils. On the other hand spectral coefficient values (aromaticity quotient and aliphaticity quotient) show that oil sample belongs to naphthenic oils. According to the data of Fourier IR spectroscopy contents of naphthenes and arenes are 5.9 and 17.8 % respectively. Thus, the obtained data of chemical structural-group composition of crude oil and its fractions indicate that this oil belongs to the heavy resinous naphthenic oils. The rheological parameters obtained at the shear deformation conditions characterize the crude oil as a visco-plastic medium.