简体中文
Qinghai Oilfield is located on the northwestern edge of the Qaidam Basin, surrounded by the Kunlun Mountains, the Qilian Mountains, and the Altyn Mountains. The basin covers an area of 250,000 square kilometers, with a sedimentary area of 120,000 square kilometers. The basin is rich in mineral resources, and its oil and natural gas exploration potential is enormous, with very promising prospects for development and utilization. The oil and gas resources of the Qaidam Basin are estimated at 4.65 billion tons of oil equivalent, including 2.15 billion tons of crude oil resources and 25,000 billion cubic meters of natural gas resources, making it one of the important inland oil and gas exploration areas in China.
The oil production plants in the oilfield use beam pumping units. Such equipment is a major electricity consumer in oil production facilities, accounting for about 40% of the oilfield’s total electricity consumption, while the overall efficiency is very low, generally around 30%.
The starting torque of the oilfield pumping unit is 3 to 4 times the actual load. When the motor is selected according to the starting torque, the operating load power is far lower than the motor’s rated power, resulting in the so-called “a big horse pulling a small cart” situation. In addition, excessive pumping capacity increases the time of reactive power draw, causing high electricity costs in Qinghai Oilfield’s production operations and serious energy waste.
With more than 40 years of technical accumulation in motors and drive systems, Wolong Electric has provided a mature solution for the pumping unit electrical system in oilfields: the WD200 inverter plus the WD230 energy feedback unit. This solution addresses the key pain points of low efficiency, low power factor, and high energy consumption in oilfield pumping units.
Qinghai Oilfield Beam Pumping Unit System
System structure: It consists of the horsehead, polished rod hanger, walking beam, balance weight, reducer, motor, and electrical control system.
Working principle: The rotation of the motor is converted through the gearbox and crank-link mechanism into the up-and-down movement of the horsehead. Through the polished rod and sucker rod, the horsehead drives the plunger of the downhole oil pump to move up and down, continuously lifting crude oil from the wellbore.
Main drive system characteristics: unstable load, large fluctuations, and high starting torque.
System Principle
The energy feedback unit adopts PWM-controlled IGBT rectifier technology to manage energy regeneration, solving the regenerative energy problem that occurs when the load drops rapidly or the system stops. It features four-quadrant operation. It can meet the speed regulation requirements of various potential-load applications and convert the motor’s regenerative energy into electrical energy fed back to the grid. This further improves energy-saving efficiency, reduces harmonic pollution on the power supply, improves the power factor, and reduces the supply current, thereby easing the burden on the grid and transformer, lowering line losses, and eliminating the need for substantial capacity expansion costs.
On-site Operation Photos
 |  |
| Operating Test Data | Power Parameter Curve |
The left chart shows the power parameter curve on the customer’s monitoring system. It displays the current, voltage, and power curves during one stroke cycle. Compared with power-frequency operation, the input current and reactive power during variable-frequency operation are significantly reduced, improving the power factor and thus lowering the energy consumption of the pumping unit.
At power-frequency operation At variable-frequency operation
Power Quality Test During Energy Feedback
The figures above show the harmonic and power factor test data during energy feedback operation. The current harmonics are below 5%, and the power factor is close to 1. This can significantly reduce harmonic pollution on the power supply, improve the power factor, and reduce the supply current, thereby easing the burden on the grid and transformer. It further lowers the energy consumption of the pumping unit and provides Qinghai Oilfield production plants with a reliable and energy-saving solution.
Customer Benefits
Direct benefits:
According to the Qinghai Oilfield test report, after adopting the variable-frequency plus energy feedback solution, the average comprehensive energy-saving rate of the pumping unit system is about 26%. Based on a single unit, for example, if a 45 kW motor consumes 200 kWh per day, the annual electricity savings would be 18,980 kWh. At 0.8 RMB per kWh, the annual electricity cost savings would be 15,184 RMB, delivering very significant energy-saving results.
At present, China’s power grid implements a penalty system for power factor. If a user’s power factor cannot reach 0.9, they may face penalties from the power supply company. Under power-frequency operation, Qinghai Oilfield’s power factor is only about 0.2, and for some well sites, the annual penalty can reach 30,000 to 40,000 RMB. After using the variable-frequency system, the power factor increased from 0.23 to 0.95, allowing Qinghai Oilfield production plants to save this expense.
Indirect benefits:
For low-yield wells, intermittent operation may cause sand jamming accidents. Using a variable-frequency solution allows 24-hour low-frequency operation, helping avoid sand jamming incidents. A sand jamming repair operation takes about 5 to 7 days. Based on a daily liquid production of 10 tons (with oil content calculated at 30%), that equals 3 tons of crude oil per day. 3 tons × 5 days = 15 tons of crude oil.
Variable-frequency starting increases the motor speed gradually, reducing impact on the belt and mechanical parts of the pumping unit, and lowering the frequency of belt pulley replacement. The fastest replacement operation for a single well takes about 1 hour, which affects 1 hour of output. At 0.5 ton × 3,000 RMB, and with 5 to 10 replacements per year, the annual direct economic loss is about 7,500 to 15,000 RMB. Using the inverter control system can maximize recovery of this loss.
