Auto Crash Model Can Simulate Offshore Oil Pipe Breaks

(U.S. Coast Guard, Courtesy X Prize Foundation)

Engineers at MIT have shown how a simulation model that tests automobile components for crashworthiness can be applied to predict the performance of pipes in offshore drilling accidents. The team from MIT’s Impact and Crashworthiness Laboratory presented their findings at the International Offshore and Polar Engineering Conference in June.

Tomasz Wierzbicki, professor of applied mechanics at MIT and director of the lab, has developed a process called fracture predictive technology. The technology offers a testing protocol that combines physical experiments with computer simulations to predict the strength and behavior of materials under severe impacts, like those that occur in a car crash.

With fracture predictive technology, tests of different shapes and sizes of materials under various pressures can determine a material’s strength, ductility, and other mechanical properties. Wierzbicki says it’s possible to create a simulation to test the behavior of materials, such as pipes used in offshore oil drilling, that are subjected to tremendous pressures at great depths.

Wierzbicki and graduate students Kirki Kofiani and Evangelos Koutsolelos used those principles to predict the strength and breaking points of the drill riser — a large-diameter pipe — used in the 2010 Deepwater Horizon explosion in the Gulf of Mexico. Direct samples from the actual collapsed riser were not available, but they tested a grade of steel commonly used in such risers, with properties closely matched to another grade of steel the team had previously tested in the lab.

The researchers devised a computer model of the drill riser attached at one end to a large rectangle that represented the surface drilling platform. The team then ran the model to partially reconstruct the Deepwater Horizon accident — methane gas erupted and shot to the surface setting the entire platform on fire, followed by the listing and sinking of the oil rig. They simulated the sinking by slowly angling the rectangular platform downward.

The drill riser attached to the platform then began to bend. A color-coded simulation showed points along the pipe where it was likely to crack:

• Green and blue showed where the material was intact
• Yellow and red indicated the breaking points.

The team found four red areas where cracks — and oil leaks — were especially likely to occur. The researchers then compared the simulation results to an image of the ruined pipe taken by an underwater robot shortly after the accident. The side-by-side comparison showed that their model’s reconstruction closely resembled that image of the actual fractured pipe.

Wierzbicki says it’s unlikely that any pipe material could have remained intact during the Deepwater Horizon disaster, but the simulation suggests there are improvements that can be made to bolster existing oil and gas pipelines. Wierzbicki and his group, whose research is partly sponsored by Royal Dutch Shell, plan to analyze samples from retired offshore pipes in the next few months.

Read more: New X Prize Challenge for Ocean Oil Cleanup

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