An advanced variable-speed drive solution for pumps has helped an energy company in the U.S. cut electricity consumption by 20% and increase its oil production by as much as 226%.

To anyone driving in the western U.S. and Canada, beam or rod-lift pumps are a familiar sight. The pumps are a necessity of life for hydrocarbon producers, because inside most established wells, the pressure is too weak to lift the crude oil to the surface. Even when the pressure is high enough to bring fluids to the surface naturally, pump technologies known as “artificial lifts” are used to boost production.

Efficient production is critical to David Ellis of Noble Energy, an energy company based in Houston, Texas. This independent company, with an estimated 820 million barrels and assets totalling close to $12 billion at the year-end 2009, pride itself on innovation. And Ellis was happy to hear that Danfoss had an innovative idea that could cut the energy consumption for the artificial lifts used in his Oklahoma fields. The idea is an advanced VLT® variable-speed drive solution called Sensorless Artificial Lift Technology (SALT) and designed specifically for oil field applications.

Turning on savings
After having installed the SALT drives in his Oklahoma fields, Ellis says: “Because we can avoid the heavy amperage draw during restarts, we’ve been able to cut electric consumption about 20%. Across the board, I’m seeing oil production increases of 51% on the rod pumps and 187% and 226% on two wells with progressive cavity pumps. Add to that longer equipment life and lower electric consumption, and I’d say that Danfoss’ sensorless artificial lift solution is really worth the salt.”

The typical beam pump is driven by an electric motor with fixed speed and voltage – so they are either on or off. To avoid starts and stops, variable-speed-drive solutions are sometimes applied to slow the pump down to match the well’s low productivity. But most drives have to be configured in a panel with an interface and pump-off controller board connected to an array of pressure and temperature sensors – a complex approach that still doesn’t respond adequately to pump conditions.

Unlike standard pump-off controllers, SALT uses an integrated interface and a powerful algorithm that reduces the pump speed, maintaining and maximizing production while reducing energy consumption. The system doesn’t need any sensors to monitor changes. It just looks at the motor’s load characteristics, understands the conditions the pump is facing and makes the appropriate adjustments automatically.

Quick and easy to install
Initially, Ellis heard about the Danfoss solution from his distributor, Randy Butler from Wilson, an industry-leading provider of pipes, valves and valve automation, fittings, and artificial lift systems. Butler explains that besides improving pump performance, the SALT system made installation easy. “I can cut external sensors, load cells, position indicators and pump cards. That’s why the SALT system installs in a quarter of the time required for traditional pump-off controllers. Plus, reduced electricity consumption means smaller motors and transformers can be used. It’s really a great solution for increasing efficiency and productivity.”