Riser Assembly and Umbilical Pull In - Katmai, US Gulf of Mexico

Conbit’s support in subsea system operations

The Katmai Field Development is located in the US Gulf of Mexico, approximately 25 miles southwest of the Tarantula Platform. Since Subsea7 needed support for the subsea system operations done from the platform, they contracted Conbit to assist.

Watch how we prepare and execute

Topview of Conbit's engineered solution to the riser assembly and umbilical pull-in

Scope

Fieldwood Energy Inc. planned to tie back the Katmai Field Development to the Tarantula Platform, surrounded by seawater 146m>. The award is for the deepwater Katmai Field Development in the US Gulf of Mexico’s Green Canyon 40. OneSubsea will provide subsea production systems (SPS). Subsea 7 will supply subsea umbilicals, riser, and flowline systems (SURF). They requested Conbit to support the subsea operations working from the platform.

The project work scope included the installation and operation of:

8” Production Riser assembly, comprising clamps and six sections
16” J-Tube assembly, comprising clamps and five sections
umbilical pull-in through the 16” J-Tube assembly

Riser and J-tube

To support the J-tube clamps and pipe segments alongside the platform jacket structure and the riser's subsea installation, Conbit provided several lift lines in the installation area. The installation procedure involved a handover from the Subsea7 Pegasus vessel crane to lift lines that Conbit provided. This is to position all the parts alongside the jacket.

Divers then finalized the installation procedures. The execution of the works took place in close coordination between vessel cranes, diving teams, ROV operations, and the daily platform operations.

Umbilical and winches

After installing the J-tube, the team changed the Conbit equipment setup to prepare for the umbilical pull-in. They positioned a winch and 25t capacity A-frame above the J-tube. Conbit used its modular A-frame equipment for this. Conbit used a total of five different winches with lift line capacities between 10-25t. The water depths required winch wires in 180-520m (600-1700 ft). To safeguard the lift operations and protect the umbilical against overstressing, Conbit's engineers continuously monitored the load and pay-in/pay-out of all the winches.