Long search goes on for the big gas or oil discovery in the South Australian southeast part of the Otway Basin
Beach Energy's drill for the Haselgrove 3 ST1 well in the South Australian southeast part of the Otway Basin shown in the map.
Main image courtesy Beach Energy; map courtesy Vintage Energy.
The discovery of carbon dioxide at Caroline1 well near Mount Gambier in 1966 (with commercial production from 1968) lifted the long-held gas and oil hopes for the South Australian section of the Otway Basin, stretching 500 kilometres long from Cape Jaffa in South Australia to northwest Tasmania.
The Otway Basin in South Australia’s southeast was its second most-explored region for oil and gas. Operating in 1881-83 near Alfred Flat on the Coorong by the Salt Creek, Petroleum Oil Prospecting Co. attempted the first systematic drill for oil in Australia. Further southeast, between 1912 and 1930, the South Australian Oil Exploration Co. drilled several shallow wells.
The Katnook gas field, south of Penola, discovered in 1987 by Ultramar, was the first commercial find in the South Australian part of the Otway Basin. Drilling confirmed sufficient reserves to justify a pipeline by Epic Energy to local markets in 1990. It was developed by SAGASCO (later Origin Energy) who bought Ultramar’s interests. Gas production started in 1991 from the Katnook gas plant and stopped in 2013.
Low-quality gas found in the Ladbroke Grove gas field was used commercially in electricity generation at the Ladbroke Grove Power Station at Monbulla, near Penola, next to the main electricity link between Adelaide and Victoria. Origin Energy saw an opportunity to make the Ladbroke Grove field commercial by using the gas to fire a 40MW power (later 80MW) station. Built in 1999, it began supplying power into the national electricity grid in January 2000 and later sourced gas from offshore Victorian fields via the SEA Gas pipeline.
Since the original discovery at Katnook, commercial quantities of gas were discovered in the neighbouring Haselgrove and Redman fields. Beach Energy discovered deeper gas reservoirs in the state government PACE (Plan for Accelerating Exploration) Gas co-funded Haselgrove 3 and a new gas field at PACE Gas co-funded Dombey 1.
Successful followup drilling at Haselgrove 4 and funding from the federal givernment’s Gas Acceleration Program enabled Beach to construct a gas plant at Katnook that supplied gas to local markets from 2020. Otway Energy and Vintage Energy discovered a gross carbon dioxide column of at least 90 metres in the top of the Pretty Hill Sandstone in Nangwarry 1 in 2019. The well was cased and suspended for further evaluation.
Commercial amounts of carbon dioxide, discovered at Caroline 1 petroleum exploration well in 1966, were produced from 1968 to 2017. Isotopic studies indicated the carbon dioxide came from a volcanic source. Caroline 1 ranked as the most productive well in South Australia (in value of product) with 810,842 tonnes of liquid carbon dioxide that was transported by road tanker to supply soft drink, firefighting, medical and other industry markets.
Otway Basin was relatively underexplored by international standards in 2021, with potential for more gas discoveries in the Penola Trough and the offshore areas of the basin.