Deepwater Development Using Novel Diverless Flowline Connection Technology
Authors: Møllerop Frank , Adamek F.C. , Sellen Peter 
Published: October 2008

The Statfjord Satellites, Statfjord Nerd and Statfjord Øst, are two smaller fields located in the vicinity of the Statfjord C' platform in the North Sea. Each satellite has two production templates and one water injection template, Water injection, methanol, production pipelines and control umbilicals will hook up the templates to the platform, 17 and 7 km away from Statfjord Nerd and Øst fields respectively. Statoil has, on behalf of the owners of Statfjord Nord and Statfjord Øst. developed the fields.

This document describes the method developed especially for utilization in the Statfjord Satellite Project (SSP) for connecting flexible and rigid pipes in up to 300 meter deep waters without diver assistance. The purpose of this paper is to convey an understanding of the connection tool named Flange Up Tool (FUT), the pipeline coupling, and the associated offshore installation experience.

BACKGROUND

The pipeline system includes flexible and rigid pipes, 12"-310 BAR for water injection, 9" -240 BAR for production, 2 ½"- 345 BAR for methanol injection, The Statfjord Satellites' flexible pipe system can be divided in the following three types;Flexible jumpers and risers at Statfjord C platformFlexible tails at the templatesIntertemplate flexibles

The original concept for connection of flexible and rigid pipes was based on a standard four bolt clamp of the Grayloc® type, Both flexible and rigid pipes are terminated with standard Grayloc® hubs. In this context, the connection was to be performed on the surface as there was no diverless tool and use of divers beyond 180 meters is not general practice.

As a result of a water depth of 300 meters. the SSP pipeline project team started investigating the possibility of a complete diverless technology, both as an installation method for tie-in of rigid and flexible pipes, as well as a system for future repair/replacement of the flexible pipe.

The pipeline installation contractor AIIseas Marine Contractors s.a. subcontracted the installation and tie-in of flexible pipes, including design and fabrication of the FUT, to Stolt Comex Seaway A/S. The Statfjord Satellite Project awarded the contract for design and fabrication of the diver-less connector/coupling, to be used with the FUT, to ABB Vetco Gray, The Statfjord Satellite Project, Stolt Comex Seaway A/S and ABB Vetco Gray jointly developed this technology in 1992 and 1993.

The technology utilized in this project also gives an important contribution to the ability to develop cost efficient methods for fields located in water depths much greater than 300 meters.

DESIGN REQUIREMENTS CONNECTOR

The remotely operated connector conforms to the following customer requested and situation necessitated requirementsThe connector must comply with existing hub profiles on the installed pipelines (sizes of 2 ½", 9". and 12"),The flow line seal must be metal-to- metal and based on proven technology.The connector, with the aid of a tool, must be capable of being installed, tested, and retrieved without using divers.Due to the high cost of vessel time. the installation and retrieval must be as simple and reliable as possible.