Woodside Petroleum has confirmed it was behind an oil spill off the coast of Western Australia that was kept secret by the regulator for more than a year.
The company said on Friday that it reported a leak from a well in the Cossack field on the North West Shelf to the National Offshore Petroleum Safety and Environmental Management Authority (Nopsema) in April 2016.
The revelation of Woodside’s spill came two days after it won an “environment excellence award” from the peak oil and gas lobby for the second year running.
The first public mention was a reference to a 10,500-litre spill in the regulator’s annual offshore performance report this week, Guardian Australia reported on Thursday.
But the report did not say when the spill took place or who was responsible.
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The company has not referred to the spill in any of its Australian Stock Exchange announcements since its discovery.
When pressed by Guardian Australia, Nopsema had revealed the leak went on for two months, at a rate of about 175 litres – equivalent to a bathtub’s capacity - a day.
Woodside said that because the leak from the CK4 well was “80% water” and 80m below the sea surface, it had “no lasting impact to the environment”.
The secrecy around Woodside’s spill contrasted with the federal regulator’s public alert around a smaller oil spill in February at an ExxonMobil platform in the Bass Strait.
A Nopsema spokesman had said the regulator had “an implied duty of confidence” not to disclose companies that reported leaks.
But an offshore oil safety expert and a Greenpeace campaigner had said the secrecy was concerning and not justified.
A spokeswoman for Woodside said the leak was believed to have taken place while all wells in the Cossack field were shut so drilling platforms could undergo routine maintenance from February to April 2016.
“Throughout this period, work continued in the field and no surface sheen was observed at any time,” she said.
The spokeswoman said the leak was a result of “a seal degrading on a subsea hydraulic valve control line”, which was isolated to stop the leak shortly after it was discovered.
She said the company reported to Nopsema “the maximum possible fluid loss from this line”, which was 175 litres a day for 60 days.
“We further reported that the fluid leaking was a mixture of hydraulic fluids, produced water and oil from the CK4 well,” she said.
“The CK4 well producing characteristics were approximately 80% water at the time of this leak. On completion of Nopsema’s investigation they determined that no additional enforcement action was required.
“Due to the composition of the fluid, small quantity released, water depth at release site and distance from environmentally sensitive areas, there was no lasting impact to the environment.
“We remain a committed, responsible and prudent operator and continue to adhere to transparent reporting and high standards of operations that have characterised our history.”
This article was written by Joshua Robertson and Michael Slezak from The Guardian and was legally licensed through the NewsCred publisher network. Please direct all licensing questions to firstname.lastname@example.org.
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