Big quake fails to stop Texan oil giant

06:59, Oct 01 2011

Seismic testing for oil and gas in the Canterbury Basin was approved by the Economic Development Ministry (MED) just over four hours after the February 22 earthquake.

Papers released to The Press under the Official Information Act show that Texan oil giant Anadarko, which has two permits to undertake deep-water drilling for oil and gas in the area, went ahead with its seismic survey off Banks Peninsula on February 23.

Anadarko is a 50-50 partner in the exploration venture with Origin Energy and part- owner of the well at the centre of the environmentally disastrous oil spill in the Gulf of Mexico last year.

It was scheduled to begin drilling in the Canterbury Basin next month or surrender its permits, but it applied successfully for a permit extension. Drilling will now start in October next year.

The magnitude-6.3 quake was centred near Lyttelton at 12.51pm on February 22.

At 5.28pm, MED Crown minerals geologist David Witkowski sent an email to Bruce Morris, of BDM Consulting, and British-based Simon Robinson, Anadarko's seismic acquisition specialist, saying Anadarko's application to begin seismic data acquisition in the "afternoon or evening of February 23" should not be hindered by the quake.

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New Zealand Anadarko spokesman Alan Seay confirmed the Singaporean vessel MV Aquila Explorer began its seismic-data acquisition on February 23 in the two permit areas and over an adjacent non-permit area.

Witkowski said he had been "firmly directed from the top" not to comment.

Ministry spokeswoman Tracy Dillimore confirmed the application for seismic line tails should have been approved on February 22, but was not officially signed off until February 28.

Seay said seismic acquisition of data took place "more or less continuously 24 hours a day" between February 23 and March 28. During this time Canterbury experienced a swarm of about 2000 quakes, 655 of which ranged in magnitude from 2.8 to 5.9.

Seay said methods used for the seismic-acquisition work on behalf of Anadarko included an array of "24 airguns".

The impulses created by the release of air from arrays of up to 24 airguns create low- frequency sound waves powerful enough to penetrate up to 40 kilometres below the sea floor. Known as reflection seismology, specialised equipment on the vessel captures geological information beneath the seabed that is analysed for potential hydrocarbons.

Scientists worldwide are divided over whether seismic testing for oil and gas can trigger seismic activity, with most believing it not possible.

Canterbury University geologist Mark Quigley said seismic testing for oil and gas caused "no real static stress change". "I would say it's almost certainly not linked to earthquakes, even when explosives are used," he said.

Seay said Anadarko was seeking natural gas in the Canterbury Basin and the company believed it had a "solid environmental history".

The Press