ARTICLES

Steel Flying Leads - Past, Present and Future

RE Smith View Supplier Profile

Originally printed in: Exploration & Production: The Oil & Gas Review - 2004

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Phase 1

To understand where the flying lead industry is today in the Gulf of Mexico (GoM), one needs to understand where it has been. Deep Down Inc. (DDI) was formed on 17 April 1997 just after the Shell Mensa campaign as Shell formed a management team to concentrate their umbilical efforts with a single team responsible for all GoM umbilical projects.

The umbilical team consisted of a core group of Shell and contract engineers, the controls supplier PM and DDI. Shortly after the team was formed, Shell switched controls suppliers from Kvaerner (FSSL) to FMC (KOS). The team worked with FMC to develop a new distribution system that would be reliable, easy to install and easy to maintain. Early in the game, DDI asked Shell if they would be interested in a steel flying lead concept soon to become known as the SFL. Steel was now used in the platform plumbing, the umbilical, the umbilical termination assemblies (UTAs), and the subsea tree, and it was time to minimise the use of hose flying leads (HFL) and maximise reliability of the distribution system.

Shell agreed to allow DDI to work with the umbilical team members to develop and qualify a workable steel tube flying lead solution. A concept was developed to allow the following:

• the remotely controlled vehicle (ROV) to fit up to the J-plate (via standard torque bucket);
• no bending of the SFL – it would depart horizontal to the seabed;
• it would need buoyancy to hold the J-plate out of the mud and to keep it in a weight range that the ROV could handle;
• a compliant section was needed between the J- plate bracket and the umbilical to allow for easier engagement;
• the termination (bracket) needed to connect easily to the SFL umbilical; and
• a righting moment was needed to reduce torsional effects imposed by the SFL.

The ‘Cobra’ was born – so named because it would resemble a striking cobra bobbing off the seafloor with its buoyancy. A bracket was developed to give the J-plate the height to allow the ROV to fit in behind but so that when it was flying the flying lead, the lead would trail underneath. The qualification programme began with a parking lot test in 1998 which combined four main elements.

• It demonstrated the new flying lead deployment system conceived by the team, which simplified the manufacturing process because it spooled up the flying lead material on a basket. The basket could be shipped easily and used for the installation. A basket was selected because it could be changed out quickly on a powered drive system, the terminations would not be subjected to the centrifugal effects of slinging around a vertical reel and the flying leads could be removed from the baskets and placed on pallets or the ground.
• A conventional j-plate connection was placed on one end where the umbilical would be required to be bent at an angle of 90º to make the connection.
• The other end had the cobra where the centre of gravity (CG) was below the j-plate as the umbilical weight was hanging below the plate. Buoyancy at the top of the cobra gave a positive righting moment.
• The mass of the ROV was transfered to the end of the Cobra to assist in the close-end manoeuvering of the J-plate for the connection – the flying lead orientation tool (FLOT) was conceived. Shell’s ROV consultants worked with Oceaneering for the development of the tool. This tool would reduce the effects of the stiffness, trim and torsional effects of the SFL.

The test was viewed as a success by the umbilical team even though some of the development project team members still felt SFLs were impossible to install. There was definite memory in the helicallywound and jacketed umbilical as it was spooled around the 8ft diameter drum. The first SFL prototype was the spare Shell Popeye umbilical with six 1/2” inside diameter (ID) super duplex tubes around one 1/2” ID tube. The umbilical sprung above the ground like sea serpents, but the Cobra connection was a success – the other end where the umbilical had to be bent was completely unmanageable, and the basket was very helpful in handling the product. The memory was going to have to be addressed. The following day, the sea serpents were half the height off the ground. The next day, it was laying flat on the ground. DDI added a five-ton caterpillar unit and a straightener to the installation kit. The thinking was that the straightener may not be necessary if the tension on the umbilical would allow the tubes to move and relax inside the extruded jacket.

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