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Vol. 16, No. 3 Week of January 16, 2011
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A chain of mistakes

Commission points to systematic failures leading to Deepwater Horizon explosion

Alan Bailey

Petroleum News

The 380-page report from the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling, published on Jan. 11 and containing a wealth of information on the tragic blowout of BP’s Macondo well, seemed to point to one key message, expressed near the front of the report’s introduction: “The explosive loss of the Macondo well could have been prevented.”

Systematic failures

The fact that the blowout did in fact occur “can be traced to a series of identifiable mistakes made by BP, Halliburton and Transocean that reveal such systematic failures in risk management that they place in doubt the safety culture of the entire industry,” the report says.

The report’s account of the events leading to the April 20, 2010, uncontrolled blowout of the Macondo well makes riveting reading and portrays a series of errors of judgment, missed warning signs and communication failures, any one of which, had it been avoided, might have averted the eventual catastrophe.

The commission investigated BP’s well design and the report questions BP’s decisions to use a long casing string in the well and only six devices for centralizing the drill pipe in the well bore, given that these design features increase the difficulty of reliably plugging the downhole section of the well with cement — at the time of the blowout, the drilling of the well had been completed, and the drillers were in the process of plugging the well for later re-activation for oil production.

A string of errors

The report says that during the course of the well plugging and temporary abandonment operations the following mistakes and oversights occurred, involving BP and its contractors, Halliburton and Transocean:

• BP personnel inadequately considered the possible reasons for abnormal mud pressures needed to circulate mud through the well prior to sealing the well with cement.

• BP inadequately evaluated the effectiveness of the cement seal, once the bottom of the well had been cemented.

• Halliburton failed to communicate that testing of the cement to be used in the Macondo well had indicated potential problems with cement stability.

• Without extra vigilance, BP relied on the downhole cement as the only barrier to hydrocarbon flow from the well, despite some known risk factors associated with the cement seal.

• BP relied on an improperly conducted pressure test for evaluating the integrity of the downhole cement plug. In retrospect, pressure anomalies observed during this test indicated that hydrocarbons were flowing into the well, but poor communications and a lack of adequate procedures compounded an assumption by the drilling crew and BP supervisors that the well was not flowing oil and gas.

• BP decided to place an uphole cement plug unnecessarily far down the well and then to displace all of the mud in the well riser with seawater before installing that plug.

• The drilling crew and others observing well instrument readings initially failed to spot a slow but anomalous rise in pressure in the drill pipe while the crew was preparing to complete the sealing of the well, and then failed to recognize the significance of the pressure rise once it had been spotted. In the event, the pressure rise signaled hydrocarbons flowing into the well, but by the time the ejection of mud from the top of the riser flagged a blowout in progress, much gas had already escaped from the well.

• When drilling mud started spewing from the rig floor as the blowout erupted, the drilling crew did not minimize the gas ignition risk by diverting the escaping drilling mud over the side of the rig. And the crew did not immediately activate the blowout preventer blind shear rams when the mud started flowing from the well.

In addition, the blowout preventer failed to operate correctly once it was activated, although the cause of that failure is still the subject of a federal investigation.

Management failures

The report says that the various errors leading to the disaster provide evidence of management failures by all of the companies involved. And although the report did not accuse the companies of making reckless decisions to save money, many decisions did save cost and time, while at the same time there appeared little evaluation of the relative risks involved in using different techniques.

The report also slams government regulatory oversight of the Macondo operation, saying that government regulations were inadequate for deepwater drilling and that the U.S. Minerals Management Service, the regulating agency, had allowed industry to make many critical decisions without agency review. Resistance by industry, congressional lawmakers and several federal administrations to ramp up regulatory oversight had led to a situation where neither the regulations nor the regulators were posing the kind of tough questions that could have prevented the Macondo disaster, the report says.

The report praised the efforts of the many responders who dealt with the oil spill resulting from the blowout but pointed out significant limitations in the technologies and organizational procedures used for the response. Spill response technologies have not kept pace with the needs of contingency planning for deepwater drilling in large, high-pressure reservoirs far offshore, the report said.

Part 2 of this story will review the lessons learned and recommendations for the future contained in the commission’s report.

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Individual evaluations, not moratoriums

The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling has concluded that it is better to evaluate the risk of specific drilling situations rather than to impose blanket drilling moratoriums in response to concerns raised by the Deepwater Horizon disaster.

“We’re recommending that drilling on specific sites be evaluated in terms of the riskiness and preparations to deal with the consequences of that risk in that particular (oil) field,” said Sen. Bob Graham, co-chair of the commission, during a Jan. 11 press conference announcing the publication of the commission’s final report.

And in the Alaska Arctic offshore that would translate to a careful evaluation of drilling risks, but not a blanket drilling moratorium.

“The commission is not asking for a moratorium in Alaska, recognizing that there are very important questions still ahead … to be answered through additional research and additional investment in Arctic-specific technologies,” said Fran Ulmer, chancellor of the University of Alaska Anchorage and a member of the commission.

And the commission’s report reflected that position.

“The need for additional research should not be used as a de facto moratorium on activity in the Arctic, but instead should be carried out with specific timeframes in mind in order to inform the decision-making process,” the report said.

“As the major leaseholder in both the Beaufort and Chukchi seas, we appreciate that the presidential commission considered offshore activities beyond the Gulf of Mexico and agree with the finding that a blanket moratorium is not warranted in the Arctic,” said Shell spokesman Curtis Smith in a Jan. 11 statement responding to the report. “We look forward to achieving a more thorough understanding of the commission’s recommendations and assessing perceived gaps against the unprecedented steps Shell has taken to pursue safe, environmentally responsible exploration in the shallow waters off the coast of Alaska.”

“I commend the ground-breaking work of this national commission, which I hope will lead to the increased safe development of America’s domestic oil and gas resources including those in the Arctic,” said Sen. Mark Begich. “Producing the enormous energy resources available within our borders is vital for our economic and national security, but we must develop these resources in a safe and environmentally responsible manner.”

—Alan Bailey