The world's largest tension leg platform (TLP) was installed in the North Sea Snorre field in May 1992. The first of the six predrilled production wells came on stream in early August, more than one month ahead of schedule following the successful installation of the rigid riser system. The rigid riser system comprises one drilling riser, one export riser, one gas export riser and up to 36 production/injection risers. The paper aims to demonstrate the immense effort required in engineering, planning and organisation to ensure a successful final riser installation. It first describes the riser system, components and tools, followed by the background and operational considerations for the installation of these risers from the TLP to a template located on the sea bed. How the "installation requirements, limitations of handfing equipment and weather windows play an integral part of the riser design process are presented. The importance of a training programme and inshore tests are then emphasized, followed by discussions of operational experience from offshore installation and lessons learned.
The TLP is located at a water depth of 307m. The risers are installed from the TLP and connected to the wellheads and export pipelines located by the subsea template. There are altogether forty-four usable well slots, spaced 4m apart, in the wellbay and on the template The two export slots are 8m away from the nearest production well slot and are confined within an enclosure on the platform. The design and installation method for this riser system are essentially similar to those of previous TLPs, except that it is in a deeper location than Hutton and exposed to a harsher environment than Joliet Stringent Norwegian statutory regulations and post-Pipa Alpha fire protection requirements have also placed additional demands on the system.
