Proc Natl Acad Sci USA. Scientific basis for safely shutting in the Macondo Well after the April 20, 2010 Deepwater Horizon blowout

[Giuseppe Michieli]

[Source: Proceedings of the National Academy of the Sciences of the United States of America, full text: (LINK). Abstract, edited.]

Scientific basis for safely shutting in the Macondo Well after the April 20, 2010 Deepwater Horizon blowout


Stephen H. Hickman^a,¹, Paul A. Hsieh^b, Walter D. Mooney^a, Catherine B. Enomoto^c, Philip H. Nelson^d, Larry A. Mayer^e, Thomas C. Weber^e, Kathryn Moran^f,², Peter B. Flemings^g, and Marcia K. McNutt^h

Author Affiliations: ^aEarthquake Science Center, US Geological Survey, Menlo Park, CA 94025; ^bNational Research Program, US Geological Survey, Menlo Park, CA 94025; ^cEastern Energy Resources Science Center, US Geological Survey, Reston, VA 20192; ^dCentral Energy Resources Science Center, US Geological Survey, Denver, CO 80225; ^eCenter for Coastal and Ocean Mapping, University of New Hampshire, Durham, NH 03824; ^fOffice of Science and Technology Policy, Executive Office of the President, Washington, DC 20502; ^gJackson School of Geosciences, University of Texas, Austin, TX 78712; and ^hOffice of the Director, US Geological Survey, Reston, VA 20192

Edited by James R. Rice, Harvard University, Cambridge, MA, and approved September 7, 2012 (received for review December 24, 2011)



Abstract

As part of the government response to the Deepwater Horizon blowout, a Well Integrity Team evaluated the geologic hazards of shutting in the Macondo Well at the seafloor and determined the conditions under which it could safely be undertaken. Of particular concern was the possibility that, under the anticipated high shut-in pressures, oil could leak out of the well casing below the seafloor. Such a leak could lead to new geologic pathways for hydrocarbon release to the Gulf of Mexico. Evaluating this hazard required analyses of 2D and 3D seismic surveys, seafloor bathymetry, sediment properties, geophysical well logs, and drilling data to assess the geological, hydrological, and geomechanical conditions around the Macondo Well. After the well was successfully capped and shut in on July 15, 2010, a variety of monitoring activities were used to assess subsurface well integrity. These activities included acquisition of wellhead pressure data, marine multichannel seismic profiles, seafloor and water-column sonar surveys, and wellhead visual/acoustic monitoring. These data showed that the Macondo Well was not leaking after shut in, and therefore, it could remain safely shut until reservoir pressures were suppressed (killed) with heavy drilling mud and the well was sealed with cement.

• oil spill - underground blowout – overpressure - reservoir modeling - marine geophysics

Footnotes

¹To whom correspondence should be addressed. E-mail: hickman@usgs.gov.

²Present address: NEPTUNE Canada, University of Victoria, Victoria, BC, Canada V8W 2Y2.

Author contributions: S.H.H., P.A.H., W.D.M., C.B.E., P.H.N., L.A.M., T.C.W., K.M., and M.K.M. evaluated hazards and helped design monitoring program; S.H.H., P.A.H., W.D.M., C.B.E., P.H.N., L.A.M., T.C.W., K.M., and P.B.F. analyzed data and interpreted results; S.H.H., P.A.H., W.D.M., C.B.E., P.H.N., and M.K.M. were members of the Well Integrity Team stationed in Houston; and S.H.H., P.A.H., W.D.M., C.B.E., P.H.N., L.A.M., T.C.W., P.B.F., and M.K.M. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

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