GNS Science says that seismic and satellite data show that the Reinga Basin, off the northwest coast of the North Island, is one of the most prospective frontier basins in the New Zealand region.

In a report commissioned by the Crown Minerals division of the Ministry of Economic Development, GNS said this view was based partly on 5,000 km of high quality two-dimensional seismic reflection data acquired in 2009 by Crown Minerals in partnership with petroleum services company CGGVeritas.

Other components in the investigation were satellite data of sea surface slicks and knowledge of the geology in the adjacent Northland and Taranaki Basins.

The analysis shows that Reinga Basin contains potentially oil-bearing sedimentary rocks that are up to 7 km thick and it has all the elements needed for a working petroleum system. Its rock sequences are similar to those in the Taranaki Basin.

Lead author of the report, Vaughan Stagpoole, said a reconnaissance seismic survey in the 1990s indicated the area was potentially prospective for oil and gas. This prompted a follow-up seismic survey in 2009 done to oil industry standards.

"When we examined the 2009 seismic data, there was clear evidence of petroleum expulsion zones, which means there is an active petroleum system in the basin," Dr. Stagpoole said.

The geology in the 150,000 square km Reinga Basin is less complex than the adjacent Northland Basin, making it more attractive to explore.

However, it is further from land and in slightly deeper water -- typically between 1,700 m and 2,000 m -- which can be a challenge for explorers.

Early in 2010 the government opened bidding for blocks in the Reinga Basin. The blocks offer will close in August, at the same time as a blocks offer closes for the adjacent Northland Basin. Permit-holders are likely to be announced in late 2010.

The Reinga Basin prospectivity report, the latest in series of such reports on New Zealand frontier basins prepared by GNS Science, is being used by Crown Minerals to help promote Reinga Basin to exploration companies internationally.

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