BHP Petroleum has submitted an environment plan for the "safe and sustainable" closure of the Griffin Gas Export Pipeline, offshore W. Australia.
The Griffin Gas Export Pipeline is located within Pipeline Licence WA-3-PL, in Commonwealth waters, and extends from the pipeline end manifold (PLEM) in the Griffin field (WA-10-L) through WA State waters (Pipeline Licence TPL/10) to the shore, ~40 km south west of Onslow.
Water depths along the Griffin Gas Export Pipeline range from 130 m at the pipeline end manifold (PLEM) to 90 m at the State/Commonwealth waters boundary. The Griffin Gas Export Pipeline is currently pressurized with a nitrogen blanket.
The scope of the environment plan includes the pigging and cleaning of the pipeline to remove mercury contamination, conducting an as-left survey of the pipeline, and decommissioning the pipeline in situ in perpetuity. The scope also includes contingent pipeline removal activities should the mercury removal be unsuccessful.
Pipeline activities managed under the environment plan are planned to start no sooner than Q1 2023, pending regulatory approvals, support vessel availability, and weather constraints. The completion is expected by the end of the calendar year 2024.
The removal of the majority of the Griffin facilities (well heads, flowlines, subsea ancillary equipment) within the WA-10-L and WA-12-L licenses is subject to an environmental approval currently under assessment by the Australian offshore oil and gas safety regulator NOPSEMA, and remaining field equipment (Riser Turret Mooring - if not fully removed, piles, anchors, concrete gravity bases) will be subject to a separate future environmental approval.
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