Capping the flow

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U.S. Geological Survey hydrologist Paul Hsieh describes the ultimate capping of the Macondo well before a packed audience at CU-Boulder.

“Sometimes when you’re in the right place at the right time, you get to do something interesting. That’s what happened to me in the summer of 2010.”

That could be one of the biggest understatements of Paul Hsieh’s career, but that’s what the United States Geological Survey groundwater hydrologist says about the crucial contribution he made to ending the largest oil leak in the nation’s history.

Hsieh, who was named U.S. Federal Employee of the Year for his accomplishment, recounted the dramatic events to a CU-Boulder audience.

In mid-July, nearly three months after the explosion of the Deepwater Horizon oil rig, a 75-ton containment cap was successfully placed on the well, stopping the flow of oil for the first time.

But the government science team convened to respond to the disaster was concerned that the cap might cause the well to rupture from beneath the seabed, resulting in an even greater release of oil. A six-hour test of the well’s integrity on July 15 indicated that the pressure reading was “smack in the middle” of the uncertainty zone.

Hsieh recalled the tight deadline he had to recommend a course of action. “A decision had to be made in 24 hours as to whether to open the well,” he said. “The default position was to open it and avoid a bigger blowout.”

Working from a screen shot of the pressure data that was sent to him by cell phone, Hsieh labored through the night in his California office to compare the data with a no-leak scenario he developed with MODFLOW, a complex USGS visualization tool used to simulate groundwater flows.

After several hours of intensive work in which he went over and over his calculations to ensure their accuracy, he concluded that the cap did not need to be removed.

Secretary of Energy Steven Chu made the final decision to go with Hsieh’s analysis, while continuing to monitor the well and update the model “as you would with any investment plan,” Hsieh said.

In fact, no evidence of leakage was observed over the next 18 days, and Hsieh’s continued modeling work ultimately gave the science team confidence that the cap was working.

Hsieh pointed to four things he said were necessary to do effective science in a crisis: knowledge of the fundamentals, mastery of skills, accuracy, and transparency.

Without those elements, he never would have been able to meet the deadline or give credible information to the ultimate decision-maker.

“Some students think that they don’t have to remember everything because they can look it up when they need it, but that’s what’s required if your timeframe is only 5 hours.”

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