Beach said 38 wells had been drilled since the project started in September 2006 with an overall success rate of 76%.

This week Santos made three more oil discoveries – Naccowlah South-15, Gambero-1 and Mudlalee-4.

The Naccowlah South-15 well encountered oil in the Hutton Sandstone higher than expected, proving a significant extension to the field, Beach said.

At Gambero-1, a 12-metre oil column was encountered in the McKinlay Formation, while the Mudlalee-4 well found a 15m column at the top of the Hutton Sandstone, which also suggested an extension to the field.

“Preliminary estimates by Beach for its key interest [38.5%] in the Naccowlah Block in particular indicate that overall the program is on track with regard to reserves with flow rates expected to be better than predicted,” the company said.

“The successful wells are expected to be online in August.”

Beach increased its Naccowlah and other Cooper Basin entitlements when it became a partner in the Cooper Basin Joint Venture after last September paying $590 million for Delhi Petroleum's 21% interest in more than 200 oil fields.

The Cooper Oil Project is located in the southwest Queensland portion of the Cooper Basin.