Origin Energy of Australia said that the Speculant-1 exploration well spudded on 23 September.
The well is being drilled using the rig Ensign 931.
The Speculant-1 well is situated approximately 3km off the Great Ocean Road in Nirranda South, about 30km south east of Warrnambool, Victoria.
Extended reach drilling technology is being employed to access offshore gas reservoirs, Origin said in a statement on Tuesday.
Prognosed total measured depth of the well is approximately 3,800 metres.