There remains one further wildcat well and the Cliff Head 4 appraisal well to be drilled in the current offshore campaign.

Mentelle initially sparked a flurry in the listed partners when the initial shows were reported, but operator Roc Oil's dampening of expectations (on Friday) unfortunately proved correct.

The partners said they had established the hydrocarbon shows reported on 14th February were residual and immovable and, as such, were of no commercial significance. The well is now in the process of being plugged and abandoned, an ASX report said.

While the result has disappointed the partners and the market, the presence of some oil in three of the P&A'd offshore Perth Basin wildcats (Livet - an early well, Morangie and Mentelle), validates the geological model of an active hydrocarbon source rock fuelling the western edge of the Perth Basin.

"Mentelle is disappointing but there's something down there, without a doubt," said Voyager exploration director, Ray Barnes. "We just have to find a valid trap."

All the partners' shares slumped in early morning trade with juniors Norwest and Voyager being the hardest hit.

The Ensco-53 jack up drilling rig will now move to drill the Vindara 1 exploration well on the boundary between WA-286-P and TP/15. It is targetting a 15-30 million barrel prospect.