Slot recovery on the Beryl B Platform, North Sea
Claxton developed a novel method to recover a potentially challenging tieback riser – resulting in a successful recovery.
The Problem
A client wanted to recover a slot on the Beryl B platform in the North Sea. To achieve this, a 20” tieback riser needed to be recovered.
However there was some concern regarding the structural integrity of the 20” riser. Similar RS type connectors had failed during another operator's slot recovery operation - resulting in a dropped riser.
Claxton developed a recovery method for the 20” riser which provided an efficient means of recovery and enhanced the integrity of the connectors. Additionally an equipment package was supplied by Claxton to facilitate the recovery.
The Solution
Claxton supplied a solution that involved running a new 13.3/8” Casing string complete with a smart anchor packer inside of the 20” tieback riser to enable a 'dual string' recovery.
The 13.3/8” internal casing riser provided structural strength and integrity to the 20” riser when the inflatable anchor package was energised.
Claxton supplied hot tapping services to vent pressure from the 20” x 13.3/8” Annuli tieback string to the Rig's choke manifold and cold cutting equipment for simultaneous severance of the 20” and 13.3/8” tieback risers directly below the 20” wellhead housing.
A Claxton Positive Grip tension ring was installed over the 20” tieback riser with heavy-duty work-slings providing a no-weld method for picking up the 20” Casing string to verify tieback disconnection.
Drilling & Pinning services were supplied to bore 4” ID holes to Anchor the 20” tieback riser to the new 13.3/8” Casing string. In addition, a hydraulically-activated centralizing clamp was used to restrict and minimise pipe movement during the rig floor recovery, severance of the dual riser string and removal of the 20” riser bolted centralizers. The centralizer clamp was set to drift the 20” LS Vetco connector 24” ID and react on to 20” OD pipe.
At rig floor level, the riser recovery was undertaken using Claxton Drilling & Pinning machines to bore through the 20” and 13.3/8” Casing Strings. Expandable Grip Pin Mandrels and load pins were used to secure the strings and our Rapier Bandsaws, supplied with 20” pipe clamp inserts were used to sever the 20” and 13.3/8” Risers directly above RS Connector allowing for conventional layout of tieback strings.
The Result
The slot was recovered as per the client’s brief and the 20” riser connectors did not fail during the recovery. Claxton has subsequently used similar equipment packages on a number of other conductor and slot recovery projects with great success.