Disaster can happen at any time.
On Tuesday 20 April 2010 (the eve of Earth Day) a large explosion onboard the TransOcean owned Deepwater Horizon drilling rig (MC252)s leased to BP to drill for oil in the Gulf of Mexico cost 11 of the 126 workers on the rig their lives.
The Warning Signs
At approximately 20:10 the first warning sign occurred with a large increase in the mud pit volume, indicating an influx of gas. Shortly after a measurable increase in gas was noticed. Approximately 1 hour after the mud pit volume increased the rig stopped drilling. This resulted in the pit volume dropping as expected. Shortly after pumping resumed but the riser flow rate then increased much quicker than it should have. Again workers stopped pumping mud at approximately 21:15 but the the pit volume increased even though pumping had stopped. Warning bells should have gone off as fluctuations in the standpipe pressure were recorded at approximately 21:35. About 10 minutes later a huge increase in standpipe pressure was recorded increasing from 1200psi to off the scale at 5000psi within the space of under two minutes - The blowout had begun. At 21:49 less than 2 minutes after the blowout began at all communications were lost.
"That's something you learn at well-control school," said Capt. Carl Smith, a former Coast Guard captain serving as an expert witness for the investigative panel. "If you're circulating fluid, you need to monitor how much is going in and how much is coming out. If you get more fluid out than in, it's an indicator that something's going on."
Anchored some 52 miles southeast of the Louisiana Port of Venice in very deep water in the Gulf of Mexico, the well had found oil beneath 5,000 feet of water and 13,000 feet of rock when something went seriously wrong causing an explosion and fire resulting in the drilling rig ultimately collapsing and sinking to the ocean floor. As the oil rig sank the riser tube of the well crumpled and split resulting in a large flow of crude oil spewing from the wells damaged riser pipeline into the waters of the Gulf of Mexico. BP estimated the flow from the damaged well to be approximately 5,000 barrels a day, a figure held onto by BP despite mounting evidence pointing to the actual rate being much higher. Based on early satellite imagery from the NASA / MODIS Terra satellite SkyTruth have estimated the actual rate of flow to be closer to 10 times that amount, a fact which BP officials denied up until quite recently. As time moves on more people have access to the video BP "didn't want you to see" and scientists have analysed the feed and agree the real extent of the spill is much larger than BP would like to admit.
British oil giant BP is coming under increasing fire from the public and US Federal Government for their actions or lack of, leading up to and since the disaster. It has been revealed that there were indications something was wrong hours before the initial explosion.
The explosion was initially caused by a lage burst of methane gas rising unchecked from the well deep under the ocean, through the blowout preventer which is meant to stop it and up the bore shaft. The rapidly expanding gas ignited causing a huge explosion which caused the rig to list badly to one side shortly before sinking to the bottom of the ocean some 5000 feet below the surface.
The rig, larger than a football field now sits upside down on the bottom of the Gulf of Mexico. The 21" riser was crumpled with the drill inside. The riser is bent at a 90-degree angle about 5 feet above the blowout preventer and oil is spewing from an "irregular crack". A second smaller leak is some 460 feet away in a section of the riser that lies on the floor of the Gulf of mexico. The third smaller leak from the end of the drill pipe about 800 feet away from the blowout preventer.
The blowout preventer is a huge valve which sits atop the well shaft on the ocean floor. In the event of the well going out of control the blowout preventer is supposed to clamp shut with huge force and close the well. The rams are designed to either crush closed or cut through and block the steel riser pipe from the well. The BOP valve is the last line of defense in shutting off a well that is out of control. It has been revealed that BP knew there was a problem with the huge valve manufactured by drilling equipment supplier Cameron. Further revelations include the fact that one of the control pod batteries in the BOP was dead, hydraulics were leaking and a missing seal which potentially could have avoided mess altogether was not in place instead a test part was in it's place.
Initially BP refused to release any photos or video footage of the oil leaks saying trying to work out the flow rate would distract from the more important task at hand of stopping the leak. After increased pressure from the government and the scientific community BP finally relented and made public a Live Feed from one of their underwater ROV's showing the oil and gas mixture leaking from the damaged riser. It shows a worrying picture and goes a long way to explaining BP's reluctance to release the live feed. The video feed from one of their underwater ROV's (remotely operated vehicle) shows huge amounts of crude oil and methane gas under incredible pressure gushing constantly into the ocean.
It should be remembered that this is not some garden hose it is a 21" (53cm) diameter pipe and the volume of oil still leaking is shocking. Especially so considering that BP now claim they are removing 5,000 barrels a day through the Riser Insertion Tube they placed into the damaged riser on day , the total quantity they initially claimed was being released from the well. It is obvious that there is a lot more oil still spilling around the insertion tube and if there was any truth to the 5,000 barrel figure at was in fact true they have placed inside the damaged riser.This has been going on for over a month now.
Timeline - A brief timeline of the disaster
Tuesday, April 20 - News broke that an explosion occurred at 11 p.m. EST on BP's Deepwater Horizon oil rig in the Gulf of Mexico, 52 miles southeast of the Louisiana port of Venice.
Wednesday, April 22 - Helicopters and ships resumed the search for 11 missing workers. The oil rig is still burning, leaving a huge plume of smoke that is more than 30 miles long. Later that day, the fire was extinguished, after which the oil rig sank.
Monday, April 26 - Search-and-rescue operations have been suspended with 11 people still missing, while underwater robots have discovered at least two leaks that are dumping an estimated 1,000 barrels of oil per day in the sea.
Wednesday, April 28 - Stopping the leak is so technically challenging that experts realize it could take months.
Thursday, April 29 - It is discovered that the leak is not spewing the equivalent of 1,000 barrels of oil per day, but rather 5,000. By end of day, the oil slick has reached the Mississippi Delta.
Friday, April 30 - The Times-Picayune reports that "The state departments of Health and Hospitals and Environmental Quality said the strong odor blanketing much of coastal Louisiana and the metro New Orleans area is 'possibly' the result of the massive oil spill in the Gulf of Mexico." Meanwhile, Obama puts a halt on any new offshore drilling
Saturday, May 1st - SkyTruth, a small non-profit, analyzed radar and satellite imagery and estimated that the oil was leaking much faster than the original official estimates. The initial figure was 1,000 barrels/day, which they successfully challenged with a new estimate of 5,000 barrels/day. But even that proved too optimistic, and on Saturday they revised their estimate to 25,000 barrels/day!
Monday, May 3rd - BP is trying to install a shutoff valve on one of the three underwater leaks, but this is a complicated operation that might not succeed.
Wednesday, May 5th - A barge begins towing a 98-ton containment chamber to the site of the leak. BP says one of the three leaks has been shut off by capping a valve, but that would not cut the amount of oil gushing out. Officials conduct controlled burns to remove oil from the open water, the first since April 28.
Thursday, May 6 - Oil washes ashore on the Chandeleur Islands off the Louisiana coast, uninhabited barrier islands that are part of the Breton National Wildlife Refuge and important nesting and breeding areas for many bird species.
Friday, May 7 - BP engineers use undersea robots to move the containment chamber over the larger of the two remaining leaks on the seabed. The firm abandons efforts to close valves on a failed blowout preventer with underwater robots. A fishing ban for federal waters off the Gulf is modified, expanded and extended to May 17.
Saturday, May 8 - BP's containment dome hits a snag when a buildup of crystallized gas forces engineers to postpone efforts to place the chamber over the oil leak and siphon oil to the surface. "Tar balls" suspected to come from the leak wash up along a half-mile stretch of Dauphin Island, Alabama.
Sunday, May 9 - BP says it might try to plug the undersea leak by pumping materials such as shredded up tires and golf balls into the well at high pressure, a method called a "junk shot."
Monday, May 10 - Latest forecasts suggest the oil spill could move significantly west of the Mississippi River delta as brisk onshore winds prevail. BP announces plans to place a small containment dome, known as a "top hat," over the blown out well to funnel oil to the surface.
Tuesday, May 11 - Executives with BP, Transocean and Halliburton appear at congressional hearings in Washington, where Senators criticize their safety records. The executives blame each other's companies for the explosion.
Wednesday, May 12 - BP brings in it's second smaller containment dome the "Top Hat". About 5 feet tall and 4 feet across the design would allow engineers to pump in methanol in order to prevent the methane hydrates from freezing and plugging the hole as happened on the earlier containment box.
Friday, May 14 - BP puts aside it's Top Hat containment dome for a different strategy, inserting a tube into the damaged riser to suck the oil out and pump it into a ship on the surface.
Sunday, May 16 - Interior Secretary Salazar issues a statement expressing caution about the effectiveness of the riser insertion tube and that it is not a solution.
Monday, May 17 - Hearings begin in the Senate as lawmakers try to assess the response to the spill.
Tuesday, May 18 - Nearly 48,000 square miles in the Gulf of Mexico are now closed to fishing
Wednesday, May 19 - BP announces it is "Very Pleased" with the success of the insertion tube as oil makes landfall on the Louisiana coastline.
Thursday, May 20 - EPA Issues directive to BP requiring them to Identify and Use Less Toxic, More Effective Dispersant
Saturday, May 22 - President Obama signs executive order establishing the bipartisan National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling tasked with providing recommendations on how we can prevent and mitigate the impact of any future spills that result from offshore drilling.
Monday, May 24 - BP is ordered by the EPA to immediately cut back its use of dispersant chemicals
- Tuesday, May 25 -
- Wednesday, May 26 -
- Thursday, May 27 - BP Starts Top Kill procedure.
Oil Cleanup Techniques
The basic techniques used to contain offshore spills haven't changed much in the past three decades, but spills are now tracked by satellite; containment booms stand up better to waves; skimming technology has improved; and chemical dispersants, used to break up the oil into smaller particles, are now less toxic, though they still have a harmful effect on the environment.
"Though methods may have been refined and improved, the techniques are still basically the same.
Recovery rates – how much of the oil is removed from the ocean – haven't improved, they still hover at around
10 percent of the total spill."
Dispersants break up oil into droplets that linger longer in the water instead of collecting at the surface. The choice to use them is inherently an environmental tradeoff. Their use in the Gulf spill has limited the instances and images of oil-covered seabirds, but has kept the effects of the spill mostly underwater. In the case of the Deepwater Horizon, dispersants have been pumped directly into the source of the leak for the first time.
Dispersant chemicals are a good option to work on spills, but the problem is that BP is using Corexit, a dispersant that was banned in the UK in 1998 due to concerns over its effectiveness and toxicity. Corexit was used in the Exxon Valdez disaster and has been linked with human health problems including respiratory problems, liver and kidney problems and nervous disorders. BP has defended it's use of Corexit by saying its "pretty effective" and "rigorously tested" and BP has ruled out testing other dispersants saying it is "focussed on stopping the spill".
According to EPA data, Corexit ranks far above dispersants made by competitors in toxicity and far below them in effectiveness in handling southern Louisiana crude. Of 18 dispersants EPA has approved, 12 were found to be more effective on southern Louisiana crude than Corexit. Two of the 12 were found to be 100 percent effective on Gulf of Mexico crude, while the two Corexit products rated 56 percent and 63 percent effective, respectively. The toxicity of the 12 was shown to be either comparable to the Corexit line or, in some cases, 10 or 20 times less, according to EPA. It has been suggested that BP are using this particular dispersant as they have strong ties to the manufacturing company Nalco.
Scientists have discovered giant plumes of dispersed oil deep in the waters of the Gulf however the EPA has said "there is no information currently available" to link the dispersants to those deep-sea plumes. But of course we can draw our own conclusions there.
HOW MUCH OIL!!!
Methods tried by BP
The first method attempted was to lower a 4 storey high, 100 tonne steel containment box over the leak and siphon the oil to the surface for collection by a processing vessel on the surface.The oil would be removed and stored onboard, while the seawater is dumped back into the ocean. The containment box idea did not work due to the freezing temperatures which caused escaping methane gas to condense and mix with the seawater. The frozen slushy mixture known as hydrate clogged the opening in the top of the containment box rendering it useless.
The Top Hat was a second containment box attempt, much smaller than the first it was intended to be placed over the leak, the smaller size meant engineers hoped to be able to pump methanol and heated water into the chamber to prevent the hydrates from forming. The chamber was constructed and transported to the MC252 site, from there it was lowered to the seabed, but it was cast aside as doubts emerged that it would work.
The "Top Kill" method attempts to stop the flow of pressurised oil by pumping heavy drilling mud into the Kill and Choke lines on the Blowout Preventer. If sufficient pressure can be generated to overcome the oil pressure and sufficient volume can be pumped into the well the pressure of the drilling mud should halt the flow of oil. If successfull an attempt will then be made to pump cement in which should hopefully seal the well. The Top Kill has never been attempted at this depth and BP rate the chances of success at about 60-70%
The so called Junk Shot, is just that. If sufficient quantities of "junk" comprised of golf balls, pieces of rubber tyres, knotted rope and the like are pumped into the blowout preventer in the hopes of clogging the chambers with the junk. If successful the junk shot would then be followed up with a cement seal to permanently close the well. It turns out the Junk shot and the Top Kill both failed. Rumour is that these failed because BP discovered that the well casing has been fractured and the drilling mud they were pumping into the well bore was leaking out about a thousand feet below the seabed. Reports are now coming in of oil seeping from the ground around the blowout preventer.
A containment cap was fitted to the well with the intention of using it to contain the oil which would then be pumped to a vessel above for processing. It seems the cap is actually containing very little oil and the majority of it is still leaking around the cap. As it was lowered onto the top of the sheared off riser on the BOP it was immediately obvious that it was collecting very little oil
The last hope. BP is in the process of drilling two relief wells, these are intended to intercept the existing bore shaft and take pressure off the blowout preventer allowing BP engineers a better chance of closing the failed BOP. As time has gone on it seems that BP have now abandoned hope of closing the BOP due to the belief the well is compromised below the seabed, and any attempt to cap it to stop the flow may force oil into cracks in the surrounding rock. It is uncertain if even two relief wells will be sufficient to stop this gusher. Reports are that it may be Christmas 2010 before the relief wells are completed. The drilling is going well, but it is now approaching hurricane season which will slow the drilling, and as we know, oil and hurricanes are a bad mix.
BP and Contractor Failures
- BP is knowingly using COREXIT dispersants banned in England with the blessing of the EPA. Some news agencies report that BP has financial connections to the company that sells the dispersant. The claims are that the dispersant company’s leadership includes executives from BP and Exxon. The EPA has ordered BP to consider less toxic alternatives to COREXIT and more recently to scale back its use of dispersants
- BP refused to allow scientists to measure the amount of oil flowing into the Gulf, all the while saying it was about 5,000 barrels a day. Yesterday (5/20/10) they finally admitted that was wrong. Yesterday a Purdue University scientist told a Congressional committee that his estimates are between 75,000 to 115,000 barrels a day. If he’s right, this spill would be the second largest in the world.
- BP may have purposely chosen not to do a final test that might have averted this catastrophe.
- The Blowout Preventer appears to have a "significant" leak in a key hydraulic system. Halliburton might have left out a seal in the pipe that would’ve avoided the catastrophe.
- The test BP chose NOT to conduct might have revealed the missing seal.
- The Blowout Preventer had been modified. A useless test ram - rather then the variable bore ram - had been connected to the socket that was supposed to activate the variable bore ram.
- The US team has learnt that the BOP was not powerful enough to cut through joints in the drill pipe
- The emergency controls on the BOP failed. The emergency controls likely failed because the explosion that caused the emergency also disabled communications to the blowout preventer.
- Another emergency control the "deadman switch” which is supposed to activate the shutoff system when all else fails may not have been enabled on the control panel prior to the BOP being installed on the ocean floor
- The deadman switch relies on two control pods. When one of the control pod panels was removed and inspected after the spill began, the battery was found to be dead.
- While some functions on the BOP may have been tested in the weeks before the explosion, emergency systems, including the deadman system and the leaking emergency hydraulic system, were unlikely to have been tested
- In desperation operators on the rig may have tried to activate the shear rams by pushing the Shear Ram "Control Button", but it would have been unsuccessful. The shear rams do not have enough power to cut drill pipe unless they are activated through the "Emergency Switch" or the "deadman switch".
BP's next attempt to stop the oil leak in the Gulf of Mexico will involve a maneuver called "top kill," in which heavy drilling fluid is to be pumped into the head of the leaking well at the seafloor.The manufactured fluid, known as drilling mud, is normally used as a lubricant and counterweight in drilling operations. The hope is that the drilling mud will stop the flow of oil. If it does, cement would then be pumped in to seal the well, according to BP. The rig will send the drilling mud into a pipe that will go nearly down to the seafloor, 5,000 feet below the surface. The fluid will split off into two flexible hoses that will connect to a manifold, which is a distribution chamber that BP has placed on the seafloor. The manifold's job is, among other things, to manage the flow of mud into the well, according to BP.The manifold will send the fluid through two other hoses that will be attached to the blowout preventer that sits atop the well. The blowout preventer is a 48-foot-tall valve-like apparatus that should have prevented the leak in the first place, but is not working. Remote-operated submarines will have attached the hoses to lines in the blowout preventer that access the well.
If the drilling mud can be pumped into the well at a sufficiently high pressure, it could overcome the pressure of the oil and gas that is trying to come out, thereby stopping the oil flow, according to BP. "[The drilling mud] is heavier than the oil and the gas. The objective is to put it into the well so it will reduce the pressure and flow from the well," which would then allow BP to pump cement into the well, BP spokesman John Curry said. BP has cautioned, however, that this procedure hasn't been tried at such a depth. BP CEO Tony Hayward told reporters Monday that the company rates the chance of success at 60 percent to 70 percent.
Using the same tubes and pipes, BP would then try a "junk shot," pumping material like golf balls, pieces of tire and pieces of rope into the blowout preventer. "Each of these [materials] has been proven to fill various sized spaces in the blowout preventer until the flow is stopped," BP says in a statement on its website. "While there is no known perfect 'recipe,' a number of combinations of materials will be used." More drilling mud would follow the junk shot, with the hope that the two methods together would stop the oil long enough for cement to be poured into the well.
Curry said BP doesn't know how long the process will take, but it won't be instantaneous. "It's a process. We will make sure we take the time to do it right," he said. A joint website for the government agencies and companies involved in dealing with the leak says the total operation could take several days. It's not clear whether that includes preparation, which already is under way.
One option is adding another valve, or an additional blowout preventer, on top of the blowout preventer already on the well, according to BP. That potentially could cut off the oil flow. BP also may try to sever the ruptured riser that extends from the blowout preventer -- it is this pipe that is leaking -- and fit a containment dome over it, BP Chief Operating Officer Doug Suttles said Monday. From this dome, the oil would be piped up to a ship on the surface, and this would be done until BP can seal the well. A larger containment dome failed to work earlier this month. BP this month also inserted a tube into the ruptured riser to capture some of the leaking oil. That captured oil is being pumped to a ship on the surface. Other ideas also are being considered, BP says.
BP says the plan to permanently kill the well, regardless of whether the "top kill" procedure works, involves drilling relief wells that will intersect with the well in question, far below the seafloor. Once contact is made, concrete will be put into the well producing the leak above. Drilling relief wells takes about 90 days. Drilling for the first one started in early May, and drilling for a second, backup relief well began two weeks later, according to BP.
Federal officials and scientists "have been working with BP engineers on the review of the various operations, procedures and contingencies" that will be used during the "top kill" attempt, according to the joint leak-response website. On Sunday, U.S. Coast Guard Commandant Adm. Thad Allen told CNN's "State of the Union" that BP "had to go step by step [with government officials] on how they're going to do this 'top kill.' " "All the assumptions that BP put forward were questioned by people like" John Holdren, the director of the White House's office of science and technology policy, Allen."What makes this an unprecedented and anomalous event is access to the discharge site is controlled by the technology that was used for the drilling, which is owned by the private sector. They have the eyes and ears that are down there. They are necessarily the modality by which this is going to get solved," Allen said. "Our responsibility is to conduct proper oversight to make sure they do that, and with the 'top kill' that will be coming up later on this week, that's exactly what's happening."
Chronology of the Disaster
1. The well had reached a depth of 13,293 ft below the sea floor. The final string of production casing from the wellhead at the sea floor to total depth had been put in the hole, and cemented in place on April 19, 2010.
2. Only 51 barrels of cement were used according to the well plan. This was not sufficient to ensure a seal between the 7-inch production casing and the previously cemented 9 7/8-inch protection casing (Figure 2).
3. Mud had been lost to the reservoir while drilling the bottom portion of the well (this is called “lost circulation”). It usually indicates good reservoir quality, an interval of lower pressure or both, and can result in an enlarged wellbore or “washout”. The significance of this is that it might have been difficult to create a good cement seal between the casing and the formation. It also would have been impossible to ensure the effectiveness of the cement seal without running a cement-bond log, and this was not done.
4. The cement contained a nitrogen additive to make it lighter so that it would flow more easily and better fill the area between the casing and the lost circulation-washout zone. This also may have decreased its sealing effectiveness. Gas from the reservoir may have further diluted the viscosity of the cement.
5. While waiting approximately 20 hours for the cement to dry on April 20, the crew began displacing the drilling fluid (“mud”) in the wellbore and riser with sea water before setting a cement plug and moving off location. This mud was pumped into tanks at the surface, and then onto a platform supply vessel alongside the rig (whose captain gave testimony before an MMS hearing last week).
6. Sea water is much lighter than drilling mud so there was less downward force in the wellbore to balance the flow of gas from the reservoir. The drilling supervisors knew that there was gas in the drilling fluid because a gas flare can be seen in photos probably coming from a diverter line in the riser (Figure 3).
7. The chart of drilling parameters for the last two hours before the blowout suggests that the riser and upper 3,000 ft of the wellbore were fully displaced with seawater by 20:00 on April 20, and the crew was circulating the drilling fluid Beginning 10 minutes later, at 20:10, the mud pit volume began to increase probably because of gas influx (Figure 4). The volume increased so much, that the recorder re-zeroed four times. When the crew stopped pumping at 21:08, the mud pit volume decreased and this may have alleviated some concern about gas influx.
8. At 21:30, they stopped pumping again and circulated, but the pit volume continued to increase(Figure 5). Standpipe pressure increased and decreased twice between 21:30 and 21:42 (standpipe pressure generally reflects bottom hole pressure). This, along with a steady increase in mud pit volume, suggests that surges of gas were entering the drilling fluid from a gas column below the wellhead, and outside of the 7-inch production casing. Gas had probably channeled past the inadequate cement job near the bottom of the well and, by now, had reached the seals and pack-offs separating it from the riser at the sea floor.
9. At 21:47, the rate of standpipe pressure and mud pit volume went off scale, and water flow was measured at the surface. The blowout had begun.
Between 21:47 and 21:49 the gas behind the 7-inch production casing apparently overcame the wellhead seals and pack-offs that separated the wellbore from the riser. Almost instantaneously, the gas shot the water out of the riser and above the crown of the derrick. Then, the gas ignited and exploded.
Deepwater Horizon was considered state-of-the-art when it was built in 2001 by Hyundai Heavy Industries. It was designed to withstand 118-mile an hour winds and waves as high as 41 feet. Last year, it set a world record for the deepest oil and gas well when it drilled 35,055 feet into the Gulf of Mexico. The blowout and oil spill was most likely caused by a flawed well plan that did not include enough cement between the 7-inch production casing and the 9 7/8-inch protection casing. The presumed blowout preventer (BOP) failure is an important but secondary issue.
The Blowout Preventer - The Failsafe that Failed
||“How can a device that has 260 failure modes be considered failsafe?” An “astonishing document” prepared by TransOcean in 2001, when it bought the BOP from Cameron said there were 260 separate “failure modes” that “could require pulling of the BOP.” According to this report, “the predominant failures” included “ram locking mechanisms.”
The blowout preventer appeared to have a significant leak in a key hydraulic system. This leak was found in the hydraulic system that provides emergency power to the shear rams, which are supposed to cut the drill pipe and seal the well. Investigators herd that when the remote operating vehicles (ROVs) tried to operate the shear rams, they noticed a loss of pressure. They investigated this by injecting dye into the hydraulic fluid, which showed a large leak coming from a loose fitting, which was backed off several turns. The leak did not seem to have been caused by the blowout because every other fitting in the system was tight. This was one of several possible failure modes: the leak depriving the shear rams of sufficient power, so that they could not cut through the drill pipe and seal the well.
Secondly, the investigation learnt that the BOP had been modified in potentially significant ways. The device has an underwater control panel which BP spent a day trying to use. The control panel should have activated a variable bore ram on the BOP, which seal tightly around any pipe in the well. When BP investigated why their attempts to activate the bore ram failed, they learnt that the device had been modified. A useless test ram - rather then the variable bore ram - had been connected to the socket that was supposed to activate the variable bore ram. An entire day’s time was spent engaging rams that closed the wrong way.
Thirdly, the US team learnt that the BOP was not powerful enough to cut through joints in the drill pipe. They cited a Transocean document that stated: most blind shear rams (BSRs) are “designed to shear effectively only on the body of the drillpipe. Procedures for the use of BSRs must therefore ensure that there is no tool joint opposite the ram prior to shearing". This is astounding because the threaded joints between the sections of drillpipe make up about 10% of the length of the pipe. If the shear rams cannot cut through the joints, that would mean that this so-called failsafe device would succeed in cutting the drillpipe only 90% of the time.
A fourth finding was that the emergency controls on the BOP may have failed. The BOP has two emergency controls. One is called the emergency disconnect system (EDS). BP officials told investigators that that the EDS was activated on the drill rig before the rig was evacuated.
“But the Cameron official said they doubted the signals ever reached the blowout preventer on the seabed,” said Stupak. “Cameron officials believed the explosion on the rig destroyed the communications link to the blowout preventer before the emergency sequence could be completed. In other words, the emergency controls may have failed because the explosion that caused the emergency also disabled communications to the blowout preventer.”
Meanwhile, the BOP also has a “deadman switch” which is supposed to activate the shutoff system when all else fails. But, according to Cameron, there were multiple scenarios that could have caused the deadman switch not to activate.
One was human oversight: the deadman switch may not have been enabled on the control panel prior to the BOP being installed on the ocean floor. Another is lack of maintenance: the deadman switch won’t work if the batteries are dead.
The deadman switch is connected to two separate control pods on the BOP. Both rely on battery power to operate. When one of the control pods was removed and inspected after the spill began, the battery was found to be dead. The battery in the other pod has not been inspected yet.
Another issue concerns the design. The deadman switch activates only when three separate lines that connect the rig to the BOP are all severed: the communication, power, and hydraulic lines. Cameron believes the power and communication lines were severed in the explosion, but it is possible the hydraulic lines remained intact, which would have stopped the deadman switch from activating.
“These are not the only failure scenarios that could impair the function of the BOP,” said Stupak. “The Cameron official we met with described many other potential problems that could have prevented the blowout preventer from functioning properly. Steel casing or casing hanger could have been ejected from the well and blocked the operation of the rams.
“The drill pipe could have been severed successfully, but then dropped from the rig, breaking the seal. Or operators on the rig could have tried to activate the shear rams by pushing the shear ram control button. This would have initiated an attempt to close the rams, but it would not have been successful. The shear rams do not have enough power to cut drill pipe unless they are activated through the emergency switch or the deadman switch.”
Stupak also revealed an “astonishing document” that Transocean prepared in 2001, when it bought the BOP from Cameron. It said there were 260 separate “failure modes” that “could require pulling of the BOP.” According to this report, “the predominant failures” included “ram locking mechanisms.”
“How can a device that has 260 failure modes be considered failsafe?” the congressman asked.
Problems with the BOP were also found to extend to the procedures for testing the device. The CEO of Transocean, Steven Newman, said in a testimony: “we have no reason to believe that they were not operational - they were jointly tested by BP and Transocean personnel as specified on April 10 and 17 and found to be functional.”
But this assertion seemed to be contradicted by a document prepared by BP on 27 April, one week after the explosion. According to this document, “BOP stack emergency systems are not typically tested once the BOP stack is on the seabed.”
“What this means that while some functions on the BOP may have been tested in the weeks before the explosion, the emergency systems, including the deadman system and the leaking emergency hydraulic system, were unlikely to have been tested,” Stupak concluded