Curlew B&D and Curlew C Decommissioning Programmes
Wednesday 20 June 2018
The Curlew cluster is located in Block 29/7 of the United Kingdom Continental Shelf (UKCS) in the central North Sea. It is situated 197 km SE of Aberdeen. The Curlew is a Floating Production, Storage and Offloading vessel (FPSO) located over the Curlew reservoir. The FPSO has equipment for oil and gas processing, storage and offloading, gas processing and export and treatment of produced water. Oil from the Curlew FPSO is exported onshore via shuttle tanker, while gas is exported from the Curlew FPSO to the St. Fergus Terminal via the Fulmar pipeline.
The Curlew FPSO was originally built at the Odense Steel Shipyard in Denmark as the tanker Maersk Dorset in 1983. In 1997, The tanker was converted at A&P Tyne on the River Tyne, while the fabrication, construction and installation of the topsides was carried out by AMEC. It was deployed in the Curlew Field in 1997, where it produced first oil that arose from the phased development of the subsea Curlew B-D fields.
There are 3 subsea tie-backs to the Curlew FPSO:
- Curlew B field produced from a single well;
- Curlew C field produces from a single well (re-uses the original Kyle dynamic riser) with gas lift and associated subsea structures;
- Curlew D field produces via two production lines from four wells tied back to a production manifold together and associated subsea structures;
Gas is exported to St Fergus via a connection to the Fulmar pipeline, with associated subsea structures.
The Kyle field was tied to the FPSO back until 2005, but is currently physically disconnected and is produced over a different host. Curlew C was brought online in 2008 as a tie back to the FPSO via a production and gas lift line. Curlew B field has been shut-in since 2007. Shell acquired ownership of the FPSO in 2013.
Shell requested Cessation of Production (CoP) on the Curlew fields including Floating Production Storage and Offloading (FPSO) facility in January 2016.
The Curlew fields are expected to reach their economic limit in Q1 2019 and there are no further developments or third-party tieback opportunities that could extend the field’s life. Approval from the Oil & Gas Authority (OGA) for cessation of production has been granted from 2016, should the Curlew FPSO become uneconomic (e.g. if a significant event such as well or equipment failure occurs from which economic recovery is not possible).
Shell has agreed a provisional draft of an Exchange of Correspondence (EoC) with BEIS in July 2017, which would be updated with specific details in the event it needed to be formally submitted, to remove the Curlew FPSO ahead of these DPs approval.
The programmes contained in this document set out the decommissioning plans for the fields.
The phasing of the decommissioning activities is as follows:
- Phase 1 – Curlew FPSO removal: Flushing of pipelines and facilities, disconnection of all lines from subsea trees, disconnection of the risers and mooring lines at the FPSO allowing sail-away at the earliest convenience.
- Later Phases
- Wells Plug & Abandonment (P&A)
- Removal of subsea infrastructure within all Curlew field areas in accordance with the approved Decommissioning Programme.
A guard vessel will be used for the duration between Phase 1 and the later phase of subsea infrastructure removal. These later phases will be finalised with trawler sweeps and as-left surveys, as required.