Re-routing a drilling rig’s high pressure gas vent in the North Sea

Drilling rig Ensco 122 and platform K14-FA-1, North Sea

As part of the interfacing of drilling rig (Ensco 122) with nodal gas platform (K14-FA-1) in the Dutch sector of the Southern North Sea, Pinnacle undertook significant works to re-route the main platform high pressure gas vent, as well as designing an interface for a 27m personnel gangway between the drilling rig and the production platform.

The re-routing necessitated designing a neoprene lined friction clamp to grab a 26” diameter vent pipe (with c50m additional height above the clamp position) and hold it on jacks. The pipe was then cut, the vent jacked up (c10mm) and a new ‘T’ spool installed and welded into position. The vent runs through a lattice mast which had to be released from the vent at key positions to avoid the jacks trying to ‘stretch’ the antenna as opposed to lifting the vent. The clamp and jacking frame was then used to lower the vent pipe back down onto the spool where it was welded into position.

Careful Planning
The work to install the clamp, jacking frame and jacks was all carried out on a live, flowing gas platform, therefore hot-works were prohibited. A carefully planned and scheduled window of time meant the platform was only shut down and depressurised to physically cut and weld the vent pipe.

The project also included designing pipe supports for flexible and fixed steel high velocity pipework between the platform and the driller, all located some 20m above the platform main deck on loadbearing scaffolding. Pinnacle designed as much construction work to happen before the driller arrived as possible, as the planned production shut down period needed to be strictly adhered to.

The costs involved with this project were vast. The shut-down imposed very large deferred revenues for the client and their partners as there are, also, several smaller platforms flowing through this nodal platform. Any delays would soon have become exceptionally expensive but Pinnacle completed everything correctly, first time and on time.