Chevron plans more work at its gas project off Australia

Chevron Australia, a subsidiary of the U.S. oil and gas giant Chevron, has handed an environment plan (EP) to Australia’s offshore regulator – on behalf of its Gorgon Joint Venture partners – for the installation of an additional control and electrical umbilical to the existing feed gas pipeline system at its natural gas project off the northwest coast of Western Australia.

The National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) confirmed that Chevron submitted this environment plan on 27 June 2022, proposing to install an additional control and electrical umbilical to the existing feed gas pipeline system that extends between the offshore Gorgon field and the facility on Barrow Island within the production licence WA-20-PL. The Gorgon gas development is expected to have a nominal operational design life of 50 years.

To support the reliability of the offshore gas gathering systems, Chevron has now submitted this EP, and a temporary power supply – e.g. via subsea batteries or a downline power cable – will be required during the transition from the use of the existing Gorgon umbilical to the additional control and electrical umbilical. If the power supply from the existing umbilical becomes unavailable prior to the commissioning of the additional control and electrical umbilical, a temporary power supply may also be utilised to maintain the electrical power supply.

This EP documents the assessment and management of potential environmental impacts and risks associated with the installation of the additional umbilical bundle and the supply of temporary power in Commonwealth waters. The scope of activities includes installation; inspection, maintenance and repairs; temporary power supply; and field support. The installation of the Gorgon umbilical is planned to occur from late 2023/early 2024 to mid-2024 and the total duration of activities is expected to be around 6 months.

The Gorgon gas field is located around 130 kilometres off the northwest coast of Western Australia and 65 kilometres northwest of Barrow Island in water depths of approximately 200 metres. The initial field development was commissioned in 2015, consisting of wells and subsea infrastructure, including the feed gas pipeline. This led to the first LNG cargo departing Barrow Island on 21 March 2016 while the domestic gas supply to the Western Australian market began in December 2016.

Chevron describes the Gorgon project as one of the world’s largest natural gas projects and the largest single resource project in Australia’s history. This project exports liquefied natural gas to customers across the Asia Pacific and produces domestic gas for the Western Australian market. 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.

Recently, The Gorgon field development was expanded by Gorgon stage 2 (GS2), which enriches the Gorgon and Jansz-Io gas fields with 11 additional wells and accompanying offshore production pipelines and subsea infrastructure to maintain future gas supply to the three existing LNG trains and the gas processing facilities on Barrow Island. 

The Chevron-operated Gorgon project is a joint venture between the Australian subsidiaries of Chevron (47.3 per cent), ExxonMobil (25 per cent), Shell (25 per cent), Osaka Gas (1.25 per cent), Tokyo Gas (1 per cent) and JERA (0.417 per cent).