Chevron Australia, on behalf of the Gorgon Joint Venture, operates the Gorgon Project (Gorgon) in Western Australia. Gorgon comprises offshore production wells and pipeline infrastructure that gathers natural gas from the Jansz–Io and Gorgon gas fields and transports it to a facility on Barrow Island for processing.

To maintain gas supply to the facility on Barrow Island and to sustain current gas production rates, Chevron Australia plans to install a subsea compression station and associated infrastructure in the Jansz–Io gas fields. Chevron Australia has developed the Gorgon Gas Development Pipeline and Subsea Infrastructure Installation and Pre-Commissioning Environment Plan (EP) to account for the installation activities.

Revision 6.0 of the EP was accepted by the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) in May 2024. Following acceptance of the EP, Chevron Australia installed suction pile moorings, mudmats and foundations and a manifold structure at the end of 2024 and beginning of 2025.

All installation activities under the EP were scheduled to be completed by mid-2026, however due to a change in the timing of the installation schedule, activities are now expected to continue into 2027 – with the subsea compression station infrastructure now planned to be installed in two separate campaigns rather than one. The methodology for installation of infrastructure has not changed. The latest schedule, vessel requirements and proposed durations of activities have also been reviewed. Therefore, the EP has been revised to account for the changed in installation schedule.

Infrastructure to be installed under the EP includes:

- Subsea compression station and associated spools
- A normally unattended, floating field control station anchored to the seabed by 12 mooring lines
- An umbilical to supply power from Barrow Island to the field control station, and power cables, known as flying leads, from the field control station to the subsea compression station
- An umbilical to transmit power and communications between the field control station and the existing Jansz CDU
- Pipeline crossings and rock stabilisation as required.

The Jansz–Io gas fields are located within production licences WA‐36‐L, WA‐39‐L and WA‐40‐L, approximately 200 kilometres off the northwest coast of Western Australia in water depths of approximately 1,350 metres. The Jansz feed gas pipeline is licensed by WA-19-PL, which extends from the State/Commonwealth waters boundary to the north west of Barrow Island, out to the Jansz–Io gas fields.

The EP documents the assessment and management of potential environmental impacts and risks associated with the installation of the subsea compression station and associated infrastructure in Commonwealth waters.

The scope of activities includes:

- Installation
- Inspection, maintenance and repairs
- Pre-commissioning
- Field support.

Installation activities commenced at the end of 2024 and will continue in 2025 under the provisions of the in force Revision 6.0 of the EP. Installation activities are expected to be completed mid-2027. Table 3-2 in the EP provides indicative durations and a potential timing window within which the planned activities are expected to be undertaken. These durations and timings are indicative and subject to potential delays caused by weather events, vessel, infrastructure and/or equipment availability, regulatory approvals, and other unforeseen factors. Therefore, while the specific activities and indicative timings and durations are described in Table 3-2, the petroleum activity may occur at any time over the 5-year in-force period of this EP.