Time filter

Source Type

Golubovskii Y.B.,Saint Petersburg State University | Kolobov V.I.,CFD Research Corporation | Nekuchaev V.O.,Ukhta State Technical University
Physics of Plasmas | Year: 2013

Plasma stratification and excitation of ionization waves is one of the fundamental problems in gas discharge physics. Significant progress in this field is associated with the name of Lev Tsendin. He advocated the need for the kinetic approach to this problem contrary to the traditional hydrodynamic approach, introduced the idea of electron bunching in spatially periodic electric fields, and developed a theory of kinetic resonances for analysis of moving striations in rare gases. The present paper shows how Tsendin's ideas have been further developed and applied for understanding the nature of the well-known S-, P-, and R-striations observed in glow discharges of inert gases at low pressures and currents. We review numerical solutions of a Fokker-Planck kinetic equation in spatially periodic electric fields under the effects of elastic and inelastic collisions of electrons with atoms. We illustrate the formation of kinetic resonances at specific field periods for different shapes of injected Electron Distribution Functions (EDF). Computer simulations illustrate how self-organization of the EDFs occurs under nonlocal conditions and how Gaussian-like peaks moving along resonance trajectories are formed in a certain range of discharge conditions. The calculated EDFs agree well with the experimentally measured EDFs for the S, P, and R striations in noble gases. We discuss how kinetic resonances affect dispersion characteristics of moving striations and mention some non-linear effects associated with glow discharge stratification. We propose further studies of stratification phenomena combining physical kinetics and non-linear physics. © 2013 AIP Publishing LLC.


Kobrunov A.I.,Ukhta State Technical University
Izvestiya, Physics of the Solid Earth | Year: 2014

Analytical properties of the solutions of the inverse problem of gravimetry are studied in the context of the approximative approach and method of linear integral representations. A new effect of the inheritance of specific analytical properties in the solutions, which is named the effect of hidden equivalence, is revealed and investigated. This effect significantly influences the interpretation informativity in the complex models of a medium, and it should be taken into account in the geological interpretation of gravity data. Hidden equivalence is studied for both linear and nonlinear inverse problems. As an example of a nonlinear problem, the inverse problem of structural gravimetry is analyzed. The correlation between the boundary equations and boundary values of the harmonic functions is demonstrated. Methods are suggested to allow for the effects that occur by expanding the approximative approach for complex conditions (the models of the media with spatially distributed parameters) by the dynamical and criterion principles. © 2014 Pleiades Publishing, Ltd.


Durkin S.M.,Ukhta State Technical University
Neftyanoe Khozyaistvo - Oil Industry | Year: 2014

This article is devoted to the improvement of the methods of well tests interpretation for heavy oil field with fractured reservoirs. Creation of the numerical mathematical model of the well, draining fractured porous reservoir is presented. The developed model will allow to describe the well tests and to identify the type of filtration flow characteristic of fractured reservoirs.


Balkin A.,Ukhta State Technical University
Offshore Engineer | Year: 2015

Flow assurance issues can be very costly to repair, or if unrepaired, can lead to erosion and corrosion and can endanger asset integrity. Furthermore, deposition of solid matter reduces the line throughput, sometimes leading to complete blockages and making profitable production of hydrocarbons practically impossible. As part of the development of a comprehensive subsea tieback management strategy, the Well Engineering Research Group at Robert Gordon University in Aberdeen, Scotland, has endeavored to create a model for sand transport in long-distance subsea tiebacks. The ideal model would have the potential to solve problems of pipe and equipment sizing, locate places of sand deposition and improve sand management strategies.


Gerzhberg Yu.M.,Ukhta State Technical University
Neftyanoe khozyaystvo - Oil Industry | Year: 2015

Article is devoted to an integrated approach to design BHA. We consider the issues of its tension at different situations along with its hole path characteristics, we determine the safety coefficient on fatigue resistance, prevention of a holding strap, depressurization of threaded connections. Fundamentals of methodology and examples of configurations complex calculation with the use of computer programs are shown here. Use of several additional centralizers (over lower full-measured) with a diameter, which is significantly smaller, than a bit allows to increase efficiency of regulation of the well path 10-20% and to reduce holding strap forces at its sticking with preservation of optimum mass of the weighted pipes.


Gerzhberg Yu.M.,Ukhta State Technical University
Neftyanoe Khozyaistvo - Oil Industry | Year: 2013

This work is devoted to prevent BHA differential sticking as a result of its sticking to well's wall. We give the methodology and some research results of various factors influence on BHA sticking to a crust by means of contact area determination and the interaction force of pipes with a crust. We show the most significant actions to prevent BHA differential sticking of the boring tool when the boring tool stops working.


Gerzhberg Yu.M.,Ukhta State Technical University
Neftyanoe khozyaystvo - Oil Industry | Year: 2015

The problem of BHA holding as a result of its sticking to a well wall is considered. There are the results of researches of comparative efficiency of various actions to prevent such holding straps including the use of lubricants in boring mud, hydraulic vibrators to decrease adhesion forces with a clay crust, inclusions in assembly structure of the basic elements reducing its contact. The most effective technological decisions to prevent such holding straps are shown.


Sergey D.,Ukhta State Technical University
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2015

Well tests are an integral part of learning the filtration characteristics of the producing formation. The article considers the main approaches of learning and interpreting the results of field research on stationary and non-stationary filtration mode. The choice of one or another mathematical model predictions depends on the quality of filtration properties interwell reservoir. Heterogeneous, low-permeability reservoirs are special problem for the study of the mechanism of filtration. In the attempt to create a mathematical model of a well draining fractured porous reservoir, based on a realistic representation of fractures. The results of the adaptation field research confirmed the efficiency of real well developed numerical model. Established model allowed to interpret the radial, linear and bilinear flow regime. It is shown that the reservoirs are characterized by a linear and bilinear flow regime, indicating that the filtering mechanism in the system of "matrix-fracture" by different laws filtering. Also it developed a methodical approach that allows to take into account the wellbore, given technological regime on the head and on the bottom of the well. Three-dimensional formulation of the problem has allowed to extend the model to the multiphase flow. © Copyright 2015, Society of Petroleum Engineers.


Ruzin L.M.,Ukhta State Technical University
Neftyanoe Khozyaistvo - Oil Industry | Year: 2012

The geological and physical characteristics of Yaregskoye and Usinskoye high viscosity oil deposits that have Influenced the choice of fields development systems are considered. The stages of development of productive objects stimulation technologies are shown. The numerical simulation and routine analysis of results of thermal methods application at these fields are executed.


Kobrunov A.I.,Ukhta State Technical University
Izvestiya, Physics of the Solid Earth | Year: 2015

The paper describes the method for solving the inverse problems of gravimetry based on the functional representations, which follow from the variational principles in the uniform metrics with respect to density models of the geological medium. The functional representations are obtained for both the linear problem (which study local density distributions) and nonlinear problem (which study a system of structural models). The explicit formulas for calculating density models are derived for the particular cases based on the introduced functional representations of the obtained solutions. In the general case, the converging iterative processes providing the solution for both the density distribution models and structural models are constructed. The relationship is established between the functional representations implementing the variational principle in the uniform metric and linear integral representations corresponding to the optimization in the quadratic norm, on one hand, and the other known density models, on the other hand. © 2015, Pleiades Publishing, Ltd.

Loading Ukhta State Technical University collaborators
Loading Ukhta State Technical University collaborators