BOP closed but failed to stop oil flow


Giant metal shears successfully sliced and closed pipe full of runaway crude in the early moments of last April’s Deepwater Horizon disaster, but the oil blasted through rubber gaskets around the blades and unleashed the nation’s largest spill, according to sources familiar with an ongoing investigation.

The shear ram system was a central component of the blowout preventer — a 45-ton array of valves that sat on top of the Macondo wellhead a mile beneath the surface of the Gulf of Mexico. The blowout preventer, or BOP in industry shorthand, has been the subject of a forensic examination since it was raised last year and transported to a NASA facility outside of New Orleans.

A joint U.S. Coast Guard/Bureau of Ocean Energy Management investigation is trying to determine why the device, which is supposed to seal off the well in an emergency, continued to let oil flow, contributing to the disaster that destroyed the rig, killed 11 men and started the 85-day spill.

The BOP is designed to cut and close pipe leading from a well in an emergency — either activated intentionally by a rig crew or automatically if the BOP loses power, communication and hydraulic connections to the rig.

Investigators believe the latter circumstance closed the Deepwater Horizon’s blowout preventer, although crew members tried to activate the system after an explosion rocked the rig, according to the sources.

The sources have varying connections to the investigation and requested anonymity because they aren’t authorized to discuss it.

They said the force of oil and gas flowing through the well apparently was too strong for rubber gaskets called packers that surround the edges of the shear ram blades. Erosion patterns inside the BOP suggest that the packers essentially were blown away, allowing oil to flow around the closed blades. 

The conclusions — if they are part of the investigation’s final report — could increase fears about the fallibility of blowout preventers that surfaced after the Deepwater Horizon explosion.

Spokesmen for Transocean, which owned the Deepwater Horizon; BP, which owned the well; and Cameron, which built the BOP, declined comment.

Gene Beck, a petroleum engineer and well expert who teaches at Texas A&M University, said BOP shear rams are quite capable of closing against high pressure, but as the rams close the fluid velocity increases and can erode sealing elements. 

“BOP’s have a better chance of working the earlier in an event they are used because pressures and velocities will be much lower,” Beck said.

David Pursell, head of macro research at Tudor Pickering Holt & Co. in Houston, said the failure of the shear ram packers opens other questions about whether the packers were maintained properly, and whether the BOP as designed could have stopped a flowing well.

“When you close your shear rams you’re at DefCon 5, your well is probably flowing,” Pursell said. “If the BOP can’t hold a well at full flow, than maybe it means its time for a redesign.”

A number of investigations into the accident are continuing, but a presidential commission, in a recent report, identified the primary causes of the accident as a poor cement job in the well combined with a failure of the rig’s crew to recognize the signs of the imminent blowout.

Blowout preventers aren’t actually designed to stop the full force of a flowing well once it’s out of control. Rather, they’re intended as a last resort when a blowout is likely, to keep hydrocarbons from flowing up a riser pipe to the rig.

Investigators have said the Macondo well was showing signs of a blowout 45 minutes before operators on the rig took any measures to seal it.

Lawmakers who investigated the disaster said they were shocked last year to learn hundreds of different ways that blowout preventers considered “failsafe” could, in fact, fail. At the time, then-House Energy and Commerce Committee Chairman Henry Waxman, D-Calif., said it was clear that blowout preventers “are not foolproof — not even close.”

A report prepared by Transocean in 2001 documented 260 different “failure modes,” including problems with old or worn packing elements that could prevent the device from sealing around drill pipe. The document also warned that a blown seal or corrosion could cause shear rams to close incompletely and that damaged packers could cause an “inability to seal (the) wellbore.”

A 2004 study into whether BOP shear ram designs were adequate to seal wells in the more challenging deep-water environments of the Gulf of Mexico noted that shear rams tend to have less rubber in the packers than other valves on the BOP, which “…could make them more vulnerable to sealing difficulties, but generally, shear rams have completely acceptable fatigue life.”

Lawmakers and federal regulators have considered mandates to improve the testing and design of blowout preventers. The House passed legislation last year that would impose new requirements for redundant rams and backup control systems to boost the reliability of BOPs.

Michael Bromwich, director of the Bureau of Ocean Energy Management, Regulation and Enforcement  said in a recent interview that the agency will enact tougher BOP rules in the future, but they weren’t included in emergency regulations developed in the weeks after the spill because it was determined it could take up to two years for all deep-water rigs to retrofit their BOPs.

Tom Fowler

39 Responses

  1. Deepwater Engineer says:

    Joe – Nice!!!!!

  2. Joe says:

    “We can clearly see massive erosion in the ram body and the closed ram.”
    Well, that’s the last time I buy a Chrysler product!

  3. Trail Trash says:

    DW Eng, No, I had not seen that. Thanks for the link. (loved the music too!).

  4. Deepwater Engineer says:

    Trail – have you seen this? Apparently it is authentic (can’t verify). It matches what Tom said. We can clearly see massive erosion in the ram body and the closed ram.

  5. Trail Trash says:

    DW Eng: Yeah, the negative test interpretation was a critical mistake. Everybody let their guard down after that.

  6. Deepwater Engineer says:

    Frank – those were pieces of the annular preventors above the blind shear rams. Has anyone found the actual report for download yet?

  7. Frank Bowers says:

    I recall that the packers were destroyed (Pieces of rubber from packers were noticed in the mud ) when one of the operators forced the pipe to be pulled/pushed through them while in the closed. This was not mentioned it said they were blown away. Perhaps some one is CTA here. Perhaps they are covering the rear of some one as the packers were not blown away by force they were blown away when pipe was forced through when in closed position. Frank Bowers

  8. Deepwater Engineer says:

    Trail –

    So the final piece of information is released. The side packers blew out when the ram was closing because of the high velocities. I guess explaining away a 1,400 psi pressure anomoly during the negative test as a “bladder affect” nipped them in the bud. All I have to say is if we don’t manage the well during the construction phase, bad things can happen…….

    Mental Recession – please stop, my sides are hurting……

  9. Trail Trash says:

    Cock_Doodler: Gweesh cuoon masilwasy bez jabberwocky.

  10. Marc says:

    You know, all you would be and actual engineers are missing the point here – either there was negligence on the part of BP that contributed to to the failure to prevent a massive spill, or there was negligence in assumption that current technology renders deep gulf drilling as safe as the industry has claimed. You can split hairs all you want, but it’s clear that the oil industry is either willfully lying or is so self-deluded that anything they say may be regarded as total crap. Either way, this means that the industry needs to start dumping some of those massive profits into research and development on environmental stuff. They FAILED to do it as an industry, so time to regulate the holy crap out of them, turn a blind ear to their WHINING (and the whining of all of their ignorant apologists and cheerleaders), and cut their subsidies.

  11. Trail Trash says:

    Mental_Regression: I do not believe it was ever stated that the reservoir pressure exceeded the pressure rating of the BOP. The failure of the BOP was due to the velocity of the flow, not the pressure.

  12. Vicki Holder says:

    I heard the BOP had been “tampered with” and that some of the safety features had been disabled. Not sure what impact that would have on the functionality, but I’m guessing that it would have some impact. Trail is right. The rig should have been shit down long before it was. Facts have shown that people knew about problems on Macondo and chose to ignore the warnings.

  13. KaliGhoulish says:

    I think that an improved design of BOPs; recognition of earlier signs of trouble and earlier activation, should prevent any further blowouts, due to their failure, in the industry.

  14. Cock_A_Doodle_Dude says:

    I dnk Trail Trash, it sounds to me like the gamis next to the frain was immobilized so that the raminfranzer could not conjubulate stopping a flow through the craminsalters. If the disenpoop caught on swirlyhasker the spoofinfrowser would reject the umpinfizer thus causing the sumporfuzer to blow the ramincrowders atop the bonenflaffers.

  15. Mental_Recession says:

    It was disclosed early on in the preliminary investigation that the type of BOP used was inadequate for this job. BP chose a lower pressure BOP against the advise of on site engineers. ..this what caused that big argument on the rig just before it exploded. Engineers wanted another BOP which withstood higher pressures but BP wanted to cut costs and chose the cheaper lower pressure BOP>

  16. Dollar says:

    Now we know why Rep. Markey was questioning the integrity of the BOP testing last month. He knew the test results and they weren’t what he wanted to hear, so he poisoned the well.

    I’m no engineer, but Trail Trash makes a lot of sense, a restricted flow rate was the first thing I thought of also.

  17. ntangle says:

    As long as we’re using non oil-world analogies, I’ll suggest one: Runaway accceleration that killed a family in CA. The car’s brakes weren’t enough for a car with a lot of momentum already AND a powerful engine apparently at W.O.T.

    Like brakes, BOP’s are energy arresters. They do it via friction, be it against brake linings or by fluid compression thru an orifice and across surfaces. Either way, heat results and it wears away the surfaces. Which can only absorb so much energy until they’re history. The amount of energy increases with the square of the speed. IOW, 100 mph means 4 X the energy to absorb as 50 mph.

    It’s unfortunate that the well’s best “brake” (its shear rams) weren’t applied earlier rather than against a reservoir’s sustained W.O.T. and full speed. Apparently they were applied by the AMF, according to the new info.

  18. rts says:

    Looks like the crew paid for their failures with their lives. And, the well was more powerful than they ever expected.

  19. Paul says:

    What I know is that gasoline will be approaching $5.00 in the very near future and that China and Russia are drilling for oil only a few miles off our shores and we have oil that is not being drilled. We have heard so many stories that it is hard to believe anybody. No matter what happened to BP, America has got to get moving on energy or we are out of business.

  20. Tex says:

    The blind shear rams have sealing rubber gaskets built into the two ram bodies. The gaskets are integrated components of the shear rams and are designed to seal once the ram has cut the drill pipe and fully closed. The annular preventer is a completely different type of seal.

    A possible problem is the reported closing of the rams on a flowing well. The seals or part of the seals may have been washed out of the ram bodies because of the flow across the rams before the rams were completely closed. You have no chance of maintaining a seal if the seal components or part of the seals are damaged or washed away, even if the rams are fully closed. You can probably stand some damage to the seal, but a high flow rate through the ram cavity will create such a high velocity through the seal leak area that it is impossible to prevent washout of the remaining sealing components.

    It will be interesting to see pictures of the rams and how much erosion there was because of the flowing well.

  21. BON JOVI says:

    Well thanks for that Tom. Way above my knowledge base though. Certainly this a well designed piece of equipment for all types of failures. So I guess the big question in my mind is will we ever know the real answer or will it be lost in rhetoric and courtroom maneuvering.

  22. BON JOVI says:

    Tom didn’t the gaskets fail a pressure test immediately prior to the incident? Wasn’t that part of the mud debacle to seal the well then leave it?

    • Tom Fowler says:

      Bon Jovi:
      I think it was a different set of rubber gaskets (and mind you, real industry people are probobly calling me an idiot for saying gaskets, but it’s the best non-oil world analogy I can think of) on a set of rams called annular preventers that it is believed to have leaked. The annual preventers are essentially big rubber pieces that compress around the drill pipe that would be in the well, preventing any flow up the riser through that path. The shearing rams would have actually cut right through that pipe.

  23. Bon Jovi says:

    Yeah weren’t there several days there before we got to tune in to video? Maybe the original leak wasn’t that big but after the gaskets blew and erosion it all just went to crap. That is a pretty normal scenario whether on the surface or a mile deep. I am kind of curious if the valve closed before it should have from loss of whatever and that caused the weak gaskets to blow. That is only a brainstorm and has no meaning but just a curious thought.

  24. FedUpInTX says:

    Oilspilllaw and other alt. news sources reported that gaskets exited the wellhead during the period in question days after the initial incident took place. We needed a multimillion dollar survey to state the same thing?

    Sounds like the final report is being delayed until it has only enough CYA built in to provide zero accountability.

    • Tom Fowler says:

      The news sources you’re referring to: can you post links to any of them? There’s been so much written about this it’s hard to remember what was out there and when.

      I’d be curious of their sources, however, since it’s highly unlikely the gaskets would have been observable. More likely an educated guess by someone in the industry. I’d say looking at the BOP itself (while clearly taking a lot longer than it should have) would have been necessary regardless to further investigate the validity of those early educated guesses.

  25. Trail Trash says:

    BJ, the BOP was rated to handle the pressure, but not ram is 100% certain to be able to close on an open flow. Now that they know the rams were closed, they should be able to come up with a measurement of the actual orifice.

    Spaghetti-Os, if you will go to the Woods Hole website, you will see daily blogs from the dives the UofG professor was on that describe areas near the blow out that were “teaming with life”. The good professor did not mention those in her press release.

  26. Bon Jovi says:

    Just an interesting thought? If this valve was a “fail closed” type on loss of power or air valve as most EBVs are how long waas it closed? How long then was it subjected to errosin?

  27. Bon Jovi says:

    I mean from both sides; the valve appeared closed? Does that mean there was less flow than calculated? No. Not at all. Could it mean that? Yes of course. So open minds right to seek reality rather than injected to sway a court battle or decision and in the public’s view at any given moment.

  28. almostdallas says:

    The research from UGA has not been peer-reviewed. She got off the boat and went straight to the media, with what? If it was ground-breaking, we would have seen it by now.

  29. cannedspaghetti says:

    Obviously a cover up story, there was way too much oil flowing to be working its way around blown gaskets. And for you Faux News tards look at the University of Georgia’s latest assessment of how much oil is laying on the bottom. They actually went down there in ROV’s and looked unlike the zeros that flap their jaws on TV 24/7.

  30. Bon Jovi says:

    My big question would be what was the actual pressure and was that valve rated for that? That was the question I had from day one after hearing all the mud journals were kept from open view.

  31. Bon Jovi says:

    Curious. Always people take the slightest opportunity to defend whats obviously and probably their chosen carreer. I would probably do the same were I in that business now. You know realistically the flow estimates were based on visuals and residual oil. So believeing that much couldn’t flow out gasket openings is hogwash. To start there would be tremendous errosin of the internals that would get worse minute by minute. That made it all that more imperative the leak would be stopped earlier rather than later and even makes the response look worse. . I have seen Hand Block Valves that appeared closed but with almost immediate errosin the flow became similar to what a wide opened valve had. So my point before we defend or persecute lets look at the established evidence before we “I told you so bandwagon gets goin because its misleading” and as one sided as when this was occurring.

  32. Commrade_Leftist says:

    The culture on that rig was such that you couldn’t blow your nose without asking permission. The driller on tower was afraid for his job had he shut the well in before layers of management gave the green light.

  33. SShaw490 says:

    BPs decision to demud the well despite a bad cement test is what caused the blowout. Anyone who’s ever worked on a rig for more than 10 minutes knows the blind rams aren’t a substitute for a company man with a functioning brain. Blind rams are there to give you enough time to get away from the rig before it blows up, not to seal off a well.

  34. pdh42 says:

    I wonder if we will hear any of the nay sayers admit that they didn’t know what they were talking about during this whole fiasco…. I wonder if the Chronicle people who have blasted BP everytime they turn around will admit that they might have been hastry in what they have printed…. Nope, none of the above will happen….

  35. Trail Trash says:

    It also brings into question the estimated flow rate of 60,000 BOPD. I may be wrong, but if both shear rams were closed, it’s doubtful there was a big enough opening to get that kind of a flow rate.

  36. Trail Trash says:

    So yet another accusation by Rep. Markey and the anti-Big Oil crowd has been proven wrong. All that talk about a dead battery in the BOP module and not having an acoustic controller was irrelevant. The bottom line is that well should have been shut-in and brought under control long before any gas or fluids hit the surface.