The influence of the niobium nitride additives on the structure, phase composition and performance characteristics of diamond composite material based on tungsten carbide matrix, obtained by hot pressing was studied. The insertion of the niobium nitride into initial materials enhances the hardness of the transition zone of the diamond - matrix from 14.4 to 28.2 GPa, ultimate stress limit from 4640 to 5260 MP at bending , and reduces composite wear rate from 1790 ×10^-6 to 630×10^-6 g/m. The mechanism, which contributes to the improvement of mechanical and tribological properties of such composites, was ascertained.

Keywords: diamond; tungsten carbide; cobalt; niobium nitride; transition zone; phase; composite; pressure; temperature; structure; mechanical properties; wear.

A mathematical operation model of a drill string with a vibrating mechanism at the top, which is used to eliminate sticking of the drilling tool, has been presented in this article. The resulting discrete-continual model, considering the wave processes, consists of separate sections of drill pipes with different parameters (material, cross-sectional area, external loads). This model is basis for a computer program to visualize oscillatory processes occurring in the pipe string and numeric calculation of the basic kinematic and dynamic characteristics of the studied system. The method of vibrator parameters matching provides a significant increase in the accuracy when determining forces, stresses and safety reserves in an arbitrary pipe string section and predicting sidewall sticking during oil and gas wells drilling. Recommendations are given on the selection the amplitude of disturbance and resonance frequencies for releasing of stuck pipe and prevention drill-string failure.

Keywords: drilling; drill pipe; elastic waves; mathematical model; vibrator; transfer function; amplitude-phase characteristic.

The paper presents the experimental studies of the gas condensate system flow in the porous medium at the pressure, which is higher than the dewpoint pressure. The experimental studies of the stationary filtration showed that the gas flow rate starts increasing at the pressure, which significantly exceeds the phase transition P = 1.74 P_с (P_с – dewpoint pressure), and, at the pressure P = 1.5 P_с, the gas flow rate reaches its peak and is almost 30% higher than the flow rate near the phase-transition point. Furthermore, the dependence of the gas flow rate on the pressure level has nonmonotonic nature and the increased values of the flow rate are reached within the range of the pressure level P = 1.4-1.74Pс. The influence of the wettability on the process of the stationary filtration was considered. It was shown that there isn’t any increase of the gas flow rate in the oleophobic porous medium. The non-stationary filtration of the gas condensate system was eperimentally studied. It was shown that a significant reduction of the system piezo-conductivity occurs during the process of the non-stationary filtration when the pressure decreases. It is related with the increase in the compressibility due to the subcritical condensate formation in the porous medium. The mechanism of observed effects was suggested based on formation of the stable subcritical condensate nuclei, associated slippage effect, and change of the system compressibility. The mechanism for stabilization of the subcritical nuclei by the combined action of the surface and electrical forces was considered. The mathematical models to describe the obtained experimental results were proposed.

Keywords: gas condensate system; dewpoint pressure; filtration; porous medium; slippage effect; gas flow rate; concentration.

The article summarizes the results of research and theoretical ideas on the influence of high-molecular components on oil rheology and formation of asphaltene-resinparaffin deposits. The industrial experience and the results of laboratory studies of the depressor efficiency and inhibitory ability of the reagents are considered in their use in commercial oils, depending on the pumping temperature. The authors analyzed the influence of the composition of oil on the efficiency of oil-field chemistry, recommendations and proposals for their application in the system of oil trunk pipelines are given.

Keywords: heavy oil; asphaltene deposits; effective viscosity; chemical reagents; rheological effect; high-molecular components; thermal treatment; flow loss.

In the article, the influence of the stratum water mineralization on the process of the natural gas hydrate formation from the Eastern Siberian platform fields differing according to their conditions of occurrence, stratum water mineralization and the natural gas composition was studied. Experimental studies showed that with increasing of the solution mineralization the hydrates of smaller volume are formed, i.e. the inhibitory effect of the stratum water increases.

Keywords: oil and gas fields; stratum temperature and pressure; mineralization of the stratum water; natural gas; thermobaric conditions of hydrate formation; gas hydrates.

The study was conducted to ascertain the possibility of applying aqueous solutions of zwitter-ionic surfactants as oil displacing reagents. Tests on  oil-displacing capability using bulk models, dynamic viscosity, surfaceactive properties of the aqueous solution were carried out and the results showed ZPAV-3 as the most versatile and effective for reservoirs with low and high temperatures.

Keywords: oil recovery factor; zwitterionic surfactants; oil displacement; dynamic viscosity; surface activity; adsorption.

The article considers the problem of total calculation of oil and condensate, pumped through the same transport communications of SOCAR oil fields. The domestic and world experience of comparing the value of various hydrocarbons based on such technical and economic concepts as fuel and oil equivalents is analyzed. Options are proposed for calculating the coefficients of gas condensate replacement for oil "fuel" by thermal equivalents, according to the oil equivalent barrel, by thermal conductivity of liquid hydrocarbons, without recalculating their quantity into conventional fuel.

Keywords: total calculation of oil and gas condensate; standard fuel; fuel equivalent; barrel of oil equivalent; heat of combustion; thermal conductivity coefficient.