Submersible Centrifugal Pumps Research Articles

Study on Wear Characteristics of a Guide Vane Centrifugal Pump Based on CFD–DEM

Guide vane submersible centrifugal pumps are a kind of submersible pump, and the fluid inside the pump is often mixed with gravel and other impurities during operation, affecting the pump’s operating efficiency and life expectancy. However, past studies on solid–liquid two-phase flow (STF) and wear characteristics in guided vane centrifugal pumps have been limited to the particle trajectory and wear region distribution. These studies have lacked research on the effect of particles on the fluid flow and the specific amount of wear on the overflow components. Additionally, most of them have used the DPM discrete-phase model, which does not consider the particle–particle and particle–wall interactions. This paper is based on the CFD–DEM method, combined with the Archard wear model. A solid–liquid two-phase flow simulation is carried out for pumps with different particle sizes and particle shapes to analyze the particle movement inside the pump, the wear distribution and average wear amount of the overflow components, and the effect of particles on the turbulent kinetic energy of the fluid. The results show that the particles mainly collide with the leading and trailing edges of the impeller blades and the leading edge of the guide vane blades and form a buildup at the trailing edge of the concave surface of the guide vane blades, resulting in the wear being mainly distributed in these regions. With an increase in particle size and a decrease in sphericity, the average wear on the overflow components increases. The change of particle size directly affects the resistance of the fluid and the structure of the flow field, which has a large impact on the fluid flow pattern and generates large turbulent kinetic energy fluctuations. The shape of the particles only changes the structure of the local flow field, which has a small impact on the fluid flow pattern.

Research on the cavitation characteristics and structural optimisation of spiral grooved thrust bearing lubricated by liquid hydrogen

AbstractIn liquid hydrogen (LH2) delivery, submersible centrifugal pump is an important device. Its reliability and efficiency rely on the stability of the bearings. In a high‐speed range, cavitation occurs due to the hydrodynamic effect induced pressure undulation. Compared with other cryogenic fluids, cavitation in LH2 is prone to happen due to its special properties. In this paper, a cavitation model considering thermal properties of LH2 is proposed based on Rayleigh–Plesset equation. Cavitation characteristics are studied in spiral grooved thrust bearing (SGTB) lubricated by LH2. The effect of cavitation on load capacity and friction torque are investigated. The most severely‐eroded location is predicted by the distribution of mass transfer rate. The influence of bearing structure parameters is studied in respect of cavitation, load capacity and friction torque. The analysis of variance (ANOVA) and range analysis results may provide a reference for optimising LH2 lubricated SGTB.

A sharp MLS penalty immersed finite element method for fluid-structure interaction of highly deformable slender body in turbulent flow

This paper presents a new computational approach to simulate challenging fluid-structure interactions (FSI) between fluids and slender deformable structures. Key innovations address limitations of standard immersed boundary methods, including spurious forces, stability at low density ratios, and accuracy at high Reynolds numbers. The method couples a sharp interface immersed boundary technique with detached eddy simulation turbulence modelling to enable precise FSI for high Reynolds number flows. A strong coupling partitioned algorithm stabilized by Aitken relaxation significantly enhances stability for low density ratios down to 1. A moving least square compact support domain approximation reduces spurious oscillations from moving geometries while providing second-order accuracy. Adaptive mesh refinement imposes jump conditions on slim deformable bodies and minimizes grid leakage. The proposed method is evaluated on three conventional FSI benchmarks and four experimental cases, confirming its robustness, accuracy, and stability in low and significantly high Reynolds numbers. A more complex fluids engineering case is considered last to test the solution under challenging conditions with fast moving solid boundaries and fast flowing fluid. A thin deformable membrane is forced through a submersible centrifugal pump under standard operating conditions. The solution is shown to produce a stable solution with good collision handling ability.

REVIEW AND CRITICAL ANALYSIS OF THE CURRENT STATE AND WAYS TO IMPROVE REGULATED POWER SUPPLIES AND AUTOMATIC CONTROL SYSTEMS FOR ELECTRIC CENTRIFUGAL PUMPING UNITS IN INTERMITTENT OPERATION OF OIL WELLS

Link for citation: Kladiev S.N. Review and critical analysis of the current state and ways to improve regulated power supplies and automatic control systems for electric centrifugal pumping units in intermittent operation of oil wells. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 9, рр. 203-215. In Rus. Relevance. At present efforts are being made to convert low- and medium-flow oil wells to cyclical or short-term operation in order to reduce the excess pumping capacity that resulted from the reduction of well flow that is caused by reduced reservoir pressure during long-lasting exploitation of the deposit. The need for such a conversion requires justification for the use of more complex configurations of regulated power supply sources and automatic control systems of centrifugal pump units electric drives in automated process control systems. The local low-level automatic control systems for a mechanized electric drive method for lifting an oil-containing liquid from the well to the surface, namely the installation of variable-speed AC electric drives consist of ground-based devices and special submersible equipment. The ground-based devices are control stations with AC voltage and frequency converters with built-in telemetry units, external sine filter, step-up transformer. The special submersible equipment includes asynchronous induction electric motor, power cable, submersible telemetry unit, process sensors, centrifugal pump. The power supply of such a unit is provided from the external electric three-phase network of 6 kV through a reducing transformer substation of 6/0,4 kV. In the continuous mode of operation of oil pumping plants the electric pumps and other equipment, operate in quasi-static modes. Unregulated electric drive, as well as the open-loop controlled electric drive does not allow for smooth acceleration to the nominal performance of pumping equipment for pumping oil out of well in difficult conditions and its smooth regulation when reducing the well flow because of reducing oil flow to the slaughter. Therefore, the main way of smoothly reducing the excess performance of the submersible centrifugal pump is the periodic activation mode, which includes pumping the oil mixture out of the well and stop – for its accumulation and recovery of formation pressure. The introduction of cyclical technology shows that it is impossible to use the open-loop system of regulated electric drive everywhere, where acceptable quality indicators of transition comparable with the quality of closed-loop control systems are objectively unattainable. Due to the fact that the amount of pressure at the well intake created by a centrifugal pump, necessary to lift the well fluid to the surface, depends on the square of the rotation speed of the pump working stages, the operating pump productivity range Qmin... Qmax (m3/day) is obtained by varying the motor stator winding voltage (80…100) % from the nominal voltage value by using AC voltage controller with a phase control mode. If the stator voltage value is less than 80 % of Unom then the well fluid is not lifted to the surface and does not flow out of wellhead equipment. Therefore, when a frequency converter with Unom/fnom=const is used, the supply voltage and frequency of the motor should be varied in the same range. The price for using cyclic operation is a decrease in the reliability of submersible pumps. It is necessary to use special designs of submersible electric motors, improve power supply systems and synthesize closed-loop control systems of automatic control of electric drive of submersible pump. The purpose of the study is the review and critical analysis of the current state and ways to improve regulated power supplies and automatic control systems for electric centrifugal pumping units in intermittent operation of oil wells. Object: systems of power supply and automatic control of centrifugal pump units in intermittent operation of oil well, telemetry systems, energy-efficient submersible motors and centrifugal pump designs. Methods: methods of the theory of the automatic control system for developing the concept of operation of low flow of wells, analysis and synthesis of open and closed loop control systems of electric submersible centrifugal pumping units. Results. The paper introduces the scientific problem of development, implementation, models and methods of identification of technological processes, complexes and integrated control systems of oil extraction by electric drive method, taking into account the influence of a long submerged cable, low flow of wells and difficult operating conditions. The author proposed scientifically based technical solutions in the form of a structure of a power channel of an electromechanical system with a frequency-regulated induction motor, long submersible cable and indirect method of measuring state variable from ground-based measurements at load changes and measurement channel characteristics.

REVIEW AND CRITICAL ANALYSIS OF THE CURRENT STATE AND WAYS OF DEVELOPING THE TECHNOLOGICAL PROCESS OF OIL PRODUCTION BY AN ELECTRIC DRIVE IN INTERMITTENT MODES OF OPERATION OF LOW- AND MEDIUM-RATE WELLS

Link for citation: Kladiev S.N. Review and critical analysis of the current state and ways of developing the technological process of oil production by an electric drive in intermittent modes of operation of low- and medium-rate wells. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 220-231. In Rus. Relevance. The Russian Federation is one of the world leaders among oil-producing countries in terms of proven oil reserves. Historically, industrial oil production in the Russian Empire began in the area of the Caspian Sea on the territory of modern Azerbaijan. The energy strategy of the Russian Federation for the period up to 2035, as one of the measures to ensure the energy security of the country, provides for the introduction into economic circulation of hard-to-recover oil reserves (including from the Bazhenov formation) based on innovative domestic technologies and equipment. The main problem of the oil industry in Russia, as well as throughout the world, is the decline in the quality of the resource base. In oil-producing regions, there is a depletion of active oil reserves. Significant residual reserves of developed fields are expected to be brought into active exploitation using new oil production technologies. Ways of growth in oil production are possible in accordance with three different scenarios: innovative – it is supposed to increase the contribution to the total indicators of Russian oil production from new provinces, such as Eastern Siberia, the Republic of Sakha (Yakutia), as well as new fields in Western Siberia and the Krasnoyarsk Territory and the development of the shelf northern seas; forced scenario – in case of more active introduction of new technologies and incentive measures that reduce the cost of the production process, it is possible to increase the efficiency of oil production in offshore and hard-to-recover fields; extensive scenario of oil production is possible only at high market prices for oil. The main volume of production is carried out and will continue to be exclusively electrically driven. The purpose: a review and critical analysis of the current state and ways of developing the technological process of oil production by an electric drive in intermittent modes of operation of low- and medium-rate wells. Object: theoretical substantiation of the introduction of cyclic or short-term operation of electric centrifugal pump installations with an electric drive method of downhole oil production into practice. Methods: geophysical research to develop a concept for the operation of a marginal well stock, ways to increase the profitability of oil production, methods for optimizing the stock of medium and marginal wells, putting them into economic circulation. Results. Based on a critical analysis of literary sources and a feasibility study, it is shown that the most promising way to extract hard-to-recover oil reserves on the example of the Bazhenov formation is the electric drive of a submersible centrifugal pump according to the scheme «ground power converter – submersible cable – submersible electric motor – electric centrifugal pump». The technology of cyclic operation of wells in oil production shown that it is economically feasible for low- and medium-rate wells and is widely implemented in wells that cannot be operated in a continuous mode.

Justification of the feasibility of use of frequency converters in control stations of submersible centrifugal pumps

The article considers the problem of determining the conditions under which the use of a frequency converter in a submersible pump control station leads to a reduction in electrical energy costs and becomes efficient from an energy point of view. Analytical expressions are given that allow calculating the specific costs of electrical energy during artificial lift oil production for the case when the operating mode and well flow rate are provided by wellhead choke throttling. At the same time, special attention is paid to determining the rotation speed of the submersible asynchronous motor, which ensures the required location of the operating point on the pump pressure characteristic. Formulas are also given that make it possible to calculate the specific costs of electrical energy during artificial lift oil production for the case when the operating mode and well flow rate are set by the frequency converter of the control station. An analytical expression has been found to determine the rotation speed and frequency of the supply voltage, which provide the required operating point of the pump with frequency regulation of the submersible motor. It is proposed, using the above analytical expressions, to use the iterative method to calculate the pump performance, at which the specific energy costs for the production of a cubic meter of liquid will be equal both in the case of using a frequency converter in the control station and without it. An example of calculating such a boundary value of pump performance for a hypothetical well is given. It is shown that a decrease in the required flow rate relative to the limiting value of the pump performance leads to a decrease in the specific consumption of electrical energy during artificial lift oil production in the case of using a frequency converter in the submersible pump control station.

Design of a Solar-Powered Water Pumping System for Irrigation in Sukkur, Pakistan

This paper presents the design of a solar-powered water pumping system that would be used for irrigation in Sukkur, Pakistan. A dependable model of the pumping system as well as the solar system is designed in PVsyst and HOMER softwares to establish the practical and economic viability of solar-powered water pumping system at the site. The proposed system consists of a submersible centrifugal multistage deep well pump and sixty 480 W solar modules. For the purpose of evaluating the backup system’s viability, a battery backup system is also connected to the system. The obtained results show that the proposed solar-powered water pumping system is a potential candidate and a viable option for employment at the selected site and at other sites that have the same conditions for water pumping and irrigation. Moreover, when compared to the cost of using nonrenewable resources, operating and maintenance costs for renewable energy systems are more manageable.

Tribological properties of doped zirconium dioxide crystals under water lubrication

The issues of a ceramic plain bearing performance under friction in the water are discussed in this article. Bearing bushings made from nanostructured partially stabilized zirconium dioxide crystals doped with rare earth elements under friction on steel and ceramic shafts are investigated. The statement about the possibility of using zirconium ceramic materials in bearings of multistage submersible centrifugal pumps for oil production is substantiated. The efficiency of alloying crystals to improve crack resistance is analyzed. Particular attention is paid to the tribological properties of the bearing when using steel and ceramic shafts. The results of comparative tribological tests of samples of the studied materials, bench tests of full-scale bearing bushings carried out under water and dry friction are presented. Based on the study, it is proposed to make bushings from a zirconium dioxide crystal for working on a steel shaft. It has been established that this plain bearing can withstand the emergency mode of friction under water or dry friction for half an hour.

Method for determining the parameters of a substitution scheme for an electromechanical module with an increased electromagnetic momentwith increased electromagnetic torque

THE PURPOSE. Consider the problems of determining the energy parameters of electrical equipment elements of electrical complexes for oil production with submersible electric centrifugal pumps. Develop a methodology for determining the parameters of the equivalent circuit of an electric motor for oil production when connecting compensating devices to the terminals of the electric motor of a submersible pump. Develop a methodology for calculating the energy performance of electrical equipment elements of an electrical complex with electric centrifugal pumps. Carry out simulation modeling of an electric motor for oil production with a directly connected compensating device.METHODS. When solving the tasks set, optimization methods were used in terms of efficiency, power factor correction methods, methods for calculating the electromagnetic field by finite elements, methods of mathematical and computer modeling in the ELCUT software package.RESULTS. Improving energy efficiency and reducing costs in the operation of submersible pumping units for oil production is an urgent problem and dictates a reasonable solution. The price of extracted oil depends on the following indicators, such as climatic conditions, equipment used, depth of oil deposits, remoteness of the field from central roads, and so on. The most significant energy-intensive processes in oil production include: electromechanized oil extraction, oil transportation, reservoir pressure maintenance system. A technique for finding the parameters of the equivalent circuit of an electric motor for oil production and a study of the effect of reactive power compensation on an electric motor in an oil well when compensating devices are connected to the terminals of the electric motor of a submersible pump are proposed. A method for calculating the energy performance of electrical equipment elements of an electrical complex with electric centrifugal pumps is proposed. The calculation of a compensating device in an oil well for an electric centrifugal pump with a frequency-controlled electric drive must be implemented taking into account the highest value of the output network frequency. Simulation modeling of an electric motor for oil production with a directly connected compensating device was carried out to establish the effect of a reactive power compensating device inside an oil well on the rotating electromagnetic moment of an electric motor for oil production. The indicators of the electromagnetic torque and the electromagnetic field of an electric motor for oil production without a connected compensating device and with a directly connected compensating device are presented, the supply wires of which in the first version are laid along a single route and in the second version are laid at an angle of 120 ° relative to each other in the corresponding grooves of the stator winding of the electric engine for oil production.CONCLUSION. When conducting a study of the effect of a directly connected compensating device on the electromagnetic torque of an electric motor for oil production, it was determined that additional windings of a directly connected reactive power compensating device, laid at an angle of 120 ° relative to each other in the corresponding grooves of the stator winding of the electric motor, increase the efficiency and electromagnetic torque of an electric motor for oil production by 11% and 15%, respectively.

An analysis of reliability of electric submersible centrifugal pumps

The average operating time before structural and technological failures of the submersible part of a typical ESP is 64.5–81.9% of the average operating time of new ESPs. Given that the set of typical ESPs includes a significant share of repaired and mixed (equipped with new and refurbished units) installations, this fact can be interpreted as evidence of poor quality of repair. The data obtained from Tatneft and Bashneft companies agree with this conclusion. The data provided by Nizhnevartovskneftegaz company do not contradict this conclusion. The high values of Ttkt obtained by Rosneft-Samaraneftegaz are a consequence of poor identification of the causes of ESP lifting during control operations, as a result of which some failures are treated as design and technological ones.

ABOUT THE SYSTEM OF ELECTRIC TRANSMISSION OF INSTALLATIONS OF ELECTRIC SUBMERSIBLE CENTRIFUGAL PUMPS USED IN OIL WELLS

The article details the materials on the elements of the electrical transmission system of electric submersible centrifugal pumps, which are used in flooded oil production wells to lift products in the form of a water-oil mixture from the bottom to the surface. At the beginning of the article, the device and purpose, the principle of operation, the technical characteristics of the cable, the order of descent into the well on the tubing string, the required geological and physical conditions for its normal operation in the well are presented. Then the purpose of using the transformer and autotransformer, the device, purpose, principle of operation and satisfactory conditions for their normal operation are announced. Further, the control station and the main functions performed by it, the purpose of each element of this station, and its operation in cold and moderate climatic conditions are described in detail. Keywords: Electric submersible centrifugal pump, cable, transformer, autotransformer, control station, submersible motor, tubing, belt, geological and physical conditions.

Investigation of the influence of the drive shaft speed on the characteristics of a submersible pump when pumping out a gas-liquid mixture

The article presents the results of small size ESP (electrical submersible pump) tests at a speed of 6000-8500 rpm in the presence of free gas at the inlet to the device. The submersible centrifugal pump is quite sensitive to the presence of free gas in the pumped gas-liquid mixture. Depending on the amount of free gas, the actual characteristics of the pump are deformed, and at a certain gas content, the pump stops supplying the gas-liquid mixture. Stable operation of the ESP is carried out with a free gas content at the pump inlet ranging from 5% to 25%, depending on the pump size. There are several ways to deal with gas in wells operated by ESP: from running the pump into the zone where the intake pressure ensures optimal pump flow and stable operation to the use of separating and dispersing devices at the intake. Results represent pump flow characteristics along with different inlet free gas contents.

Algorithm for calculating the optimal value of the field substation voltage

The article is devoted to improving the energy efficiency of mechanized mining by selecting the optimal voltage level at the field substation, which provides the required optimization criterion. An unbranched line extending from the field substation, which supplies an arbitrary number of electrical complexes of producing wells, is considered. It is shown that these complexes can contain both submersible centrifugal pumps and rod borehole pumping units driven by asynchronous motors. Mathematical models of electrical complexes of producing wells are nonlinear and are described by high-order differential equations. Therefore, the problem of finding the optimal voltage level of a field substation can only be solved using numerical methods. An algorithm for calculating the optimal voltage value is developed, taking into account the technological features of mechanized oil production. It is a search algorithm that contains three internal cycles: voltage variations at the asynchronous motor farthest from the field substation, sorting out the nodes of the outgoing line, and equalizing the voltage at the nodes when the load of the electrical complexes of the producing wells changes. Well-known analytical expressions are given for calculating the active, reactive and full load of step-up and step-down transformers used in the considered electrical complexes, as well as power losses on these elements and on air and cable lines. A distinctive feature of the presented algorithm is the calculation of the speed of submersible and ground asynchronous motors when the supply voltage changes, taking into account the mechanical characteristics of centrifugal and plunger pumps. An example of calculating the optimal voltage value of a field substation feeding a hypothetical outgoing line with three nodes is given. It is noted that the developed algorithm is a reflection of the method of choosing the optimal voltage of the field substation. Moreover, this algorithm can be adapted to any outgoing line, no matter how complex and branched it is.

RELIABILITY ANALYSIS OF SUBMERSIBLE CENTRIFUGAL PUMPS IN OIL COMPANIES

Background In the event of failure of any of the submersible units, it is necessary to carry out underground repairs - killing the well with process fluid, removing the submersible from the well, installing the arc submersible part in it, starting the installation, developing the well (removing the process fluid from it) and removing the installation of the submersible centrifugal electric pump to the operating mode. The duration of underground repairs reaches several days, the costs for its implementation are comparable to the cost of the submersible centrifugal electric pump, and the losses from the downtime of the well during this period significantly exceed it. Therefore, for the consumer, the most important indicators are the reliability of the submersible centrifugal electric pump unit. Aims and Objectives The article is devoted to the analysis of the reliability of installations of submersible centrifugal pumps in a number of oil companies. The mean time to failure of the submersible part of the submersible centrifugal pumps is taken as the most important indicator of submersible centrifugal pumps reliability, which exists as a single assembly unit only during the run into the well before the first lift (failure). Methods The average operating time to structural and technical failure of the submersible part of the new submersible centrifugal pumps unit, based on the results of control operation, was determined as follows. It was assumed that the operating time to failure of the loaded parts obey the Weibull distribution law. The analysis was carried out on 22 samples of control operation of the 9 most common submersible centrifugal pumps units in oil companies: Tatneft, Bashneft, Rosneft-Samaraneftegaz and Nizhnevartovskneftegaz. The samples consisted of 1-89 submersible centrifugal pumps units with the number of failures 0-31. 6 of them (2 in OAO NK Tatneft, 3 in OAO NK Bashneft, 1 in OAO Rosneft-Samaraneftegaz) had statistics sufficient to check the correspondence of the theoretical distribution law to the statistical one with acceptable reliability (the number of monitored submersible centrifugal pumps units is at least 25 and the number of objects with credited failures is at least 12). Results The average operating time for the four associations to structural and technological failure of the submersible part of a typical submersible centrifugal pumps unit is 64.5-81.9% of the corresponding average operating time for new submersible centrifugal pumps units. Considering that the aggregate of typical installations includes a significant proportion of repaired and mixed (equipped with new and repaired units) installations, this fact can be interpreted as evidence of the low quality of repair of units by the consumer. The data obtained in Oil companies: Tatneft and Bashneft fully agree with this conclusion. The data of Oil company Nizhnevartovskneftegaz do not contradict this conclusion either. The high values obtained in Oil company Rosneft-Samaraneftegaz are most likely the result of insufficiently thorough identification of the reasons for the rise of the submersible centrifugal pumps during control operation, as a result of which some of the failures for operational reasons are interpreted as failures for structural and technological reasons.

Повышение качества электроэнергии для потребления в нефтедобывающей отрасли

Currently, 50-60 percents of power consumption in oil fields falls on mechanized oil production. The specificity of the operation of a submersible electric centrifugal pump (ESP), powered by a submersible electric motor (SEM) as consumers of electricity, is due to their operation at a considerable distance from the earth’s surface, the variable nature of the load, the aggressiveness of the produced fluid, and the presence of an extended cable line. (Research objective) To study devices for improving the quality of electricity in the oil industry. (Materials and methods) The results of the survey of the parameters of power consumption of the Novoportovskoe oil and gas condensate field of the PREO «Yamal» Network district No. 1 Kust 18 KTP 10 / 0.4 kV No. 1 input-2. (Results and discussion) The results of studies of the parameters of electricity at the Novoportovskoye oil and gas condensate field have shown that it is advisable to use devices that improve the quality of electricity. Devices can be different, both in design and in scope. Such as voltage stabilizers, phase voltage balancing devices, reactive power compensation devices, filter compensating devices, active mains filters. (Conclusions) Having considered the variety of devices on the market that improve the quality of electricity, as well as devices that compensate for reactive power, it is advisable to use static thyristor reactive power compensators manufactured by JSC Electrointer, Serpukhov.

Environmental Issues of Transient Behavior

We are currently witnessing a high-rate of exploitation of oil fields at the stage of declining production. This decline is a result of the depletion of oil fields, which leads to the use of electric submersible centrifugal pumps (ESP) with dynamic head below saturation pressure. In this operating mode, the ESP’s efficiency deteriorates, leading to the overheating of its working elements during operation. The boiling of water contained in the wellstream and salt deposition can take place in an overheated pump. This, in turn, can lead to a premature failure of the centrifugal pump and reduce the economic viability of this oil production method. To eliminate premature failure, such units must be transferred to an operating mode with periodic shutdowns. Yet, the planning of trip-out and restart time schedules is performed in the absence of a proper theoretical justification. Such planning often leads to ESP failures due to the reduction of the electric resistance of cable lines or salt deposition. To prevent salt deposition, oil production companies use different chemicals, which are pumped into the hole annulus and are expected to stop salt deposition when propelled into the pump pot. Chemical treatment practice shows that these reagents perform poorly and may not prevent salt deposition at all. In reality, chemical compounds can damage downhole equipment and its structural elements. Long-term use of these reagents may lead to ecological disaster – the contamination of productive formations and confined groundwater beds. This work investigates the possibility of ESP operation in periodic mode without salt deposition and the exploitation of oil fields without the application of chemical reagents. The development of a periodic operation method allowing for ESP operation without salt deposition could eliminate the use of reagents in oil production and thereby reduce the risk of ecological disasters.

Salt Deposition in Electric Submersible Centrifugal Pumps under Intermittent Operation

“Salt deposition in a centrifugal pump under intermittent operation” is the first article to address the cause of failures among electric submersible centrifugal pumps operating intermittently. The causes of said failures are analyzed. The failure of electric submersible centrifugal pumps is caused by their temperature behavior during operation. The problem of the thermal condition of a centrifugal pump under intermittent operation must be solved. Moreover, the number of failures caused by salt deposition or the electric resistance drop of the “cable – motor” system can be reduced.

Improvement of three-phase group transformers for powering the electric drive of submersible centrifugal pumps and comparison of their technical level indicators

The possibility of improving the power supply system of the electric drive of submersible pumps is indicated. The modernization is carried out by replacing the design of single-phase toroidal transformers composed into the group transformer, with spatial single-phase transformers with a radial electromagnetic system. The radial electromagnetic system is characterized by the convenience of embedding into shells of a limited diameter, by a shorter average turn length, and the absence of winding laying disadvantages. The main task is to determine and to analyze the technical level indicators for spatial twisted electromagnetic systems options. The objective function optimization method is used to solve the problem. The objective function contains technical condition dimensionless indicators as well as relative geometric controlled variables. The extremum of the objective function relative components is a function of the winding window, the conductive material of the winding and three universal identical geometric controlled variables which can be used for any of the existing electromagnetic systems variants. In accordance with the principle of electromagnetic equivalence, the same materials, the average values of the amplitudes of the magnetic flux induction in the rods and yokes, the filling factor of the magnetic circuit with steel, as well as cooling methods of the induction static devices are respectively used. The results of the comparative analysis of the technical level indicators (mass, active materials cost and active power losses) showed that the design of a twisted radial electromagnetic system with a rectangular cross-section of rods provides a significant reduction in mass, cost and losses, as compared to an equivalent analogue with a toroidal electromagnetic system

Effect of Blade Outlet Angle on the Flow Field and Preventing Overload in a Centrifugal Pump.

The influence of the blade outlet angle on preventing overload in a submersible centrifugal pump and the pump performance characteristics were studied numerically for a low specific speed multi-stage submersible pump. The tested blade outlet angles were 16°, 20°, 24°, 28°, and 32°. The results show that the blade outlet angle significantly affects the external flow characteristics and the power curve can be controlled to prevent overload by properly reducing the blade outlet angle. Increasing the blade outlet angle significantly increases the low pressure area at the impeller inlet, which makes cavitation more likely. Therefore, β2 = 16° provides the best anti-cavitation flow field. Increasing the blade outlet angle also increases the flow separation near the blade working face, which increases the size of the axial vortex along the blade working surface, which rotates in the direction opposite to the impeller rotation and then extends towards the impeller inlet.

Computer simulation and investigation vibration parameters of a centrifugal submersible pump

The dynamic characteristics of one of the centrifugal pump critical parts such as the rotor shaft are studied in the article whilst the highest level NASTRAN CAD PATRAN module was used to carry out the dynamic analysis. During the analysis a computational mechanical scheme has been compiled as well as force factors generating rotor vibrations have been determined. The axial, radial and hydrodynamic forces affecting the impeller and pump shaft have been calculated according to the analytical formula. Under the given boundary conditions in the FE model and the chosen method for determining the natural vibrations, a numerical solution of the equations of free and forced vibrations has been found using the algorithms of the NASTRAN program. The natural vibrations of the rotor have been determined using the Lanczos method. The dynamic stability of the shaft, the stress-strain state of the shaft and its displacement under static loads, the frequency and shape of the natural vibrations of the rotor necessary for the calculations have been determined. The amplitude-frequency characteristics of the system have been determined and analyzed for affection by external forces at the reverse and blade frequencies. Using the amplitude parameters of the forced oscillations, the dynamic gain of the rotor has been determined. Based on the amplitude-frequency parameters, the option of the number of blades for the working centrifugal impeller of the pump has been justified. The technique of computer simulation and determination of the vibroactivity parameters of a submersible centrifugal pump rotor shaft is given in the article.