Otway Basin

The Otway Basin is a major sedimentary onshore and offshore basin for oil and gas. The basin’s onshore section covers an area of 155,000 km2 between Geelong and Lucindale in South Australia.

Since the 1970s, exploration in the basin has resulted in numerous onshore and offshore gas discoveries. All of the commercially viable gas discoveries within the Victorian section of the basin have been in the Peterborough and Port Campbell areas.

Currently, natural gas is being produced from the basin’s offshore fields including Halladale, Blackwatch and Speculant, and stored in onshore underground depleted gas fields.

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Power stations

Mortlake Power Station

Origin Energy’s Mortlake Power Station is a 566 MW (megawatt) open cycle gas-fired power station that commenced operation in 2012. It is designed to generate electricity when demand is at its highest, and fuelled by natural gas via an 83 km pipeline from the Otway Gas Plant near Port Campbell. The power station site is 12 km west of Mortlake, adjacent to the Moorabool to Heywood 500kV high voltage transmission line.

In September 2020 Origin received approval to add a further four turbines which if constructed, would increase the plant’s generation capacity by up to 280 MW and enable it to supply base-load power.

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Gas pipelines

Moyne Shire is host to a system of pipelines that transport natural gas from wells to production and processing facilities such as the Otway Gas Plant, and for power generation at the Mortlake Power Station.

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Gas Extraction, Drilling and Exploration

Halladale, Blackwatch and Speculant Gas Project

Beach Energy’s Halladale, Blackwatch and Speculant Gas Project has developed several offshore natural gas reservoirs in the Otway Basin located around 6 km from the coast line. The reservoirs were accessed using conventional ‘extended reach’ drilling from the onshore well site located at Nirranda South in the south east of the Shire. The Halladale 1 and Speculant 1 and 2 wells produce raw gas that flows from the reservoirs to the Otway Gas Plant near Port Campbell via a 33km underground pipeline. Drilling of the Black Watch well was completed in 2020 and it will tie in to the existing well site infrastructure and pipeline.

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Cooper Energy

Cooper Energy extracts gas from four production wells installed between 2005 and 2009 in the Otway Basin.

The wells connect via a 55km pipeline to the onshore Athena Gas Plant near Port Campbell.

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In February 2023, ConocoPhillips Australia commenced preparation of an Environmental Plan to undertake an exploration drilling program within two of its tenements located in the Otway Basin, in Commonwealth waters off the coast of south west Victoria between Cape Otway and Port Fairy.

The Plan needs to be submitted to the offshore regulator, NOPSEMA, before any work can commence.

If NOPSEMA grants the permits, the initial activity will be seabed assessments which will commence no earlier than January 2024.

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