Application of FGI FD5000 Medium Voltage Drive in Oilfield Water Injection Pump
1.Overview
Water injection is a powerful measure to maintain efficient and stable production in the middle term. The method is to restore or even increase the formation pressure by using water injection, so that the formation fluid pressure is greater than the static liquid pressure in the wellbore, so as to achieve the purpose of the oil and gas production. Because oilfield each block water injection often adjust with the change of mining conditions, oilfield water injection generally used plunger pump, mainly by adjusting the pump return, in the traditional way, in order to meet the demand, most of the injection station rated flow and the actual flow mismatch (general rated flow is greater than the actual flow), and the rated speed of the injection pump motor basically remains unchanged, make the plunger, valve core, filler, combination valve accessories for a long time, various parts wear and damage frequency is very high, the overall operation process is complex, high labor intensity, bring inconvenience to production. In addition, most of the injection pump motors used in the oil field are high-power motors, which are running in a high energy consumption state for a long time. It is a very effective energy saving measure to adjust the variable speed of the oil field injection pump motor and realize the variable water control of the injection pump.
2.Implementation plans
This load is opposed large-flow reciprocating plunger pump. The plunger pump structure adopts opposite pistons on both sides, and five pistons are distributed on one side. Double pipelines inject water into the underground to suppress the respective output pipelines to realize the utilization rate of the equipment. Before starting, first open the circulation valve, reduce the water pressure to reduce the starting current, and then wait for the pump to run at full speed and then close the circulation valve, the pressure of the output pipeline drives the output check valve to open, the pressure rises to the required pressure, the water to the underground several thousand meters.
Frequency conversion transformation control scheme
Fig. 3-3 Main loop of system modification
The main circuit is shown in Figure 3-3, where K1, K1 ', K2 and K2' are high voltage isolation knives, electromagnetic interlock between K1 and K1 ', and electromagnetic interlock between K2 and K2'. KM5 is 7 # motor power frequency contactor and KM6 is 5 # motor.7 # motor power frequency contactor KM5 and KM3 contactor are interlocked, and 5 # motor power frequency contactor KM6 and KM4 contactor are interlocked. KM1 and KM2 are used for the current limiting resistance switch, and KM1 is in the suction state during normal operation.
For 7 # motor, K1, K2 and KM3 are closed, K2, K2, K 2 and KM4 are disconnected, and KM5 is disconnected. After frequency conversion, the internal program KM2 will automatically absorb the current limiting resistance into the main loop to eliminate the large current impact. After 3s, KM1 absorbs, KM2 is disconnected after 1s, and the frequency converter is in standby state and can be put into operation according to the situation. After the frequency conversion start, the power frequency / frequency conversion hand automatic conversion knob is hit to the automatic position. After the motor speed reaches 50Hz, press the power frequency button to automatically break the KM3 contactor, and then automatically absorb the KM5 contactor to automatically switch to the power frequency operation, and realize the soft start control of 7 # plunger pump. Similarly, the 5 # motor flexible start operation control process is similar.
During normal operation, the 5 # and 7 # plunger pump units have one power frequency and one frequency conversion operation, and the 5 # and 7 # plunger pump units can realize the power frequency and frequency conversion operation state. When selecting the variable frequency operation of 5 # plunger pump and 7 # plunger pump, the FD5000 medium voltage drive first drags 5 # frequency conversion soft start and turn the knob to the automatic position after the frequency conversion start. After the motor speed reaches 50Hz, the frequency converter transfers the 5 # motor to power frequency operation; then drag the frequency conversion start of 7 # plunger pump, control the pump operation and adjust the pressure through the frequency of the pressure converter. You can also start the 7 # motor first and then automatically switch to the power frequency operation, and then start the frequency conversion operation of the 5 # motor, so as to realize the control function of one tow and two frequency converter.
When the FD5000 medium voltage drive fails, the plunger water pump will automatically transfer to the power frequency operation to ensure the normal water injection in the oil field.
3.Application advantage
There are many water injection systems in the oil field. Through the use of frequency conversion device, it not only saves electric energy, improve the automatic operation degree of the system, reduce the wear and tear of the equipment, but also automatically adjust the speed according to the demand, reduce the labor intensity of personnel, and the operation parameters of the injection pump are improved, and the system efficiency is greatly improved. As a high and new technology and energy saving technology, frequency conversion speed regulation technology has been widely used in the industrial production of enterprises and people's common life. With the further maturity of its technology, it will bring a more positive role in energy saving and consumption reduction in oil production plants and oil fields.
