Oil recovery by rod pump is realized by a rod pumping system based on “three pumping” equipment (pumping unit, pumping rod and oil pump). That is, under the drive of the pumping unit, the plunger of the pumping pump (also known as the deep well pump) is driven up and down by the pumping rod going down into the well, and the well fluid is drawn to the ground.
An oil pumping machine is a kind of machinery and equipment for extracting petroleum, commonly known as a “kowtow machine”. The oil pumping unit is the most important lifting equipment in the rod pumping system. According to whether there is a traveling beam, it can be divided into a traveling beam pumping unit and a non-traveling beam pumping unit.
Ⅰ. Working principle:
The working process of a beam pumping unit is that the power unit (usually an electric motor, a diesel engine, or a natural gas engine) transmits the high-speed rotational movement to the reducer through the transmission belt. After the three-axis two-stage deceleration, the crank connecting rod mechanism changes the rotational movement to the upper and lower movement of the beam. The suspension rope hanging on the head of the donkey drives the plunger of the oil pump to reciprocate up and down through the sucker rod to draw the well fluid to the ground.
Ⅱ.The composition of the beam pumping unit:
The oil pumping unit is mainly composed of four parts：
1. Travel beam part: Donkey head, travel beam, beam, tail beam, connecting rod, balance plate (composite balance pumping unit)
2. Bracket part: Central bearing seat, work ladder, guard ring, console, bracket.
3. Reducer parts: Bottom boat, reducer cylinder seat, reducer, crank, counterweight, brake and other parts.
4. Power distribution part: Motor seat, motor, distribution box, etc.
Ⅲ.The technical characteristics of the beam pumping unit:
The beam-type oil pumping unit has the characteristics of reliable performance, simple structure, easy operation and maintenance.The main features include：
1. The structure of the whole machine is reasonable, the work is stable, the noise is low, and the operation and maintenance are convenient.
2. The beam adopts box-type or I-beam structure, which has high strength, good rigidity and large carrying capacity.
3. The reducer adopts herringbone involute or double arc toothed gears, which have high machining accuracy, strong carrying capacity and long service life.
4. The central bearing seat bearing adopts medium-width series roller bearings, which have good sealing and strong carrying capacity. The central bearing and crank pin bearing adopt self-aligning bearings to reduce installation errors and vibration during the operation of the pumping unit.
5. The donkey's head can be turned upside down, hung up or turned sideways in one of three forms.
6. The bracket adopts a tower structure, which has good stability and is easy to install on site.
7. The crank counterweight is driven by rack and pinion, which is light and accurate to adjust.
8. The brakes adopt an external holding structure and are equipped with a safety device, which is flexible in operation and brakes quickly, safely and reliably.
9. The base is connected by anchor bolts or pressure bars in one of two ways.
According to different structures, beam-type oil pumping units are usually divided into two types: Conventional and front-mounted.In order to save energy and increase the stroke, a variety of variants of beam-type oil pumps have appeared.
Ⅳ. Classification of beam-type oil pumping units:
1. Conventional beam pumping unit (rear-mounted)
The donkey head and crank connecting rod mechanism are located at the front and rear of the bracket, and the balance angle is zero.
This is the most common oil pumping machine currently in use. The bracket is between the donkey head and the crank connecting rod. The upper and lower stroke times are equal, and more mechanical balance is used.(The connecting rod mechanism is located behind the bracket)
2. Front-mounted beam-type oil pumping unit
The donkey head and crank connecting rod mechanism are both located in the beam-type oil pumping unit in front of the bracket.
The connecting rod mechanism is located in front of the bracket, and pneumatic balance is used.
The upper stroke gas expands to help the pumping unit work.The gas in the lower stroke is compressed to store energy.
The upper stroke of the front-mounted beam-type pumping unit is slower than the lower stroke.
3. Low-impulse downstream beam pumping unit
The low-impact downstream beam pumping unit is mainly used in the mining of existing low-yield oil wells at home and abroad, so that a large number of low-yield wells can be fully exploited under the premise of low energy consumption.The machine is based on a conventional machine and uses a special large transmission ratio three-stage reducer for the pumping unit to reduce the stroke of the pumping unit. In addition to the advantages of a conventional beam-type pumping unit, it also has the following advantages：
(1) The impulse is low, reaching 1-2 times/min.
(2) The supporting motor power is low, and the motor power is reduced by 2-3 grades compared with conventional machines of the same model to achieve energy-saving effects.
(3) The foundation is the same as that of ordinary conventional pumping units of the same model, which is convenient for users to use and maintain.
Technical features: The low-impulse pumping unit is an energy-saving pumping unit developed for low-permeability oil layers. The impulse is reduced, which is more suitable for low-yield wells, suitable for complex geographical environments, reduces management costs, and improves the operating efficiency of the pumping unit.
4. Special-shaped beam pumping unit (double donkey head pumping unit)
Special-shaped beam pumping unit, also known as double donkey head pumping unit, its structural characteristics: a rear donkey head is used instead of the tail shaft of an ordinary beam pumping unit, and a drive rope braid is used to connect the beam, forming the four-link mechanism of the pumping unit.
The donkey head and crank connecting rod mechanism of the hanging light rod are located at the front and rear of the bracket. During the one-stroke process, the length of the rear arm and the length of the connecting rod are not constant. Beam-type oil pumping unit.
By changing the law of change of the torque factor of the pumping unit, the balance effect is strengthened and the purpose of energy saving is achieved. It is based on a conventional machine as the basic model, and its four-bar mechanism (beam-connecting rod-crank mechanism) has undergone key technological changes. It adopts a special curved rear arm of the beam, and a flexible connection structure is adopted between the beam and the beam to obtain a special four-bar mechanism with the length of the rocker (rear arm of the beam) and the length of the connecting rod that changes with the angle of the crank, namely the “variable parameter four-bar mechanism”, which forms a new type of power transmission pumping unit structure that can adapt to the actual working conditions of oil production.
When the machine is working, it relies on regular changes in the effective length of the rear arm of its beam to achieve a working state with a large balance torque when the load is large and a small balance torque when the load is small, thereby strengthening the balance effect of the pumping unit and realizing the purpose of energy saving.
5. Lower-biased barbell beam-type oil pumping machine：
The main feature is the use of the down-biased barbell to balance and reduce the peak torque of the pumping unit, which can reasonably match the position and weight of the down-biased barbell according to the well conditions, inheriting all the advantages of conventional beam-type pumping units, with good balance effect and reliable performance.
6. Diameter-adjusting and torque-shifting beam-type oil pumping machine
The beam is biased and balanced, and the structure is novel. The adjustment is simple and easy. When the donkey's head is dead, the counterweight box is close to the ground.It is easy to add or subtract small and medium balance blocks in the counterweight box.
The balance is good, and the balance is accurately adjusted for the peak position of the load. Locking the travel beam and the bracket during stroke adjustment has changed the status quo of poor safety and labor intensity in stroke adjustment operations in the past, and auxiliary operations such as cranes are required. The small and medium-sized machines adopt a rear-mounted structure, and the mainframes adopt a front-mounted structure.
7. Pendulum rod type beam type oil pumping machine：
Pendulum rod-type beam-type oil pumping unit is a new type of energy-saving product, and a series has been formed.This type of energy-saving oil pumping machine is a new structure oil pumping machine that uses a crank-pendulum rod to drive the rocker mechanism for reciprocating linear motion. The pendulum rod adjusts the torque according to the changes in the load size of the upper and lower stroke of the suspension point, so that the working torque of the reducer is always in the best condition, and it achieves the effect of saving energy by about 50% compared with the upstream beam pumping unit. It is a kind of pumping unit with broad prospects for development.Has the following characteristics：
(1) The whole machine runs smoothly and has low noise.
(2) The matching reducer is small, and the torque is about 50% smaller than that of the beam pumping unit.
(3) The energy-saving effect is significant, and the energy consumption can be reduced by about 50% compared with the beam pumping unit.
(4) The installed capacity of the motor is small, and the power can be reduced by about 50%.
(5) Easy to install, more convenient to use and maintain, especially to adjust the stroke.
8. Partial wheel beam pumping unit：
The oil pumping unit is developed on the basis of an out-of-phase beam pumping unit. A bias wheel is configured at the tail of the beam, and a six-link mechanism is formed with the bias wheel as the center. By changing the law of change of suspension point load, the length of the equivalent rear arm and the crank bias angle, the torque of the reducer is gentle. The machine is suitable for general oil wells, but also for special oil wells. Compared with conventional models, it has the characteristics of small suspension jog load and small maximum linear speed.
9. Hydraulic beam pumping unit：
Hydraulic beam-type pumping unit is a new generation of pumping equipment developed and produced on the basis of conventional beam-type pumping units. It not only maintains the advantages of conventional units, but also has the characteristics of adjustable operating parameters, energy saving and high system efficiency. It is a new type of energy-saving pumping unit.
Ⅴ. How should the pumping unit be checked after it starts?
The inspection method is“ "Listen, see, and model”.
Listen: Listen to whether the rotation sound of each part of the pumping unit is normal, and whether there is any sound of touching or hanging.
Look: Look at the connection parts of the pumping unit. In particular, whether the crank pin and balance block are loose or prolapse, whether the gearbox is leaking oil, whether the back pressure and sleeve pressure are normal, whether the wellhead is leaking oil, whether the square clamp is loose, whether the rope suspender is twisted, and whether the three-phase current is balanced.