Finding the Weakest Links in Oil Leaks
Offshore oil spills are currently contaminating the waters off China and the North Sea near Scotland. But in the future, Massachusetts Institute of Technology (MIT) engineers might be able to predict the weak points in oil rigs and pipelines and predict disasters before they occur.
A leak from two ConocoPhillips oil rigs in Bohai Bay, east of Beijing, has been fouling Chinese waters since June 7. China's State Oceanic Administration is loosing patience with the American owned company and recently demanded a public apology from the company for missing an August 7th deadline to clean up the spill.
Originally estimated at 1,500 barrels of oil, CononoPhillips released a statement earlier this month saying that the spill might actually be worse. The AFP reported that local fisherman blame the spill for the death of their catch, while environmental groups call for greater transparency in the clean-up process.
Another spill was spotted August 10 in the North Sea 112 miles east of Aberdeen, Scotland. The leak spurted from a pipeline connected to Royal Dutch Shell's Gannet Alpha platform.
"We deployed a remote-operated vehicle to check for a subsea leak after a light sheen was noticed in the area,” said a Shell spokesman to the AFP.
"We have stemmed the leak significantly and we are taking further measures to isolate it. The subsea well has been shut in, and the flow line is being de-pressurised."
British authorities believe this may be the largest spill in the area in a decade. More that 100 tonnes (110 short tons) of oil have been released, they believe.
"Although small in comparison to the Macondo, Gulf of Mexico, incident, in the context of the UK continental shelf the spill is substantial," a spokesman from Britain's Department of Energy and Climate Change told the AFP.
Mechanical engineers at MIT have a modeling program that can show the breaking points in materials used in the oil and gas extraction industry. MIT’s Impact and Crashworthiness Laboratory developed the program originally to model automobile accidents, but applying it to offshore drilling operations could help identify structural weakspots before they become far worse. Of course taking action to fix the problem areas would be needed in order to avoid disasters such as the current spills or one like BP's Deepwater Horizon blow out last year.
To test their model, MIT’s Impact and Crashworthiness Laboratory simulated the forces involved in the 2010 Deepwater Horizon explosion in the Gulf of Mexico. They found that their model accurately predicted the location and spread of cracks in the oil rig’s drill riser.
“We are looking at what would happen during a severe accident, and we’re trying to determine what should be the material that would not fail under those conditions,” said Tomasz Wierzbicki, professor of applied mechanics at MIT in a press release. “For that, you need technology to predict the limits of a material’s behavior.”
To simulate the Deepwater Horizon blowout, Wierzbicki and two graduate students, Kirki Kofiani and Evangelos Koutsolelos, first looked up what type of steel was used to construct the riser that failed. It was a variety known as X70.
The technical specifications of the material were fed into the crash testing program. The team also built a computer model of the Deepwater Horizon riser attached to its platform.
They then simulated the explosion of the platform and its subsequent plunge into the depths. The computer program showed how the riser bent and snapped, simulating four cracks in the riser as the platform tumbled into the sea.
When the simulated breaking points were compared to a photograph of the real thing, they found an almost perfect match.
“The deeper you go in the ocean, two or three miles down, the stronger material you need to withstand the pressure,” Wierzbicki said. “But stronger materials are more brittle and break more easily. So there’s a difficult problem for the offshore industry, and I think they can learn a lot from us.”
The group presented their results at the International Offshore and Polar Engineering Conference in June.
Deepsea Delta oil drilling rig in the North Sea. (Wikimedia Commons)
Sunlight illuminated the lingering oil slick off the Mississippi Delta on May 24, 2010. (Wikimedia Commons/NASA)
Fire boat response crews battle the blazing remnants of the off shore oil rig Deepwater Horizon April 21, 2010. (Wikimedia Commons)