from the commonwealth v WMC case notes
It may well be that if, after the discovery of petroleum, an exploration permit were extinguished or modified with the consequence that the right to apply for a lease or production licence was destroyed or otherwise negated, that would constitute an acquisition for the purposes of
s 51(xxxi) of the
Constitution. In that situation, some benefit with respect to that petroleum would accrue to the Commonwealth or, perhaps, to the authority charged with the grant of leases and production licences. And that would also be the case if an exploration permit were modified or extinguished with the consequence that the holder of a permit were denied a lease or production licence to which it was otherwise entitled.
www.austlii.edu.au/cgi-bin/sinodisp/au/cases/cth/HCA/1998/8.html?query="acquisition of property"