Rod Column Research Articles

Development of the Rodsim numerical simulator for the study of a sucker rod pump, comparing the Gibbs (1963) and Lea (1990) models

It is of great importance to be fully cognizant of the sucker rod pump system in order to make reliable production forecasts and to evaluate potential strategies for optimizing production processes. A frequently employed methodology in such circumstances is numerical simulation. A numerical sucker road pump simulator can provide valuable insights into production performance by generating dynamometric charts that represent the efficiency of this activity. Since the rod column behaves like a thin rod, it is possible to represent the mathematical model by a one-dimensional wave equation that describes the forces acting on this rod column. Lea (1990), proposing an improvement of the work of Gibbs (1963), considers the effects of the viscosity of the fluid produced in a vertical well without heat exchange, the piston diameter, the production column and the rods to obtain the damping factor, thus being more complete and producing a more accurate result in the dynamometric charts. Both models are implemented and discussed herein. The equations are discretized and solved in the Matlab® environment. The code includes a graphical user interface that generates the internal Rodsim application. The application is used to solve a typical case of a sucker rod pump and to obtain the surface and downhole dynamometric plots for certain scenarios.

Badania turbulentnego przepływu płynu w pompach głębinowych w celu poprawy bezpieczeństwa środowiskowego

When the plunger moves downwards, the local hydraulic resistance in the injection system causes a hydraulic force from the bottom upwards, which prevents the plunger from falling freely in the cylinder and is the source of the bending of the pump rod column. For this reason, the plunger takes an eccentric position in the cylinder and presses against it, delaying the plunger fall from the head of the balancer of the rocking machine and disturbing coaxial connection of the stock-discharge valve-plunger. These complications lead to increased wear of the plunger-cylinder pair, breakage of the injection valve cell, broken pump rod column, loss of the plunger stroke, etc. It should be noted, however, that in these tests, the flow factor μ is taken as the hydraulic resistance for determining the pressure loss in the valve assembly, and the valve seat cross-section is calculated. When calculating the friction force in the plunger-pressure valve system, the loss of pressure in it is taken to be equal to the loss of pressure of the valve unit. As is known, the downhole pump suction and injection system is a complex system of local resistance, as it consists of different combinations of elements that strongly affect the overall hydraulic resistance of the unit. It is therefore advisable to adopt the local hydraulic resistance coefficient as the hydraulic resistance of the respective unit. The reliability of downhole pumps in general and their individual components is ensured during their design and manufacture and depends on the design features, the quality of manufacturing of components thereof, assembly of the downhole pump in general and their components, as well as a number of other process indicators.

Design of Titanium Alloy Mixed Sucker Rods Using API Recommendation Method

Titanium alloy, as a new type of material, has many advantages compared to ordinary metal materials: high specific strength, excellent toughness and fatigue resistance, excellent corrosion resistance, etc. Firstly, the wave equation of titanium alloy pumping rods was established. Then, the equivalent stiffness, equivalent bulk density, and equivalent elastic modulus of titanium alloy mixed pumping rods were derived, and the frequency coefficients of different rod column combinations were calculated. Finally, based on the above research, the steps for designing titanium alloy pumping rods using API recommendation method were summarized. Based on this, the design of titanium alloy pumping rods can be completed using API recommendation method through the above formulas and steps.

ELASTOMERS FOR DOWNHOLE SCREW PUMP

One of the most promising means of lifting oil is the installation of a downhole screw pump with a drive that rotates the rod column by rotating the plunger. Screw pumps are capable of producing high viscosity oil, characterized by a high sand content. The use of screw pumps reduces capital and operating costs by 25-95% compared to other types of mechs. production. Efficiency increases by 40-80% and transportation costs are reduced, as the screw pumping system has a compact design and is easily mounted on the well. The structural parts of screw pumps made of elastomers are fundamental factors in determining the service life and performance of the pump. Studies of changes in swelling and hardness of various series of elastomers within 96 hours revealed the most suitable commercial elastomer of a screw pump for the oil fields of Kumkol, Aryskum, Maybulak.

IMPROVING THE WORK EFFICIENCY OF WELLS EQUIPPED WITH PROGRESSIVE CAVITY PUMP

For difficult operating conditions of oil wells, one of the most effective methods of mechanized extraction is the use of progressive cavity pump with surface drive, providing a complete or partial solution to the problems of high-viscosity oil production. The volume of oil production and the cost of oil directly depend on their trouble-free operation, therefore, measures to improve the efficiency of progressive cavity pump, optimize pump operation, identify and combat the causes of premature failure of underground equipment are an urgent issue. This article analyzes the reasons for the workover of oil wells operated with progressive cavity pumps at the «Ashchysai» oilfield. In order to ensure long-term operation of the pump, the main parameters controlled during the operation of the rod column are determined, and the method of their calculation is demonstrated. Recommendations have been developed for choosing the optimal operating mode of the pump. The analysis of the efficiency of using polymer-coated tubing in wells equipped with progressive cavity pumps, increasing the intercleaning period and inter-repair period of wells.

Ensuring the operational-technological characteristics of the new design solution of the sucker-rod pumping unit

In Azerbaijan oil production is carried out both in the offshore and onshore. Offshore production is carried out on special platforms, while the onshore exploitation carried out directly by a mechanized method. Thus, the object of study is downhole pumps, which consist of a surface mechanical transmission and downhole equipment. For direct mechanization of ground equipment, a device called rocking machine is used, consisting of transmission and converting mechanisms. The main task of the rocking machine is to ensure the conversion of the rotational motion of the engine into the up and down stroke of the plunger of the pump. The downhole equipment includes rods column that lift liquid from the well, a cylinder and a plunger. However, the existing classic rocking machines have some advantages as well as some disadvantages. In order to overcome them, developed new design solution of the sucker-rod pumping unit, which consisting of a crank-rope-movable counterweight system has been designed. As a result of the research carried out in the article, a progressive expression was proposed for determining the strength condition of the rods column, which is one of the main working elements of the rocking machine. Then, in order to specify the wells in which the rocking machine can be applied, the statement regarding the determination of the value of the linear density of liquid column based on the strength condition of the rod column was put forward. These, in turn, can be determined in which oil wells with specific physical characteristics of the rocking machine with the given technical characteristics can be applied. All this can contribute to the prevention of accidents that may occur due to the breakage of the rods column of rocking machine. The formula proposed in this paper can be applied not only to the existing classic rocking machines, but also to other new design of rocking machines.

Synthesis of the transforming mechanism of the rocking machine

This article discusses the synthesis of a six-link transforming mechanism of a rocking machine.First, the problem of synthesizing a four-link articulated-lever mechanism for reproducing a verticalline was solved. For this purpose, the problem of synthesizing a rectilinear-guiding mechanism ofthe Evans type, which is a hinged-lever four-link mechanism with a straight vertical line drawingpoint, is considered. The task of synthesis is to implement the constraint equation. The geometricmeaning of the constraint equation is to determine the hinge, the positions of which in the absolutecoordinate system are equidistant from the origin of the OXY coordinate system.The problem of synthesis is formulated as a problem of quadratic approximation. According to thefound dimensions of the articulated four-link, performing the position analysis, the true positionsof the suspension point of the rod column were determined. After that, the found parameterswere refined using the output criterion directly, that is, the deviation from the given rectilineartrajectory.After the synthesis of a straight-line guiding mechanism, a drive kinematic chain was synthesized,which consists of a crank and a connecting rod.Thus, a rocking machine drive mechanism was obtained, containing a base, a crank pair connectedto the main hinged four-link mechanism. The technical result is achieved by the fact that a two-linkgroup is attached to the main four-link mechanism, forming a class III mechanism. The attachedtwo-drive group is the leading crank connected to the rack and connecting rod.Based on the obtained dimensions of the six-link converting mechanism, an experimental modelwas developed, which fully confirmed the efficiency of the transforming mechanism.

Effective course of pumping of a well rod pump

Determining the length of the plunger’s pumping is an integral part of the calculation of the well pump. However, it should be borne in mind that the pumping course of the plunger is different for each well. Therefore, the article proposes to define it from the dynamogram, on the coordinate parameter “pumping course” which is length, starting from the point of the minimum load on the TPS before the start of the suction. The opening of the supercharged valve shows a minimum load level, which has reached the lowest value due to the maximum high pressure of liquid compression in the working cylinder, after opening load begins to increase. This is the main sign of the opening of the supercharged valve. Mathematical modeling of the interaction of the column of rods and liquid showed: the column of rods, having a higher mass than the mass of liquid, is not subjected to a large forced oscillation, which is reflected on the dynamogram. The opening moment of the discharge valve indicates the beginning of liquid injection or the effective stroke of the plunger, therefore, we need to find exactly this point on the dynamogram circuit.Towards the end of the turn down the column comes to its original state, freed from longitudinal bends and vibrations. Then it can be argued: on the distance of the plunger’s run his intermediate state cannot have an impact. However, this allegation requires proof.

The research beam pumping unit of start-up mode

In the article, research of the beam-pumping unit start-up mode has been performed in accordance with the existing configurations of the rod column, the diameter of the plunger and the dynamic fluid level in the well. A mathematical model of the pumping unit actuator has been developed, it takes into account the mechanical characteristics of the drive motor, the moments of inertia of the belt drive and gears of the gearbox and the mass of the actuator components. Calculations have been performed for the variant of the pump rod column layout - two-stage, for the diameters of the plunger 55mm and depths of pump suspension of 1456 m. The problem of the beam-pumping units’ startup is defined for two cases. The first case is applied when the mass of the counterweights installed on the cranks of the pumping unit exceeds the mass of the column of rods and liquid, which is located in the tubing column above the plunger of the pump (rebalance of the beam pumping unit). The second - when the mass of counterweights is insufficient to balance the column of rods and the liquid in the tubing column above the pump plunger (imbalance of the beam pumping unit). The cases of rebalancing and imbalancing of the pumping unit occur in wells that are under periodic operative conditions. The first case - rebalancing occurs when the oil rocking pumping unit does not work, and the liquid level behind the tubing gradually increases up to its static level. After switching on the drive motor, the torque created by the crank counterweights exceeds the moment caused by means of the weight of the rod column and the liquid in the tubing column. Therefore, it is recommended to start the pumping unit from the lowest position of the rod suspender. In the second case, the imbalance occurs when the liquid’s dynamic level behind the tubing is lowered before receiving the submersible pump. Then the torque, created by the crank counterweights is insufficient to compensate the moment, caused by means of weight of the rods’ column and the liquid in the tubing column. Therefore, it is recommended to start the beam pumping unit from the top position of the rod suspension. As a result of calculations, the conditions of overload occurrence in wells with periodic operative conditions of the pumping unit are determined

Nonlinear Finite Element Analysis of Rod String in Rod Pumping System

Rod pumping is the main oil recovery method at home and abroad. The corresponding displacement and load of the sucker rod section are important parameters in the system. This paper uses the advantages of the finite element method to solve the three nonlinear problems in the rod string model, and establishes its finite element analysis model. According to the upper and lower boundary conditions and initial conditions, the software is used to program and calculate. The surface dynamometer card of multi-level steel rod columns and glass fiber reinforced plastics-steel hybrid rod string is predicted, and the calculation results with and without considering mass nonlinearity are compared and analyzed. The feasibility of predicting the surface dynamometer card by the finite element method is verified. It is proved that the coupling has a great influence on the mechanical properties of the glass fiber reinforced plastics-steel hybrid rod string.

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.

ВЛИЯНИЕ ГЕОЛОГО-ТЕХНИЧЕСКИХ И ТЕХНОЛОГИЧЕСКИХ ПАРАМЕТРОВ НА НАГРУЗКИ И УСТАЛОСТНУЮ ПРОЧНОСТЬ В ШТАНГОВОЙ КОЛОННЕ ВИНТОВЫХ НАСОСОВ

Актуальность исследования обусловлена необходимостью повышения надежности и ресурса штанговых винтовых насосных установок, используемых для осложненных условий эксплуатации скважин, поскольку они имеют низкую надежность в сравнении с электроцентробежными насосами, что ограничивает их применение. Винтовые насосные установки используются в скважинных условиях, характеризующихся высокой вязкостью откачиваемой пластовой жидкости (более 30 мПа·с) и высоким содержанием механических примесей в ней (коэффициент взвешенных частиц более 500 мг/литр). Опыт эксплуатации винтовых насосных установок показывает, что надежность насосных установок зависит в первую очередь от надежности штанговой колонны. Помимо крутящей нагрузки, необходимой для передачи вращения от асинхронного двигателя к винтовому насосу, погруженному на расстояние более одного километра от устья скважины, штанговая колонна испытывает растягивающие нагрузки от веса насосных штанг и осевой нагрузки винтового насоса, а также изгибающие нагрузки, вызванные пространственным искривлением ствола скважины. Цель исследования заключается в оценке влияния различных факторов эксплуатации на нагрузки, действующие на колонну насосных штанг в процессе эксплуатации скважины, а также на усталостную прочность насосных штанг. Методы: методика расчета штанговых колонн винтовых насосных установок с учетом осевых, крутящих и изгибающих нагрузок, учитывающая процессы трения штанговой колонны о насосно-компрессорные трубы, возникающие от Эйлеровых сил прижатия штанг к трубам из-за пространственного искривления ствола скважины, реализованная на языке программирования Python; факторный анализ нагрузок, действующих на привод насосной установки. Результаты. С помощью программного обеспечения, реализованного на языке программирования Python, произведены расчеты, показавшие влияние различных осложняющих факторов на величину нагрузок на штанговую колонну. Показано влияние нагрузок вследствие воздействия геолого-технических и технологических параметров на усталостную прочность насосных штанг. Разработанное программное обеспечение позволяет учесть степень влияния осложняющих факторов на стадии подбора компоновки винтовой насосной установки, а также в процессе эксплуатации и тем самым существенно увеличить межремонтный период работы штанговых винтовых насосных установок.

Research Concerning the Optimization of the Mechanism of the Conventional Sucker Rod Pumping Units

Finding optimal solutions to design the mechanism of the conventional sucker rod pumping units is always present due to many problems that involve. The study in this case involves both the cinematic and dynamic analysis of the mechanism of the conventional pumping units, making sure that the optimization solution maintain unchanged certain operating parameters of the pumping equipment such as the stroke of the sucker rod column. In the paper is presented a method of determining the optimal dimensions of the structural elements of the mechanism of the conventional pumping units in order to reduce the maximum values of the connection forces in the bearings in the conditions of maintaining unchanged the stroke of the sucker rod column. The simulations have been performed in the case of a C-640D-305-120 pumping unit.

Three channel GHz-ranged demultiplexer in solid-solid phononic crystals

We present the design procedure for the elastic GHz-ranged demultiplexer based on a solid-solid phononic crystal platform. It consists of a T-shaped waveguide with three arms. The PnC platform consists of a square array of infinitely long rods of Tungsten embedded in PMMA background. In order to have a wide band gap, it is essential that constituent materials have large contrast in physical properties. These materials have large contrast in their physical properties and it gives us the possibility of having complete band gaps with low filling fractions. To calculate the band diagram and transmission field map, the finite element method (FEM) has been employed. The main waveguides are made by removing one row or one column of rods. For each arm, the radius of rods is modified to have three different defects. Therefore, the designed demultiplexer can separate three frequencies in the range of GHz. To the best of our knowledge, it is for the first time.

Efficiency of a submersible plunger pump linear motor

Modern oil extracting has difficulties with extraction at depths exceeding 2 kilometers from mid and low debit wells. Traditional way for extraction from mid and low debit wells (pumping unit) is unacceptable for this task, because of rod column break hazard. Meanwhile, submersible electrical centrifugal pumps that are usually used for oil extracting from big depth have very low efficiency on low debit wells. Due to that, a new class of oil extraction equipment has appeared—submersible plunger pumps. Their world-leading manufacturer is China. The biggest progress in submersible plunger pump linear drive research was reached in Perm National Research Polytechnic University. Although efficiency of this type of pumps on low debit wells is much higher than centrifugal pumps have, it is still very low and does not exceed 30%. Thus, efficiency improvement of gaining popularity submersible plunger pumps is an important task not only for oil extraction but also for energy saving. Major power loss happens in windings of submersible linear motors. Because of that, first step of pump efficiency improvement is improvement of linear drive efficiency. Motor design optimization allows to significantly raise its efficiency to 50%. Higher efficiency could be reached by optimizing motor operation algorithm and using better materials.

Monolithic rod columns for HPLC based on divinylbenzene-styrene copolymer with 1-vinylimidazole and 4-vinylpyridine

ABSTRACTMonolithic chromatographic columns for HPLC based on divinylbenzene-styrene both with 1-vinylimidazole and with 4-vinylpyridine are prepared. The monoliths were synthesized in glass tubes with the inner diameter of 2 mm. Texture, hydrodynamic and chromatographic properties of the prepared columns were studied. Linear solvation energy relationships model was applied for the characterization of columns selectivity It is shown that changing the on 1-vinylimidazole or 4-vinylpyridine content in the initial solution allows to change the selectivity of the columns. An examples of small molecules and some proteins separations are presented.

Simulation of the Sucker Rod Column Dynamics for Different Pumping Regimes

Proper functioning of the sucker rod pumping installations is strongly influenced by the sucker rod column dynamics and can be appreciated, as is well known and widely applied in practice, by the allure of the surface dynagraph. The paper presents some results concerning the simulation of the sucker rod column dynamics obtained with a computer program developed by the authors. The simulation results are compared with experimental results obtained at two pumping installations. Then, the computer program is used to study the sucker rod column dynamics for another pumping regime at one of analyzed installations.

Optimizing pump-drive operation to improve the energy-efficiency of oil extraction

Equivalent systems (analogs) are employed in developing a model of the drive mechanism in a sucker-rod borehole pump. Normal and emergency pump operation is simulated on the basis of Matlab-Simulink software. The rod column is regarded as a coupled sequence of active quadrupoles. The results of the simulation are compared with experimental data, and recommendations are made for reducing the energy consumption.

Determining the parameters of oscillation dissipation in a column of sucker rods

In order to calculate a column of pumping rods as a mechanical system with concentrated masses, to determine dissipation coefficients, we applied a traditional method of analytical mechanics. A mathematical model is developed of longitudinal oscillations of a three-stage conditionally vertical column of sucker rods using the functions of displacement and load of its separate stages. Dependence for determining the dissipation coefficient of oscillations is derived from the solution of the system of equations. In accordance with the chosen set-up of a three-stage column of sucker rods, we examined a change in the dissipation coefficient of oscillations depending on the relationship between the rigidities of its stages. A change in the relationship between rigidities of the stages was carried out by changing their material. It was found that for the selected set-up of a column of sucker rods, the use of a fiberglass stage instead of that made of steel reduces its rigidity by approximately 4 times, and increases the dissipation of oscillations almost as much. Such approach makes it possible to prevent the phenomenon of resonance in the operation of a SR column during transition modes under the action of alternating load.