In what is regarded as a major advance in subsea technology, cable specialist Nexans is to design and manufacture for BP’s America Production company the world’s first subsea service umbilical to integrate a high voltage supply line.

The $15 million, 26 km cable is to be installed in the Gulf of Mexico as part of a project to retrofit two existing subsea wells in BP’s King complex with multi-phase pumps.

Integration of the power cable and umbilical functions in a single unit will cost less and enable an HV (24 kV) supply to be provided in deep waters, which has not previously been possible.

The concept of integrating HV electrical power cables in a subsea umbilical is very challenging from both the mechanical and electrical design aspects, with electrical interference between conductors and inductive losses in the steel tubes of particular concern. An additional challenge is that the cable will operate at depths of over 1700 m.

The two King subsea sites are connected to the Marlin Tension Leg platform located approximately 135 km south east of New Orleans in block Viosca Knoll, at 988 m water depth.

The umbilical system for this project consists of a main dynamic and an infield umbilical to provide the necessary services to accommodate the two subsea well pumping systems. These services include high voltage (HV) electrical power, low voltage (LV) electrical power, fiber optic communications, and chemical injection and lube oil services.

The umbilical will be manufactured at Nexans’ plant in Halden, Norway, while the fibre optic element and LV cables will be delivered by Nexans factory in Rognan, Norway. The contract award is a part of a frame agreement with BP America Production Company which started in 2002 with the Thunder Horse and Atlantis projects.

Delivery is scheduled for the second half of 2006.