Tasman's depths hide rich promise

By CHRIS DANIELS

A major seismic survey has found "very promising" early signs that big deposits of oil lie under the deep ocean waters off the Taranaki coast.

The signs were found in an ambitious deep water seismic survey conducted this year.

Senior geophysicist at the Institute of Geological and Nuclear Sciences, Chris Uruski, revealed the findings at a geological conference in Melbourne yesterday.

He said the survey showed good evidence of potentially large oil reserves below the seabed in very deep water in the Tasman Sea.

Developments in drilling technology mean that oil in such deep water can be extracted and many oil companies are now focusing on such prospects.

A smaller survey was done in 1997 and when the data from that was analysed it revealed what the Institute of Geological and Nuclear Sciences described as "a surprisingly thick" sedimentary section under the deep water.

These sediments, deposited between 65 and 144 million years ago, form a layer at least 5000m thick that comes from an ancient river delta.

Mr Uruski, one of the proponents of the survey effort, said similar ancient deltas in other parts of the world, including one in Indonesia, had turned up significant amounts of oil.

"We're at a pretty early stage with it at the moment, so I am only able to show the preliminary results.

"But there's nothing I've seen so far which has downgraded the basin at all, in fact it's looking very promising as a prospective region."

"We are at an early stage of confirming it, but at this stage it's looking really good."

The executive officer of the Petroleum Exploration Association of New Zealand, Dr Mike Patrick, said that the positive findings of the latest survey were fantastic news for the local oil industry.

Most of the new big oil fields were now being discovered in deep sea areas such as near Timor, the Gulf of Mexico, the North Atlantic and off the west coast of Africa.

"We tend to know an awful lot about what is happening on land," said Dr Patrick.

"The technology to drill in deep water has advanced astronomically in the past five years."

Pipelines were no longer needed to be laid on the seabed to transport the oil to land.

Instead, production units floated over the wells and were able to load tankers at sea.

New drilling ships with powerful positioning motors could sit over drilling sites, even in rough weather.

This year's seismic survey was able to gather information from under the seabed in water depths ranging from 200m to 1800m over an area of 59,340 sq km, equivalent to more than half the size of the North Island.

The survey was described by the Institute of Geological and Nuclear Sciences as New Zealand's "first large-scale marine reconnaissance seismic survey targeting oil prospectivity for more than 20 years."

Norwegian company TGS-NOPEC, which helped run the survey, and the institute own all the data that has been gathered.

Oil companies will be required to pay a fee to them to study the survey's results.

These companies will then apply to the Crown for the right to start drilling for oil in the parts of the ocean where they think oil is likely to be found.

Because only the very large oil companies have the money and expertise to undertake such deep sea drilling projects, a marketing programme is underway to attract their interest in the prospects.