Optimizing Plunger Lift with an Electric Actuator

Case Study: Does an Electric Actuator Make Sense?

Electric actuators make production operations when pneumatics are involved more efficient. We were invited to a well site to determine if the Kimray R2L would work effectively on a conventional plunger set up.

The field in question relies entirely on pneumatics. They use supply gas to actuate several valves at a time. Stainless steel tubing (usually 3/8”) is used to pull gas off of a scrubber bottle upstream of a regulator. This gas is used to run the Kimray actuator and the solenoid valve. The solenoid valve receives the signal from the ABB box and motherboard, telling it to send supply gas to the actuator.

A Kimray team examines a conventional plunger lift to determine whether it's suitable for an Electric Actuator.The actuator itself is the valve that controls flow from the well. It continually opens and closes to stop or start a plunger cycle. The figure to the left shows the components of a typical plunger set up.

The issue with this set up is that it relies on a steady supply of dry gas to run the pneumatics. Considering the fact that the plunger is (hopefully!) bringing liquid to surface, there is always the chance that the supply gas stream is not as dry as needed.

 

Issues for Operators

Operators encounter issues when the regulator of the valve are running off a potentially wet gas stream.

Condensate in the gas stream can cause o-rings in a valve to swell up around the piston that regulates flow.

When this occurs, the piston is no longer able to move along its axis, and thus the valve is no longer functional. Operators can sand the o-ring to fix it temporarily, but this is a Band-Aid solution and does not address the root of the problem.

• A wet gas stream can also cause the diaphragm to blow.

When this happens, the valve cannot hold pressure to keep it shut. It cannot properly regulate the actuator to cycle the plunger. Operators diagnose this problem by hearing gas constantly vent out of the valve.

Solenoid valves were prevalent throughout the field. Approximately one third of the wells in the field used plunger or intermitter as their form of artificial lift. By utilizing battery power instead of pneumatics, the electric actuator (in theory) would have significantly fewer operational issues by eliminating the use of solenoid valves to regulate flow. The end goal is to have operators spend more time optimizing plunger cycles and less time fixing faulty surface equipment.

How Does an Electric Actuator Work?

To address the issues that come with using pneumatics, operations trialed the R2L. They sound great in theory, but how do they work?

The photos below show the R2L in the office with the actuator casing off so you can see the internal components, including the card, gears, and backup battery. The R2L uses the same valve body as the conventional pneumatic actuator and has a universal power input (24/115/230AC & 12/24DC). It comes with a battery backup that can be manually overridden.

The table below shows key characteristics of the actuator.

Once the cycles started looking promising, Kimray allowed the client to test the R2L with the option to purchase. The R2L operated with few hiccups upon installation February. The company purchased the unit in May! The results have been exciting and display the potential these actuators have for future implementation on a larger scale.

Results and Benefits of the Electric Actuator

The R2L electric actuator has proven to be a success. There are three main benefits to using the electric actuator over conventional pneumatic equipment:

  1. The primary motivation is to increase efficiency. This is done by reducing the amount of time operators have to spend fixing solenoid valves and replacing top works on the actuator.
  2. There is a significant cost savings opportunity. While the electric actuator is more expensive upfront than pneumatic equipment, not having to continually buy replacement kits or new solenoids presents an opportunity to save approximately $1,200 per year.
  3. The battery voltage of the electric actuator consistently stays between 12.7 and 14 volts. This allows for more efficient operation and energy conservation. The battery charges during the day and gets down to about 12.7 volts at night.

The field operates more reliably thanks to the added efficiency of the electric actuator. While the R2L is not the least expensive piece of equipment, it provides excellent ROI in this field. Going forward the company will see considerable benefits.

Dell Bishop serves as a Product Manager at Kimray, and is responsible for Kimray’s line of electric actuators and control products. He collaborates with Kimray’s engineering, manufacturing, and quality teams to optimize the performance of our products and make a difference for our customers.