"The Canterbury Basin is little-explored and is considered highly prospective," Associate Minister of Energy Harry Duynhoven said.
Recent exploration in the Basin has identified a new offshore prospect named Corvette, which is thought to contain approximately 1 trillion cubic feet of gas, 50 million barrels of condensate and significant volumes of liquid petroleum gases.
Other offshore prospects were identified in the 1970s and 1980s. The Galleon-1 well north of Dunedin tested 10 million cubic feet a day of gas and 2300 barrels a day of condensate, but was judged sub-economic at the time. The Clipper-1 well off Oamaru also had shows of gas and condensate.
"Geological understanding of the Basin, particularly of potential source rocks, has considerably improved since these earlier exploration efforts," Mr. Duynhoven said. "The basin has a proven petroleum system with excellent potential for both oil and gas, so I expect strong interest in this permit round."
The Canterbury Basin contains Mid-Cretaceous to Quaternary basin fill with sediment thickness over 6 km deep in places. This gives good comparable petroleum generation characteristics to most Late Cretaceous-Tertiary coaly sediments in the producing Taranaki Basin.
There are three main types of exploration plays in the Canterbury Basin. Two are associated with drape structures over basement horsts that formed during mid-Cretaceous normal faulting, which were targets for three of the four offshore wells, or with stratigraphic trapping beneath a Late Cretaceous unconformity. The third play is associated with faults and anticlines that have grown during Miocene to Recent time. Primary reservoir targets are Late Cretaceous or Eocene sandstones, with secondary targets of Oligocene limestones.
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