Impact of Integrated Technologies of Enhanced Oil Recovery on the Changes in the Composition of Heavy Oil

Abstract

This paper deals with the impact of an integrated technology for enhanced oil recovery on the composition of high-viscosity heavy oil produced at the Usinskoye oilfield (Russia, Komi Republic). In order to increase the effectiveness of the thermal-steam stimulation, a surfactant-based composition generating carbon dioxide and an alkaline buffer system is injected into the formation. The analysis of the oil composition is performed via the methods of gradient-displacement liquid adsorption, gas-liquid chromatography, and IR spectroscopy. The results obtained show that two parallel processes are proceeding when pumping an oil-displacing composition. The first process is the additional extraction of residual oil. This process is controlled by an increase in the content of resin-asphaltene substances in oil. The second process is an increase in the coverage of reservoir and the involvement into the development of previously uncovered areas with oil compositionally similar to that at the beginning of development. Using the results of the analysis of the component composition, the individual composition of alkanes, and structural fragments of oil samples in order to control the development of the Usinskoye oilfield, the frontal oil-water boundary advance of the Northern area in the direction of the upper production facility is determined. The obtained patterns of changes in the oil composition after the application of an integrated technology using a surfactant-based composition can be characteristic of other deposits of heavy oil occurring in low-permeability reservoirs