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Water-alternating-gas injection into oil reservoirs, i.e., the gas method of enhancd oil recovery that supposes water and carbon dioxide injection in the reservoir with the aim to increase the oil recovery is investigated. The use of such stimulation is complicated by the possibility of gravity override that leads to non-uniform sweep efficiency. Dimensionless parameters which characterize phase override are determined from the system of equations that describe the flow of water and two-phase hydrocarbon mixture. It is shown that the efficiency of water-alternating-gas injection depends on three similarity parameters. The parametric investigation of the optimum strategies of water and carbon dioxide injection is carried out when one of the dimensionless similarity parameters varies. The diagram of optimal strategies of water-alternating-gas injection is constructed. The optimum completion intervals for the injection and producing well are investigated for various values of the taken parameter. [ABSTRACT FROM AUTHOR]

An incompressible-fluid flow in a vortex tube is studied at a temperature close to the boiling point. In the near-axial region of the vortex tube, the existence of a precessing steam vortex and secondary vortex structures is confirmed. The radial distributions of the thermodynamic parameters and velocity components are obtained. [ABSTRACT FROM AUTHOR]

A novel method of dispersing a gas in a liquid by pressure pulses generated by waves propagating from a hydrodynamic oscillation generator is proposed. Devices that realize this method, wave dispersers, are created and investigated experimentally. The amplitude-frequency characteristics of the wave processes in the dispersers and the size distribution density functions of the gas bubbles are obtained. It is shown that there are optimal pressure values at the disperser inlet at which a minimum bubble size is achieved. The average diameter of the gas bubbles produced by water wave dispersers in the optimal operation regimes varied on the range from 0.3 to 0.6 mm, depending on the gas flow-rate. [ABSTRACT FROM AUTHOR]

The quasi-adiabatic regime of free oscillation of a bubble in the presence of irreversible interphase heat transfer between the bubble and the ambient liquid is studied. On the basis of simplified model equations of a rarefied bubble mixture, a nonlinear-oscillation equation of the relaxation type is obtained. In constructing an exact particular solution of this equation, the heat transfer law associated with bubble compression is established. For studying the harmonic oscillations, the Krylov-Bogolyubov-Mitropol’skii asymptotic method is used. It is shown that, for a small bubble, the viscosity and heat transfer effects are of the same order. For a small bubble, the influence of these effects on the formation of the natural-oscillation frequency, which is small in the linear approximation, may be significant in the nonlinear formulation. For a large bubble, the influence of these effects is negligible in both approximations. For the approximate solution of the nonlinear equation, a uniformly valid second-order expansion is constructed. [ABSTRACT FROM AUTHOR]

The plane one-dimensional and radially symmetric problems of injection of superheated steam into a porous medium saturated with gas are considered. Self-similar solutions are constructed on the assumption that in this case four zones are formed in the porous medium, namely, a gas flow zone, superheated and wet steam zones, and a water slug zone formed due to steam condensation. On the basis of the solution obtained, both the effects of the boundary pressure, mass flow rate, and temperature of the injected superheated steam and the effect of the initial state of the porous medium on the propagation of the hydrodynamic and thermal fields in the porous medium are studied. [ABSTRACT FROM AUTHOR]

Quasi-isothermal wave propagation in a gas-liquid mixture, in which the thermodynamic behavior of the gas in the bubbles in near-isothermal, is investigated. A fourth-order evolutionary equation with a basic hydrodynamic nonlinearity and an additional nonlinearity attributable to the interphase heat transfer is derived. An exact particular solution of this equation predicting an increase in pressure wave amplitude for a specific law of interphase heat transfer is constructed. A range of permissible initial bubble radii on which the wave amplification effect is observed is determined. [ABSTRACT FROM AUTHOR]

An evolutionary equation with two nonlinearities (basic hydrodynamic and an additional nonlinearity attributable to interphase heat transfer) describing the wave dynamics in a mixture in the presence of viscosity is obtained. For a quasi-adiabatic regime, depending on the heat transfer laws determined by the relations between the thermophysical parameters of the mixture two exact particular solutions predicting different pressure behaviors in the wave are given. Nonmonotonous pressure behavior associated with an increase in the wave amplitude is interpreted as wave amplification as compared with the case of monotonous behavior. Depending on the thermophysical parameters, an interval of permissible Weber numbers is found for which the amplification effect is observed. The surface tension reduces the wave amplitude and width and results in a nonmonotonous dependence of the wave velocity on the Weber number. [ABSTRACT FROM AUTHOR]

The influence of the composition and thermophysical properties of gas-liquid bubbly systems with a dissociating component in the gaseous phase on the laws of small-disturbance propagation and attenuation is investigated. It is found that the reacting gas component in the bubbles significantly affects the sonic-wave attenuation coefficient in the bubbly liquid. This follows from the fact that when a gas bubble is compressed isothermally, a recombination reaction occurs which prevents pressure growth in the bubble. Small-disturbance propagation in bubbly liquids was investigated in a number of publications discussed in review [1]. The acoustics of a bubbly liquid with a gas phase containing active admixtures are of both methodical and practical interest. The dynamics of such multicomponent bubbles were investigated in [2]. [ABSTRACT FROM AUTHOR]