Thialf vessel set to embark on removal campaign offshore Ireland

Ireland-based PSE Kinsale Energy, a Petronas subsidiary, is preparing to kick off its platform removal campaign for the Kinsale Head gas field, located in the Celtic Sea, in late May. These decommissioning activities will be carried out by Heerema Marine Contractors’ second largest semi-submersible crane vessel (SSCV), Thialf.

After 42 years of production, PSE Kinsale Energy ceased gas production at the Kinsale area gas fields in July 2020 due to depleting reserves. The Stena Drilling-owned Stena Spey rig was used last year as part of the Kinsale area decommissioning campaign. The campaign started in mid-April 2021 following the arrival of the rig. In October 2021, the rig was set to head to its final location as part of this campaign, which was expected to run through to November 2021.

Located some 50 kilometres offshore in the Celtic Sea, the Kinsale field consists of two steel platforms, which were installed as part of the initial field development, commissioned in 1978.

According to a recent marine notice from the Irish Department of Transport, PSE Kinsale Energy confirmed that the Kinsale Head platform removal campaign would start in late May 2022 and run through to September 2022.

The planned activities will be carried out off the South Coast of Ireland at various locations with three areas of operation, encompassing the Alpha platform in Block 49/16, the Bravo platform in Block 48/20 – both located in the Celtic Sea – and a nearshore backloading location, near Old Head of Kinsale. PSE Kinsale Energy intends to deploy a weather-monitoring buoy – a wave-rider buoy – between the two platforms for the duration of the incoming works.

The semi-submersible, self-propelled crane vessel Thialf has been selected to perform this part of the Kinsale area decommissioning project. The scope of work includes the removal of both platforms, which will be removed in a number of sections and backloaded to cargo barges. Afterwards, the backloading of the removed components on cargo barges is planned at the offshore location but may be performed at a nearshore backloading location depending on environmental conditions.

Initially, the upper sections (topsides) of the platforms will be removed, followed by the lower sections (jackets). Once this has been done, they will be transported to a dismantling yard in Vlissingen in the Netherlands for disassembly. PSE Kinsale Energy also plans to remove all equipment from the Inch onshore terminal in 2022 and undertake additional work offshore to install protective rock covering over exposed ends of the pipelines and umbilicals which will be left in situ.

The planned decommissioning activities will involve several vessels. While the campaign will be conducted by the 1985-built Thialf semi-submersible crane unit, two Heerema’s anchor handling vessels – MV Kolga and the MW Bylgia – will accompany it throughout the entire campaign, towing cargo barges H-541, H-407 and H-542.

In addition, the 2015-built crew transfer vessel Merel-G will be used for the transfer of crew between the vessels and shore throughout all operations.

As informed recently by Heerema, the Thialf vessel was working on hook-down and removal activities for the Dunlin Alpha platform.