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Direct electrical heating (DEH) system offers an attractive method for flow assurance with the potential of reducing OPEX. The system gives the possibility for active hydrate and wax control by controlling thermal conditions inside the flowline.
Electrical current through the pipe wall
The principle behind a DEH system is to pass an electrical current through the pipe wall. By controlling the current, the pipeline inner wall will at all times be kept above the wax and hydrate formation temperature. As a result, problem free and reliable transportation will be achieved. Traditional methods for flow assurance, by use of chemical treatments and pressure evacuations, have considerable operational costs with long down time and may present a risk to the environment.
Flow assurance
Norwegian oil companies have since 1987 been investigating different electrical heating methods for flow assurance. Nexans has been involved in development of the alternative methods.
Eight fields and 17 flowlines
As a result of this work, direct electrical heating has at the time of writing been installed at seven different fields, and field number eight will be installed in 2010. Nexans has supplied the cables and subsea components for all eight projects.
Delivery to Åsgard, Huldra, Kristin, Udr, Tyrihans, Alve, Morvin for Statoil, and Skrav for BP. Altogether 17 flowlines are instelled with Nexans DEH systems. Delivery lengths between 6 and 44 km per flowline.
Works as expected
The experience from the installations is that the systems are working according to expectations. Similar systems are planned for other projects around the world.
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