"Unrealized at the time, a critical point had passed: BP would not have to reopen the stack, and oil had finally stopped leaking from the Macondo well into the Gulf."
They had successfully stopped the flow of oil into the Gulf of Mexico but the government's science advisory team did not realize BP had been successful. It did not fit their assumptions. The government overseers were unanimous that they ought to re-open the capping stack and let oil flow once again.
Divine Providence intervened and the "Nobel Prize winning physicist" and his team were convinced by Coast Guard Admiral Cook to keep to their promise and leave the stack closed for the full 24 hour design period of the well integrity test. The pressure curve of the well then demonstrated that it had mechanical integrity and thus could be safely left shut in.
The prevailing hypothesis among the scientists had been that the well was leaking by annular flow into the surrounding formations. It was discredited by the facts. The current opinion of the Oil Spill Commission is that the flow was due to a failure of the primary cement job and "was exclusively through shoe track and up through casing", not through the annulus. Secretary Chu and team were totally wrong about the flow path. Here is a direct quotation from pages 32-34 of the report with emphasis added. The story begins with the shutting in of the capping stack.
...BP shut the stack and began the well integrity test at 2:25pm on July 15. For the first time in 87 days, no oil flowed into the Gulf of Mexico. Initial wellhead pressure readings were just over 6,600 psi, squarely in the uncertain middle range, and rising slowly. Later that afternoon, the science advisors, including Dr. McNutt and Dr. Hunter, met with Secretaries Salazar and Chu to consider the pressure data and whether to keep the well shut in. A member of the Well Integrity Team reported that, according to his original model, the shut-in pressure indicated a leak into the formation of about 3,500 bbls/day. From there, discussion within the group appears to have turned firmly against keeping the well closed. Dr. Garwin, who had opposed even undertaking the well integrity test, voiced the strongest opinion to that effect. He argued that BP ought to stop the test immediately and wondered whether it was already too late. Several participants were concerned that the monitoring systems might be unable to detect leakage. No one at the meeting appears to have argued in favor of keeping the well shut in. After an hour and a half, a consensus among the science advisors had developed: Oil was leaking into the formation, and the Coast Guard should order BP to reopen the capping stack and resume collecting oil from the well.
BP evidently learned of this emerging consensus within the government to reopen the capping stack, and became concerned. Suttles called MMS Regional Director Lars Herbst to ask for his view of the well integrity test. Herbst, who had not participated in the meeting with the science advisors, examined the pressure data and agreed with BP that the well should stay closed overnight. BP apparently relied in part on Herbst's support in making its case to the government that the well should remain shut in. [SNIP]
The public wanted the well shut in and the flow of oil into the Gulf stopped, but the risk of causing greater harm was real. According to interviews conducted by Commission staff, Admiral Cook made the argument that eventually prevailed. He reminded the others that, before the test began, BP and the government had considered the possibility of pressure measurements like those being observed. Both parties had agreed that, in such a case, the test should last 24 hours, with consultation between the parties prior to reopening the well. One participant recalled general agreement that, while the data supported reopening the capping stack, under the guidelines established prior to shut-in, the stack could stay closed during the night. [SNIP]
The next morning, the government principals and the science advisors-who had been convinced the night before that opening up the stack was necessary-hosted a meeting. BP presented its explanation of why pressures had built to the level observed and argued, in detail, that the well should remain shut in. Hsieh also presented his model, demonstrating that there was a reasonable explanation for why the pressure was lower than expected. Participants with whom staff spoke had different recollections as to whether BP's or Hsieh's presentation carried more weight. The outcome of the meeting, however, was clear. The stack would stay shut, with government reevaluation of that decision every six hours.
Unrealized at the time, a critical point had passed: BP would not have to reopen the stack, and oil had finally stopped leaking from the Macondo well into the Gulf. [emphases added]
How utterly clueless! They were fixated on an invalid set of assumptions and were ready to start resuming the flow of oil, thereby polluting the gulf, rather than realize their many mistakes and simply leave well enough alone.