The oilfield water injection stations mostly adopts traditional water well borehole pump as water injection pumps. The water is supplied to a large storage tank at first, and then to the water injection pump by a feed pump. At last, the water is injected into the stratum by the water injection pump. Mostly, the injection pump motors are large power motors (110, 185kW) and the outlet pressure of injection pump is adjusted by regulating the valve. Operators could observe the pressure of the pressure gauge to adjust valve at any time, but the rated speed of pump motor remains basically the same, by which, a lot of power is wasted. There are many water pumps in the pipe network and the process is very complicated, which not only wastes energy, but also increases the labor intensity of the operators. Stepless speed regulation of water pump motor could be realized by using inverter constant-pressure water-supply control system, and automatically adjust the operation parameters according to the water injection pressure, remaining a constant pressure of pipe networks when the water consumption changes, to meet water injection demand. The frequency control system is an advanced and reasonable energy-saving water supply system, which is greatly developed in practical applications. With the rapid development of electricity and electronic technology, the function of inverter is becoming more and more powerful. It makes a great significance for the application of constant-pressure variable-frequency water supply system to make full use of various functions of inverter.
2. Process Requirements
The working principle of equipment control system：
The pressure feedback signal of water supply network is collected by the pressure transmitter. Then, with the A/D conversion module, the setting value and collection deviation signal are compared by the PID control at the same time, which performs data process according to the parameter setting of inverter and outputs the processing results in form of running frequency. There are comparison and difference function in the PID control module, and if the pressure of water supply network is lower than the setting value, inverter will increase the running frequency, otherwise will decrease it.
3. Solutions of VEICHI Products
In oilfield production, being similar with water injection pump, the rated displacement of oil pump is often greater than the actual required value, leading to a great waster of energy. On the one hand, if just the valve is used to adjust the oil displacement, once it changes rapidly, the valve will be adjusted frequently as well, increasing the labor intensity, and more personnel are needed. If the valve is improperly adjusted, it is easy to cause the pump to dry run or tank boil-overs. On the other hand, in order to ensure constant oil displacement, it is necessary to ensure constant pipe pressure. The opening of valve affects the pipe pressure directly, and too big or too small will not be allowed.
If you use VEICHI AC80C inverter, this problem can be completely solved. The PID algorithm in AC80C could precisely adjust the motor speed with pressure changing, to adjust the actual displacement of pump. Therefore, when the displacement is changed, the output frequency of inverter can also be adjusted to control the displacement, ensuring a constant pipe pressure. In this way, the efficiency of motor is greatly improved, and the loss and output power of motor can be effectively reduced, to achieve the purpose of energy saving.
The Oilfield water injection electric system could operate stably and reliably with VEICHI inverter, which gains good economic benefits for the enterprise. By actual production tests, customers are highly appreciated with VEICHI solutions, of which the advantages are as below:
1. Remarkable energy-saving effect, and impressive economic benefit;
2. With the automatic pressure control of closed-loop system, the operation is simple, and the frequent adjustment of valve is reduced, ensuring the stable production and the lightened labor intensity;
3. Because of the decrease of motor frequency, noise and vibration are greatly reduced, which improves the working environment, and avoids the waste of energy;.
4. Due to the decrease of equipment speed, the equipment works stably with less wear, extending the product life and overhaul cycle;
5. With the frequency speed control system, the water injection pressure is kept constantly, which on one hand maintains the underground pressure balance and promises the good displacement and high productivity; on the other hand protects oil well and oil-bearing, so as to achieve civilization mining to prolong life;
6. Adopt the soft starting mode of inverter, which greatly reduces the impact on power grid due to the large starting current of motor, and ensures the normal operation of power grid.