Case Study

Invertek Drives has supplied its Optidrive P2 variable frequency drives to a number of oil field beam pumping projects in China, reducing energy consumption by more than 10 per cent.

Optidrive P2s are being used to control the pumping rate on beam pumps in the Qinghai oil field energy saving retrofit project. Qinghai oilfield is located in the Qinghai plateau, Qaidam Basin. Founded in 1955, it was one of the earliest oil fields to be established after the founding of the People’s Republic of China (PRC). Located at an altitude of 2,600 – 3,000 meters, it is the highest oil field in the world. The surrounding natural environment is extremely challenging, so a key requirement for the project was to achieve a high level of reliability from the drives.

Dr YongKui Man, CEO at Invertek Drives China Ltd, explains why the customer chose Invertek: “Optidrive P2 was chosen for this project because the user recognised the benefits arising from its superior performance, unique motor control and strong reliability. This is particularly important in harsh environments such as Qinghai.”

Dr Man, who is also a Professor of Electrical Machines and Drives at Northeastern University in Shenyang, said: “The advanced performance, features and functionality of Optidrive P2 offers excellent motor control capabilities with easy to program, flexible parameters and technology that is so sophisticated it can run in open loop without the need for position sensors, inefficient dynamic braking resistors or complex regeneration systems normally associated with this type of application. The system is simple to install and free from DC bus voltage fluctuations and voltage surge problems.”

The customer in the Qinghai project had previous experience of using Invertek’s variable speed drives and trusted the P2 to deliver significant energy and maintenance savings - so far thirty-eight Optidrive P2s have been installed at Qinghai and have run smoothly since December 2012.

Invertek Drives Technical Manager, Kes Beech, said: “The volume of oil which can be extracted from any oil well will vary depending on the underground conditions and the age of the well.

"The P2 can detect the slightest changes and will adjust the speed of the pumping cycle accordingly, thereby optimising pumping output and energy efficiency. The P2 can also maintain the motor torque within pre-set maximum and minimum limits ensuring that the beam pump can be operated smoothly throughout each cycle reducing mechanical stress and saving energy on a per cycle basis.

“The P2 enclosure is also rated to IP55, making it the perfect self-contained product for this type of application.”

Regenerated energy is stored within the mechanical system as kinetic energy during the pumping stroke and reused later, when required. This approach provides a reduction in the maximum motor current of 40% during normal operation of the counterbalanced pump, whilst also reducing the starting current and can result in the average running current being reduced by more than 10 per cent.

Dr Man, said: “Using Optidrive P2 drives also ensured that the site was ‘future proof’ thanks to the inbuilt PLC function which provides opportunities to develop bespoke beam pump operating functions in the future. A further consideration for our customer was the access to DC Bus terminals; in the future this may allow some of the operating power to be developed from Photovoltaic sources – again, this is particularly important in energy efficiency projects such as Qinghai.”

Invertek Drives has a long history of supplying variable speed drives to oil field applications in China and many other countries around the world including Canada, Brazil, and Venezuela.

• Short-term benefits: P2 offers cycle by cycle variation in speed resulting in energy savings of up to 10 per cent

• Long-term benefits: Optidrive P2 has the ability to vary the overall speed of a pumping system in line with the changing characteristics of a particular oil well to maximise pumping output and optimise energy usage. P2’s smooth operation also reduces mechanical stress and hence the need for maintenance