Platform slot recovery on the Beryl B Platform, North Sea

Aged connectors posed no problem for Claxton’s slot recovery team when we were deployed on Beryl B.

The Problem

A client wanted to recover a slot on the Beryl B platform in the North Sea, but a 20-in. tieback riser needed retrieving. However, there was concern regarding the structural integrity of the riser’s RS-type connectors, as a similar connector had failed during a slot recovery operation and resulted in a dropped riser.

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Slot recovery has proved to be a robust solution for operators looking to extend the life of their assets.

The Solution

Claxton developed a recovery method for the 20-in. riser that provided an efficient means of recovery and enhanced the riser’s integrity during retrieval. Additionally, we also supplied an equipment package to facilitate recovery.

We supplied a solution that involved running a new 1.3 3/8-in. casing string complete with a smart anchor packer inside the 20-in. tieback riser to enable dual-string recovery. The 13. 3/8-in. internal casing riser provided structural strength and integrity to 20-in. riser when the inflatable anchor package was energised.

Claxton supplied hot-tapping services to vent the pressure from the 20- × 13. 3/8-in. annuli tieback string to the rig’s choke manifold, and cold cutting equipment for simultaneous severance of the 20 and 13. 3/8-in. tieback risers directly below the 20-in. wellhead housing.

Drilling and pinning services were supplied to bore 4-in.-inside-diameter holes to anchor the 20-in. tieback riser to the new 13. 3/8-in. casing string. In addition, a hydraulically activated centralizing clamp was used to restrict and minimise pipe movement during the rig floor recovery, the severance of the dual riser string and the removal of the 20-in. riser-bolted centralizers. The centralizer clamp was set to drift the 20-in. LS Vetco connector 24-in. inside diameter and react onto 20-in.-outside-diameter pipe.

At rig floor level, the riser recovery was undertaken using Claxton drilling and pinning machines to bore through the 20- and 13. 3/8-in. casing strings.

Expandable-grip pin mandrels and load pins were used to secure the strings, and Claxton RAPIER™ bandsaws dressed with 20-in. pipe clamp insets were used to sever the 20- and 13. 3/8-in risers directly above the RS connector to allow for the conventional layout of the tieback strings.

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Claxton RAPIER™ casing bandsaws  and drilling and pinning equipment in action.

The Result

The slot was recovered as per the client’s brief and the 20-in. riser connectors did not fail during recovery.

Claxton has subsequently used similar equipment packages on several other conductor and slot recovery projects with great success.

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