South Australia has a long history of petroleum exploration, extending back to 1866, when the first well was sunk adjacent to the Otway Basin in the search for oil. In the 1950s the early Palaeozoic sediments in the state’s NE were the focus of effort until gas was discovered in the overlying Permo Carboniferous section in the early 1960s (Cooper Basin). The Cooper and Eromanga basins, which span northeastern South Australia and South West Queensland, are now Australia’s largest onshore petroleum province. Over the last 40 years, exploration and development activity in South Australia has focused largely on this mature basin.

Gas and liquid pipelines throughout Australia are shown in Figure 1. Cooper Basin gas supplies markets in South Australia, New South Wales, Queensland and Victoria via an extensive pipeline network. The Cooper Basin Liquids Project (1980–84) was initiated to market the oil and existing gas liquids. A liquids pipeline links Moomba to a processing plant and storage and export loading facilities at Port Bonython. Oil and gas fields of the Cooper and Eromanga basins are shown in Figure 2.

The other basin in South Australia currently producing commercial hydrocarbons is the onshore Otway Basin, where gas was discovered in 1987. The Otway Basin remains a proven gas province, with potential on- and offshore oil plays in South Australia and Victoria, and in offshore Tasmanian waters. Large offshore gasfields were discovered in 2001 at Thylacine (Tasmania) and Geographe (Victoria), and in 2002 at Casino (Victoria).

Bona fide oil and gas shows have been recorded in the state’s early Palaeozoic basins, however, these remain underexplored by world standards.

Historical highlights of South Australia’s petroleum exploration history can be viewed here. 

A map showing petroleum and geothermal tenements in South Australia is given in Figure 3. More information on holders of petroleum and geothermal tenements in South Australia is given in the Earth Resources Information Sheet P1.

Cooper and Eromanga basins

Exploration and development in the South Australian part of the Cooper Basin have taken place in five distinct phases. The first followed the discovery of gas at Gidgealpa in 1963. By 1969 gas from the Cooper Basin was piped 790 km to Adelaide. The second was the A$1.4 billion ‘liquids scheme’ in the early 1980s following Eromanga Basin oil discoveries and their combined development with that of liquids from the wetter gasfields. The third phase, which began in 1982, was the accelerated search for gas to ensure supplies for South Australia into the 21st century. This phase was partially completed in 1991, and in 1992 a 10-year contract was signed to supply gas to South Australia.

The fourth phase saw a peak in oil and gas exploration in the Cooper–Eromanga area around the expiry of Petroleum Exploration Licences (PELs) 5 and 6 in February 1999, and to meet new market opportunities as the gas market became de-regulated. Santos undertook a three-year A$200m exploration program from 1996–98 prior to the expiry of PELs 5 and 6.

PIRSA held three releases of former PELs 5 and 6 acreage between 1998 and 2000, with a total of 27 new petroleum exploration licences offered. Cooper Basin petroleum acreage release results for 1998–2000 are given in the Earth Resources Information Sheet P7. The total expenditure contained in the winning bids over the first five years of the licences is forecast as A$201 million with a minimum of 103 exploration wells to be drilled. In November 2001 the first of the new licences were granted to the successful bidders in the CO98 acreage release following signing of a historic native title agreement.

In 2002 the fifth phase of exploration in the basin commenced when the new Cooper Basin entrants began exploration. Exploration levels continue to increase in the region with the conclusion in 2002–03 of a total of 27 access agreements for the CO98, CO99 and CO2000 acreage release areas. Another access agreement arose from the CO2003 release enabling grant of PEL 182 in 2005, with a further agreement expected in 2006 following the successful CO2005 acreage release in the Nappamerri Trough. Work programs for the two most recent releases include 21 exploration wells.

From 2002 to end December 2005, new entrants had participated in drilling 59 exploration, and 13 appraisal and development wells. The 25 new commercial fields are Acrasia, Aldinga, Arwon, Christies, Crocus, Derrilyn, Flax, Ginko, Harpoono, Hornet, Juniper, Kiana, Kiwi, Mirage, Nutmeg, Padulla, Paranta, Reg Sprigg West (operated by Santos), Sellicks, Smegsy, Stimpee, Teringie, Ventura, Worrior and Yarrow. The new entrants were 92% successful in their 13 appraisal and development wells.

Otway Basin

Exploration and development in the Otway Basin was spurred on by the discovery of gas at Katnook in 1987, and five gasfields now supply local markets. Two wells were drilled in the Otway Basin in late 2005. Cowrie 1 was drilled by Beach in PEL 27 and was plugged and abandoned in November. Wynn 2 was drilled by Origin in Petroleum Retention Licence (PRL) 1 and was cased and suspended. Economic oil discoveries remain elusive, although 21 wells have oil shows.

Construction of a new pipeline from Port Campbell in Victoria to Adelaide (SEA Gas Pipeline) has doubled gas supply capacity into South Australian gas markets. The pipeline was completed in November 2003 and is 690 km in length with a capacity of 140 PJ/y. The Prime Minister John Howard and South Australian Premier Mike Rann officially opened the pipeline in March 2004. This project has created more competition amongst gas wholesalers, and provides greater security of supply for South Australia.

Geothermal energy

The South Australian Government is leading Australia with expeditious and effective processing of activity approvals for geothermal energy. At end 2005, there was a total of 64 geothermal exploration licences and applications in South Australia (Figure 2, Geothermal energy in the ‘Prospectivity’ section) compared with only six geothermal licence applications for the remainder of Australia.

PACE

The Plan for Accelerating Exploration (PACE) is a five-year, A$22.5m project, with A$2m a year allocated for the collaborative drilling component — a total of A$10m over five years. In the first call in 2004, 47 proposals were received and 27 were granted funding totalling A$1.75m. In Round 2 early in 2005, nearly 70 proposals were received and 44 were granted funding totalling A$2.4m. Three geothermal submissions (Eden Energy Ltd, Petratherm Ltd and Scopenergy Ltd) were granted a total funding of A$191 000 under Round 2. Petratherm has completed its PACE program, whilst Scopenergy and Eden Energy are due to drill in early 2006.

In December 2005 the South Australian Government released the results of the collaborative drilling bids under Round 3. Nearly 80 proposals were submitted and $2m in grants were allocated to 35 companies. One petroleum and two geothermal bids were successful. Stuart Petroleum Ltd, Geothermal Resources Ltd and Green Rock Energy Ltd received funding of A$100 000, A$68 000 and A$100 000 respectively.