ESPs - avoid ground faults

Friday, February 24, 2012

Zenith Oilfield Technology has launched a technology to help operators of Electrical Submersible Pumps (ESPs) avoid ground fault problems.

Ground faults occur when some of the electric current to run the pump leaks from the cable due to a break in the insulation, and the system is shorted.

This means that the data stream from the pump, which provides information about the status of the pump, sent through the same cable, is interrupted.

Zenith's technology "Ground Fault Immune," has a new power and communication system which means that if there is an insulation break on the main cable, the system is not shorted and the data communications can continue.

Therefore the monitor will continue to run as long as the ESP cable is operational.

Zenith says that over 15 per cent of downhole monitoring systems are affected by ground faults.

Zenith designs, assembles and supports high-spec technology related to the gathering and analysis of downhole data and the design of completions equipment.

'All too often in ESP operations a ground fault will cause downhole monitoring systems to fail and leave operators running blind. While the ESP will still be running," says Dave Shanks, Development Manager at Zenith.

"The interference in data transmission means that pressure, fluid levels and temperature readings are unobtainable.

"Operators are then faced with running motors at lower pumping rates to keep motor temperatures in safe operating areas, and also with a larger head of fluid to make sure the pump does not pump off.

"This can result in up to 25% reduction in fluid output compared to a pump optimised with a live down hole gauge, resulting in a significant loss of production.

The technology has been put through demonstration tests in the Middle East and will be installed in trial wells later this year.

In the demonstration test, on a medium sized ESP, 3 different types of fault were applied to the cable system, and the ESP monitoring gauge remained operational.

The system can operate at 125°C and at pressures of up to 5,000 psi. Logging data at 0.5 seconds per reading.