BOEMRE - ,2010 MACONDOWELLBLOWOUT September14,2011...

THE BUREAU OF OCEAN ENERGY MANAGEMENT,
REGULATION AND ENFORCEMENT
REPORT REGARDING THE CAUSES OF THE APRIL 20, 2010
MACONDO WELL BLOWOUT
September 14, 2011

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TABLE OF CONTENTS
Executive Summary ................................................................................................ 1
I. Introduction ..................................................................................................... 10
A. The Investigation ......................................................................................... 10
B. Background Regarding Deepwater Drilling in the Gulf of Mexico ............ 13
C. Companies Involved in the Macondo Well .................................................. 16
D. The Deepwater Horizon ............................................................................... 18
E. The Macondo Well ....................................................................................... 19
F. The Blowout ................................................................................................. 23
II. Well Design ...................................................................................................... 25
A. Cost of the Macondo Well ............................................................................ 25
B. Drilling Margin ........................................................................................... 27
C. Casing Program ........................................................................................... 31
D. Mud Program and Type .............................................................................. 32
E. Mud Losses .................................................................................................. 33
F. Well Ballooning ........................................................................................... 34
G. Planned and Actual Total Depth ................................................................. 34
H. Designing the Production Casing – Long String versus Liner ................... 36
III. Cementing ........................................................................................................ 40
A. Cementing Process ....................................................................................... 40
B. Cement Design and Modeling ..................................................................... 41
C. Gas Flow Potential ....................................................................................... 46
D. Centralizers .................................................................................................. 47
E. Float Collar .................................................................................................. 49
F. Cementing the Macondo Production Casing .............................................. 53
G. Industry Standards for Cementing .............................................................. 57
IV. Possible Flow Paths ........................................................................................ 61
V. Conclusions on Well Design, Cementing, and Flow Path ........................ 68
A. Cause of the Failure of the Cement Barrier .................................................. 68
B. Contributing Causes of the Cement Barrier Failure ................................... 68
C. Possible Contributing Causes of the Cement Barrier Failure ..................... 70
D. Flow Path Cause .......................................................................................... 73
VI. Challenges at the Macondo Well .................................................................. 75
A. Kicks and Stuck Drill Pipe .......................................................................... 75
B. Scheduling Conflicts and Cost Overruns .................................................... 78
C. Personnel Changes and Conflicts ................................................................ 79
D. Safety Stand ‐ down ....................................................................................... 83
VII. Temporary Abandonment of the Macondo Well ....................................... 85

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A. Installing the Lock ‐ Down Sleeve ................................................................. 85
B. Setting the Cement Plug .............................................................................. 86
C. The Use of Lost Circulation Material as Spacer .......................................... 87
D. Well Integrity Testing ................................................................................. 88
VIII. Kick Detection and Rig Response ................................................................. 98
A. Kick Detection Methods and Responsibilities .............................................. 98
B. Multiple Simultaneous Operations That Hampered the Crew’s Ability to
Detect Kicks ................................................................................................. 99
C. Rig Floor Response .................................................................................... 103
D. The Use of the Mud Gas Separator ............................................................ 104
E. Activity on the Bridge ................................................................................ 106
F. Emergency Disconnect System .................................................................. 107
IX. Conclusions on Temporary Abandonment, Kick Detection, and the
Emergency Response ................................................................................... 109
A. Kick Detection and Response Failure Cause ............................................. 109
B. Kick Detection Failure Contributing Causes ............................................ 109
C. Kick Detection Failure Possible Contributing Causes .............................. 110
D. Response Failure Contributing Causes ..................................................... 112
E. Response Failure Possible Contributing Causes ....................................... 113
X. Ignition Source(s) and Explosions .............................................................. 115
A. Main Engines and Engine Switch Gear Rooms ........................................ 115
B. Mud Gas Separator .................................................................................... 119
C. Other Possible Ignition Sources ................................................................ 122
XI. Conclusions on Ignition Source and Explosion ........................................ 125
A. Ignition Sources ......................................................................................... 125
B. Contributing Causes of the Explosion ....................................................... 125
C. Possible Contributing Causes of the Explosion ......................................... 126
D. Other Possible Ignition Sources ................................................................ 127
XII. The Deepwater Horizon BOP Stack ............................................................... 129
A. Design and Configuration ......................................................................... 129
B. Control and Power Systems ....................................................................... 132
C. Emergency Disconnect System .................................................................. 133
D. Automatic Mode Function (“Deadman”) ................................................. 134
E. Autoshear Function ................................................................................... 134
F. Forensic Examination of the BOP ............................................................. 135
G. Examination Methods Used by DNV ........................................................ 137
H. DNV’s Forensic Examination Findings .................................................... 138
I. Evaluation of Other Possible Failures ....................................................... 142
J. Studies Evaluating the Reliability of BOPs .............................................. 144
K. Maintenance of the Deepwater Horizon BOP ........................................... 146

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L. BOP System Leaks ..................................................................................... 151
M. ROV Interventions .................................................................................... 153
XIII. BOP Stack Conclusions ................................................................................ 155
A. Cause of the BOP Stack Failure ................................................................. 155
B.