In 2009 petroleum titles WA-36-L, WA-37-L, WA-38-L, WA-39-L, and WA-40-L were transferred to the Gorgon Joint Venturers, and Chevron Australia Pty Ltd (CAPL) became the nominated titleholder. Some of these titles included legacy appraisal wells that had previously been managed by West Australian Petroleum (WAPET), CAPL and other titleholders. All wells were plugged and abandoned, with wellheads left in situ during well abandonment by the previous operators. CAPL propose to leave the wellheads permanently in situ.

A Decommissioning Options Assessment was performed for the wellheads which compared removal of the wellheads to leaving them in situ. The assessment found that the leave in situ decommissioning option was preferred as it delivers equal or better environmental outcomes, eliminates any potential cultural heritage risks by minimising seabed disturbance and delivers better health and safety outcomes.

The defined petroleum activity for this Environment Plan comprises of leaving the wellheads in-situ in perpetuity. No further operations or works are required.

This Environment Plan covers the impacts and risks associated with the wellheads remaining in situ. This Environment Plan has been prepared in accordance with the requirements of the Commonwealth Offshore Petroleum and Greenhouse Gas Storage Act 2006 and Offshore Petroleum and Greenhouse Gas Storage (Environment) Regulations 2009 as administered and for regulatory acceptance by NOPSEMA. The activity will be considered complete upon acceptance of the Environment Plan from NOPSEMA.