Location map with landfall and up-to-date status map up-to-date status map Times-Picayune, 22 May BP Miss Canyon 252 #1
Deepwater Horizon: State of the art “Semi-Submersible” Mobile Offshore Drilling Unit Built in Korea, completed 2001 Cost $560 Million Contracted to BP since 2002, $500k/day Designed for 8000 ft water depth, 30000 ft drill depth When operating, rig is partially submerged to keep it stable. Equipped with real-time monitoring (satellite link to BP’s Houston office)
MC 252: Normal well operations to complete a successful well Drilled to 18000 ft total depth, to be completed as a productive oil/gas well Production casing set and cemented 20 hours prior to explosion Preparing for temporary abandonment Bottom hole packer, production tubing and perforations to be installed at a later date (the wellbore should not permit fluid entry at this time).
MC 252: Normal well operations to complete a successful well Under normal operations, neither oil from depth or surface “shallow gas” can enter the wellbore in this condition Main question: What part of the wellbore integrity was breached?
April 20: Blowout and fire Explosion 9:59pm CDT 126 on board: 79 TransOcean employees, 6 BP employees, 41 contractors 115 survivors; 9 man drilling crew (TransOcean) and 2 mud engineers (Smith Intl) lost
Video of the oil leaks Multiple leak points: http://www.youtube.com/watch?v=RngYv4SYMCY http://www.youtube.com/watch?v=RngYv4SYMCY Comparison of before and after riser insertion tube: http://www.youtube.com/watch?v=hyxjGoBn-YM http://www.youtube.com/watch?v=hyxjGoBn-YM
What happened and why? Areas of concern and who would bear responsibility Routine BOP test followup (BP as operator, TransOcean as drilling contractor, MMS exemptions) Risky(?) well plan (BP) Integrity of casing cement (Halliburton) Wellhead seal integrity (TransOcean and DrilQuip (supplier)) Post-cementing test procedure and time allotted for cement to cure (BP) Hurried preparation for temporary abandonment (BP) Continued
What happened and why? Areas of concern and who would responsibility Prudent monitoring of wellbore condition during prep for temporary abandonment (TransOcean) should trump any hurry Blowout preventer (BOP) activation (TransOcean) and mechanical failure (Cameron)
Plenty of blame to go around This disaster was due to a series of errors and mistakes that compounded one another. Had any one of these preventable problems been avoided, this disaster might have been averted. Details and analysis of events follow. Analysis taken from opinions at www.drillingahead.com, a social network for oil and gas drillers and engineers. Those pages are highlighted in light blue. www.drillingahead.com
Oil field terminology Bbl – barrel of oil, 42 US gallons BOP – blowout preventer Drilling mud – heavy fluid used to control pressure while drilling and completing Casing – large diameter pipe cemented into well at various depths for safety Drillpipe – smaller pipe that connects drilling rig to drilling bit, removed when well is completed
Oil field terminology Riser – used in offshore wells to protect drillpipe from seawater BHP – bottom hole pressure (measured in mud weight equivalent (pounds per gallon) or pounds per square inch (psi)
Connecting drill rig to the subsea wellhead: Riser/BOP stack on sea floor Subsea blowout preventer (BOP) Riser: flexible 22” OD pipe; drillpipe and wellbore fluids contained within.
Riser is conduit for drillpipe into BOP on seafloor Volume between drillpipe and riser or between casing and wellbore is known as an “annulus” Specific part of BOP closes off the annulus; other parts clamp down and “shut in” the drillpipe
Analysis (1): Did the riser fail when the rig sunk? “The riser did not burst or break. When the rig went down, it took the riser with it. From the schematics I've seen, it pretty much sticks up from the BOP about 1,500', then is kinked downward to the gulf floor, and a good portion of it lies on or beneath the seabed.“ – independent analysis at www.drillingahead.com
“One tough well”: Four drilling liners, 9 strings of pipe indicate pressure problems while drilling --Times-Picayune, 19 May (from nola.com)
Analysis (2): BP’s well plan “BP's well design had a fatal flaw (ie. long string production casing instead of liner and tieback). This casing design depends upon a 100% effective cement job in order to keep the production out of the annulus behind the production casing right up to the wellhead.” -- drillingahead.com
TransOcean CEO testifies to Senate committee, 11 May "At this point, drilling mud was no longer being used as a means of reservoir pressure containment; the cement and the casing were the barriers controlling pressure from the reservoir," Newman said. "Indeed, at the time of the explosion, the rig crew, at the direction of the operator, was in the process of displacing drilling mud and replacing it with seawater."
Known bottom hole pressure problems Drilling mud: 14.5 pounds per gallon (ppg), at total depth equates to 13000 psi at the bottom of the well Prior to abandonment, cemented casing controls this pressure; drilling mud is displaced from drillpipe with seawater via routine pumping operation. Seawater at 8.3 ppg alone is incapable of withstanding that BHP. Any cement or casing failures at this time can cause well to start flowing.
TransOcean CEO testimony, 11 May “… the one thing we do know is that on the evening of Apr. 20, there was a sudden, catastrophic failure of the cement, the casing, or both," Newman said. "Without a failure of one of those elements, the explosion could not have occurred. It is also clear that the drill crew had very little, if any, time to react. The initial indications of trouble and the subsequent explosions were almost instantaneous." -- Quoted in Oil and Gas Journal, 17 May 2010
Testing cement integrity Cement Bond Log is normally run after cement has set to verify solid contact between casing and wellbore. Performed by cementing company (Halliburton) or by logging contractor (Schlumberger).
BP did not run Cement Bond Log… “BP had a Schlumberger team and equipment for sending acoustic testing lines down the well "on standby" from April 18 to April 20. But BP never asked the Schlumberger crew to perform the acoustic test and sent its members back to Louisiana on a regularly scheduled helicopter flight at 11 a.m.” -- Times-Picayune, 19 May (Nola.com)
… despite known deepwater cementing issues … Gas flow may occur after a cement job in deepwater environments that contain major hydrate zones. Destabilization of hydrates after the cement job is confirmed by downhole cameras. The gas flow could slow down in hours to days if the destabilization is not severe. However, the consequences could be more severe in worse cases. Presented by Halliburton to AADE, 18 Nov 09
… in the presence of methane hydrates Cement slurry should be placed in the entire annulus with no losses Temperature increase during slurry hydration should not destabilize hydrates There should be no influx of shallow water or gas into the annulus The cement slurry should develop strength in the shortest time after placement Conclusion reached by Halliburton: Conditions in deepwater wells are not conducive to achieving all of these objectives simultaneously Presented by Halliburton to AADE, 18 Nov 09
Methane Hydrates known to be present in deepwater Gulf of Mexico Ice crystals surrounding methane bubbles Ice forms in cold water at the seabed, not in the warmer conditions at the bottom of a deep well. Cement curing gives off heat, the ice melts, methane released, resulting in “the ice that burns.”
Analysis (3): Cementing “This flaw was "enabled" with an equally fatal cement design. The 51 bbl cement job was too small to begin with and was undoubtedly very contaminated by the time it reached the casing shoe, ie. being pumped 18,360 ft through 3 different sized inside diameters …. Any experienced cement hand would have counseled against it and would have recommended running a liner just to get the cement in place uncontaminated.” -- drillingahead.com
Damages during prior operations? At the top of each liner, a rubber packer is installed to seal the joint with the liner above. Mike Williams … claimed that the blowout preventer was then damaged when a crewman accidentally moved a joystick, applying hundreds of thousands of pounds of force [?]. Pieces of rubber were found in the drilling fluid, which he said implied damage to a crucial seal. But a supervisor declared the find to be “not a big deal”, Mr Williams alleged. --http://www.timesonline.co.uk/tol/news/world/us_and_americas/ article7128842.ece
Analysis (4): What were the exact order of procedures? “monitoring the volumes and rates that fluids are pumped and returned from a well is the number one cardinal rule to maintaining constant BHP and control of the well. ” “Probably … taking the well returns to the rig and pumping them to the workboat at the same time made it difficult to measure and track the returns rate. ” “If the fluid was going to the boat from the same tank it was being received from the well - it would be very difficult to determine pit gain or loss with any degree of accuracy. ”
Analysis (5) “Nature always finds the hidden flaw” “it may be true that BP had the misfortune to have two bad things happen - bad primary cement job (ask here how long they [waited for cement to cure]?), and to also have the wellhead seals fail (ask here why displace the well to seawater until the cement plug is hard and why was the riser open during the displacement?)” -- drillingahead.com
Events recorded on Halliburton’s real-time log, 20 April At 2010, mud pit volume increases At 2018, mud is gas-cut At 2020, flow up riser detected Gas units Mud pit vol change Flow up riser Note: this is a chronological record; time increases down the page
Halliburton log: 20 April At 2108 downhole ciruculation was stopped; indication that driller was working the problem At 2110 mud pit pumped down At 2112 static pressure rise confirms that well is flowing up riser, BOPs partially activated Mud pit vol Static pressure
At 2130 circulation stopped: well manually shut in? At 2147 pressure jump (1200-5800 psi), prior to explosion, could this be seawater in riser pushed up gas from below? At 2149 (not logged) gas in riser escapes at surface, reports of loud hissing noise, explosion follows Halliburton log: last minutes Static pressure
Analysis (6): well control procedure “With a gas & oil influx rising in the annulus increasing the pressure in the annulus - BP further lightened the weight of the casing string by displacing with seawater - the entire production became buoyant and lifted allowing the seals to become unseated which allowed the gas & oil into the BOP's and riser.” --drillingahead.com
Eyewitness account: TransOcean rig hand "The derrickman called the driller and said he needed help, he had mud going everywhere, and about this time the drill floor disappeared, then there was an explosion, then a second explosion." -- quoted on www.drillingahead.com Derrickman works up here
Captain of the nearby workboat Damon Bankston Shortly after 9 p.m. CDT, "my mate advised there was mud coming off the rig. It looked like it was a black rain coming down," Landry said. Landry said he heard something else that concerned him: the loud hiss of a high-pressure release of air and gas that lasted for 30 seconds or more. … this was the sound of a surge of methane rushing up the drill pipe which engulfed the rig's deck in highly-flammable gas. --- money.cnn.com, 11 May
Captain of the Damon Bankston The rig's captain, Curt Kuchta, said his crew had slammed a "kill switch" on the drill deck meant to activate an underwater blowout preventer that is designed as a fail-safe method of shutting off the well. "He said they pressed the kill switch," Landry said. "They didn't know if it worked." Driller’s control panel on modern rig
Subsea BOP stack: Manual controls on rig floor and fail-safe automatic controls at seafloor If communication with rig is lost or other serious problem detected, BOP shuts itself in.
MMS grants subsea BOP stacks an exemption? 10 Feb test http://energycommerce.house.gov/Press_111/20100512/Transocean- Deepwater%20Horizon%20BOP%20Test.pdfhttp://energycommerce.house.gov/Press_111/20100512/Transocean- Deepwater%20Horizon%20BOP%20Test.pdf
No backup needed for the automatic kill system? In 2003, U.S. regulators decided remote- controlled safeguards needed more study. A report commissioned by the MMS said "acoustic systems are not recommended because they tend to be very costly." (WSJ, 28 April) … it decided the remote device wasn't needed because rigs had other back-up plans to cut off a well." (WSJ) WSJ
TransOcean studied prior BOP failures “Floating drilling rig downtime due to poor BOP reliability is a common and very costly issue confronting all offshore drilling contractors.... Depending on the drilling contract in place and the nature of the downtime cause, BOP failure can result in substantial revenue loss” -- http://media.mcclatchydc.com/static/pdf/Les-oilspill-ABSC.pdf
BOP Problems Continue “A 2008 paper co-authored by Jeff S. Shepard,” [a TransOcean manager], "cautioned that "BOP shear rams may also have difficulty shearing today's high- strength, high-toughness drill-pipe” --http://www.courthousenews.com/2010/05/14/27286.htm
BOP problems addressed by UNOCAL moving this equipment to the surface (SBOP) In a study … 7,200 subsea BOP days were considered in water depths greater than 1,312 ft. … 31 BOP failures occurred that had the potential for uncontrolled flow. This translates to 4.1 incidents per 1,000 BOP days. In comparison, Unocal has recorded four incidents that had the potential for uncontrolled flow over 1,360 SBOP days. This yields 2.9 incidents per 1,000 SBOPdays. -- http://www.iadc.org/dcpi/dc-julyaug03/July3-surface%20BOP.pdf
No question that the BOP failed “oil was flowing into the [BOP] at 8,000 to 9,000 psi and flowing out into the Gulf at around 2,650 psi.” http://blog.al.com/live/2010/05/national_incident_commander_oi_1.h tml http://blog.al.com/live/2010/05/national_incident_commander_oi_1.h tml
Conclusion: The TransOcean driller did his job to the end, knowing he was in imminent grave danger. If the activated BOP worked as designed at this point, the fire could still have taken the rig with the losses, but the well’s subsequent flow (and resulting massive oil spill) would have stopped.
Analysis (7): BOP failure and failure to react “When the blind/shear rams were closed - they couldn't quite cut cleanly through the production casing and the 3-1/2" tubing.” “Basic well control procedures were overlooked (ie. we are now in a cased hole situation - what could possibly happen?), and the rapidly expanding gas resulting in classic kick signs of rapid increase in returns rate and pit gains - were not recognized and acted upon.” -- drillingahead.com
How big is the spill? BP’s initial guess of 5000 Bbl/day * 60 days to relief well (hopefully) = 300 MBbl Other estimates mid range 50000 Bbl/day * 60 days = 3 MMBbl If relief well takes 90 days, at current flow rate, that’s 4.5MMBbl The reservoir is estimated to contain 100 MMBbl recoverable oil with a high ratio of gas to oil (unconfirmed) Note: oil industry uses ‘M’ to indicate thousands, ‘MM’ for millions
Compare 3-4.5MMBbl to the three largest spills on record Gulf War (Persian Gulf, 1991) 10 MMBbl Ixtoc 1 (Bay of Campeche, 1979-80) 3.4 MMBbl Atlantic Empress (Caribbean Sea, 1979) 2.1MMBbl (most spills of this size are tanker accidents) Note: this is much worse than the Exxon Valdez (Alaska, 1989) 250MBbl, a relatively small volume of oil as spills go Note: oil industry uses ‘M’ to indicate thousands, ‘MM’ for millions
Beware: there’s lots of overstatement going on! Brian Williams, 5/25: “this well could give off oil, unfettered, for the rest of our lives”Brian Williams, 5/25 NO offshore oil field has EVER produced that much or flowed for that long. Most blowouts that are left uncontrolled eventually die on their own: High flow rates damage the oil reservoir.
What didn’t happen North Korean torpedo attack Secret conspiracy between BP and government to thwart offshore drilling Secret government weapons test
Use explosives to blow it up – just makes a small hole much bigger Use a nuclear weapon – this isn’t a movie Use a submarine – at 5000’ water depth? Government take over operations – neither DOE nor MMS have drilling expertise “Mother of all gushers could kill Earth’s oceans” – check those volume comparisons again!kill Earth’s oceans What can’t happen
Additional information One easy-to-read explanation of offshore oil exploration and drilling; another and yet anothereasy-to-read explanationanother Live video feed from seafloorLive video feed Video of rig fire and sinkingrig fire and sinking Official response siteresponse site EPA spill sitespill site NOAA spill sciencespill science List of over 200 deepwater (>1000’) oil and gas discoveries in the Gulf of Mexicooil and gas discoveries