Written by Amanda Ellis Tuesday, 15 September 2009 15:47
THE Gorgon joint venture partners have made a historic decision to proceed with Australia’s largest liquefied natural gas (LNG) project and the world’s largest carbon dioxide geosequestration project.
At a press conference early this week, Chevron executive vice president of global upstream and gas, George Kirkland, announced the Gorgon project partners had made their final investment decision, giving the multi-billion-dollar project the go-ahead.
“In today’s dollars, the project is estimated to cost AU$43 billion. With total gas resources of 40 trillion cubic feet, this will be the largest resources project in Australia’s history and make a significant contribution towards Western Australia’s prosperity over the next 30 years,” Premier Colin Barnett said.
Gorgon’s partners, Chevron, ExxonMobil and Shell, have signed contracts to supply close to 3 million tonnes of LNG to China, Japan, and Korea.
The project demonstrates Western Australia’s status as the “engine room” of Australia’s economy, Curtin University of Technology Professor of Economic Policy Peter Kenyon says.
“It reinforces WA as a leading resources-intensive state.”
Curtin’s Professor of Petroleum Engineering Brian Evans believes the decision to include underground sequestration in the $43 billion Gorgon project was good corporate citizenship.
He chaired Gorgon phase one and two due diligence committees for the former Department of Industry and Resources, and finished up his involvement close to a year ago.
While some have claimed CO2 reinjection is untested, Prof Evans points to Norway’s StatoilHydro liquefied natural gas (LNG) project, Snøhvit, as a precedent.
In that project, 1 million tonnes is injected beneath the ocean each year.
“Chevron took the correct decision to try and get rid of [greenhouse gas] rather than vent it to atmosphere,” he says.
Gorgon’s CO2 injection project will be the world’s biggest, Premier Barnett said.
It will reduce the project’s greenhouse gas emissions by 40 percent, or 3.4 million tonnes per annum, through reinjection of carbon dioxide from the natural gas into a hyper-saline aquifer below Barrow Island.
“[The project] will reinject the CO2 down beneath Barrow Island and enter the Dupuy sandstone which is at about 2.3 kilometres down,” Prof Evans says.
At this stage we do not understand the fine details of the geology of the Dupuy sandstone, he says. However, this will change as 3D ‘before’ images are generated with further investigation.
A monitoring scheme is to be implemented so the gas’s direction can be tracked.
“The major issue anywhere is if the CO2 tracks up a fault or structure,” Prof Evans says.
Any unpredicted movement of CO2 could be observed with 4D imaging over a number of years and be addressed with remedial methods well before it approaches the top.
“We could force it back down by drilling a well, applying high-pressure water to the formation above that crack,” Prof Evans says.
“The higher-pressure water then pushes the CO2 back down the crack – and then cement it off.
“These are the techniques that have been round since drilling commenced at the turn of the 1900s.”
