Deepwater Horizon Accident2 Horizon Accident2.pdf · – BP Deepwater Horizon Accident...
Transcript of Deepwater Horizon Accident2 Horizon Accident2.pdf · – BP Deepwater Horizon Accident...
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January 3, 2011January 3, 2011 11
Deepwater Horizon AccidentWhat Happened and Why?
Deepwater Horizon AccidentWhat Happened and Why?
Roland N. HorneThomas Davies Barrow Professor of
Earth SciencesStanford University
Roland N. HorneThomas Davies Barrow Professor of
Earth SciencesStanford University
Photo: US Coast Guard
January 3, 2011January 3, 2011 22
What and Why?What and Why?
• Understanding the catastrophe is the first step in preventing another.
• An important event should be understood by forward-thinking individuals.
• Decisions need to be based on knowledge.
• Understanding the catastrophe is the first step in preventing another.
• An important event should be understood by forward-thinking individuals.
• Decisions need to be based on knowledge.
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January 3, 2011January 3, 2011 33Photo: US Coast Guard
January 3, 2011January 3, 2011 44
SourcesSources• An interpretation of the observations and
testimony of others.– House Energy and Environment Subcommittee of the
Energy and Commerce Committee Investigation (June)
– Transcripts - The Joint United States Coast Guard/Bureau of Ocean Energy Management Investigation (May-Oct) http://www.deepwaterinvestigation.com
– BP Deepwater Horizon Accident Investigation Report (Sept 8)
– BP Deepwater Horizon Investigation: Preliminary Insights [Halliburton] (Sept 26)
– National Academy of Engineering Committee http://sites.nationalacademies.org/BlowoutPrevention
– Personal conversations with members of government and industry (May-Oct)
• An interpretation of the observations and testimony of others.– House Energy and Environment Subcommittee of the
Energy and Commerce Committee Investigation (June)
– Transcripts - The Joint United States Coast Guard/Bureau of Ocean Energy Management Investigation (May-Oct) http://www.deepwaterinvestigation.com
– BP Deepwater Horizon Accident Investigation Report (Sept 8)
– BP Deepwater Horizon Investigation: Preliminary Insights [Halliburton] (Sept 26)
– National Academy of Engineering Committee http://sites.nationalacademies.org/BlowoutPrevention
– Personal conversations with members of government and industry (May-Oct)
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5 Main Topics5 Main Topics
1. The process and equipment of deep-water drilling.
2. A series of questionable issues.3. The ones that mattered in the accident.4. How to do it better.5. Why do we do it at all?
1. The process and equipment of deep-water drilling.
2. A series of questionable issues.3. The ones that mattered in the accident.4. How to do it better.5. Why do we do it at all?
1. Deep-water Drilling1. Deep-water Drilling
• Riser and BOP• Dynamic positioning or
anchoring of vessel• Crew rotation (21/21, 12/12)• Isolation from shore/office• Access for remediation• Multiple contractors• Expense
• Riser and BOP• Dynamic positioning or
anchoring of vessel• Crew rotation (21/21, 12/12)• Isolation from shore/office• Access for remediation• Multiple contractors• Expense
Source: BP Report Sept. 8, 2010
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BOP Separation from RigBOP Separation from Rig
Sources: US Coast Guard, BP Report Sept. 8, 2010
Dynamic PositioningDynamic Positioning
• Vessel must have power at all times• Vessel must have power at all timesSources: Cargolaw.com, BP Report Sept. 8, 2010
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In the event of DP failure, requires EDSIn the event of DP failure, requires EDS
Source: BP Report Sept. 8, 2010
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Remotely Operated Vehicle ROVRemotely Operated Vehicle ROV
Source: http://www.oceaneering.com
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2. Series of Questionable Issues2. Series of Questionable Issues1. Casing design
a) Long string, rather than liner and tie-backb) No lockdown sleeve (at time of accident)c) Single string over several formations of
different pressure2. Cement design
a) Few centralizersb) Big casing, small holec) Nitrogen foam cementd) No cement-bond log
1. Casing designa) Long string, rather than liner and tie-backb) No lockdown sleeve (at time of accident)c) Single string over several formations of
different pressure2. Cement design
a) Few centralizersb) Big casing, small holec) Nitrogen foam cementd) No cement-bond log
January 3, 2011January 3, 2011 1212
2. Series of Questionable Issues2. Series of Questionable Issues3. Negative pressure test
a) Unclear proceduresb) Conducted soon after cementingc) Confusing because of unusual spacerd) Misunderstood by crew
4. Flow monitoringa) Flows confusing due to offloadingb) Insufficient response to flow indicationsc) Hydrocarbons entered the riser
3. Negative pressure testa) Unclear proceduresb) Conducted soon after cementingc) Confusing because of unusual spacerd) Misunderstood by crew
4. Flow monitoringa) Flows confusing due to offloadingb) Insufficient response to flow indicationsc) Hydrocarbons entered the riser
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2. Series of Questionable Issues2. Series of Questionable Issues5. Ignition
a) Hydrocarbon flow through MGSb) Gas entry into engine room, intake not autoc) Engine overspeed, power loss, fire
6. BOPa) Crew shut BOP, but failed to seal wellb) EDS pushed but link to BOP lost in firec) Automatic function didn’t workd) ROV operation of BOP didn’t work
5. Ignitiona) Hydrocarbon flow through MGSb) Gas entry into engine room, intake not autoc) Engine overspeed, power loss, fire
6. BOPa) Crew shut BOP, but failed to seal wellb) EDS pushed but link to BOP lost in firec) Automatic function didn’t workd) ROV operation of BOP didn’t work
January 3, 2011January 3, 2011 1414
3. The Bad Stuff3. The Bad Stuff
a) The cement job failed to seal off the producing reservoir(s). Casing seal failed.
b) Hydrocarbon inflow was not recognized, and hydrocarbon entered the riser.
c) Gas ignited on the rig, causing fire and loss of power.
d) The BOP failed to seal the well.
a) The cement job failed to seal off the producing reservoir(s). Casing seal failed.
b) Hydrocarbon inflow was not recognized, and hydrocarbon entered the riser.
c) Gas ignited on the rig, causing fire and loss of power.
d) The BOP failed to seal the well.
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(a) The Cement Job(a) The Cement Job
• There is no question that the cement job failed to isolate the formation.
• Unclear why. BP and Halliburton not in agreement.
• There is no question that the cement job failed to isolate the formation.
• Unclear why. BP and Halliburton not in agreement.
Source: BP Report Sept. 8, 2010
January 3, 2011January 3, 2011 1616
•Converting the float collar required excessive pressure (3000 vs. 400-700 psi).
•Small pressure window required lightened cement.
•Lost circulation zones.
•Few centralizers.
•No cement bond log run.
Source: BP Report Sept. 8, 2010
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Pressure “Window”Pressure “Window”
• Well pressure mustexceed pore pressure.
• Well pressure must notexceed frac pressure.
• Casing protects shallower formations from deeper pressures.
• Well pressure mustexceed pore pressure.
• Well pressure must notexceed frac pressure.
• Casing protects shallower formations from deeper pressures. Pore Pressure
Frac Gradient
Source: Mark Zoback “Reservoir Geomechanics”
January 3, 2011January 3, 2011 1818
Modeled with 7 Centralizers Modeled with 21 Centralizers
TOC16,353
TOC17,259
Reference: 9.875 X 7 Prod Casing Design Report - 21 Cent.pdf; & 9.875 X 7 Prod Casing Design Report - 6 Cent.pdf; April 15, 2010
• Modeling indicated “severe”channeling could occur across the reservoir with only six centralizers installed
• Modeling was also run with 10 centralizers
• Channeling was still predicted
• Modeling was run with 21 centralizers
• No channeling was indicated• Casing was loaded on rig
with 6 centralizers• 15 additional centralizers
were flown to the rig, but were not to used
Halliburton ReportsHalliburton Reports
Source: Halliburton presentation Sept. 26, 2010
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January 3, 2011January 3, 2011 1919Source: BP Report Sept. 8, 2010
16ppg Spacer
14.17ppg SOBM (Mud)
8.6ppg Seawater
Influx
CasingShoe
Failure
SealAssembly
FailureYYYYYYYYYY
YYYYYY
NN1400 psi recorded on drill pipe during negative test at 18:30
NNStatic Kill
NNTiming for Gas Arrival to Surface
NNPressure Response from 21:31 to 21:34
NNPressure Increase from 21:08 to 21:14
NNAbility to flow from 20:58
NNRealistic Net Pay Assumption
YYMechanical Barrier Failure Mode Identified
Key Observations for FlowThrough Shoe vs. Seal
Assembly
CasingShoe
Failure
SealAssembly
Failure
YYYYYYYYYY
YYYYYY
NN1400 psi recorded on drill pipe during negative test at 18:30
NNStatic Kill
NNTiming for Gas Arrival to Surface
NNPressure Response from 21:31 to 21:34
NNPressure Increase from 21:08 to 21:14
NNAbility to flow from 20:58
NNRealistic Net Pay Assumption
YYMechanical Barrier Failure Mode Identified
Key Observations for FlowThrough Shoe vs. Seal
Assembly
CasingShoe
Failure
SealAssembly
Failure
Casing Shoe or Seal Failure?Casing Shoe or Seal Failure?
January 3, 2011January 3, 2011 2020
(a) The Cement Job(a) The Cement Job
1. It is clear that the cement job failed to isolate the producing formation.
2. It seems likely that the float collar check valves and shoe track cement failed to seal the casing.
3. The casing shoe can not be recovered from the well.
1. It is clear that the cement job failed to isolate the producing formation.
2. It seems likely that the float collar check valves and shoe track cement failed to seal the casing.
3. The casing shoe can not be recovered from the well.
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(b) Flow Condition Not Recognized (b) Flow Condition Not Recognized
• Two negative tests conducted, and accepted by the crew as successful.
• Negative test interpretation made more difficult by the presence of unusual spacer.
• No standard procedure for negative test.• Pit levels confusing because of fluids
being offloaded to service vessel.
• Two negative tests conducted, and accepted by the crew as successful.
• Negative test interpretation made more difficult by the presence of unusual spacer.
• No standard procedure for negative test.• Pit levels confusing because of fluids
being offloaded to service vessel.
January 3, 2011January 3, 2011 2222
The SpacerThe Spacer
• 425 barrels of mixed lost circulation material LCM, Form-A-Squeeze and Form-A-Set.
• Unconventional to use as a spacer, about four times more material than usual.
• Dischargeable material, but only if it had been used in the well.
• Spacer may have entered kill-line and caused anomalous U-tube pressures.
• 425 barrels of mixed lost circulation material LCM, Form-A-Squeeze and Form-A-Set.
• Unconventional to use as a spacer, about four times more material than usual.
• Dischargeable material, but only if it had been used in the well.
• Spacer may have entered kill-line and caused anomalous U-tube pressures.
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• First test• Annular leaked• Spacer backflowed
below BOP• Crossed kill-line
• First test• Annular leaked• Spacer backflowed
below BOP• Crossed kill-line
Source: BP Report Sept. 8, 2010
January 3, 2011January 3, 2011 2424Source: BP Report Sept. 8, 2010
• Second test• Possible kill line
blockage or U-tube• Zero pressure on
kill line
• Second test• Possible kill line
blockage or U-tube• Zero pressure on
kill line
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January 3, 2011January 3, 2011 2525Source: BP Report Sept. 8, 2010
• Second test• Possible kill line
blockage or U-tube• Zero pressure on
kill line
• Second test• Possible kill line
blockage or U-tube• Zero pressure on
kill line
Sea Floor
Shoe – 18,304’
FC – 18,115’
TOC – 17,260’
Shoe – 17,168’
KillChokeBoost
SOBM
Spacer
Seawater
Influx
SOBM
Spacer
Seawater
Influx
BOP
1400PSI
0PSI
Spacer
January 3, 2011January 3, 2011 2626
http://www.deepwaterinvestigation.com/go/doc/3043/820875/
spacerapproachessurface
trip tankemptiedinto line
DP pressincreasingat const flow
flow outwithoutflow in
Flow diverted overboard,no more flow-out indicator
DP pressincreasingat zero flow
sheentest
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January 3, 2011January 3, 2011 2727
spacerapproachessurface
trip tankemptiedinto line
DP pressincreasingat const flow
flow outwithoutflow in
Flow diverted overboard,no more flow-out indicator
DP pressincreasingat zero flow
sheentest
http://www.deepwaterinvestigation.com/go/doc/3043/820875/
flow outwithoutflow in
flow diverted overboard,no more flow-out indicator
DP pressincreasingat zero flow
sheentest
spacer fullydisplaced,pumps shut
DP pressincreasingat zero flow
HC entersriser
January 3, 2011January 3, 2011 2828http://www.deepwaterinvestigation.com/go/doc/3043/820875/
HC entersriser mud overflows
flow line
mud shootsup derrick
annular closed
annu
lar le
aking
VBRclosed?
gas hissinggas alarm
engineoverspeed
explosion
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(c) Gas Ignited on the Rig(c) Gas Ignited on the Rig
• Gas was diverted to the MGS, instead of to the overboard diverter [BP].
• IBOP was not closed [BP]. • Engine room intake closure was not
activated automatically on gas alarm [testimony].
• Engine overspeed loss of power (and source of ignition?) [testimony]
• Gas was diverted to the MGS, instead of to the overboard diverter [BP].
• IBOP was not closed [BP]. • Engine room intake closure was not
activated automatically on gas alarm [testimony].
• Engine overspeed loss of power (and source of ignition?) [testimony]
January 3, 2011January 3, 2011 3030
Gas Dispersed Over DeckGas Dispersed Over Deck
Source: BP Report Sept. 8, 2010
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Engine Intakes on Aft DeckEngine Intakes on Aft Deck
Source: Mark Zoback, Deepwater Nautilus
January 3, 2011January 3, 2011 3232
Fire and Gas Alarm SystemsFire and Gas Alarm Systems
• BP Investigation Report:– “A flammable mixture was likely transferred
into the engine rooms because the engine room HVAC fans were not designed to shut down automatically on gas detection.”
– “There was a high level of reliance upon manual/human intervention in the activation of DH safety systems…”
• BP Investigation Report:– “A flammable mixture was likely transferred
into the engine rooms because the engine room HVAC fans were not designed to shut down automatically on gas detection.”
– “There was a high level of reliance upon manual/human intervention in the activation of DH safety systems…”
Source: BP Report Sept. 8, 2010
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(d) BOP Failed to Seal the Well(d) BOP Failed to Seal the Well
Source: BP Report Sept. 8, 2010
Sea Bed
Wellhead Connector
Wellhead
Upper Annular
Lower AnnularStripping Element
Casing Shear Ram(Non Sealing)
Upper VBR
Middle VBR
Lower (Test) VBR
Blind Shear Ram
Flex Joint LMRP
Sea Bed
Wellhead Connector
Wellhead
Upper Annular
Lower AnnularStripping Element
Casing Shear Ram(Non Sealing)
Upper VBR
Middle VBR
Lower (Test) VBR
Blind Shear Ram
Flex Joint LMRP• Manual:– HP line (BSR)– EDS
• Automatic:– AMF on loss of
power/mux/HP• ROV:
– Hot stab– Autoshear
• Manual:– HP line (BSR)– EDS
• Automatic:– AMF on loss of
power/mux/HP• ROV:
– Hot stab– Autoshear
3 modes of closure
January 3, 2011January 3, 2011 3434Sea Bed
Wellhead Connector
Wellhead
Upper Annular
Lower AnnularStripping Element
Casing Shear Ram(Non Sealing)
Upper VBR
Middle VBR
Lower (Test) VBR
Blind Shear Ram
MUX cables provide electronic communication and electrical power to
the BOP control pods.
Annular BOPgradually opens
BOP Response (Impact of Explosions)
April 20th
Damage to MUX cables and hydraulic line
– Opening of annular BOP
Rig drifted off location
– Upward movement of the drill pipe in the BOP
Source: BP presentation to NAE PanelSept. 26, 2010
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January 3, 2011January 3, 2011 3535Sea Bed
April 20th
EDS attempts failed to activate BSR
AMF sequence likely failed to activate BSR
April 21st – 22nd
ROV hot stab attempts to close BOP were ineffective
ROV simulated AMF function likely failed to activate BSR
ROV activated auto-shear appears to have activated but did not seal the well
April 25th – May 5th
Further ROV attempts using seabed deployed accumulators were unsuccessful
Wellhead Connector
Wellhead
Upper Annular
Lower AnnularStripping Element
Casing Shear Ram(Non Sealing)
Upper VBR
Middle VBR
Lower (Test) VBR
Blind Shear Ram
BSR activated byAuto-shear
BOP Response (After the Explosions)
There are several emergency methods of activating the BSR to seal the well.
Source: BP presentation to NAE PanelSept. 26, 2010
January 3, 2011January 3, 2011 3636
BSR the Only OptionBSR the Only Option• Even if the annulus had been closed, the
drill pipe was still open.• Even if the annulus had been closed, the
drill pipe was still open.
Source: BP web site
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Why AMF Unsuccessful?Why AMF Unsuccessful?
Source: BP Report Sept. 8, 2010
January 3, 2011January 3, 2011 3838
ROV OperationsROV OperationsSource: US Coast Guard
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January 3, 2011January 3, 2011 3939Source: US Coast Guard
January 3, 2011January 3, 2011 4040
Why ROV Operations Unsuccessful?Why ROV Operations Unsuccessful?
• Hydraulic leak on BOP• Hydraulic leak on BOP
Source: BP Report Sept. 8, 2010
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Why ROV Operations Unsuccessful?Why ROV Operations Unsuccessful?
• BSR can only shear drill pipe – not tool joints, casing, or collars.
• BSR functioned by EDS(1), AMF and ROV.
• If tool joint in bore, cannot cut it.
• BSR can only shear drill pipe – not tool joints, casing, or collars.
• BSR functioned by EDS(1), AMF and ROV.
• If tool joint in bore, cannot cut it.
Source: BP Report Sept. 8, 2010
Sea Bed
Wellhead Connector
Wellhead
Upper Annular
Lower AnnularStripping Element
Casing Shear Ram(Non Sealing)
Upper VBR
Middle VBR
Lower (Test) VBR
Blind Shear Ram
Flex Joint LMRP
Sea Bed
Wellhead Connector
Wellhead
Upper Annular
Lower AnnularStripping Element
Casing Shear Ram(Non Sealing)
Upper VBR
Middle VBR
Lower (Test) VBR
Blind Shear Ram
Flex Joint LMRP
Source: BP Report Sept. 8, 2010
January 3, 2011January 3, 2011 4242
4. How to Do It Better?4. How to Do It Better?
• Bureau of Ocean Energy Management (was Minerals Management Service MMS)
• US Coast Guard• American Petroleum Institute• “Flag State” (Republic of Marshall Islands
for Deepwater Horizon)
• Bureau of Ocean Energy Management (was Minerals Management Service MMS)
• US Coast Guard• American Petroleum Institute• “Flag State” (Republic of Marshall Islands
for Deepwater Horizon)
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My SuggestionsMy Suggestions
• A second blind shear ram (BSR).• Independent BOP activation control (audio
wave activation).• More comprehensive data from BOP
(position of rams, contents of tubulars).• Real-time modeling of fluids and pressures
in tubulars (as in simulations).• Complete off-site transmission of data.
• A second blind shear ram (BSR).• Independent BOP activation control (audio
wave activation).• More comprehensive data from BOP
(position of rams, contents of tubulars).• Real-time modeling of fluids and pressures
in tubulars (as in simulations).• Complete off-site transmission of data.
January 3, 2011January 3, 2011 4444
5. Why Don’t We Stop Doing This?5. Why Don’t We Stop Doing This?
• Gulf of Mexico accounts for 30% of US oil production, a 33% increase since 2008.
• 80% of Gulf of Mexico oil production is due to deepwater oil fields.
• One quarter of US oil production comes from deepwater oil fields.
• Global deepwater production capacity has tripled since 2000.
• Gulf of Mexico accounts for 30% of US oil production, a 33% increase since 2008.
• 80% of Gulf of Mexico oil production is due to deepwater oil fields.
• One quarter of US oil production comes from deepwater oil fields.
• Global deepwater production capacity has tripled since 2000.
Source: Shell presentation, August 25, 2010
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January 3, 2011January 3, 2011 4545
Can It Be Done Safely?Can It Be Done Safely?
• Gulf of Mexico (1/1/2000 – 12/31/2009)8499 wells spudded
• 5224 were development wells• 3426 were exploratory wells• 21 were research/other wells• 6365 were in water depths < 500 feet• 186 were in water depths 501 – 1000 feet• 1948 were in water depths > 1000 feet
• Gulf of Mexico (1/1/2000 – 12/31/2009)8499 wells spudded
• 5224 were development wells• 3426 were exploratory wells• 21 were research/other wells• 6365 were in water depths < 500 feet• 186 were in water depths 501 – 1000 feet• 1948 were in water depths > 1000 feet
Source: BOEM presentation, August 12, 2010
January 3, 2011January 3, 2011 4646Photo: US Coast Guard