Fish survey would do more harm than Tui drilling
Fish sampling proposed by submitters to Tamarind Resources’ planned drilling at the Tui field would do more harm than the campaign itself, a board of inquiry heard today.
Marine ecologist Alison MacDiarmid said surveys proposed by Te Korowai O Ngaruahine Trust for the remainder of the Tui consent would require bottom trawling which is a “destructive” process for both the seafloor and the fish caught.
The surveys were proposed as a way of measuring the direct and cumulative environmental effects of the drilling on fish stocks.
But to do that properly, MacDiarmid said surveys would have to be carried out at a large number of sites to provide a realistic control and probably for at least three years to allow for the potential year-to-year population variation.
She doubted they could capture the “extremely subtle” population changes that might result and said the trawling would do greater harm to fish stocks and the surrounding seafloor environment than the present application.
“The trawl surveys, in my opinion, would cause much greater harm to the fish population and the environment,” she told the inquiry in New Plymouth today.
“To me it makes no sense to cause more harm, by investigation of a minor harm.”
Tamarind is seeking approval to drill a series of side-track wells from three of the field’s existing wells next year. It has contracted a new, high-tech rig to help minimise the environmental impacts of the work, which a succession of experts have characterised as negligible to minor.
Yesterday the board heard the project, expected to take about three to four months and nine months in the worst-case scenario, could extend the life of the 11-year-old project by as much as six years and boost the Taranaki economy by about $110 million.
While the expected environmental impacts are temporary and minor, the board has spent some time assessing the potential for an unlikely, but potentially high-risk event, such as a loss of well control.
Today board chair David Hill sought greater detail from Tamarind as to the drilling process and the nature of the reservoir to help determine “whether it’s something we really need to worry about.”
“Our thinking is it’s not.”
Yesterday the board heard that side-tracking drilling is slightly less risky than drilling a new well, given the integrity of a cased well, which is where the activity starts from.
Iain McCallum, who is managing the drilling project, said the target reservoir is also low-pressure and would be contained by sea water alone.
The principal means of controlling a well is by maintaining a greater weight of drilling mud in the well to keep reservoir fluids contained. A blow-out preventer also provides secondary protection for the rare risk of a failure.
“It’s always a risk in the drilling industry. So we take it very seriously, but with these wells it’s highly unlikely,” McCallum said.
Tamarind country manager Jason Peacock said the company has drilled more than 20 wells in the area and could not have more knowledge of the temperatures and pressures within the field.
He said a blow-out is an “extremely rare” event, does not happen quickly, and would require successive failures of several of the rig’s systems.
The committee heard such an event may take eight to 10 hours.
Peacock said for the rig crew to lose control of a well their monitoring system would have to fail and they would have to lose pumping capacity on the rig. That in turn would require a failure of the rig’s power and back-up power systems.
Even if the rig was to lose power, the blow-out preventer would activate automatically, shutting off the well.
The hearing concludes tomorrow.
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