New Methodology for Calculating the Impact of High Free Gas Content in the Flow on ESP Characteristics for the West Siberia Fields

2021 ◽  
Author(s):  
Kirill Alexandrovich Goridko ◽  
Rinat Alfredovich Khabibullin ◽  
Vladimir Sergeevich Verbitsky ◽  
Arturas Rimo Shabonas ◽  
Guzel Kazakbaeva
Keyword(s):  
Mathematical Model ◽  
Specific Energy Consumption ◽  
Experimental Studies ◽  
Liquid Mixtures ◽  
Engineering Method ◽  
Gas Content ◽  
Free Gas ◽  
Power Characteristics ◽  
Wide Range ◽  
The Impact

Abstract One of the most common complications in the operation of wells with electric submersible pumps (ESP) is the presence of free gas in the produced well product. The work considers a model of ESP operation taking into account a large share of free gas in the flow obtained on the basis of bench tests and its applicability for analyzing the operation of real producing wells equipped with ESPs. Tests of ESP5-50 (118 radial stages) with model gas-liquid mixtures in a wide range of inlet gas volume-flow rate (0-60%), inlet pressure (0.6-2.1 MPa), shaft speed (2400-3600 rpm) with simultaneous pressure measurement along the pump length and direct measuring of power at the shaft by means of motor weights were performed at the oilfield development and operation department. Mathematical model is obtained by means of regression analysis of experimentally received characteristics of ESPs on gas liquid mixtures; a simple engineering method of calculating the degradation of ESPs characteristics by flow, head and power is suggested. The experience of building similar models described in the literature was taken into account. Experimental studies and creation of a mathematical model of ESP were carried out during Kirill Goridko's PhD thesis. As a result of the research we obtained the degradation dependencies of the pump's delivery and the head of ESP while pumping mixtures of different foam capacity, which simulate the pump operation in low and high watercut wells. The patterns of delivery and head coefficients depending on the zone (left, optimum, right) of ESP characteristic are revealed. The degradation of ESP power during pumping gas liquid mixture is clarified, which allows to calculate more accurately the specific energy consumption of well products lifting. The developed method of recalculation of the pressure and power characteristics of ESPs is implemented in the form of calculation modules designed for engineering calculations in oil production. The proposed tool has been tested on the data of the Western Siberia fields while analyzing the operation of wells with high gas content in the produced product. Calculation modules have been made publicly available. A new simple engineering method was developed to account for the degradation of the pressure and flow and power characteristics of ESPs for low- and medium-rate wells based on a large number of benchmark studies. Оbtained degradation dependences are programmed in the form of calculation modules, which allows to analyze the operation of a large number of wells on the basis of their technological mode, as well as to propose optimization measures to change the ESP operation at a higher level.

scholarly journals Image Statistics Preserving Encrypt-then-Compress Scheme Dedicated for JPEG Compression Standard

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 421
Author(s):  
Dariusz Puchala ◽  
Kamil Stokfiszewski ◽  
Mykhaylo Yatsymirskyy
Keyword(s):  
Statistical Analysis ◽  
Image Encryption ◽  
Experimental Studies ◽  
Quality Measures ◽  
Input Image ◽  
Jpeg Compression ◽  
Image Statistics ◽  
Compression Stage ◽  
Wide Range ◽  
The Impact

In this paper, the authors analyze in more details an image encryption scheme, proposed by the authors in their earlier work, which preserves input image statistics and can be used in connection with the JPEG compression standard. The image encryption process takes advantage of fast linear transforms parametrized with private keys and is carried out prior to the compression stage in a way that does not alter those statistical characteristics of the input image that are crucial from the point of view of the subsequent compression. This feature makes the encryption process transparent to the compression stage and enables the JPEG algorithm to maintain its full compression capabilities even though it operates on the encrypted image data. The main advantage of the considered approach is the fact that the JPEG algorithm can be used without any modifications as a part of the encrypt-then-compress image processing framework. The paper includes a detailed mathematical model of the examined scheme allowing for theoretical analysis of the impact of the image encryption step on the effectiveness of the compression process. The combinatorial and statistical analysis of the encryption process is also included and it allows to evaluate its cryptographic strength. In addition, the paper considers several practical use-case scenarios with different characteristics of the compression and encryption stages. The final part of the paper contains the additional results of the experimental studies regarding general effectiveness of the presented scheme. The results show that for a wide range of compression ratios the considered scheme performs comparably to the JPEG algorithm alone, that is, without the encryption stage, in terms of the quality measures of reconstructed images. Moreover, the results of statistical analysis as well as those obtained with generally approved quality measures of image cryptographic systems, prove high strength and efficiency of the scheme’s encryption stage.

scholarly journals Kinetics of filtration consolidation of water-saturated clay soils

2020 ◽  
pp. 86-95 ◽  
Author(s):  
O. V. Ageikina ◽  
V. V. Vorontsov ◽  
R. R. Sufyanov
Keyword(s):  
Mathematical Model ◽  
Porous Medium ◽  
Saturated Porous Medium ◽  
Experimental Studies ◽  
Saturated Soils ◽  
Consolidation Process ◽  
Filtration Consolidation ◽  
Wide Range ◽  
Water Saturated ◽  
The Mathematical Model

The relevance of the research processes filtration consolidation due to the place of water-saturated soils in various design solutions related to the exploration, production and transportation of hydrocarbons. It should be noted that the diversity of soils led to the emergence of a wide range of mathematical models, obtained on the basis of generalization of experimental data and various assumptions to simplify engineering calculations. The article presents the results of theoretical and experimental studies of the mathematical model of the consolidation process of a water-saturated porous medium. This model is based on simplifying assumptions that are different from those adopted in well-known solutions. A fundamental approach to the formation of the model was developed on the basis of the kinetic representations of chemical reactions used in solving the environmental problems of epoxidation reactions of olefins. We determined the parameters of the mathematical model of the consolidation process of the saturated porous medium of clayey soil and confirmed its adequacy by the research results. In addition, we established the parameters of the field of non-equilibrium filtration, reducing the nonexistent ability of water-saturated soils.

Experimental Studies of Liquid Holdup in the Impeller of Electric Submersible Pump

2021 ◽  
Author(s):  
Kirill Goridko ◽  
Vladimir Verbitsky ◽  
Evgeny Nikonov ◽  
Max Nikolaev
Keyword(s):  
Volume Content ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Experimental Studies ◽  
Performance Degradation ◽  
Gas Content ◽  
Liquid Volume ◽  
Liquid Holdup ◽  
Free Gas ◽  
Special Stand

Abstract Artificial lift of oil by electric submersible pumps (ESP) is often complicated by free gas in production. Free gas content in production leads to ESP performance degradation in rate and head. Gas slip in the ESP impeller is one of the reasons of ESP performance degradation. Thus, the goal of the work is to determine the gas slip coefficient i.e. liquid holdup in the ESP impeller. It is known that a gas-liquid mixture (GLM) flow characterized by a slippage effect. Gas slippage relative to the liquid determines the GLM structure (bubble, dispersed-bubble, slug, stratified or annular), as well as the difference between the GLM densities calculated by liquid holdup or liquid volume content. Special stand was designed and created to determine the liquid holdup at the Department of Oil Fields Development and Operation of Gubkin University. Liquid holdup in the impeller of the ESP was measured by the method of cutting off the flow. This paper shows the results of experimental studies of liquid holdup and gas slip velocity in the ESP impeller (ESP5-50) at a rotational speed n = 2997 rpm, at an absolute intake pressure Pin = 0.4 MPa. The dependence of the liquid holdup on liquid volume content (i.e. the dependence of the gas void fraction on gas volume fraction) was determined for the model GLM "water-air", "water-surfactant-air" with different foaming capacity. The degradation of the ESP characteristics, boundaries of surging and gas locking limits are determined taking into account liquid holdup. The dependence of gas holdup was experimentally obtained over the entire range of ESP operation (from 0.5∙Qopt to Qmax). A comparison of the obtained correlation with existing models is presented too. A new correlation for predicting liquid holdup in the ESP impeller for the low-rate wells operation is obtained. A new approach to determining the liquid holdup and consequently gas slip velocity in the ESP impeller is proposed.

A Mathematical Model and Performance Evaluation for a Single-Stage Grid-Connected Photovoltaic (PV) System

2008 ◽  
Vol 9 (6) ◽  
Author(s):  
Prajna Paramita Dash ◽  
Amirnaser Yazdani
Keyword(s):  
Mathematical Model ◽  
Control Strategy ◽  
Voltage Control ◽  
Current Control ◽  
Operating Conditions ◽  
Single Stage ◽  
Control Loop ◽  
Pv System ◽  
Wide Range ◽  
The Impact

This paper proposes a control strategy for important transients of a single-stage, three-phase, PV system that is connected to a distribution network. The proposed control strategy adopts an inner current-control loop and an outer DC-link voltage control loop. The current-control mechanism renders the PV system protected against external faults, enables control of the DC-link voltage and, therefore, controls/maximizes the PV system power output. The paper also proposes a feed-forward compensation strategy for the DC-link voltage control loop to mitigate the impact of the nonlinear characteristic of the PV array on the closed-loop stability, and to permit design and optimization of the DC-link voltage controller for a wide range of operating conditions. A mathematical model and a control design methodology are presented for the PV system, and it is shown that under the proposed control, the PV system fulfills the operational requirements of a grid-connected PV system. The effectiveness of the proposed control strategy and the most important transients of the PV system are evaluated through simulation studies conducted on a detailed switched model of the PV system in the PSCAD/EMTDC software environment.

scholarly journals The Impact of Peer Assessment on Academic Performance: A Meta-analysis of Control Group Studies

2018 ◽  
Author(s):  
Kit S Double
Keyword(s):  
Academic Performance ◽  
Peer Assessment ◽  
Meta Analysis ◽  
Experimental Studies ◽  
Teacher Assessment ◽  
Medium Effect ◽  
Practice Research ◽  
Control Group ◽  
Wide Range ◽  
The Impact

Peer assessment has been the subject of considerable research interest over the last three decades, with numerous educational researchers advocating for the integration of peer assessment into schools and instructional practice. Research synthesis in this area has, however, largely relied on narrative reviews to evaluate the efficacy of peer assessment. Here we present a meta-analysis (54 studies, k = 141) of experimental and quasi-experimental studies that evaluated the effect of peer assessment on academic performance in primary, secondary, or tertiary students across subjects and domains. An overall small to medium effect of peer assessment on academic performance was found (g = 0.31, p < .001). The results suggest that peer assessment improves academic performance compared with no assessment (g = 0.31, p < .001) and teacher assessment (g = 0.28, p = .007), but was not significantly different in its effect from self-assessment (g = 0.23, p = .209). Additionally, meta-regressions examined the moderating effects of several feedback and educational characteristics (e.g. online vs offline, frequency, education level etc.). Results suggested that the effectiveness of peer assessment was remarkably robust across a wide range of contexts. These findings provide support for peer assessment as a formative practice and suggest several implications for the implementation of peer assessment into the classroom.

scholarly journals Optimal parameters of physical and mechanical properties of sawdust concrete

2021 ◽  
Vol 244 ◽  
pp. 04007
Author(s):  
Nikolay Plotnikov ◽  
Olga Burova
Keyword(s):  
Mechanical Properties ◽  
Mathematical Model ◽  
Mechanical Characteristics ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Optimal Parameters ◽  
Coniferous Species ◽  
Variable Factor ◽  
Object Of Study ◽  
The Impact

The purpose of the conducted experimental studies is to examine the effect of various influences on the object of study. These effects are called factors. Some of them vary while examining of the object and then they are called variable factors. Each factor takes one or more values in the experiment and then they are called factor levels. The set of values of this factor is called range of factor values – the smallest interval, where are all the values accepted by this factor in the experiment. According to GOST 19222-84, the dependence of the physical-mechanical characteristics of sawdust slag concrete (grade M10) on the specific gravity (share) of wet sawdust of coniferous species and ash-slag mixture in the composition was studied. Regression analysis was used to build a mathematical model of the process with quantitative factors, to verify its adequacy, and to assess the impact of each variable factor on the process. To obtain regression dependencies, a composite second-order B-plan was implemented.

THE IMPACT OF THE DIMENSION OF A MATHEMATICAL MODEL OF INTERNAL BALLISTICS ON DESIGN PARAMETERS OF A SHOT FOR GRAIN GUNPOWDER CHARGES

2021 ◽  
pp. 95-110
Author(s):  
I.G. Rusyak ◽  
◽  
V.A. Tenenev ◽  
Keyword(s):  
Mathematical Model ◽  
Powder Mixture ◽  
Thermodynamic Model ◽  
Dynamic Models ◽  
Design Parameters ◽  
Variable Cross ◽  
One Dimensional ◽  
Gas Dynamic ◽  
Wide Range ◽  
The Impact

The problem of the impact of the mathematical model dimension on the calculated intraballistic characteristics of a shot for the charges made of granulated powder is considered. Mathematical models of the shot are studied using the spatial (axisymmetric), one-dimensional, and zero-dimensional (thermodynamic) formulations. The thermodynamic model takes into account the distribution of the pressure and velocity of a gas-powder mixture behind the shot for a channel of variable cross-section. Comparison of simulation results is carried out in a wide range of loading parameters. It is shown that there is a range of the loading parameters for a thermodynamic approach to give satisfactory approximation to the parameters obtained using the gas-dynamic approach, which describes the flow of a heterogeneous reacting mixture with a separate consideration of phases and intergranular interactions between them. Notably that in the entire range of the charging parameters studied in this work, the one-dimensional and twodimensional gas-dynamic models only slightly differ from each other. Therefore, in the main pyrodynamic period, the actuation of the charge, made of granulated powder, can be simulated using a one-dimensional gas-dynamic model or a zero-dimensional thermodynamic model with allowance for spatial distribution of the pressure and velocity of the gas-powder mixture.

scholarly journals Mine aerology of dust aerosols under conditions of hydro-vortex coagulation

2020 ◽  
pp. 155-165
Author(s):  
Nikolay Petrovich KOSAREV ◽  
◽  
Vladimir Nikolaevich MAKAROV ◽  
Aleksandr Vladimirovich UGOL'NIKOV ◽  
Nikolay Vladimirovich MAKAROV ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Aerodynamic Drag ◽  
Coal Dust ◽  
Aerodynamic Resistance ◽  
Experimental Studies ◽  
Similarity Criteria ◽  
Dust Suppression ◽  
Dust Aerosols ◽  
Wide Range ◽  
Mine Workings

Dust suppression is the most popular method for depositing dust from the air to blast isolation. Improving the isolation system for probable coal dust explosions is an integral part of the problem of dust explosion protection of mining enterprises, the solution of which is one of the most important tasks in the field of occupational safety and health. Purpose: study of physics of the process and the construction of a mathematical model of the movement of aerosols in mine workings in a wide range of changes in the inertial kinematic parameters of the air flow. Research methods. Based on the Boussinesq equation, the Fourier rule and the similarity theorem of complex systems, the analogy of vorticity dispersion and kinematic viscosity, a mathematical model of the movement of dust aerosols under hydro-vortex coagulation conditions is constructed. Some similarity criteria are obtained that ensure the identity of experimental studies and real aerological processes in mines, as well as criterion equations for calculating the coefficient of aerodynamic drag and the time of unsteady inertial motion. Results. Equations are obtained that make it possible to identify aerodynamic processes of aerosol motion under hydro-cyclonic dust suppression through the criteria of Reynolds, Euler and Archimedes, corresponding to the overStokes and Stokes flow regimes. The possibility of reducing the aerodynamic resistance to 20% during hydro-vortex coagulation has been confirmed, which makes it possible to increase the energy efficiency of dust suppression by up to 15% and to increase the turbulization coefficient by at least 20%, thereby reducing the likelihood of a hazardous concentration of dust aerosols. Application. The use of the proposed mathematical model will make it possible to better calculate local aerological processes in mine workings and, as a consequence, to increase the efficiency of turbulization and dust suppression process control at mining enterprises.

Impact of performance properties of regenerated engine oil on marine diesel wear when it runs on different grades of fuel

2019 ◽  
Vol 2019 (4) ◽  
pp. 71-81
Author(s):  
Валерий Тарасов ◽  
Valery Tarasov ◽  
Анатолий Соболенко ◽  
Anatoly Sobolenko
Keyword(s):  
Diesel Engine ◽  
Experimental Studies ◽  
Motor Fuel ◽  
Engine Oil ◽  
Oil Refining ◽  
Fuel Quality ◽  
Marine Fuel ◽  
Wide Range ◽  
Marine Diesel ◽  
The Impact

The article focuses on studying the operational properties of regenerated engine oils in terms of the impact on the wear of friction units of the trunk diesel engine when it works on the fuel of different grades. There have been built generalized models of marine diesel parts wear on the basis of experimental studies. Diesel 2Ч10,5/13 was used for experiments. Wear was determined by the method of artificial bases and by weighting. Four groups of the main indicators of fuels used on ships have been considered (depending on the quality indicator). The first group includes distillate fuels and low-viscosity marine fuel which is close in its characteristics to foreign fuels. The second group includes motor fuel, naval fuel oil and export fuels (medium viscosity fuels). The third group presents high-viscosity marine fuel; the fourth group - fuels made from the remains of oil refining. The description of the generalized model of details wear of the tested diesel engine was carried out by a polynomial of the second order. To obtain the model, a non-position plan was chosen for three test variables: concentration of additives in oil, a fuel quality factor and a level of diesel forcing. The superposition of the hypersurfaces of the response of wear functions of the internal combustion engine with diesel boosting factors at zero, lower, and upper levels with visualizing the effect on engine wear parameters depending on the additives concentration and quality of the fuel used in testing regenerated engine oil has been illustrated. Verification of the model's adequacy has proved that the model is adequate for machines with average effective pressure and a wide range of fuel grades. There has been given the possibility of using the obtained model to estimate the wear value at different values of parametric factors

ENGINEERING METHOD FOR CALCULATING SHOCK NOISE ISOLATIONBETWEEN FLOORS WITH FLOORS MADE OF WOOD MATERIALS

2020 ◽  
Vol 90 (4) ◽  
pp. 3-11
Author(s):  
V.A. GORIN ◽  
◽  
V.V. KLIMENKO ◽  
M.A. POROZHENKO ◽  
◽  
...  
Keyword(s):  
Noise Level ◽  
Computational Models ◽  
Experimental Studies ◽  
Engineering Method ◽  
Sound Insulation ◽  
Good Correspondence ◽  
Method Of Calculation ◽  
Impact Noise ◽  
The Impact ◽  
Approximate Formulas

An engineering method for calculating shock noise isolation by floor-to-floor overlappings with wood-based materials is proposed. The calculation considers overlaps with floors made of wood materials laid on glue and with floors laid on an elastic substrate. The calculation takes into account the effect on sound insulation of the surface density and stiffness of the floor covering material and the sound insulation layer. The calculation is reduced to calculating the frequency characteristic of reducing the impact noise level due to the construction of a floor made of wood materials and comparing the calculated value of the index of the reduced impact noise level with the standard ones. The list of necessary input data and the sequence of calculation execution is given. Approximate formulas for calculating the frequencies that limit the application of computational models of the overlaps under consideration are compiled. Equations and approximate formulas are given for determining the critical (antiresonance) and resonant frequencies of vibrations, one -, two-and three-layer overlaps, and their values are determined for various mechanical and geometric parameters of layers. Frequency ranges of growth and decrease of shock noise level by these overlaps are determined. Comparison of the calculated and measured frequency characteristics of shock noise reduction showed a good correspondence of the results obtained by the engineering method of calculation with experimental studies. The developed practical recommendations for improving the isolation of shock noise between floors with floors made of wood materials, used in the construction of civil buildings, can increase acoustic comfort in buildings under construction and under reconstruction.

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