Pump jack balancing control method depending on the load

. This article focuses on the method of balancing the pump jack and optimizing its operation. In the course of the work, the main balancing methods were considered and a method based on changing the balancing value by moving the movable carriage was proposed. In the course of the work, a model was developed that made it possible to simulate loads, the results of which determined the effectiveness of the proposed balancing method. Based on the results of the study, a graph of the change in torque when the support is located during the operation of the drive was built. Based on the results of the work, the corresponding conclusion was made.


Introduction
One of the most common methods of lifting fluid from wells is a sucker-rod pumping unit, and a pump jack is used as its drive.This type of drive is widely used due to its simple and dependable design.The pump jack converts the rotational motion of the crank into the translational motion of the rod string [1,2].
Rod pump units are designed to lift fluid from the well to the surface during the production of oil or gas.They are one of the main equipment systems used in the oil industry.
The basic principle of operation of rod pump units is based on the use of a rod system consisting of a pump rod, suspension and rods.The pump rod is connected to the rods and lowered into the well.It is then lifted and lowered by the pump mechanism, creating the pressure needed to lift the fluid through the well.
Rod pump units often operate in tandem with booster head pumps, which allow more efficient lifting of fluid to the surface.In addition, they can also be equipped with special valves, filters and other devices to ensure more efficient and reliable operation.
The efficiency of the pump jack depends on its counterbalancing.Insufficient counterbalance leads to the occurrence of cyclic variable loads of large amplitude, which affects the drive units and leads to increased wear [3,4,5].
Cyclic loads have a greater effect on the transmission elements and the electric motor.The weight of the string and the column of liquid being lifted loads the pump jack, and depending on the ascent or descent of the plunger, the weight may differ by 30-50% [6].

Balancing methods
The uneven loads of the pump jack are solved by installing special counterweights.There are three main balancing methods [7]:  counterbalance;  crank balancing;  combined balancing.The use of a pneumatic actuator in rod pump units can provide a number of advantages.The pneumatic drive operates on compressed air and provides automatic operation of the pump unit.
One of the main advantages of a pneumatic drive is its high performance and efficiency.It is capable of creating powerful pressure, which allows you to effectively raise fluid from the well to the surface.The pneumatic drive also has high reliability and durability, which contributes to the continuous and continuous operation of the pump unit.
The pneumatic drive is also more environmentally friendly and energy efficient than other types of drives.It does not use electricity or fuel to operate, but only compressed air, which reduces the negative impact on the environment and reduces energy costs [8].
The use of a pneumatic drive in rod pump units improves their performance, reliability and environmental efficiency.This makes the pneumatic actuator an attractive choice for use in the oil and gas industry.
Another advantage of the pneumatic drive is its safety.In the event of emergencies or loss of power, the pneumatic actuator stops supplying compressed air, which prevents further fluid lift and reduces the risk of emergencies.
A method is proposed for solving uneven loads, shown in Figure 1 and consisting of the following elements: a pneumatic system, including a compressor station, a pneumatic line and a pneumatic cylinder; the pneumatic cylinder drives the carriage mounted on the body of the balancer and connected to the rear support of the pump jack.A distinctive feature of this solution is the ability to change the balancing value during operation by moving the movable carriage, an example of a change is shown in Figure 2, with the traditional method, balancing is possible only when the machine is completely stopped.Also, this solution allows collecting well telemetry data, for example, well debit.During the operation of the pump jack, the automation system changes the balancing arm with a high degree of accuracy.If the pneumatic system fails, the actuator is transferred to the neutral position and continues to operate normally.

Simulation of the balancing method
When developing this solution, a 3D model was created that allows simulation of loads depending on the change in the balancing value.On the created model, a study was made of the dependence of the torque on the crank mechanism, the results are shown in Figure 3.The graph shows the change in torque when the location of the support during the operation of the drive.When using a stationary support system, the torque curve is large, while the value of the torque when lowering and raising rod string is different.When using a movable support value torque are smaller and the values of the torque are equalized when lowering and raising the rod string, which leads to a decrease in the loads on the structural elements of the pump jack, as well as on the transmission elements.

Conclusion
The use of the proposed solution will make it possible to change the balancing value in real time and with a high degree of accuracy when the loads change.This method reduces the uneven loads acting on the pump jack elements, which increases their service life and reduces downtime.Also, this solution allows you to automate the operation of the pump jack and measure the telemetry data of the well.