Suncor Energy has a pair of offshore construction ships lined up to start replacing seabed equipment at the Terra Nova oilfield in August.
The operator of the Terra Nova oilfield will install a pair of new flowlines equipped to handle hydrogen sulphide encountered in four wells late last year.
Since then, the wells have been shut in — cutting the oilfield’s production in half.
The flowline replacement work will continue in mid-September during a four-week maintenance shutdown of the Terra Nova production ship.
Sour gas is hydrogen sulphide, which is flammable, poisonous and corrosive. It can result naturally from decaying organic material in oil and gas.
John Downton, spokesman for Suncor, said the current flowline equipment does not meet the specifications required to handle sour gas.
“With slightly higher levels we have to adjust the equipment,” he said. “We’ll tie those in with the planned four-week turnaround in September.”
That annual round of maintenance and certifications will include preventative maintenance on electrical and instrumentation systems, five-year inspections of pressure vessels, and maintenance on the production ship’s gas compression system and main power generator.
“It’s planned work,” said Downton.
Suncor will use the pipe-laying vessel Deep Constructor, and the dive support vessel Wellservicer, to install the new flowlines.
Flowlines are the flexible pipes that sit on the seabed and carry oil, gas and water from the seafloor to the production ship.
The first task is to lay the two flowlines on the seabed — a job the Deep Constructor and its crew will begin in the latter half of August.
In September, divers onboard the Wellservicer will start connecting those flowlines to well equipment on the seabed and to the production ship.
Operated by Technip Canada, both ships are also carrying out work at the Hibernia platform — replacing a pair of offshore loading systems that transfer crude to oil tankers and upgrading production equipment.
The Hibernia partners have estimated those upgrades to be worth about $400 million.
Downton said Suncor has shut in four Terra Nova wells.
Two are shut in because of sour gas problems, the other two because they share common flowlines with the first two.
Once the new flowlines are installed this year, production from two wells will resume.
“It will enable us to recover some of the shut-in production, but obviously not all of it,” said Downton.
“We’ll have to do some more work on flowlines next year to be able to recover the deferred production.”
Oil production at Terra Nova is down 50 per cent during the first six months of the year compared with the same period in 2010. That production information is posted on the Canada-Newfoundland and Labrador Offshore Petroleum Board’s website.
The next round of Terra Nova maintenance is scheduled for 2012.
Suncor will send the production ship to Marystown for 15 weeks of dockside maintenance to replace its damaged swivel and upgrade equipment for sour gas.