Pneumatic Compensator Research Articles

Superfinishing robotic cell to automate belt polishing process on critical aeronautical components

Surface quality requirements on aeronautical components are critical. When components are manufactured via casting or forging processes, functional surfaces should be machined and, later on, these surfaces should be finished using polishing or other superfinishing techniques. These final processes are usually performed manually by experienced operators, mainly due to their complexity. Nowadays, new technologies provide a chance to automate these processes, but some aspects must be taken into account. On the one hand, it requires technological advances that allow process to be carried out in compliance with the required tolerances. Many of these technologies do not include in their scope the usual materials employed in aeronautical components, which are critical in terms of geometries and machinability. On the other hand, tests must be carried out with different tools and abrasive materials to establish optimum processing conditions in this type of automated process. In this line, the driver of the proposed work is to analyse the behaviour of different abrasive materials and their influence in material removal rate when process parameters increase. Test were performed using a robotic cell equipped with a pneumatic compensation system for pressure and cutting speed control. Obtained results may serve as a basis for defining operating conditions of this type of processes and help to understand their behaviour when dealing with different cutting conditions.

ПНЕВМОКОМПЕНСАТОР ДЛЯ ПЛУНЖЕРНОГО НАСОСА С ПОГРУЖНЫМ ЛИНЕЙНЫМ ПРИВОДОМ

Актуальность. Разработана конструкция и принцип работы пневмокомпенсатора для плунжерного насоса с погружным магнитоэлектрическим двигателем, позволяющего снизить амплитуду колебаний давления на выкиде насоса путем выравнивания скорости потока жидкости в лифтовых трубах. При использовании в пневмокомпенсаторах диафрагмы, выполненной из резины с армированием, она становится устойчивой к разрушению, что в целом увеличивает эффективность работы и срок эксплуатации пневмокомпенсатора. Цель: разработать пневмокомпенсатор для плунжерного насоса с погружным магнитоэлектрическим двигателем. Провести прочностной анализ и оценку эффективности применения диафрагмы с армированием в пневмокомпенсаторах, применяемых для снижения пульсаций скорости и давления потока флюида в насосно-компрессорных трубах; обосновать выбор материала диафрагмы пневмокомпенсатора. Объекты: скважинные пневмокомпенсаторы, погружной бесштанговый плунжерный насос с линейным магнитоэлектрическим двигателем, колонна насосно-компрессорных труб. Методы: имитационное моделирование диафрагмы, закрепленной на перфорированной трубе, с применением программного комплекса «Компас 3D» модуль APMFEM; задание в граничных условиях расчетной модели технологических параметров при моделировании численных значений скорости, расхода, давления, температуры аналогичными действующей скважинной установке. Результаты. Установлено, что максимальные напряжения, возникающие в диафрагме в процессе работы пневмокомпенсатора, в 4 раза меньше предельно допускаемых, что показывает работоспособность пневмокомпенсатора в скважинных условиях. Показано положительное влияние армирования диафрагмы с точки зрения снижения максимальных напряжений в эластичной оболочке. Проанализировано влияние технологических параметров пневмокомпенсаторов (суммарного газового объема, начального давления в газовой камере) на эффективность их работы. Обосновано оптимальное давление зарядки пневмокомпенсаторов, которое не должно превышать минимально давление в насосно-компрессорных трубах в течение цикла откачки, чтобы исключить негативное влияние прижатия эластичной оболочки к перфорированной трубе (внутренней стенке пневмокомпенсатора).

Method of calculating pneumatic compensators for plunger pumps with submersible drive

One of the most promising ways to improve the efficiency of mechanized oil production is a plunger pump with a submersible drive, which allows obtaining harmonic reciprocating movement of the plunger. In the pumping process of well products by plunger pumps, oscillations in the velocity and pressure of the liquid in the lifting pipes occur, which lead to an increase in cyclic variable loads on the plunger, a decrease in the drive life period and the efficiency of the pumping unit. 
 To eliminate the pulsation characteristics of the plunger pump and increase the reliability indicators of the pumping unit (in particular, the overhaul period), pneumatic compensators can be used. A method for calculating the optimal technological parameters of a system of deep pneumatic compensators for plunger pumping units with a submersible drive, based on mathematical modeling of hydrodynamic processes in pipes, has been developed.
 Calculations of the forming flow velocity and pressure in the lifting pipes of submersible plunger units equipped with pneumatic compensators (PC) have been carried out. Influence of the PC technological parameters on the efficiency of smoothing the oscillations of velocity and pressure in the pipes has been analyzed. Non-linear influence of the charging pressure and PC total volume on the efficiency of their work has been established. Optimal pressure of PC charging, corresponding to the minimum pressure in the tubing during the pumping cycle for the considered section of the tubing, is substantiated. 
 Two ultimate options of PC system placement along the lifting pipes are considered. In the first option, PC are placed sequentially directly at the outlet of the plunger pump, in the second - evenly along the lift. It is shown that the first option provides the minimum amplitude of pressure oscillations at the lower end of the tubing and, accordingly, variable loads on the pump plunger. Nature of the pressure and flow velocity oscillations in the tubing at the wellhead for both options of PC placement has similar values.

EXPERIMENTAL EFFICIENCY ESTIMATION OF THE DRILLING DOWNHOLE COMPENSATOR FOR PRESSURE FLUCTUATIONS OF THE DRILLING FLUID

Background When drilling oil and gas wells, an unavoidable circumstance is the occurrence of vibration processes with different amplitude and frequency characteristics in the circulation system of the drilling rig, downhole wellhead and downhole equipment. Of the many reasons for the occurrence of these vibrations, you can highlight the work of the mud pump, downhole motors associated with the interaction of the bit on bottom and the inevitable reaction of the last bit, the variability of axial load in the form of a manual tool feed for slaughter etc. The result of oscillating processes is a decrease in the durability of equipment, deterioration of technical and economic indicators of drilling. Aims and Objectives The article describes a device developed and patented at the level of the invention, which is mounted in the bottomhole assembly and allows to have a significant impact on the oscillatory processes occurring at the bottom of the mine. The results of research conducted on a developed laboratory stand equipped with modern sensors are presented, and their analysis is provided. The efficiency of the compensator is evaluated. Results 1. Fluctuations in the pressure of the flushing liquid despite the presence of a standard pneumatic compensator of the drilling pump have a significant amplitude and lead to unproductive energy costs, premature wear of drilling equipment. 2. In order to reduce the harmful effect of pressure pulsations and flow of flushing liquid in the drilling rig circulation system on the durability of drilling equipment and drilling performance, the design of a piston downhole hydro-mechanical compensator developed and patented at the level of the invention is proposed. 3. During laboratory tests, the use of a downhole hydro-mechanical compensator made it possible to reduce the amplitude of liquid pressure pulsations at the outlet of the compensator by approximately 2 times, which is an effective indicator of the downhole device operation.

HYDRODYNAMICS OF GAS-LIQUID FLOW IN THE TUBING OF ROD PUMP INSTALLATIONS

During the operation of rod installations, pressure oscillations occur in the pump and compressor pipes due to the influence of hydrodynamic friction and inertia forces under conditions of uneven supply of the plunger pump during the pumping cycle. Pressure oscillations have a negative impact on the operation of pumping units: they lead to an increase in loads on pumping equipment components, the rate of fatigue wear of pumping rods, etc. Promising direction for improving the efficiency of rod installations is the development of methods and technologies for reducing pressure oscillations in pumping pipes. To smooth out pressure oscillations, pneumatic compensators are used. Pneumatic compensators are designed to equalize the speed of the liquid in the pipes. A mathematical model of the unsteady flow of gas-liquid flow in the pumping pipes of rod installations has been developed. By modeling the pumping of products with different rheological properties (differing in water content, viscosity, and compressibility), the features of pressure dynamics in the lower end of the tubing and in the flushing line at the wellhead are analyzed to assess the potential efficiency of placing wellhead (located in the flushing line at the mouth) and deep (located in the lower part of the tubing) pneumatic compensators. By modeling the pumping of high-viscosity oil it is shown that the maximum pressure at the wellhead and the lower end of the tubing is achieved in different half-cycles of the plunger (at the mouth of the upstroke, at the lower end of the tubing - at moving down) that is associated with the influence of relative movement of the rods and fluid on the formation pressure in the tubing. As a result, when pumping out high viscosity products, the wellhead pneumatic compensator reduces the component of the maximum load on the balancer head due to the hydrodynamic friction of the liquid when it moves in the collector, while the deep one reduces the load of hydrodynamic friction acting on the rod column and ensures free movement of the rods downwards. It is shown that when pumping low-viscosity oil with a high gas content, the amplitude of pressure oscillations is small and in the considered examples does not exceed 0.02 MPa. The influence of inertia forces that are crucial for pumping high-water oil is analyzed. Calculations show that the amplitude of pressure oscillations at the mouth is about 70 % of the amplitude of oscillations at the lower end of the tubing, which allows using wellhead pneumatic compensators to reduce the component of pressure pulsations in the tubing caused by the forces of inertia when the fluid moves in the reservoir.

MATHEMATICAL MODEL OF A ROD INSTALLATION WITH A WELLHEAD PNEUMATIC COMPENSATOR FOR HIGH-VISCOSITY OIL PUMPING

Maintaining the profitability of oil fields entering the final stage of development is largely determined by improving oil production techniques and technologies. Currently, due to the growth of hard-to-recover reserves, an urgent task is to develop technical means to improve the efficiency of high-viscosity oil production, in particular, when wells are operated with rod pumping units. One of the most promising ways to solve this problem are pneumatic compensators (РС) - devices that allow to reduce the hydrodynamic friction loads acting on the plunger and rod column by smoothing the pressure and flow rate fluctuations in pumping pipes. Based on numerical modeling, hydrodynamic processes are studied in the pumping pipes of rod installations equipped with wellhead (located on the surface and connected with the switch line) and deep (located in the tubing cavity) pneumatic compensators. A mathematical model of non-stationary fluid flow in pumping pipes and a switch line of a rod installation equipped with pneumatic compensators has been developed. The mechanisms of operation of the wellhead and deep PC are analyzed. It is shown that the PC wellhead allows to significantly smooth out fluctuations in the flow rate at the wellhead during the pumping cycle, thereby reducing the amplitude of pressure fluctuations at the wellhead and in the tubing, hence, the load on the pump plunger and the rod column when the plunger goes up. When working with a deep PC, its working chamber receives liquid when the plunger moves down, which reduces the speed of the liquid in the pumping pipes and the force of hydrodynamic friction of the pumping rods against the liquid. Theoretical dynamograms of the rod installation equipped with pneumatic compensators are constructed. It is shown that due to a combination of effects, characterizing the operation of wellhead and in-depth PC (reducing the load on the plunger when the plunger stroke up to the wellhead of the PC, reducing the hydrodynamic friction force of the rod on the fluid when the plunger stroke down to the deep PC) placement system of pneumocompensators in the pumping pipe and wellhead allows to maximize the efficiency of their work: to increase the minimum and decrease the maximum load on the sucker-rod column and the head balancer to reduce tension in the rods.

DYNAMICS OF FLOW RATE AND PRESSURE IN THE TUBING OF PLUNGER PUMPS WITH DOWNHOLE DRIVE

Background Significant progress has been achieved in improving the design of sucker rod pump units (SRPU), which have the highest efficiency in comparison with alternative methods of mechanized production during the operation of low flow rate production wells. Successful development of scientifically-based methods for selecting and optimizing the operation mode of sucker rod wells is being carried out, thanks to which efficient SRPU production of oil is achieved over a wide range of changes in production parameters. However, it should be noted that when operating wells with rod installations, there are significant limitations associated with the presence in the system of the pumping unit and the string of pump rods. Aims and Objectives Mathematical modeling of hydrodynamic processes in lift pipes and wells flow lines with the aim of calculating the pneumocompensators optimal geometric dimensions and technological parameters, predicting changes in their characteristics when changing the well operating mode. Results The mechanisms and features of the flow velocity and pressure in the lift pipes and flow lines of the wells equipped with plunger pump units with a linear drive are investigated. A mathematical model of the unsteady flow of a gas-liquid mixture is proposed. The analysis of the formation of the pressure field and the flow velocity in the cavity of the lift pipes during pumping of the produced products is presented. Simulation of the pumping out of high-viscosity oil and water-oil emulsion by the plunger pumps with a linear drive showed that with an increase in the viscosity of the fluid, the oscillation amplitude at the pump tip increases. At the mouth, with an increase in viscosity to 0.1 Paˑs, the amplitude of pressure fluctuations decreases, and with a further increase to 0.2 Paˑs, it increases. Calculations show that with an increase in the gas content of oil, the amplitude of the pressure fluctuations at the pump cradle and at the mouth decreases, which is associated with the damping properties of the gas due to its high compressibility, as well as a decrease in the viscosity of the gas-liquid mixture with increasing volume gas shares in well production. By modeling the pumping out of highly watered oil, it was shown that the pressure fluctuations formed during its flow are insignificant. In accordance with the simulation results, it was concluded that when pumping out highly viscous products (viscosity more than 0.05 Paˑs), the greatest effect due to equalization of the fluid flow rate in the pipes can be obtained when the well is equipped with deep pneumatic compensators, for example, placement of pneumatic compensators on the pump side and higher in depth.

ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ РАБОТЫ ПНЕВМОПРУЖИННОГО КОМПЕНСАТОРА ДАВЛЕНИЯ С КВАЗИНУЛЕВОЙ ЖЕСТКОСТЬЮ

Актуальность исследования обусловлена воздействием вибрации на элементы установки погружного электроцентробежного насоса. Наличие вибрационных процессов увеличивает количество преждевременных отказов узлов установки. Одной из причин проявления вибрационного воздействия на электроцентробежную насосную установку являются перепады давления на выкиде погружного электроцентробежного насоса, при этом частоты таких перепадов невелики. Цель: разработка лабораторной установки, которая имитирует колебательные процессы, происходящие на выкидной линии электроцентробежного погружного насоса в нефтяной добывающей скважине. Объекты: модель пневмопружинного компенсатора давления с квазинулевой жесткостью, конструктивно представляющего собой пневматическую пружину, внутри которой расположен пакет из пяти последовательно установленных тарельчатых пружин. Методы: численные решения дифференциальных уравнений, теория колебаний, математический анализ, математическая статистика, методы математического моделирования. Результаты. Разработана лабораторная установка, позволяющая провести исследования модели пневмопружинного компенсатора давления с квазинулевой жесткостью, конструктивно представляющего собой пневматическую пружину, внутри которой расположен пакет из пяти последовательно установленных тарельчатых пружин. Система с квазинулевой жесткостью представляет собой совокупность пневмопружины, имеющей силовую характеристику с рабочим участком положительной жесткости, и пакета последовательно соединенных тарельчатых пружин, имеющего силовую характеристику с рабочим участком отрицательной жесткости. Экспериментально подобраны параметры тарельчатых пружин таким образом, чтобы получить силовую характеристику с участком квазинулевой жесткости при заданном давлении. Результатом исследований на лабораторном стенде стало совпадение с заданной погрешностью замеров размаха колебаний и теоретически предсказанных результатов, что позволило доказать правильность теоретических выводов.

CALCULATION METHOD OF WELLHEAD PNEUMATIC COMPENSATORS OF SUCKER ROD PUMPS

The paper discusses the calculation method of wellhead pneumatic compensators of sucker rod pumps. It is proposed to install the wellhead pneumatic compensator in the close proximity to the wellhead on the flow line of the well. The calculation of pneumatic compensators was carried out as the calculation of a gas cap. The article discusses such examples of the operation of borehole sucker-rod pumps, when the volume of fluid displaced into the discharge line when the plunger moves down and calculated by the known formulas is greater than the volume of fluid during the upward movement. Examples when fluid is sucked into the well when the plunger moves upward are considered. It is shown that in this case, the magnitude of the degree of non-uniformity of the downhole pump can be significantly greater, almost twice, as much as possible for conventional single-cylinder single-piston pumps. In this regard, the relevance of the use of wellhead pneumatic compensators during the sucker-rod pumping unit operation is no doubt. When calculating the parameters of pneumatic compensators, the values of the pressure pulsation coefficients were taken in the range from 0.10 to 0.35. For the considered examples, the dependences of the instantaneous specific feed of the borehole pump are constructed depending on the angle of rotation of the crank of the pumping unit. For these dependences the magnitude of the change in the volume of the pneumatic compensator for one double stroke of the plunger was determined by integration. The average volume of the gas cushion of pneumatic compensators was determined by the magnitude of the change in the volume of the pneumatic compensator, after which their energy intensity factors were determined. According to the energy intensity values of pneumatic compensators, their initial volumes of gas chambers were determined.

METHODS OF PRESSURE DAMPING UPON THE OSTIUM OF SUCKER ROD PUMPS

In the article the methods of pressure damping in well flowline that arise in the work of the downhole sucker rod pumps due to ostium compensators of pressure with different force characteristics are proposed. As ostium compensators the known modern pneumocompensators (diaphragm and piston) and the compensators having the force characteristic with quasi- zero stiffness are considered. Diaphragm and piston and pneumatic com- pensators are in fact pneumatic springs having corresponding force char- acteristics. In a diaphragm pneumatic compensator, its force characteristic is influenced by the fact that a certain «jump» of the diaphragm takes place. This may cause undesirable effects when the diaphragm pneumatic compensator is operating. A mathematical model for a piston of pneu- matic compensator is proposed. The differential equation describing the movement of the pneumocompen- sator’s piston is solved numerically. Calculation of coefficient of a pulsa- tion of the ostium piston pneumocompensator taking into account dynam- ics of his work is carried out. The analysis of the developed mathematical model showed that pressure pulsation coefficient calculated by the known technique can have the underestimated value to 50 %. The version of essentially new scheme of the compensator having the force characteristic with the working site of quasi-zero stiffness is pre- sented. The offered compensator with quasi-zero stiffness represents the pneumo spring moving between guides of a settlement form. The form of guides pays off so that the restoring force of the compensator was to the constant and equal value determined by the average pressure upon the ostium of the well. At the same time the coefficient of a pulsation of pres- sure will be close to zero that can't achieve by means of known pneumo- compensators. The field of application of pneumatic compensators has been determined.

THE LOOSE MATERIALS METERING

The weight and volume metering were compared in the article and some advantages of the volume metering were defined. The methods of the volume metering accuracy improvement were regarded by the examples of the semi-dry press' metering device and of the pneumatic compensator's metering device's aspiration quality.

Development Experiment of 1 Degree of Freedom Rotation Mechanism by Pneumatic Gravity Compensation Device

Development Experiment of 1 Degree of Freedom Rotation Mechanism by Pneumatic Gravity Compensation Device

Value of Heave Compensators to Floating Drilling

This examination of the motion compensator concludes that it is one of the biggest advances made in offshore drilling in recent years. Analysis of the operation of rigs equipped with motion compensators indicates a saving of about 16 days per rig-year. Optimum bit loads allow maximum penetration rates and increased bit life. Another advantage is safety in penetration rates and increased bit life. Another advantage is safety in well killing and BOP-stack handling. Introduction Before the design and introduction of the first heave or drillstring compensators, variations in the distance between the bit and the drilling level owing to wave action were accounted for with the aid of bumper subs. As offshore exploration moved into deeper and rougher water and failures achieved new dimensions in terms of cost, an alternate and more flexible method was sought. The result was the motion compensator first produced in the late 1960's when Vetco Offshore, Inc., installed a twin-cylinder model on the Wodeco IV, a drill barge working in the Santa Barbara channel. This equipment operated successfully within its design limits, and the concept of hydraulic or pneumatic heave compensation was proved viable. At least seven companies are now engaged in the design and manufacture of compensators. Each machine has a mode of operation peculiar to itself and possesses its own series of peculiar to itself and possesses its own series of problems. Shell Expro has been able to analyze the problems. Shell Expro has been able to analyze the performance of both the Vetco and the RUCKER Shaffer performance of both the Vetco and the RUCKER Shaffer models since they were installed on Shell-contracted rigs in the North Sea in Jan. 1974. Operating problems of other models such as the Western Gear Single Cylinder and the Ocean Science and Engineering, Inc., Crown Compensator have been assessed wherever possible. Savings in terms of weather down-time, bit life, and personnel and equipment safety have been observed during the latter part of the winter and throughout the summer of 1973-74 and are discussed in some detail. Now that drilling has moved further north, almost to latitude 62 degrees, the weather has produced a greater impact on rig operations. West of the Shetland Islands, where extremely long swells have been observed with correspondingly high heaves, one rig would certainly have been shut down without a heave compensator. Drilling has continued successfully in weather conditions producing heaves in excess of 12 ft and blowout-preventer producing heaves in excess of 12 ft and blowout-preventer (BOP) stacks have been landed with similar movement. Principles of Operations Principles of Operations Motion compensators may be located in the crown block or between the traveling block and the hook; they may operate either pneumatically or hydraulically, or by a combination of the two. During rig heave conditions, the operating medium is forced back and forth by means of hoses between the compensator's piston/cylinder arrangement and a number of pressure bottles or accumulators (Fig. 1). In the traveling-block units, hydraulic hoses hang from their respective standpipes in the derrick, whereas the compensated crown eliminates these - all hoses are fitted to the outside of the derrick. The mode of operation may be considered active or passive, or a hybrid of the two. In the purely passive passive, or a hybrid of the two. In the purely passive system (Fig. 2), the activating fluid results in air being compressed and expanded in and out of a bank of accumulator bottles; use is made of the adiabatic gas law: p1V1k = p2V2k V1 k p = p2 − p1 = p1 [(--------) −1],.......(1) V1−AX JPT P. 938

Pneumatic compensator of a double-beam interferometer for measuring block gauges

Pneumatic compensator of a double-beam interferometer for measuring block gauges