Study of the Hydrocarbon Composition of Viscous Oil when Displacing by the Integrated Method Using Urease
Yu. Z. GUSEVA, L. K. ALTUNINA, L. I. SVAROVSKAYA
Institute of Petroleum Chemistry, Siberian Branch, Russian Academy of Sciences, Tomsk, Russia
Keywords: вязкие нефти, нефтеотдача, карбамид, уреаза, гидролиз, viscous oils, oil recovery, carbamide, urease, hydrolysis
Abstract
The consistent pattern of distribution and transformation of petroleum hydrocarbons after displacement from the reservoir model was studied by the integrated method using oil-displacing the composition containing carbamide and natural sources of the enzyme urease (amidohydrolase EC 3.5.1.5). Depending on the time and concentration the catalytic activity of natural sources of urease in the processes of carbamide hydrolysis was determined. The optimum enzyme/substrate ratios and time of carrying out hydrolysis to achieve the maximum alkaline reaction with pH 9.0-10 were selected. Chromatographic analysis of gaseous products of carbamide hydrolysis at a temperature of 25-30 °C showed that under identical experiment conditions, urease of the beet mass represents a higher enzymatic activity in comparison with soybean flour. The effect of gaseous products of carbamide hydrolysis on rheological properties of viscous tarry oil of the Usinsk deposit and viscous paraffin oil of the Tamsagbulag deposit (Mongolia) was studied. It was found that the composition of gaseous hydrolysis products did not affect rheological properties of oils. On the example of viscous oil of the Usinsk deposit, model displacement was carried out by the integrated method at a temperature of 25 °C using urease of beet mass and soybean flour. The additional volume of oil in the control variant with application of a solution of oil-displacing composition amounted to (16±1.2), soy - (20.3±1.8), and beet mass - (24.9±2.2) mass %. Additional oil displacement in the control variant is carried out due to the detergent properties of the composition containing a surfactant, in experimental - due to the detergent properties of the composition and gaseous products of enzymatic hydrolysis of carbamide that form inside of the reservoir an oil-displacing system. Chromato-mass spectrometry analysis of original oil and displaced by the developed method confirmed the identity of the composition of hydrocarbons, including n-alkanes, hetero-organic and aromatic structures, among them steranes and hopanes.
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