THE STRUCTURAL FEATURES OF RESINS AND ASPHALTENES OF CRUDE OILS FROM UDMURTIA OILFIELDS

The physicochemical properties, group chemical and structural-group composition of oils from the Karsovay and Gremikha fields, as well as the composition of the stabilizing layer of an oil-in-water emulsion (W/O) formed by oil from the Gremikha field were investigated. Resins and asphaltenes were isolated from the studied oils and the interphase layer of water-oil emulsion and they were studied by FTIR spectroscopy, H-1 and C-13 NMR spectroscopy, and the features of their structure-group composition were revealed. It was determined, that content of asphaltenes is 3 times higher in oil from Gremikha field, while content of resins and wax is lower than thouse in oil from Karsovay field. Structural group analysis of asphaltenes and resins isolated from the studied oils by standard methods showed, that the asphaltenes of the Gremikha oil field are close in molecular weights to the asphaltenes extracted from the oil of the Karsovai oilfield, but are characterized by a higher contant of condensed aromatic and naphthenic structures. In the composition of the resins of the studied oils, the opposite pattern was observed. The quantitative and qualitative composition of natural surface-active compounds presented in the oil of the Gremikha field explains the high aggregate stability of the water-oil emulsion formed by this oil. Analysis of nature stabilizers of the W/O emulsion interphase layer showed a significant predominance in its composition of asphaltenes (92.6%), characterized by a higher molecular weight and a higher content of condensed cyclic structures, with a predominance of aromatic rings and with a significant content of naphthenic structures in comparison with the original oil. The increased content of heteroatoms (S, N and 0) in the composition of asphaltene molecules from the stabilization layer also indicates the higher surface-active properties of these compounds.