Polished Rod Research Articles

Intelligent diagnostic method for beam pumping units based on torque indicator cards

An innovative approach is introduced to the intelligent diagnosis of torque indicator card conditions using electric parameters, effectively addressing the high costs associated with acquiring polished rod indicator cards and the convergence difficulties encountered when converting electrical parameters. The proposed method begins by establishing a library of 15 typical operating conditions, followed by an engineering feature analysis. Key to this approach is the use of the AlexNet model for intelligent recognition training, which successfully enhances model convergence and stability, even with varying sample sizes. This allows for automated recognition and classification of operating conditions through model training. The research outcomes demonstrate that the model achieved a fault diagnosis accuracy of over 95% for beam pumping units. This not only improves the accuracy and efficiency of fault diagnosis in oil well pumping units but also presents a novel and effective approach for intelligent diagnostic applications in oil field extraction, offering substantial practical value.

Classification of The Analog Informative Parameters of the Rod Deepwell Pump Dynamograph Signals

In mechanized oil production, rod deep-well pumps are widely used. They consist of surface and underground parts. The above-ground part includes pump drive and wellhead fittings. The wellhead fitting is designed to seal the well. The underground part is the pump itself. The pump consists of a plunger, rod string and tubing. The main method of diagnosing a rod deep-well pump is dynamometry. Dynamometry allows to determine the equipment defects and control the efficiency of the pump operation mode without stopping the well operation. Dynamometry is a process of measuring the loads, which are perceived by the polished rod during the operation of the well. There are theoretical and practical dynamograms. Practical dynamogram is a closed non-periodic curve with variable amplitude. There are various methods to automate the process of the dynamometry result processing. In this paper we analyze the analog informative parameters of dynamometer signals. These parameters depend on the friction forces in the underground part of the rod pump, inertial forces, tightness of valve assemblies, dynamic liquid level, etc. The results obtained can be used in the development of the pumping process. The obtained results can be also applied to develop processing algorithms of practical dynamograms.

Trajectory Recognition and Working Condition Analysis of Rod Pumping Systems Based on Pose Estimation Method with Heatmap-Free Joint Detection

Summary Rod pump systems are the primary production tools in oilfield development. Analyzing their working conditions provides a theoretical foundation for formulating production optimization plans and adjusting equipment parameters. Existing machine learning–based condition analysis methods rely on dynamometer cards and cannot capture the actual operational trajectory of the pumping unit. To address this issue, this paper proposes a keypoint detection method for pumping units based on pose estimation of heatmap-free joint detection from video data. A data annotation scheme suitable for the task of detecting pumping unit keypoints was developed, and the learning criteria for this task were optimized. An end-to-end heatmap-free pose estimation algorithm was used to process images of the pumping unit, yielding predicted keypoint positions, thereby enabling the identification of the keypoint motion trajectories of the pumping unit. Experiments validated the proposed method and compared it with general learning criteria. Results show that this method accurately captures the keypoint positions of the pumping unit, with the optimized learning criteria model improving by more than 5% compared with general methods and increasing the keypoint object keypoint similarity (OKS) by more than 30%. The model’s results can be used for the actual operational trajectory recognition of the pumping unit, automatically calculating the motion parameters of the polished rod, and intelligently assessing the balance and working condition analysis of the pumping unit. This realizes the intelligent application of video surveillance data, significantly contributing to the dynamic study of rod pump systems.

Pump System Model Parameter Identification Based on Experimental and Simulation Data

In this paper, the entire downhole fluid-sucker rod-pump system is replaced with a viscoelastic vibration model, namely a third-order differential equation with an inhomogeneous forcing term. Both Kelvin’s and Maxwell’s viscoelastic models can be implemented along with the dynamic behaviors of a mass point attached to the viscoelastic model. By employing the time-dependent polished rod force measured with a dynamometer as the input to the viscoelastic dynamic model, we have obtained the displacement responses, which match closely with the experimental measurements in actual operations, through an iterative process. The key discovery of this work is the feasibility of the so-called inverse optimization procedure, which can be utilized to identify the equivalent scaling factor and viscoelastic system parameters. The proposed Newton–Raphson iterative method, with some terms in the Jacobian matrix expressed with averaged rates of changes based on perturbations of up to two independent parameters, provides a feasible tool for optimization issues related to complex engineering problems with mere information of input and output data from either experiments or comprehensive simulations. The same inverse optimization procedure is also implemented to model the entire fluid delivery system of a very viscous non-Newtonian polymer modeled as a first-order ordinary differential equation (ODE) system similar to the transient entrance developing flow. The convergent parameter reproduces transient solutions that match very well with those from fully fledged computational fluid dynamics models with the required inlet volume flow rate and outlet pressure conditions.

A Novel Method for Predicting the Behavior of a Sucker Rod Pumping Unit Based on the Polished Rod Velocity

Fault dynamometer cards are the basis of the diagnosis technique for sucker rod pumping systems. Predicting fault cards with a pumping condition model is an economical and effective method. The usual model is described by a mixed function of the pump displacement and pump load, and it is difficult to use in the prediction method based on the analytical solution of the sucker rod string wave equation. In this paper, a normal pumping condition model described by a function of polished rod velocity is proposed. For the analytical solution of the sucker rod wave equation, an iterative prediction algorithm with pumping condition models is proposed, its convergence is analyzed, and then it is validated by classical finite difference method simulated cards and measured surface dynamometer cards. The results show that the proposed algorithm is accurate. The algorithm has a maximum relative error of 0.10% for the classical method simulated card area and 1.45% for the measured card area. The research of this paper provides an effective scheme for the design, prediction, and fault diagnosis of a sucker rod pumping system with an analytical solution.

Research on the Soft-Sensing Method of Indicator Diagram of Beam Pumping Unit.

An accurate calculation of the indicator diagram of a pumping unit is the key factor in analyzing the performance of an oilfield production and operation and in preparing and optimizing an oilfield development plan. Aiming at the problems of the poor stability of the conventional load-displacement sensor method and the wave equation method, owing to the influence of an alternating load on the force sensor and the difficulty in measuring the crank angle using the electrical parameter method, a new soft sensing method employing the input electrical parameters of the motor and the beam inclination has been proposed to obtain the indicator diagram. At first, this method is established based on the beam angle of the pumping unit, which is easily measured using the suspension point displacement mathematics calculation model and the torque factor. Subsequently, the electric motor input parameters, the parameters of the four-bar linkage, and the relationship between the polished rod load have been established. Finally, the motor and the beam angle of the measured electrical parameters have been substituted into the calculation of the suspension point displacement and load value and pull in accordance with the guidelines to eliminate the singularity mutation values. After processing the measured data through a Butterworth filter, the indicator diagram is obtained. The results of the engineering experiment and application show that the average relative error of the method is less than 3.95%, and the maximum relative error remains within 2% for 6 months, which verifies the stability of the soft sensing method.

Intelligent intertraverse dynamograph of the mesdoza of sucker-rod deep-pumping units

Rod downhole pumping units widely used in oil production are described. It is shown that oil production depends on the mode of operation of these units, which is selected based on the results of the analysis of closed dynamometer charts. Dynamograms describe the load on the suspension depending on the course of the polished rod of the installation, the quality of the construction of the dynamograms is decisive for diagnosing the technical condition of the installation. The trends in the development of existing dynamometer systems and methods for diagnosing the state of a sucker rod pumping unit are analyzed. One of the ways to create an intelligent intertraverse mesdoza dynamograph based on the mesdoza of a pocket dynamograph using modern pressure, acceleration, temperature sensors, STM32 controllers, a graphic liquid crystal display with an I2C interface, radio communication protocols and digital technologies for processing periodic sensor signals is presented. Based on the analysis of existing dynamometer systems and force and stroke sensors installed in various places of the installation design, and taking into account modern advances in technology and technologies for analyzing the noise of the measured signals, the possibility of developing an intelligent stationary dynamograph is shown. This dynamograph must provide early diagnostics of the technical condition of the installation and meet the following criteria: low cost; ease of installation; high sensitivity, reliability, flexibility and accuracy. A block diagram of an intelligent intertraverse dynamograph of the mesdoza of a sucker-rod deep pumping unit, based on the mesdoza of a pocket dynamograph, is presented. The proposed intelligent intertraverse dynamograph will be useful for early diagnostics of the technical condition of downhole pumps and tubing pipes connecting them with ground equipment, which will ultimately help to improve the reliability of oil production equipment. The proposed intelligent intertraverse dynamograph can also be used in other areas of technology where there is a need to measure force.

Fluid–structure interaction of a dynamic seal with a 3D‐printed surface

AbstractAdditive manufacturing (AM) methods are finding more and more applications in the manufacturing of machine parts. One consequence of this method is that generated surface qualities are typically lower than in other processes. This becomes especially relevant when the surface quality is critical for the mechanical function: This is the case in dynamic sealing technologies, for example, in seals between a moving rod and a hydraulic cylinder. Between the seal lip and the polished rod, a thin lubrication film is established with the goal of minimal leakage. How well this goal is reached depends on the surface quality of the seal. For spare part production of seals, we investigate AM methods, which have a surface defined by layers from fused filament fabrication (FFF). We apply a coupled model for fluid–structure interaction of the elastic seal and the film flow. This model provides information on flow field and pressure distribution. Results change when the ‘ideal’ seal lip is replaced by the seal lip geometry from FFF. The continuous loss of solid body contact is replaced by a stepwise loss of contact for the FFF surface.

Wyznaczanie siły tarcia pomiędzy cięgłem a prowadnicą cięgła w żerdziowych pompach wgłębnych oraz analiza odkształcenia naprężeniowego zespołu zaworowego

The article is devoted to the determination of the friction force between the draw rod and the guide and to the analytical study of the stress deformation state of the valve assembly of the rod well pump. In sucker rod well pumps, a hollow cylindrical guide is used to ensure the same axis of the plunger as the cylinder during operation. The guide is attached to the upper end of the pump cylinder. The draw rod connecting the sucker rod and the plunger of the pump moves up and down in the internal cylindrical cavity of the guide in the corresponding movements of the balancer head. There must be a certain clearance between the draw rod and the guide to ensure free movement of the draw rod. Based on the calculation scheme for determining the friction force between the draw rod and the guide is given, and the necessary parameters are determined. According to the values obtained from the calculation, the graphs were built based on the dependences of the friction force between the draw rod and the guide on the angle φ, and on the path of the plunger when φ = 30. At the same time, according to the calculation scheme of the "ball-saddle" pair, the force acting on the ball, the stresses generated on the contact surfaces of the ball and the saddle, and other parameters were found. The friction and wear between the draw rod and the guide is also typical of the friction and wear between the polished rod and the wellhead forming structure. Because, in the latter case, as a result of the suspension point of the balancer head not having the same axis as the wellhead, the polished rod cannot move with the straight axis in wellhead valve.

Coupling Simulation of Longitudinal Vibration of Rod String and Multi-Phase Pipe Flow in Wellbore and Research on Downhole Energy Efficiency

The wellbore of a sucker–rod pumping well experiences a multi–phase flow consisting of oil, gas, and water. The flow pattern and pump discharge pressure are greatly impacted by oil well production, which in turn significantly affects the simulation results of longitudinal vibration in the sucker–rod string. When calculating the discharge pressure in a hydrostatic column containing both oil and water (HC), the pressure is not affected by the oil well’s production. This thereby avoids interference between vibrations in the sucker–rod string’s longitudinal direction and the flow from the wellbore. Considering the coupling characteristics between the longitudinal vibration of the sucker–rod string and the wellbore flow, a mathematical model of the sucker–rod pumping system (CMSRS) and a mathematical model of the downhole energy efficiency parameters were established. In detail, the CMSRS comprises two parts: the discharge pressure mathematical models of multi–phase flow dynamics (MD) and the wave equation of the longitudinal vibration of the sucker–rod string. A numerical simulation model of the sucker–rod pumping system was constructed based on a mathematical model. We compared the experimental results, the simulation results of the CMSRS and the simulation results of the sucker–rod string based on the oil–water two–phase hydrostatic column (SMSRS) and found good agreement, indicating the feasibility of the CMSRS. The simulation details show the following: (1) The HC model’s discharge pressure exceeds that of the MD model by more than 33.52%. The polished rod load for the CMSRS is 18.01% lower than that of the SMSRS, and the pump input power for the CMSRS is 36.23% lower than that of the SMSRS. (2) The effective power simulation model based on the energy balance relationship is essentially the same as the effective power calculated by the model based on multi–phase flow effective power. This validates the accuracy of the multi–phase flow effective power model. (3) The limitations of the industry standard effective power model are that (i) the effective head is the net lift height of the fluid in the wellbore reduced to the oil and water phases rather than the effective lift height based on the energy balance relationship and (ii) the power of the gas phase delivered by the pumping pump is disregarded, and only the effective power of the pump delivering the oil–water mixture is considered. (4) The influence of the wellbore parameters on the wellbore efficiency and sub–efficiency is systematically analyzed. The analysis results have an important significance in the guidance of energy saving in pumping wells.

IMPROVEMENT OF OPERATING CAPACITY OF OIL PRODUCTION EQUIPMENT CONSIDERING THE INFLUENCE OF DYNAMIC LOADS

In the presented article, the analysis of the effect of the dynamic load falling on the polished rod of the sucker rod pump unit on the normal function of the operating unit during the oil extraction process was carried out. The general formula for the damage caused by the impact of the pump's wellhead packing seal has been derived. The dependence graph of damaged work on the length of the packing seal and the Poisson's ratio of the material was made. Due to the dynamics of the frictional force generated in the packing seal of the stuffing box appropriately located below the suspension point of the rods, its forced cyclic movement occurs as a result of the impact transmitted to the system which consists of an incompressible fluid column, and the elastic rods. This requires the investigation of the dynamics of the rod pump associated with the probability of unpleasant situations such as the possible resonance occurrence in the specified system, the time between repairs, and the reduction of the working coefficient of the pump, in this regard. At the same time, the questions such as the coefficient of friction depending on the selection of the material of the packing seal, the reduction of the dynamic accumulation of the load on the system, and the saving of electric energy are also important. It needs to be considered that the operation process is accompanied by a certain energy loss. It should be taken into account that even a small reduction in energy loss can manifest great economic benefits. It should be noted that some issues encountered in the process of operation of oil wells through the rod pump and depending on certain arguments affecting this process were also resolved by those experts. Keywords: oil production, frictional force, sucker road pump, dynamic load, logging operations, logging cable, separator, energy loss, wellhead packing seal

Intelligent Diagnosis Model of Working Conditions in Variable Torque Pumping Unit Wells Based on an Electric Power Diagram

Because of the problems, such as the lack of an electric power diagram atlas under different working conditions and the difficulty in intelligent diagnosis of variable torqued pumping unit wells, this paper proposes a diagnosis model of working conditions based on feature recognition. The mathematical relationship model between the polished rod load and motor output power is derived based on the analysis of geometric structure, motion law, and process of energy transformation and transfer of the variable torque pumping unit. It can calculate the electric power diagram based on a dynamometer card. On this basis, the electric power diagram atlas is created, and the feature analysis and eigenvalue extraction of the electric power diagrams under different working conditions are carried out to realize the direct diagnosis of the working conditions in the variable torque pumping unit wells. The application and analysis of examples show that the electric power diagram atlas created in this paper has good practicability, and the working condition diagnosis model accuracy is high. It can provide a theoretical basis and technical support for the intelligent diagnosis of oil production working conditions and improve the intellectual management level of the oilfield, which is conducive to reducing production management costs and improving the oilfield’s production efficiency and benefits.

A Hybrid Approach of the Deep Learning Method and Rule-Based Method for Fault Diagnosis of Sucker Rod Pumping Wells

Accurately obtaining the working status of the sucker rod pumping wells is a challenging problem for oil production. Sensors at the polished rod collect working data to form surface dynamometer cards for fault diagnosis. A prevalent method for recognizing these cards is the convolutional neural network (CNN). However, this approach has two problems: an unbalanced dataset due to varying fault frequencies and similar dynamometer card shapes that complicate recognition. This leads to a low accuracy of fault diagnosis in practice, which is unsatisfactory. Therefore, this paper proposes a hybrid approach of the deep learning method and rule-based method for fault diagnosis of sucker rod pumping wells. Specifically, when the CNN model alone fails to achieve satisfactory accuracy in the working status, historical monitoring data of the relevant wells can be collected, and expert rules can assist CNN to improve diagnostic accuracy. By analyzing time series data of factors such as the maximum and minimum loads, the area of the dynamometer card, and the load difference, a knowledgebase of expert rules can be created. When performing fault diagnosis, both the dynamometer cards and related time series data are used as inputs. The dynamometer cards are used for the CNN model to diagnose, and the related time series data are used for expert rules to diagnose. The diagnostic results and the confidence levels of the two methods are obtained and compared. When the two diagnostic results conflict, the one with higher confidence is preserved. Out of the 2066 wells and 7 fault statuses analyzed in field applications, the hybrid approach demonstrated a 21.25% increase in fault diagnosis accuracy compared with using only the CNN model. Additionally, the overall accuracy rate of the hybrid approach exceeded 95%, indicating its high effectiveness in diagnosing faults in sucker rod pumping wells.

Methods for Monitoring and Diagnosing the State of Sucker-rod Pumping Equipment

There are plenty ways to enhance the efficiency and extend the life of downhole sucker-rod pumping units, one of the vital ones is timely diagnostics, monitoring of downhole sucker-rod pumping units. There are two widespread methods to monitor the operation of downhole pumping units: dynamometry and wattmetry. One of the effective ways of monitoring is dynamometry, which provides complete information about the state of underground equipment and enables to evaluate the operating mode of the well. Dynamometry is mostly used for monitoring and obtaining information on the condition of downhole equipment and underground pumping units. Dynamograms are recorded with dynamographs, which include force and position sensors to measure the load on the polished rod and obtain data on the movement of the polished rod. Wattmetry is applied to monitor the surface equipment of rod and well pump units, represents the dependence of the power consumed by the pump motor or the power of the unit on time. The article describes the methods of monitoring and diagnosing the operation of sucker rod and well pumping equipment, as well as reviews of modern methods of monitoring the operation of these units.

Intelligent Method to Optimize the Frequency Modulation for Beam Pumping System Based on Deep Reinforcement Learning.

A mathematical simulation model of a beam pumping system with frequency conversion control is established, considering the influence of the real-time frequency variation on the motion law of a pumping unit, the longitudinal vibration of a sucker rod string, the crankshaft torque, and the motor power. On this basis, the key links such as state space, action space, and reward function are defined by using deep reinforcement learning theory, and an intelligent model to optimize the frequency modulation for a beam pumping system based on deep reinforcement learning is constructed. The simulation and field application results show that the frequency optimization model can significantly reduce the fluctuation amplitude of the polished rod load, crankshaft torque, motor power, and input power of the system, making the operation of the pumping system more stable and energy-saving. More importantly, the model can realize the independent learning and control of the corresponding parameters without manual intervention to ensure the normal operation of the system and improve the level of information and intelligent management of oil wells.

Identification of the Four-Bar Linkage Size in a Beam Pumping Unit Based on Cubature Kalman Filter

While the size of the four-bar linkage is the basis of kinematic performance analysis in a beam pumping unit, there is still a lack of effective and direct measurement of it. Since the motor input power and the polished rod position are commonly used production data, a size identification algorithm of the four-bar linkage based on the motor input power and the polished rod position is proposed in this paper. Firstly, the kinematic model of a beam pumping unit, the speed model of a motor, the initial value, and the state space model are established. Secondly, a Cubature Kalman filter with nonlinear constraints is designed and the size identification algorithm is worked out. Lastly, the model and the size identification algorithm are validated based on the simulated and measured data, and the characteristics of identification with different measurement covariance are studied. The results demonstrate that both the model and the algorithm are feasible. The maximum relative error between the identified and the real size increases from 0.23% to 9.37% when the covariance increases from 10−6 to 10−1. With the measured covariance of the polished rod velocity, the maximum relative error is 7.09%. A comparison of several current identification methods demonstrates that the proposed algorithm is more accurate.

A novel method for trajectory recognition and working condition diagnosis of sucker rod pumping systems based on high-resolution representation learning

The pumping unit is the most important lifting equipment in the rod pumping system, which transmits ground power to the downhole pump through its sucker rod. Trajectory identification of the rod pumping system can be used to study the motion law of the pumping unit, and it is the basis for the design of the pumping parameters and the analysis of the working conditions. Most of the studies on the dynamics of the pumping unit are to discuss the simple harmonic motion of the suspension point or the motion of the crank-slider in the ideal state, which is quite different from the actual situation. In this paper, a key point detection method for oil pumping units based on high-resolution representation learning is proposed. The model adopts a multi-resolution parallel network, which connects multiple network branches with different resolutions in parallel. Then it performs multi-stage processing on the input pumping unit images and outputs the predicted Gaussian heatmaps of key points to realize the trajectory recognition of the pumping unit. Different from the traditional series convolutional network structure, which needs to recover high resolution from low resolution, the parallel structure of this model is able to maintain the high resolution of the backbone network and thus the learned representations are more accurate in spatial location. This method is also experimentally verified and compared with the latest convolutional network structure. The results show that the model accuracy of the high-resolution representation learning method is more than 6% higher than that of the comparison methods. In addition, the results of this model can be used to judge the balance of the pumping unit, automatically calculate the maximum stroke and polished rod stroke, and have guiding significance for the working condition diagnosis of the rod pumping system.

A Novel Hybrid Method for Indirect Measurement Dynamometer Card Using Measured Motor Power in Sucker Rod Pumping System

The dynamometer card (DC) is crucial for the remote monitoring of the sucker rod pumping system (SRPS). However, the DC sensors have poor real-time performance and high maintenance costs leading to difficulties in obtaining datasets of the downhole working states from different oil wells. Moreover, the motor power curve is easy to obtain in real-time and can reflect the changes in pumping unit load. Thus, this paper proposed a novel hybrid model for indirect measurement DC based on measured motor power. Firstly, based on the mechanical model analysis of SRPS, the dataset is constructed by transforming the motor power and geometric parameters of the SRPS into the polished rod torque, the first-derivative of polished rod torque, the second-derivative polished rod torque, and the torque factor. These four parameters are merged as the inputs of the data-driven model. Subsequently, a data-driven model implements the particle swarm (PSO) algorithm to optimize the weights and thresholds of the Back Propagation (BP) neural network model, which was trained to predict DCs of three common working states. Finally, the proposed method is verified experimentally through the measured DC and motor power data. Both experimental and prediction results demonstrate the effectiveness of the proposed method for generating DC. The mean DC area relative error of the hybrid method proposed in this paper is 2.52%.

The Rod String Loads Variation during Short-Term Annular Gas Extraction

This paper highlights field studies to determine the nature of variations in the load on the sucker-rod string during short-term gas extraction from the wellbore annulus. The results of step-by-step gas extraction from the annular spaces of the wells of fields developed by PJSC TATNEFT are provided. In the course of investigations, we have obtained both the trends of maximum and minimum loads on the polished rod during annular gas extraction, and the dependence of maximum load increment on the rod string with respect to pump size and pressure variation in the annular space. The analysis of the research data resulted in the elaboration of guidelines for short-term extraction of annular gas from wells operated by the PCP units.

Mathematical modeling of the deformation of a cylindrical ring under the influence of an external load distributed along the generatrix

The article is devoted to the mathematical modeling of the deformation of a cylindrical ring under the influence of an external load applied to it by pressing parallel plates. It is shown that at the last stage of oil field operation, the main method of artificial lift is the use of sucker rod pumping units (SRPU), on whose failure-free operation the profitability of oil production largely depends. It is also shown that the technical condition of the SRPU is controlled by the dynamometry method, which is the dependence of the rod string force on the suspension on the stroke of the polished rod. In this case, the main source of information is the force transducer. In the article, we propose using a hollow thick-walled cylinder, which is compressed between traverses consisting of parallel flat plates, as the primary sensitive element of the force transducer. The question of refinement and determination of the non-Hertzian contact deformation during compression of a thick-walled hollow cylinder by two parallel flat plates within the elasticity range is considered. It is shown that the well-known formula for the convergence of the axes of the cylinders being compressed according to the Hertzian method does not take into account the real deformation and convergence of the points of the cylinder due to compression and contact deformation between the generatrices of the cylinders. By solving the differential equation, formulas are derived to determine the value of the elastic deformation of a cylinder depending on its geometric dimensions under the influence of an external load applied to it by pressing plates. An example of calculating elastic deformation for different values of cylinder thicknesses depending on the load is given and its graph is plotted.