PROPERTIES OF BASE OILS FROM HEAVY CRUDES AND NATIVE BITUMENS OF PERMMIAN DEPOSITS OF TATARSTAN AS FUNCTION OF DEGREE OF THEIR NATURAL METAMORPHOSIS

摘要

Distinctive features of the composition and properties of base oils and their narrow fractions separated by thermodiffusion from various types of heavy crudes are identified. The differing degree of biochemical degradation of crude oil is expressed in pour points viscosity index, and thermooxidative stability of the base oils. The density, refractive index, and average molecular weight of the oils rise with increasing degree of biochemical degradation. In this case, the viscosity index and pour point of the oils fall, but the thermooxidative stability rises. The refractive indices and densities are found to correlate with viscosity indices and pour points in several studied oil fractions from various types of crudes. The correlation found can be used to predict technological properties of oil fractions of fairly limited information about their composition and properties. On the one hand, irregular composition of the crude oils is a demerit against this feedstock, and on the other, the diversity of compositions of the crudes broadens their potential use for production of lubricants by both selection of the parent stock and compounding of various fractions.