"We were expecting to start the well on April 24, but rig maintenance work will delay the drilling by about 10 days," company managing director Barry Smith said.
Orion had contracted rig operator Ensign Australia for Rig 20 to drill the well in PEL 6.
Willaroo-1 is targeting 40 million barrels of in-place oil resources in the Precipice Sandstone and 160 billion cubic feet of gas in-place in the Back Creek Formation.
The Willaroo prospect is immediately north of proven gas reserves near Narrabri in NSW.
Following Willaroo-1, the company's next well is planned to be Nyngynderry-1 in the Darling Basin in northwestern NSW, with drilling to begin using a higher capacity rig in late May or early June.
Orion, which floated on December 12, is a spin-off of all the conventional oil and gas assets formerly belonging to coal seam methane producer Eastern Star Gas.
