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Reduction of oil viscosity is of great importance for the petroleum industry since it contributes a lot to the facilitation of pipeline transportation of oil. This study analyzes the capability of acoustic waves to decrease the viscosity of oil during its commercial production. Three types of equipment were tested: an ultrasonic emitter that is located directly in the well and affects oil during its production and two types of acoustic machines to be located at the wellhead and perform acoustic treatment after oil extraction: a setup for ultrasonic hydrodynamic treatment and a flow-through ultrasonic reactor. In our case, the two acoustic machines were rebuilt and tested in the laboratory. The viscosity of oil was measured before and after both types of acoustic treatment; and 2, 24 and 48h after ultrasonic treatment and 1 and 4h after hydrodynamic treatment in order to estimate the constancy of viscosity reduction. The viscosity reduction achieved by acoustic waves was compared to the viscosity reduction achieved by acoustic waves jointly with solvents. It was shown, that regardless of the form of powerful acoustic impact, a long lasting decrease in viscosity can be obtained only if sonochemical treatment is used. Using sonochemical treatment based on ultrasonic hydrodynamic treatment a viscosity reduction by 72,46% was achieved. However, the reduction in viscosity by 16%, which was demonstrated using the ultrasonic downhole tool in the well without addition of chemicals, is high enough to facilitate the production of viscous hydrocarbons.

An ultrasonic technology for enhanced oil recovery is described. For the implementation of this technology, the equipment was specially developed, taking into account the working conditions. The criteria for selections of well candidates were developed. The technology has been tested in two different regions in different geological conditions. The results of these field tests indicate the high efficiency of the proposed technology. The success rate of the method reached 90% and the increase in oil production was in the range of 40%-100%.

We have investigated the critical temperature behavior in periodic superconductor/ ferromagnet (S/F) multilayers as a function of the ferromagnetic layer thickness d f and the interface transparency. The critical temperature Tc(d f ) exhibits a damped oscillatory behavior in these systems due to an exchange field in the ferromagnetic material. In this work we have performed Tc calculations using the self-consistent multimode approach, which is considered to be exact solving method. Using this approach we have derived the conditions of 0 or π state realization in periodic S/F multilayers. Moreover, we have presented the comparison between the single-mode and multimode approaches and established the limits of applicability of the single-mode approximation, frequently used by experimentalists.