In deepwater conditions, hydrates may form and plug production lines. There are currently two ways to avoid hydrates. First, insulate sufficiently the subsea system to prevent effluents from reaching a too low temperature in case of production shut down. This solution works for a limited amount of time. Second, inject methanol in production jumpers at a high flow rate in order to inhibit the reaction. This high flow rate has a direct impact on umbilicals size.
A third way, efficient for both prevention and dissociation of hydrates, is the electrical heating of production jumpers. For usual values of insulation this system does not require any additional power. It can be supplied by electrical lines in umbilicals, only a connector on a SUT and a flying lead are needed.
Two tests were performed by Doris Engineering and EMC3: one consisted in dissociation of hydrate plugs by electrical heating and the other was a full scale underwater qualification test on an insulated well jumper. Results proved efficiency and reliability of the heating and temperature-controlled system.
Electrical heating provides solutions for future deepwater developments that will reduce methanol and topsides requirements and give flexibility in the operational hydrate prevention strategy.
Doris Engineering is based in Paris, France. www.doris-engineering.com
