NZ's isolation adds to oil spill dangers

New Zealand's isolation makes it particularly vulnerable to a Gulf of Mexico-style oil spill, marine pollution experts say.

Maritime New Zealand pollution response operations manager Neil Rowarth said that, although containment, dispersal and cleanup processes were in place for a spill, the only way to shut off the undersea geysers was to ship in a new platform and siphon off the oil.

In the Gulf of Mexico, where there are more than 3800 oil and gas platforms, towing in a relief operation was relatively easy, even though oil was still escaping two months after the April 20 sinking of the Deepwater Horizon.

In New Zealand, where there are just seven platforms, help could take longer to arrive, with potential rescue platforms a long distance off, Mr Rowarth said.

A similar leak at Montara oil field, in the Timor Sea, last year took 79 days to shut off.

In New Zealand, a similar spill would have different characteristics. Oil platforms here are in shallower waters but deep-water exploration has started off the east coast. Cold waters around the country would stop the oil from spreading as readily as it did in warm waters and the oil could form a wax that had different cleanup demands.

Two of Mr Rowarth's colleagues, Scott Read and Dayne Maxwell, have recently returned from the Gulf of Mexico. They described fighting an ever-shifting menace that disappeared and reappeared along the Gulf Coast's white-sand beaches.

Mr Read said that, because the oil was emanating from the seafloor 1500 metres below the surface, it was surfacing in different areas each day. Much of the oil was being contained at the source but the slicks reaching the shore were making landfall in localised areas.

Rather than an ever-expanding sea of oil, the slick emerged in plumes and extended arms in different directions according to weather conditions.

Mr Read said that, although there was clearly a large quantity of oil involved, its appearance was sporadic. "On some days it was a 10 to 15-mile-long (16-24km) slick ... some days it was hard to see."

Mr Maxwell was based in the response command centre in Mobile, Alabama, for 21 days. Although the oil spill was having an environmental impact, it needed to be put in perspective, he said. There was natural oil seepage into the Gulf and the water area was very large.