Failure of a cement barrier in the production casing string was identified as a central cause of the 2010 Gulf of Mexico oil spill, according to the Report Regarding the Cause of the April 20, 2010 Macondo Well Blowout released by the U.S. Department of the Interior, Bureau of Ocean Energy Management, Regulation and Enforcement in September 2011. 

According to the report,

The failure of the cement barrier allowed hydrocarbons to flow up the wellbore, through the riser and onto the rig, resulting in the blowout. The precise reasons for the failure of the production casing cement job are not known. The Panel concluded that the failure was likely due to: (1) swapping of cement and drilling mud (referred to as “fluid inversion”) in the shoe track (the section of casing near the bottom of the well); (2) contamination of the shoe track cement; or (3) pumping the cement past the target location in the well, leaving the shoe track with little or no cement (referred to as “over‐displacement”).

Contributing factors to the incident noted in the report included “poor risk management, last-minute changes to plans, failure to observe and respond to critical indicators, inadequate well control response, and insufficient emergency bridge response training.”

Changes to applicable regulations, agency oversight procedures, and the training curriculum for well operators were among the recommendations for future improvement.

Related Article in the EHS Journal

Deepwater Drilling: Oil Spill Response

Photograph: Butterfly 1, hebomoia leucippe, by Oleg Ivanov, Tartu, Estonia.

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Hurricane Ivan in the Gulf of Mexico on September 15, 2004

It’s been 82 days since the April 20, 2010 explosion occurred on the Deepwater Horizon drill rig and caused the ongoing oil spill in the Gulf of Mexico. The hurricane season in the Atlantic Basin is already upon us, commencing on June 1, 2010 and lasting through the end of November. The U.S. Department of Commerce National Oceanic and Atmospheric Administration (NOAA) predicts that 8 to 14 hurricanes will occur during the 2010 hurricane season, which leads me to wonder what effect a hurricane would have on the Gulf of Mexico oil spill and, conversely, what impact the spill could have on a potential hurricane?  These questions and more are answered in a fact sheet prepared by NOAA.      

What effect will a hurricane have on the Gulf of Mexico oil spill?

• The high winds and seas will mix and “weather” the oil which can help accelerate the biodegradation process.
• The high winds may distribute oil over a wider area, but it is difficult to model exactly where the oil may be transported.
• Movement of oil would depend greatly on the track of the hurricane.
• Storms’ surges may carry oil into the coastline and inland as far as the surge reaches. Debris resulting from the hurricane may be contaminated by oil from the Deepwater Horizon incident, but also from other oil releases that may occur during the storm.

A hurricane’s winds rotate counter-clockwise. Thus, in VERY GENERAL TERMS:

• A hurricane passing to the west of the oil slick could drive oil to the coast. 
• A hurricane passing to the east of the slick could drive the oil away from the coast. 
• However, the details of the evolution of the storm, the track, the wind speed, the size, the forward motion and the intensity are all unknowns at this point and may alter this general statement.

What effect will the oil spill have on a hurricane?

• Most hurricanes span an enormous area of the ocean (200-300 miles) — far wider than the current size of the spill. 
• If the slick remains small in comparison to a typical hurricane’s general environment and size, the anticipated impact on the hurricane would be minimal.
• The oil is not expected to appreciably affect either the intensity or the track of a fully developed tropical storm or hurricane. 
• The oil slick would have little effect on the storm surge or near-shore wave heights.
• Oil will not be swept up into the storm and rained down in other places.

In general, the oil slick is not expected to have an impact on a potential hurricane.

For More Information

Click here to read the NOAA hurricane fact sheet.

Click here to visit the NOAA web site.

About the Author

Michael Bittner is an associate partner in the Boston, U.S.A. office of Environmental Resources Management (ERM) and editor of the EHS Journal. He has more than 20 years of experience in the EHS field, including 17 years of EHS consulting experience and four years as the corporate environmental manager for a U.S. Department of Defense contractor. Mr. Bittner specializes in global EHS solutions including

• Compliance and management systems auditing.
• EHS management systems implementation and design.
• Sustainability solutions.
• Strategic planning.
• Mergers and acquisitions support.

Image: Hurricane Ivan in the Gulf of Mexico, September 15, 2004, courtesy of NOAA.

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