New Zealand Crown Minerals offered six exploration blocks in the Northland basin northwest of Auckland and two off East Cape in the Raukumara basin off the North Island. The bidding round will close in January 2010.
The Northland blocks cover 3,900-11,000 sq km each. Three are on the shelf, and three are adjacent in intermediate to deep water.
The Waka Nui-1 well changed the understanding of the sequences of the region with Jurassic sediments being intersected, while the Karewa-1 well intersected significant, but as yet noncommercial, biogenic methane in the Neogene sediments, Crown Minerals noted. Recent satellite radar imaging highlighted a large number of potential offshore oil seeps indicative of the presence of an active petroleum system.
Numerous potential reservoir facies include transgressive coastal sands and conglomerates of Cretaceous and Paleogene ages and turbidite sands of Neogene age.
Origin Energy Ltd. and OMV AG are exploring in the permitted southern part of the basin and have shot 2D and 3D seismic in the link area to the northern part of the Taranaki basin.
The two Raukumara blocks cover 9,907 and 7,381 sq km. The unexplored Raukumara basin is at the northern end of the East Coast basin.
Satellite radar imaging indicates a number of potential oil seeps, which along with many large high-amplitude direct hydrocarbon indicators on seismic suggest that a petroleum system operates in the basin.
Unlike most of the East Coast, the Raukumara basin is a relatively undeformed depocenter that occupies a marine plain that extends north-northeast from the northern coast of the Raukumara Peninsula. The 25,000 sq km depocenter extends 300 km north and is 100 km wide, bounded to the east by the East Cape subduction ridge and to the west by the Kermadec ridge.
Water is more than 3,000 m deep at the northern end of the basin.
Two recent industry standard seismic surveys reveal more than 11 km of sediment in three megasequences.
As the basin has not been drilled, the stratigraphy has been correlated to the onshore geology.
