Buchan and Hannay
The Buchan fields spans blocks 20/5a and 21/1 and is located c. 154km northeast of Aberdeen and c. 103km from the UK/Norwegian median line in a water depth of c.115m. The field was discovered in 1974 and first oil was achieved in May 1981.
In total, 12 wells have been drilled in the Buchan field: seven production wells; two appraisal wells: one exploration well and two water injection wells. The nine wells with trees present are shut-in and the flow lines have been disconnected. Four of the seven production wells are drilled at the Buchan template; and one production well is drilled next to it. The remaining two production wells and the two water injection wells are located c. 2 km to the west and southwest of the Buchan template and are tied back to the template.
The Hannay field spans block 20/5c and was discovered in 1996 and commenced production in 2002. The field is located c. 13.5km northwest of the Buchan template in water depth of c. 123m.The Hannay field comprises two production wells which are currently shut-in and disconnected from the flowlines.
The fields were produced via the floating production unit (FPU), Buchan Alpha. Processed hydrocarbons were transported to the Forties Charlie platform via a c. 56.3km export line. The Buchan Alpha FPU was taken off station in August 2017 and transferred to the Shetland Isles for recycling. The flexible risers remained in situ over the mid-water arch until post Buchan Alpha off-station and were subsequently recovered in 2019.
Repsol Resources UK Limited has submitted, for the consideration of the Secretary of State for Business, Energy and Industrial Strategy, four (4) draft Combined Decommissioning Programmes for the for the installations and subsea infrastructure associated with the Buchan & Hannay fields in accordance with the provisions of the Petroleum Act 1998.
The items/facilities covered by the Decommissioning Programme(s) are:
- Sub-structures (jackets/FPSO etc): Buchan Alpha Floating Production Unit (FPU) has been removed and transferred to onshore recycling facility
- Subsea Installations: will be completely removed and transferred onshore for recycling in accordance with the waste management hierarchy. Where piles exist, these will be cut to -3m below seabed
- Pipelines, Flowlines and Umbilicals: trenched and buried pipelines will be decommissioned in situ, with remediation of any exposed sections. Surface laid lines, spools, jumpers and any associated deposits will be recovered and returned to onshore for recycling in accordance with the waste management hierarchy.
- Wells: all wells will be plugged and abandoned to Repsol Resources UK Limited standards which comply with 'Offshore Installations and Wells (Design and Construction, etc.) Regulations 1996' and align with Oil & Gas UK Well Decommissioning Guidelines.
- Drill Cuttings: have been determined to be below the oil loss and footprint persistence set by OSPAR and will be left to degrade naturally.