The certification by consulting company Gaffney, Cline and Associates (GCA) reported a best estimated recoverable contingent resource for the Judith field of 193.7 billion cubic feet of gas.

GCA also found a 290m gross gas column and 135.5m of net pay at the Judith-1 well.

Judith-1 was drilled by Shell in 1989, but not production tested or appraised.

Bass said a key factor in its decision for appraisal planning was that a significant portion of prospective resource volume was found near Judith-1, in either deeper sands not penetrated by the original well or in adjacent fault blocks.

"This suggests the potential for an appraisal drilling program near Judith-1 could notionally address a combination of contingent and prospective resources, with a best estimate value on the order of 300 billion cubic feet," the company said.

"Importantly, such an appraisal program could also potentially target a combined high estimate resource volume of over 1000 billion cubic feet."

Bass added the timing of any potential drilling at Judith depends on further appraisal studies and planning, the availability of drilling slots and on the progress of funding.

The Judith gas discovery is 22km east of Nexus Energy's Longtom gas field, where Nexus is planning first gas from its development in April next year.

Bass Strait is operator of VIC/P47 and has 40%. Moby Oil and Gas holds 35% and Eagle Bay Resources has 25%.