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Bass Basin

BASS BASIN (victoria)

The Bass Basin is located offshore between the southern tip of Victoria and the northern margin of Tasmania in the shallow waters of Bass Strait.

In the Bass Basin, Beach extracts natural gas from the Yolla field, transporting it to shore via a 147 kilometre subsea pipeline. There, it joins the 32km-long raw gas pipeline to the BassGas processing plant near Lang Lang in Victoria.

Once processed, the gas from the Lang Lang Gas Plant is sold to retailers who use it for domestic or commercial consumption in the East Coast natural gas market.


Construction of BassGas began in 2001.

Installation of offshore platform Yolla-A, drilling of Yolla-3 and Yolla-4 development wells, and the construction of an export pipeline and Lang Lang Gas Plant were completed in 2004. Gas production began in 2006.

Two additional production wells, Yolla-5 and Yolla-6, were drilled in 2015 and commenced production in August of that year.

The BassGas Operations Environment Plan is reviewed every five years. The current Environment Plan can be viewed here

Map of Bass-Gas sites

Yolla West & Trefoil Opportunity

Beach is progressing planning for the drilling of Yolla West in the first half of 2024 and will also update Trefoil, White Ibis and Bass resource estimates from the Prion 3D seismic survey – this will inform our development strategy for these opportunities.

The Trefoil discovery is close to existing infrastructure, located ~38km west of the Yolla production platform in Commonwealth waters.

Lang Lang Gas Plant Safety Case

The Lang Lang Gas Plant is licensed as a Major Hazard Facility in accordance with the Victorian Occupational Health and Safety Regulations and is required to have a Safety Case in place. The Safety Case is assessed by WorkSafe Victoria and provides the basis for the facility licensing decision. The document below presents a summary of the Lang Lang Gas Plant Safety Case and is provided to the local community and municipal councils in accordance with the requirements of the Victorian OH&S Regulations.




Beach owns and operates the BassGas Raw Gas Pipeline (PL243) and the BassGas Sales Pipeline (PL244) which flow the raw natural gas to the Lang Lang Gas Plant. To view information regarding Beach’s pipeline safety awareness, click the link below.


Bass Pakenham Pipeline


Yolla Platform, Bass Basin, Victoria

Trefoil Seabed Assessment

Beach is planning further development of the Bass offshore natural gas reserves within existing Commonwealth offshore exploration permits and production licences. Seabed assessments, including geotechnical and geophysical activities, are required to determine the suitable locations for drilling and installation of infrastructure to connect new production wells to the existing Yolla Platform.

Beach has carried out stakeholder consultation in the preparation of the Environment Plan for the seabed assessment activities. The accepted Environment Plan can be viewed at

The geophysical survey was completed in June 2020 and the geotechnical activities are expected to be completed before 31 December 2023. Beach will continue to engage stakeholders and provide advanced notice of the further activities once a commencement date is determined.

Download the information sheet below for further information.

The Trefoil Seabed Assessment

Suspended Wells – inspection and maintenance

Within Beach’s Bass Basin leases and licence there are three exploration wells: Trefoil-1; White Ibis-1 and Yolla-1. These wells are suspended and isolated from hydrocarbon zones, managed in accordance with a Wells Operation Management Plan to ensure well integrity, and planning is underway for their future decommissioning, a process called ‘plug and abandonment’.

Beach has carried out stakeholder consultation in the preparation of the Environment Plan for this activity.

Environment plan

Suspended Wells – inspection and maintenance information sheet

Prion Seismic Survey

Beach Energy carried out a three-dimensional (3D) marine seismic survey (the Prion Survey) to enable assessment of the natural gas reservoirs in Commonwealth offshore retention licenses (see map). The survey commenced on 11 November and was completed on 16 December 2021.

The Environment Plan (EP) for the Prion Survey was accepted by the National Offshore Petroleum Safety Management Authority (NOPSEMA) on 9 September 2021 and can be viewed here.


prion seismic survey INFO SHEET


Seismic Impact Research Studies

Beach is conducting biomass and impact assessment of potential new scallop beds in a small south-west part of the survey area, and has a fair compensation procedure in the event of a direct economic loss to a fisher due to the survey. See further information below.

Fair ocean access info sheet

Upon completion of the Prion Survey, Beach will be conducting a collaborative research project to trial emerging seismic survey technologies and at the same time, research the sound impacts to scallop and lobster from the new and traditional seismic sound sources. The marine species research will be carried out by leading Australian research institutions. See further information below.

Collaborative research project info sheet


To learn more about Beach’s operations in the Victorian Otway Basin, contact our Community Relations team:
Ph: 1800 797 011

For more information on the petroleum industry regulatory processes in Victoria please visit:


To register interest in tendering for key goods and services for the Trefoil program, please visit the following link:


Or contact:

Leanne Brennan
Ph. 0437 925 581