Structural Transformations of Heavy Oil Resins From the Nurlat Oilfield Under Thermal Action

Resins extracted from heavy high-viscous oil of the Nurlat oilfield were investigated. The composition of fragments bound through sulphide and ether bridges in the molecules of initial resins and the liquid products of their conversion at 450 °C under the conditions of laboratory experiment was studied using a set of physicochemical methods (IR spectroscopy, UV spectroscopy, gas chromatography - mass spectrometry, chemical destruction). It is shown that the fragments undergoing destruction are mainly those bound in the structure of the initial sample through the least thermally stable functional groups of esters and aliphatic sulphides. Sulphur- and ether-bound compounds in the structure of both resin samples are represented by n-alkanes, n-alkylcyclopentanes, n-alkylcyclohexanes and hopanes. The presence of nickel porphyrins was established among the sulphur-bound compounds. It is the molecular composition of bound n-alkanes that changes most noticeably during thermolysis. Ether bond cleavage in the molecules of secondary resins leads to the formation of products containing mono- and dibromides of alkyl biphenyls. This fact provides evidence that these aromatic compounds are present in resins in the form of fragments bound with other structural fragments through one and two ether bridges.