| History | |
|---|---|
| Name: | Deepwater Horizon |
| Owner: | Transocean's Triton Asset Leasing GmbH |
| Operator: | Transocean |
| Port of registry: | |
| Route: | Gulf of Mexico |
| Ordered: | December 1998 |
| Builder: | Hyundai Heavy Industries |
| Cost: | US$560 million[3][4] |
| Way number: | 89 |
| Laid down: | 21 March 2000 |
| Completed: | 2001 |
| Acquired: | 23 February 2001 |
| Maiden voyage: | Ulsan, South Korea – Freeport, Texas |
| Out of service: | 20 April 2010 |
| Identification: |
|
| Fate: | Sank on 22 April 2010 after an explosion and fire |
| Notes: | Located in the Gulf of Mexico at a depth of 5,000 ft (1,500 m) at 28.736667°N 88.386944°WCoordinates: 28.736667°N 88.386944°W |
| General characteristics | |
| Class and type: | ABS +A1 DPS-3 Column Stabilized MODU |
| Tonnage: | |
| Displacement: | 52,587 t (51,756 long tons; 57,967 short tons) |
| Length: | 112 m (367 ft) |
| Beam: | 78 m (256 ft) |
| Height: | 97.4 m (320 ft) |
| Draught: | 23 m (75 ft) |
| Depth: | 41.5 m (136 ft) |
| Deck clearance: | 34.010 m (111.58 ft) |
| Installed power: |
|
| Propulsion: | 8 × Kamewa 7,375 hp, 360° fixed propeller azimuth thrusters |
| Speed: | 4 knots (7.4 km/h; 4.6 mph) |
| Capacity: |
|
| Crew: | 146 |
| Notes: | [5][6] |
On 20 April 2010, while drilling at the Macondo Prospect, a blowout caused an explosion on the rig that killed 11 crewmen and ignited a fireball visible from 40 miles (64 km) away.[13] The fire was inextinguishable and, two days later, on 22 April, the Horizon sank, leaving the well gushing at the seabed and causing the largest marine oil spill in history.
Design
Deepwater Horizon was a fifth-generation, RBS-8D design (i.e. model type), deepwater, dynamically positioned, column-stabilized,[2] semi-submersible mobile offshore drilling unit, designed to drill subsea wells for oil exploration and production using an 18.75 in (476 mm), 15,000 psi (100,000 kPa) blowout preventer, and a 21 in (530 mm) outside diameter marine riser.[5]
Deepwater Horizon was the second semi-submersible rig constructed of a class of two, although Deepwater Nautilus, its predecessor, is not dynamically positioned. The rig was 396 by 256 ft (121 by 78 m) and capable of operating in waters up to 8,000 feet (2,400 m) deep, to a maximum drill depth of 30,000 ft (9,100 m).[5] In 2010 it was one of approximately 200 deepwater offshore rigs capable of drilling in waters deeper than 5,000 ft (1,500 m).[16] Its American Bureau of Shipping (ABS) class notations were "A1, Column Stabilized Drilling Unit, AMS, ACCU, DPS-3".[2]
In 2002, the rig was upgraded with "e-drill", a drill monitoring system whereby technical personnel based in Houston, Texas, received real-time drilling data from the rig and transmitted maintenance and troubleshooting information.[17]
Advanced systems played a key role in the rig's operation, from pressure and drill monitoring technology, to automated shutoff systems[18] and modelling systems for cementing. The OptiCem cement modelling system, used by Halliburton in April 2010, played a crucial part in cement slurry mix and support decisions. These decisions became a focus for investigations into the explosion on the rig that month.
History
Construction and ownership
Deepwater Horizon was built for R&B Falcon (which later became part of Transocean) by Hyundai Heavy Industries in Ulsan, South Korea. Construction started in December 1998, the keel was laid on 21 March 2000, and the rig was delivered on 23 February 2001, after the acquisition of R&B Falcon by Transocean. Until 29 December 2004 the rig was registered in the Republic of Panama.
Transocean, through its Steinhausen, Switzerland subsidiary Triton Asset Leasing GmbH, operated the rig under the Marshallese flag of convenience. The rig was leased to BP on a 3-year contract for deployment in the Gulf of Mexico following construction. The lease was renewed in 2004 for a year, 2005 for 5 years, and 2009 for 3 years covering 2010 to 2013. The last contract was worth $544 million, or $496,800 a day, for a "bare rig", with crew, gear and support vessels estimated to cost the same.
According to R&B Falcon's filings to SEC in 2001, the transfer document between R&B Falcon and Transocean was dated 17 August 2001, and the rig was specified as "official registration number of 29273-PEXT-1, IMO number of 8764597, with gross tonnage of 32,588 and net tonnage of 9,778"[31] and the transfer value as US$340 million. As of 2010, the rig was insured for US$560 million covering the replacement cost and wreckage removal.
Drilling operations
Deepwater Horizon worked on wells in the Atlantis (BP 56%, BHP Billiton 44%) and Thunder Horse (BP 75%, ExxonMobil 25%) oil fields. It was described at times as a "lucky" and "celebrated" rig, and in 2007 was still described as "one of the most powerful rigs in the world". In 2006 it discovered oil in the Kaskida oil field, and in 2009 the "giant" Tiber oil field. The well in the Tiber field had a true vertical depth of 35,050 ft (10,683 m) and a measured depth of 35,055 ft (10,685 m), below 4,132 ft (1,259 m) of water. The well was the deepest oil well in the world, and more than 5,000 feet (1,500 m) further below the seabed than the rig's official drilling specification stated on the company's fleet list.
In February 2010, Deepwater Horizon commenced drilling an exploratory well at the Macondo Prospect (Mississippi Canyon Block 252), about 41 miles (66 km) off the southeast coast of Louisiana, at a water depth of approximately 5,000 feet (1,500 m). The Macondo prospect exploration rights had been acquired by BP in 2009,[42] with the prospect jointly owned by BP (65%), Anadarko Petroleum (25%) and MOEX Offshore 2007 (10%).[43] Deepwater Horizon was still working on the Macondo site on 20 April 2010, when a violent explosion occurred leading to destruction of the rig and the subsequent oil spill. The well was in the final stages of completion after cement had been emplaced for its last casing string. The exploratory work had been described as "concluded" with permission already having been requested from MMS to terminate operations at the Macondo site. The rig was scheduled to move to its next roles as semi-permanent production platforms, initially at the Tiber site followed by a return to the Kaskida field, an oil dome 50 miles off the coast of Louisiana.
During its operational lifetime, the rig was actively in operation for 93% of its working life (2,896 of 3,131 days). The remainder partly was time spent moving between sites.
Regulation, safety, and inspection
The Minerals Management Service (renamed on 18 June 2010 to the Bureau of Ocean Energy Management, Regulation and Enforcement, or Bureau of Ocean Energy (BOE)) is the regulatory and inspecting body for offshore oil drilling and rigs in the United States of America.[50] According to an Associated Press investigation, certain safety documentation and emergency procedure information, including documentation for the exact incident that later occurred, was absent.[49] The exact number of required monthly inspections performed varied over time; the inspections were carried out as required for the first 40 months, but after that around 25% of inspections were omitted,[49] although the investigation notes this is partly expected, since there are circumstances such as weather and movement which preclude an inspection.[49] Reports of the last three inspections for 2010 were provided under Freedom of Information legislation. Each of these inspections had taken two hours or less.[49]
During its lifetime the rig received 5 citations for non-compliance, 4 of which were in 2002 (safety, including the blowout preventer) and the other in 2003 (pollution).[49] A sixth citation in 2007 related to non-grounded electrical equipment was later withdrawn when the equipment was determined to be compliant with regulations.[49] Overall the Deepwater Horizon's safety record was "strong" according to a drilling consultant reviewing the information.[49] In 2009 the Minerals Management Service "herald[ed] the Deepwater Horizon as an industry model for safety".[49] According to AP's investigation "its record was so exemplary, according to MMS officials, that the rig was never on inspectors' informal 'watch list' for problem rigs".[49]
Explosion and oil spill[edit]
At 7:45 p.m. CDT on 20 April 2010, during the final phases of drilling the exploratory well at Macondo, a geyser of seawater erupted from the marine riser onto the rig, shooting 240 ft (70 m) into the air. This was soon followed by the eruption of a slushy combination of drilling mud, methane gas, and water. The gas component of the slushy material quickly transitioned into a fully gaseous state and then ignited into a series of explosions and then a firestorm. An attempt was made to activate the blowout preventer, but it failed.[51] The final defense to prevent an oil spill, a device known as a blind shear ram, was activated but failed to plug the well.[52]
Eleven workers were presumed killed in the initial explosion. The rig was evacuated, with injured workers airlifted to medical facilities. After approximately 36 hours, Deepwater Horizon sank on 22 April 2010. The remains of the rig were located resting on the seafloor approximately 5,000 ft (1,500 m) deep at that location, and about 1,300 ft (400 m) (quarter of a mile) northwest of the well.
The resultant oil spill continued until 15 July when it was closed by a cap.[55] Relief wells were used to permanently seal the well, which was declared "effectively dead" on 19 September 2010.[56]
Aftermath
Transocean received an early partial insurance settlement for total loss of the Deepwater Horizon of US$401 million around 5 May 2010.[57] Financial analysts noted that the insurance recovery was likely to outweigh the value of the rig (although not necessarily its replacement value) and any liabilities – the latter estimated at up to US$200 million.[58]
Litigation, ultimate roll call of damage, and the scope of final insurance recovery were all unknown as of June 2010, with analysts reporting that the aftermath was of unprecedented scale and complexity compared to previous disasters which themselves took many years to unfold and resolve. A July 2010 analysis by the Financial Times on the aftermath cited legal sources as saying that "at some point the scale of the litigation becomes so large that it really is novel", that "the situation is likely to be complicated further because the variety of probable cases means it will be hard to aggregate them into so-called class actions" and that there was "no way to put this in historical context because we have never faced anything like this before".[61] As with the Exxon Valdez disaster, litigation was being discussed in terms of a 20-year timescale.[59]
In January 2013, Transocean agreed to pay US$1.4 billion for violations of the US Clean Water Act. BP had earlier agreed to pay $2.4 billion but faced additional penalties that could range from $5 billion to $20 billion.[62] In September 2014, Halliburton agreed to settle a large percentage of legal claims against them by paying $1.1 billion into a trust by way of three installments over two years.[63] On 4 September 2014, U.S. District Judge Carl Barbier ruled BP was guilty of gross negligence and willful misconduct under the Clean Water Act (CWA). He described BP's actions as "reckless," while he said Transocean's and Halliburton's actions were "negligent." He apportioned 67% of the blame for the spill to BP, 30% to Transocean, and 3% to Halliburton. BP issued a statement strongly disagreeing with the finding, and saying the court's decision would be appealed.[64]
On 8 December 2014, The US Supreme Court rejected BP's legal challenge to a compensation deal over the 2010 Gulf of Mexico oil spill. The settlement agreement had no cap, but BP initially estimated that it would pay roughly $7.8bn (£6.1bn) to compensate victims.
Deepwater Horizon explosion
The Deepwater Horizon drilling rig explosion was the April 20, 2010, explosion and subsequent fire on the Deepwater Horizon semi-submersible Mobile Offshore Drilling Unit (MODU), which was owned and operated by Transocean and drilling for BP in the Macondo Prospect oil field about 40 miles (64 km) southeast off the Louisiana coast. The explosion and subsequent fire resulted in the sinking of the Deepwater Horizon and the deaths of 11 workers; 17 others were injured. The same blowout that caused the explosion also caused an oil well fire and a massive offshore oil spill in the Gulf of Mexico, considered the largest accidental marine oil spill in the world, and the largest environmental disaster in U.S. history.Background[edit]
Deepwater Horizon[edit]
The $560 million platform was built by Hyundai Heavy Industries in South Korea and completed in 2001. It was owned by Transocean, operated under the Marshalese flag of convenience, and was under lease to BP until September 2013.[6] At the time of the explosion, the Deepwater Horizon was on Mississippi Canyon Block 252, referred to as the Macondo Prospect, in the United States sector of the Gulf of Mexico, about 41 miles (66 km) off the Louisiana coast.[7][8][9] In March 2008, the mineral rights to drill for oil on the Macondo Prospect were purchased by BP at the Minerals Management Service's lease sale.[10] The platform commenced drilling in February 2010 at a water depth of approximately 5,000 feet (1,500 m).[11] At the time of the explosion the rig was drilling an exploratory well.[12] The planned well was to be drilled to 18,360 feet (5,600 m) below sea level, and was to be plugged and suspended for subsequent completion as a subsea producer.[11] Production casing was being run and cemented at the time of the accident. Once the cementing was complete, it was due to be tested for integrity and a cement plug set to temporarily abandon the well.[13]
Transocean safety record[edit]
The rig owner, Transocean, had a "strong overall" safety record with no major incidents for 7 years.[14] However an analysts' review "painted a more equivocal picture" with Transocean rigs being disproportionately responsible for safety related incidents in the Gulf and industry surveys reporting concerns over falling quality and performance. In the 3 years 2005 to 2007, Transocean was the owner of 30% of oil rigs active in the Gulf, and 33% of incidents that triggered a Minerals Management Service (MMS) investigation were on Transocean rigs. However, in the 3 years from 2008 to February 15, 2010, it owned 42% of rigs but was responsible for 73% of incidents. Industry surveys saw this as an effect of its November 2007 merger with rival GlobalSantaFe. Transocean "has had problems" previously with both cement seals (2005) and blowout preventers (2006), which are the suspected cause of the Deepwater Horizon loss, although Transocean states that cementing is a third party task and that it has "a strong maintenance program to keep blowout preventers working".[14] According to the Wall Street Journal online:
Pre-explosion risks and precautions[edit]
In February 2009, BP filed a 52-page exploration and environmental impact plan for the Macondo well with the Minerals Management Service (MMS), an arm of the United States Department of the Interior that oversees offshore drilling. The plan stated that it was "unlikely that an accidental surface or subsurface oil spill would occur from the proposed activities".[15] In the event an accident did take place, the plan stated that due to the well being 48 miles (77 km) from shore and the response capabilities that would be implemented, no significant adverse impacts would be expected.[15] The Department of the Interior exempted BP's Gulf of Mexico drilling operation from a detailed environmental impact study after concluding that a massive oil spill was unlikely.[16][17] In addition, following a loosening of regulations in 2008, BP was not required to file a detailed blowout plan.[18]
The BP wellhead had been fitted with a blowout preventer (BOP), but it was not fitted with remote-control or acoustically activated triggers for use in case of an emergency requiring a platform to be evacuated. It did have a dead man's switch designed to automatically cut the pipe and seal the well if communication from the platform is lost, but it was unknown whether the switch was activated.[19] Documents discussed during congressional hearings June 17, 2010 indicated that Transocean previously made modifications to the BOP for the Macondo site which increased the risk of BOP failure, in spite of warnings from their contractor to that effect. Regulators in both Norway and Brazil generally require acoustically activated triggers on all offshore platforms, but when the Minerals Management Service considered requiring the remote device, a report commissioned by the agency as well as drilling companies questioned its cost and effectiveness.[19] In 2003, the agency determined that the device would not be required because drilling rigs had other back-up systems to cut off a well.[19][20]
Pre-explosion problems and warnings[edit]
The US Coast Guard had issued pollution citations for Deepwater Horizon 18 times between 2000 and 2010, and had investigated 16 fires and other incidents. These incidents were considered typical for a Gulf platform and were not connected to the April 2010 explosion and spill.[21] The Deepwater Horizon had other serious incidents, including one in 2008 in which 77 people were evacuated from the platform when it tilted and began to sink after a section of pipe was incorrectly removed from the platform's ballast system.[22]
The American Bureau of Shipping last inspected the rig's failed blowout preventer in 2005.[23]
Internal BP documents show that BP engineers had concerns as early as 2009 that the metal casing that BP wanted to use might collapse under high pressure.[24] According to a number of rig workers, it was understood that workers could get fired for raising safety concerns that might delay drilling.[25]
In March 2010, the rig experienced problems that included drilling mud falling into the undersea oil formation, sudden gas releases, a pipe falling into the well, and at least three occasions of the blowout preventer leaking fluid.[24] The rig's mechanic stated that the well had been experiencing problems for months, and that the drill repeatedly kicked due to resistance from high gas pressure.[25] On March 10, a BP executive e-mailed the Minerals Management Service about a stuck pipe and well control situation at the drilling site, and stated that BP would have to plugback the well.[26] A confidential survey commissioned by Transocean weeks before the explosion stated that workers were concerned about safety practices and feared reprisals if they reported mistakes or other problems.[27] The survey raised concerns "about poor equipment reliability, which they believed was a result of drilling priorities taking precedence over maintenance." The survey found that "many workers entered fake data to try to circumvent the system. As a result, the company's perception of safety on the rig was distorted".[28]
The blowout preventer was damaged in a previously unreported accident in late March.[29][30] According to Transocean, workers had been performing standard routines and had no indication of any problems prior to the explosion.[31]
By April 20, the operation was running five weeks late.[25]
An April draft of a BP memo warned that the cementing of the casing was unlikely to be successful.[24] Halliburton has said that it had finished cementing 20 hours before the blowout, but had not yet set the final cement plug.[21][32] A nitrogen-foamed cement was used which is more difficult to handle than standard cement.[33]
BP Vice President of drilling, Patrick O'Bryan, was on the platform two hours prior to the explosion[34] to celebrate seven years without a "lost-time incident" with the rig's crew.[35] A BP official on board the rig directed the crew to replace the drilling mud with lighter seawater even though the rig's chief driller protested.[25]
Preliminary findings from BP's internal investigation indicated several serious warning signs in the hours prior to the blowout.[36][37] Equipment readings indicated gas bubbling into the well, which could signal an impending blowout.[24] The heavy drilling mud in the pipes initially held down the gas.[33] A House Energy and Commerce Committee statement in June 2010 noted that in a number of cases leading up to the explosion, BP appears to have chosen riskier procedures to save time or money, sometimes against the advice of its staff or contractors.[38]
Blowout[edit]
The fire aboard the Deepwater Horizon reportedly started at 9:56 p.m. CDT on April 20.[25] At the time, 126 crew were on board: 7 employees of BP, 79 of Transocean, and employees of other companies, including Anadarko Petroleum, Halliburton and M-I Swaco.[citation needed]
Transocean employees on the vessel stated that the electric lights flickered, followed by two strong vibrations. Jim Ingram stated that "on the second [thud], we knew something was wrong."[39] After the explosion, Adrian Rose stated that abnormal pressure had accumulated inside the marine riser and as it came up it "expanded rapidly and ignited."[13] According to BP's internal investigation, a bubble of methane gas escaped from the well and shot up the drill column, expanding quickly as it burst through several seals and barriers before exploding.[40] Rose said the event was basically a blowout.[13] Survivors described the incident as a sudden explosion that gave them less than five minutes to escape as the alarm went off.[41]
The explosion was followed by a fire that engulfed the platform. After burning for more than a day, Deepwater Horizon sank on April 22.[42] The Coast Guard stated on April 22 that they received word of the sinking at approximately 10:21 am.[43]
On September 8, BP published a report that suggested that the ignition source was the released gas entering the air intakes of the diesel generators, and engulfing the deck area where the exhaust outlets for the main generators were emitting hot exhaust gas.[44]
Casualties and rescue efforts[edit]
Survivors[edit]
According to officials, 126 people were on board, of whom 79 were Transocean employees, seven were from BP, and 40 were contracted; several of the BP and Transocean executives were on board for a tour of the rig, maintenance planning, annual goals review, a "Drops" safety campaign, and to congratulate the senior staff of the rig for 7 years of operations without a lost time incident.[31][45]
A total of 115 people were evacuated. Lifeboats took 94 workers to the Tidewater-owned supply boat Damon Bankston, with no major injuries, four were transported to another vessel, and 17 were evacuated by helicopter to trauma centers in Mobile, Alabama and Marrero, Louisiana.[31] Most were soon released.
The Coast Guard interviewed the uninjured workers on the Damon Bankston for several hours and then transferred them to another rig; the workers arrived in Port Fourchon, Louisiana, more than 24 hours later. The workers were transported to a hotel in Kenner, Louisiana, where they were provided with food, medical attention, and rooms with showers, and asked to fill out incident response forms. An attorney for a worker who brought suit against Transocean claimed that once the workers got to shore, "they were zipped into private buses, there was security there, there was no press, no lawyers allowed, nothing, no family members" and were coerced into signing the forms before being released; Transocean denied the allegation.[50][51]
Casualties[edit]
Initial reports indicated that between 12 and 15 workers were missing;[52] reports soon narrowed the number of missing to nine crew members on the platform floor and two engineers.[40] The United States Coast Guard immediately launched a rescue operation involving two Coast Guard cutters, four helicopters, and a rescue plane.[53][54] The two cutters continued searching through the night and by the morning of April 22, the Coast Guard had surveyed nearly 1,940 square miles (5,000 km2).[46] On April 23, the Coast Guard called off the search for the 11 missing persons, concluding that "reasonable expectations of survival" had passed.[49][55] Officials concluded that the missing workers may have been near the blast and unable to escape the sudden explosion.[56]
The following eleven individuals died:
- Jason C. Anderson, age 35
- Aaron Dale Burkeen, 37
- Donald Clark, 49
- Stephen Ray Curtis, 39
- Gordon L. Jones, 28
- Roy Wyatt Kemp, 27
- Karl D. Kleppinger, Jr., 38
- Keith Blair Manuel, 56
- Dewey A. Revette, 48
- Shane M. Roshto, 22
- Adam Weise, 24
Discovery of oil spill[edit]
On the morning of April 22, Coast Guard Petty Officer Ashley Butler stated that "oil was leaking from the rig at the rate of about 8,000 barrels (340,000 US gallons; 1,300,000 litres) of crude per day."[58] That afternoon Coast Guard Senior Chief Petty Officer Michael O'Berry used the same figure. Two remotely operated underwater vehicles (ROVs) were sent down in an attempt to cap the well but were unsuccessful.[43] Butler warned of a leak of up to 700,000 US gallons (17,000 bbl) of diesel fuel, and BP Vice President David Rainey termed the incident as being a potential "major spill."[43] On April 23 a ROV reportedly found no oil leaking from the sunken rig and no oil flowing from the well.[59] Coast Guard Rear Admiral Mary Landry expressed cautious optimism of zero environmental impact, stating that no oil was emanating from either the wellhead or the broken pipes and that oil spilled from the explosion and sinking was being contained. On April 24 Landry announced that a damaged wellhead was indeed leaking oil into the Gulf and described it as "a very serious spill".[64]
Investigation into explosion[edit]
In June, the House Committee on Energy and Commerce said BP should have tested cement at the well, which would have cost $128,000 and taken 8–12 hours.
On September 8, 2010, BP released a 193-page report on its web site. The report says BP employees and those of Transocean did not correctly interpret a pressure test, and both companies neglected ominous signs such as a riser pipe losing fluid. It also says that while BP did not listen to recommendations by Halliburton for more centralizers (devices to keep the casing from contacting the bore hole[65]), the lack of centralizers probably did not affect the cement. BP also said the crew should have redirected the flow of flammable gases. The blowout preventer, removed on September 4, had not reached a NASA facility in time for it to be part of the report. Transocean, responding to the report, blamed "BP's fatally flawed well design."[66]
On November 8, 2010, the inquiry by the Oil Spill Commission revealed its findings that BP had not sacrificed safety in attempts to make money, but that some decisions had increased risks on the rig.[67] However, the panel said a day later that there had been "a rush to completion" on the well, criticizing poor management decisions. "There was not a culture of safety on that rig," co-chair Bill Reilly said.[68] One of the decisions that met with tough questions was that BP refuted the findings of advanced modelling software that had ascertained over three times as many centralizers were needed on the rig. It also decided not to rerun the software when it stuck with only six centralizers, and ignored or misread warnings from other key tests, the panel revealed.[69]
A slide briefly appeared on the Oil Spill Commission's website which enumerated eight "risky" and "unnecessary" steps that BP was deemed to have taken. The New York Times newspaper has published a screenshot of the slide here.[70][71]
A review of seven reports[which?] on the causes of the blowout indicates that six operations, tests, or equipment functions went wrong in the final 32 hours:
1. Small diameter hole obstructed dirt circulation. The 18,300-foot, 400-ton casing string had a 5,800-foot lower portion with a 7-inch diameter. Most of the hole over this portion of casing had a 9.875 inch diameter. However, the lowest 180 feet of 7-inch casing with 4 equally spaced centralizers were squeezed into an 8.5-inch hole with only 56 feet of rathole clearance (space between the lower end of the casing string and the bottom of the drilled hole). Compressed sediment and granular infill in the 0.75-inch wide annulus (Halliburton's best practices document recommends 1.5 to 2-inch annular gap tolerance) most probably explains the need for a much-higher-than-normal pressure of 3142 psi to liquefy it (on the ninth attempt) and allow mud to circulate. The unexpectedly high pressure and subsequent lower-than-specified mud flow led to problems 2 and 3.
2. Valves to prevent cement backflow did not close. Weatherford's Auto-Fill float collar, which includes two flapper-type check valves, was installed at Macondo 180 ft above the reamer shoe at casing bottom. The valves are held open by a 2-inch diameter auto-fill tube to allow the casing to fill with mud while it is lowered down the well. BP's casing installation procedure stated: "slowly increase (mud) pump rates greater than 8 bpm to convert the float equipment (~ 500 – 700 psi) per Weatherford recommendation".[72] As the flow rate drag force during circulation and cementing was only around 30% of that required, the auto-fill tube was almost certainly not ejected and the flapper valves never closed. Some evidence suggests that personnel on the Deepwater Horizon mistakenly believed that the high pressure needed to establish mud circulation had converted the float collar.
3. Cementing inadequate. Cementing proceeded a) without flushing the annulus around the shoe track at sufficiently high rate and duration to ensure full circumferential removal of compressed sediment and good distribution of cement, and b) without converting the float collar to activate its two check valves to prevent cement backflow. Cement quality and strength may have been reduced by contamination on its way down the casing, or by mixing with lower density mud in the rathole. There was no cementing evaluation log at Macondo, which may have shown it to be inadequate.
4. Pressure test wrongly interpreted. Drill pipe was run to 8,367 ft, and was thought to be ready for mud displacement. During the "negative pressure test", for which there was no detailed procedure, a "no flow" result from the kill line was accepted, while a 1,400 psi result on the drill pipe was ignored.
5. Rising oil and gas not monitored. While displacing the mud with seawater, reservoir fluids rising up the casing should have been detected by water inflow and mud outflow monitoring before arrival of hydrocarbons at the rig floor, but no reasonably accurate outflow versus inflow observations were made.
6. Fail-safe on seabed wellhead was unable to close. After uncontrolled arrival of oil and gas at the rig floor, the blind-shear rams in the BOP stack failed to close due to the presence of off-center drill pipe.
Lawsuits[edit]
On April 21, 2011, BP filed $40 billion worth of lawsuits against rig owner Transocean, cementer Halliburton and blowout-preventer manufacturer Cameron. The oil firm alleged that failed safety systems and irresponsible behaviour of contractors had led to the explosion, including claims that Halliburton "negligently" failed to use cement-modelling software OptiCem properly to analyze safe well requirements. Part of the modelling concern was about the number of stabilising devices, known as centralisers, the well required; 21 were called for, but only 6 were used.[73]
In May 2011, MOEX Offshore, which owned a 10% stake in the well through a subsidiary and which in turn itself was majority-owned by Mitsui & Co., agreed to pay US$1.08 billion to settle BP claims against it over the accident. Some analysts had thought BP would realize a larger settlement from MOEX but there was also relief to have a first step toward resolving the multiple claims. BP's most recent estimate at the time was that the spill would cost $41.3 billion. Anadarko Petroleum held a 25% stake in the Macondo well and was an immediate focus of attention with MOEX's agreement. Also the Department of Justice was still at the time investigating whether BP was "grossly negligent" in the spill. Such a determination could lead to a "much larger liability under the Clean Water Act," a financial analyst said. With MOEX agreeing to share in the financial burden—though "the agreement isn't an admission of liability by either party"—the possibility of such a ruling by the Department of Justice seemed to some to be perhaps lessened.[74]
In June 2011, supplier Weatherford International settled with BP for $75 million.[75]
In October 2011, Anadarko Petroleum agreed to pay BP $4 billion and the two companies settled all claims between them.[76] Anadarko yielded its 25% stake in Mississippi Canyon Block 252 (Macondo) to BP in the agreement and BP will indemnify Anadarko for damage claims arising under the U.S. Oil Pollution Act, among other costs.[77]
In December 2011, Cameron International agreed to pay a $250 million settlement to BP PLC to settle all claims related to the Deepwater Horizon with neither party admitting responsibility. "BP still has not reached a settlement with Transocean ... nor Halliburton ... A trial date over lawsuits related to the accident awaits BP in February (2013)", the update continued.[78]
In September 2014, Halliburton agreed to settle a large percentage of legal claims against it over the Deepwater spill by paying $1.1 billion into a trust by way of three installments over two years.[79]
On September 4, 2014, U.S. District Judge Carl Barbier ruled BP was guilty of gross negligence and willful misconduct under the Clean Water Act (CWA). He described BP's actions as "reckless," while he said Transocean's and Halliburton's actions were "negligent." He apportioned 67% of the blame for the spill to BP, 30% to Transocean, and 3% to Halliburton. Fines would be apportioned commensurate with the degree of negligence of the parties, measured against the number of barrels of oil spilled. Under the Clean Water Act fines can be based on a cost per barrel of up to $4,300, at the discretion of the judge. The number of barrels was in dispute at the conclusion of the trial with BP arguing 2.5 million barrels were spilled over the 87 days the spill lasted, while the court found that 4.2 million barrels were spilled. BP issued a statement disagreeing with the finding, and saying the court's decision would be appealed.[80]
In July 2015 BP reached an $18.7bn settlement with the US government, the states of Alabama, Florida, Louisiana, Mississippi and Texas, as well as 400 local authorities. BP's costs for the clean-up, environmental and economic damages and penalties had reached $54bn.[81] In January 2018 a detailed estimate of the "Ultimate Costs of the Oil Spill", published in the Journal of Corporate Accounting and Finance, amounted to US$145.93 billion.[82]
In popular culture[edit]
Documentary[edit]
- In 2011, Dispatches aired March 28, 2011 a documentary by James Brabazon, BP: In Deep Water, about the oil company, BP, covering oil spills in the gulf of Mexico and other incidents and its relationship with Governments.[83][84]
- In April 2012, the National Geographic Channel's documentary series Seconds From Disaster featured the accident in an episode titled "The Deepwater Horizon," released.[85]
- In 2012, Beyond Pollution 2012[86][87][88] traveled across the gulf coast interviewing environmental experts, government authorities, fishermen, scientists, drilling engineers, and key BP contractors, examining economic and health effects.
- In 2012, The Big Fix, documented the April 2010 oil spill in the Gulf of Mexico following the sinking of the Deepwater Horizon oil rig
- In 2014, The Great Invisible, by Margaret Brown chose to focus on the social impacts on people whose lives have been affected by this tragedy.[89][90][91][92][93][94][95] Later airing April 19, 2015 as the season 16, episode 14 of Independent Lens.[96][97]
- In 2014, Vanishing Pearls: The Oystermen of Pointe a la Hache, Louisiana, documented the town of nearly 300 struggling to survive following the BP Oil Spill that left their crop dead and finances in ruin.[98][99][100][101]
- In 2016, Pretty Slick, documented the cleanup effort and locals across four Gulf states about the largest man-made environmental disaster in U.S. history.[102][103][104][105]
- In 2016, After the Spill,[106] Jon Bowermaster investigates how the disaster affected local economies and the health of humans, animals, and food sources, and with Corexit, where all the oil went, as a follow-up to the pre-spill SoLa, Louisiana Water Stories, in post-production when the Deepwater Horizon exploded.[107][108][109][110]
- In 2016, Dispatches From The Gulf,[111][112] Hal Weiner[113][114] follows scientists[115][116] investigating the oil spill's effect on the Gulf.[117][118][119]
Drama[edit]
- In 2012, "We Just Decided To", the pilot of the HBO TV series The Newsroom, featured its characters covering the Deepwater Horizon story.[120]
- The 2015 film The Runner, directed by Austin Stark and starring Nicolas Cage, is a fictional story of a politician and his family set in the aftermath of the Deepwater Horizon disaster.[121][122]
- In 2016, Deepwater Horizon, a film based on the explosion, directed by Peter Berg and starring Mark Wahlberg was released.[123]
Music[edit]
- In June 2010, Steve Goodie,[124] a comedy musician, wrote parody lyrics to The Doobie Brothers' hit song "Black Water" related to the BP oil spill. "Black Water [BP Version]" also had a YouTube video[125] and was a Top Ten hit on The Dr. Demento radio show.
- In 2011, Rise Against released a song titled "Help Is on the Way" on their album Endgame. The song is about the slow response time for aid to disaster-stricken areas, with lyrics that allude to the Macondo spill and Hurricane Katrina.[126]
- In 2012, the Dutch band Epica wrote a song titled "Deep Water Horizon" on their album Requiem for the Indifferent which highlighted humanity's take on the effect we have on global warming inspired by the events of the oil spill.
- The oil spill inspired Steve Earle's song "Gulf of Mexico".
 Anchor handling tugs and platform supply vessels combat the fire on the Deepwater Horizon while the U.S. Coast Guard searches for missing crew. | |
| Date | April 20, 2010 |
|---|---|
| Time | 22:00 UTC-6 |
| Location | Gulf of Mexico, Louisiana, United States 28°44′12.01″N 88°23′13.78″W |
| Deaths | 11 |
| Non-fatal injuries | 17 |
| Crew | 126 |
 |
Deepwater Horizon semi-submersible drilling rig. |
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