Griffin Decommissioning and Field Management
|Activity type||Decommissioning, dismantling or removing a facility|
|Activity subtypes||Any other petroleum-related activity|
|Submitted by||BHP Petroleum (Australia) Pty Ltd|
|Submission date||22 December, 2021|
|Status||Under assessment (with NOPSEMA)|
|Link to previously accepted EP|
Phone: 08 6321 2789
BHP Petroleum Pty Ltd (BHP) is planning for the safe and sustainable closure of the Griffin facilities, located in Production Licence WA-10-L off the coast of Western Australia, 65 km north-west of Onslow and 94 km north-east of Exmouth, in a water depth of approximately 130 m.
The Griffin Field comprises 12 former subsea oil production wells, which were permanently plugged in 2017, as well as associated subsea infrastructure, which has been flushed of hydrocarbons. A Gas Export Pipeline extends from the field through Commonwealth (pipeline licence WA-3-PL) and State waters (pipeline licence TPL/10) to the former onshore Griffin Gas Export Facility, south of Onslow.
Decommissioning of the Griffin Field is planned to be undertaken in stages under relevant Commonwealth and State Government approvals, with the first stage including the removal of flowlines, wellheads and subsea ancillary equipment from WA-10-L. These activities will be managed under this Griffin Decommissioning and Field Management Environment Plan (EP). This EP will also cover the removal of the wellhead of an exploration well in neighbouring title, WA-12-L, along with ongoing field management activities so all equipment is maintained in suitable condition so as not to preclude its removal.
The scope of the EP includes the removal of sixteen wellheads and guide bases, twelve xmas trees, the removal of the top riser turret (RTM) mooring, six RTM mooring lines, nine flexible production risers, (~ 47km) of flexible production flowlines, (~12km) rigid production spools and flow lines, twelve electrohydraulic umbilicals and flying leads, Pipeline end manifold, six mooring chains, four distribution skids and assorted mud mat structures (heat exchanger, 3 x Umbilical termination assemblies and electrical distribution units, choke skid, 17 x pyramid anode skids). During the removal activities the full removal of the RTM will be assessed and undertaken if practical.
Removal activities managed under this EP are planned to commence no sooner than Q4 2022, pending regulatory approvals, support vessel availability and weather constraints. The activities covered in the EP may occur at any time of year, with completion by the end of calendar year 2024.
The Gas Export Pipeline and remaining field equipment (Riser Turret Mooring - if not fully removed, piles, anchors, concrete gravity bases) will be subject to separate future environmental approvals.