At present, the most commonly used type of pumping unit in China is beam type pumping units, tower type pumping units, and screw pump type pumping units. The beam pumping unit is commonly referred to as a “sweeping head machine†and it is pressurized. The method has made oil out of wells and has been widely used as a simple, efficient, and easy-to-operate oil extraction equipment in the mining of various sand-containing, gas-containing, and water-containing crude oils.
The beam pumping unit is mainly composed of four parts: donkey head, beam, connecting rod, crank mechanism, speed reducer, power equipment and auxiliary equipment. During work, the transmission of the electric motor is changed into a donkey head up and down movement via the gearbox and the crank connecting rod mechanism. The donkey head moves the plunger of the downhole oil pump up and down by the light rod and the sucker rod, thereby continuously extracting the crude oil from the wellbore out of the wellbore . As shown below:
Pumping pumping principle is relatively simple, similar to rural pressure wells.
1) Upward Stroke
The rod of the sucker rod moves upwards with the plunger, and the valve on the plunger is closed by the pressure of the liquid column in the tube. The pressure in the pump is reduced and the fixed valve is opened by the difference between the liquid column pressure (submergence pressure) in the annular space and the pressure in the pump. The pump sucks liquid and the wellhead discharges liquid.
Pump suction conditions: The pressure in the pump (suction pressure) is lower than the sunk pressure.
2) The downstroke plunger descends and the fixed valve closes under gravity. The pressure in the pump increases. When the pressure in the pump is greater than the pressure above the plunger, the valve is opened. The liquid in the lower part of the plunger enters the upper part of the plunger through the traveling valve, causing the pump to discharge the liquid.
Pump discharge conditions: Pump pressure (discharge pressure) is higher than the plunger pressure above the plunger.
When the hoe machine is working, the load acting on the donkey head is changed. On the upstroke, the head of the donkey needs to lift the sucker rod and the liquid column. Under the condition that the pumping unit is not balanced, the motor must pay a lot of energy. On the down stroke, the pump rod turns to work on the motor, leaving the motor in generator operation. Therefore, when the pumping unit is not balanced, the load on the upper and lower strokes is extremely uneven, which will seriously affect the efficiency and life of the four-bar linkage mechanism, the reduction gear box and the motor of the pumping unit, and deteriorate the working conditions of the sucker rods. , increase its number of breaks. In order to eliminate these disadvantages, the balance weight is generally added to the tail or the crank of the pumping unit or both. In this way, in the lower stroke of the hanging point, the balance weight should be lifted from a low position to a high position to increase the potential energy of the counterweight. On the upstroke, the counterweight falls from a high position and releases the stored positional energy during the downstroke. This helps the motor to raise the sucker rod and the liquid column, reducing the amount of energy the motor needs to give in the upstroke. With the method of adding balance weights, there are two motor operating states and two generator operating states in one working cycle of the pumping unit. When the balance weight adjustment is good, both the generator operating time and the energy generated are small.
On the other hand, the impact current is a problem. The beam pumping unit is a deformed four-bar linkage. Its overall structure is like a balance. One end is a pumping load and the other is a balance weight load. For the bracket, if the torque formed by the pumping load and the balancing load is the same or changes in consistency, the pumping unit can be continuously and continuously operated with little power. When the balance rate is 100%, the power provided by the motor is only used to raise the weight of the 1/2 liquid column and overcome the friction. The lower the balance rate, the more power the motor needs to provide. Because the pumping load changes every moment, and the balance weight can not be completely consistent with the pumping load, the energy saving technology of the beam pumping unit becomes very complicated. Therefore, it can be said that the energy saving technology of the beam pumping unit is the balancing technology.
In addition to the above two issues, the special geographic environment of oilfield production determines the unique operating characteristics of oil extraction equipment: Large oil reserves and sufficient liquid supply in the early stage of oil well exploitation, and can be run at high frequency to ensure higher oil production efficiency. In the middle and late period, due to the reduction of oil reserves, it is easy to cause shortage of liquid supply. If the motor is still running at industrial frequency, it is bound to waste energy and cause unnecessary losses. In this case, the actual working conditions must be taken into consideration, and the motor speed should be properly reduced to reduce the stroke. Increase the filling rate.
The beam pumping unit has the following three main advantages after installing the frequency converter:
(1) Significantly increase the power factor (from the original 0.25-0.5 to 0.9 or more), reducing the power supply (appearance) current, thereby reducing the burden on the power grid and the transformer, reducing the line loss, can save a lot The "capacity" expenses, which are mainly concentrated on occasions where the power supply enterprises require high quality of the power grid, need to introduce variable frequency control in order to avoid the decline in the quality of the power grid. Its main purpose is to reduce the influence of the working process of the pumping unit on the power grid.
(2) Realizing energy saving: On the one hand, according to the actual fluid supply capacity of oil wells, the extraction speed can be dynamically adjusted to achieve the purpose of energy saving, and at the same time, the output of crude oil can also be increased.
(3) Due to the realization of a true "soft start", excessive mechanical shocks are avoided for motors, gearboxes, and pumping units, greatly extending the life of the equipment. Reduce costs and increase production efficiency.
3, 7-height HD700 frequency changer plan 3.1, plan compositionUnder normal circumstances, the HD700 inverter controls the motor operation. When the inverter fails to stop, the inverter's electrical structure combined with the control cabinet will automatically cut the control status from the inverter to the industrial frequency to ensure that the pumping unit does not stop. At the same time, in the downstroke of the pumping unit, the frequency converter incorporates an external braking resistor to release the regenerative energy.
HD700 frequency converter and data acquisition telemeter communication connection, the motor operating conditions, current, torque and other data transmitted to the central control room.
3.2, terminal wiring diagramParameter ID
parameter name
Setting value
Note
P00.03
Start and stop control
1
P00.04
Frequency source
According to the system
P00.09
acceleration time
Set according to need
P00.10
deceleration time
Set according to need
P00.12
Keyboard initial value after power-on
Set according to need
P00.14
Rated current of motor
According to the motor nameplate setting
P00.16
Motor rated speed
According to the motor nameplate setting
P00.19
Motor power factor
According to the motor nameplate setting
3.4 Features of HD700 Inverter1, the input voltage range is wide, more able to adapt to the harsh oil grid.
2. The air duct is independent, and the bad environment has strong adaptability.
3, module margin design, overload ability.
4. All the core components use international famous brands, stable and reliable.
3.5 System FeaturesDuring the production process of the production well, the oil condition may change at any time, and the frequency converter can send the load condition to the control system for analysis and calculation in real time, so as to obtain reasonable rotational speed control. At the same time, according to the oil production index of the oil production plant, the oil production worker can change the output frequency on his own or on a regular basis, which meets the two-in-one function of manual and automatic control, which not only saves electric energy, but also saves manpower and material resources.
Guangzhou Chengwen Photoelectric Technology co.,ltd , https://www.cwleddisplay.com