 ROBERT, La. - A file photo shows a view of the Deepwater Horizon Blowout Preventer, Sunday, April 25, 2010. The unified command has approved a plan that utilizes Remotely Operated Vehicles (ROV) in an effort to activate the blowout preventer on the sea floor and to stop the flow of oil that has been estimated at leaking up to 1,000 barrels/42,000 gallons a day.  BillWilliam says:Hi bradridertx, i used to be a field engineer in the area where this "crime" happened. For a short background on deep water drilling here goes. The drilling rigs are called boats or ships as they always float and some have a means to propel them selves. They also have a captain who is "master of the ship". They are called semi submersibles because while operating part of the vessel is under water to give stability from wave action. The vessel still moves some with the wave action and tides so the drill floor moves to counter this movement because the other end of the drill pipe is attached to the sea floor. This is a big deal, the slightest failure and the drill pipe breaks. There are multiple redundant systems to keep the rig floor stationary to the sea floor. See the current headlines for the results. But this is not what happened to this rig. On this rig in some order the rig started listing, the well blew out, (uncontrolled release of oil and natural gas), the rig caught on fire, the rig sunk. For all of this to happen is beyond accident. This type of rig has many water tight compartments and rarely sink. The sister vessel to the second semi I worked I worked on had a little incident. Someone had a ballast water valve in the wrong position and the vessel turned over. Every one died but the vessel did not sink, in the North Atlantic, in a massive storm. I thought massive till I saw the Gulf on a bad day, week, month. 1998 had interesting weather. My first ride to an offshore rig was on a work-boat just like I saw in the movies of the North Sea. I ask one of the crew if he liked the mild weather of the Gulf of Mexico compared to the North Sea, he laughed and said it was worse here but warmer. The next year I saw it up close and personal. 47' waves, land in a helicopter in full hurricane force winds... just another commute to work. Back to the rig. The photo of the Blow Out Preventer shown is an old stock photo. Look to the lower right for the date. The close up with the ROV arm is what it really looks like on the sea floor. That BOP is supposed to work under any condition as it has stored gas pressure to operate the 5 or more valves that control the well. one of the valves can cut the drill string off and seal the well permanently. Did they charge the gas pressure storage tanks to operate the BOP before putting it on the sea floor? Because of the pressure at that depth the pressure must be set so the valves can operate. If the sea water pressure is greater than the tank pressure when you hit the big red button on the drill floor nothing happens on the BOP and everything happens that we have seen. Just one of many things I can think of. But no one thing can account for what we have seen. A blow out can cause a fire, but not the list, not the sinking. If there is a huge amount of gas released from the well the bubbles in the water will reduce the buoyancy of the water and the rig might sink some but it would come back up when the gas stopped or the currents of the Gulf moved the gas stream away from the rig. No large quantities of gas leaking were reported, and the fire would have much larger. Bigger than a MOAB bomb. More like a 100KT nuke. I think this was a string of, enter bad word here, mistakes, each one would have killed people and destroyed the rig. BP has a safety record as bad as it can be. They seem to not care about who dies, how much damage is caused or even if it costs them more money that having safety controls in place. Maybe the CEO just likes the smell of burning human flesh. Saw your bikes. Do they still have enduros in the forests North of town? I rode those in the 1970's.  billlorch says:According to information and photos, 1)the well blew out, 2) the rig caught fire and THEN 3)the rig began listing a couple of days after the fire started. The rig did not begin listing first.  Horizon37 says:In actuality the fire boats probably sunk the rig, as this incident happened without warning during calm weather, the watertight doors leading to the caissons (legs) were probably open, and if anybody was down in the sponsons (pontoons below the water line) working they left in a big hurry when the initial explosion occurred, and neglected to close the doors when they left to head to the survival craft. The doors being open allowed water from the fire boat water monitors to eventually fill up the caissons which sunk the rig. Just an educated guess. billlorch,Granted the BOPS should have shut off the well, but since there was no one left on the rig floor to pull the cut pipe out of the BOPs even if they had cut it, the blind rams would still not have closed as the pipe would still be in their way. In a BOP stack the shear rams are on bottom then next up are the blind rams, above that are 2 sets of pipe rams, 1 dressed out to fit the size of drill pipe to be used the other are variable size that will adjust themselves to fit several sizes of pipe, above that on a subsea stack are 2 annular BOPs which are for lower pressure use and are basically oil filled wire reinforced elastomer doughnuts (inner tubes) they will close on pretty much any tubular good they would run into the well, they close by filling the bladders with high pressure oil causing them to swell shut. billwilliam,You should be ashamed of yourself, rig floors don't move. There are hydraulic motion compensators at the crown of the derrick, this allows the rig to go up and down with wave motion, and the drill string / casing or whatever is hung from the blocks to remain relatively stable in relation to the seabed. The riser has a slip joint where the top end is attached to the rig superstructure and the riser body below the slip joint is supported by it's own set of compensators which maintain a set hydraulic pressure to keep the riser at a preset load dependent upon how much riser is being supported. Posted 3 days ago. ( permalink )  Ex Engineer says:Has back pumping water down the pipe line any prospect of reducing oil flow into Gulf?  BOP2005 says:ANYONE KNOW WHAT MAKE & DESIGN OF BOP INSTALLED ON THIS WELL? IE, HOW MANY ELEMENTS, WHAT WAS THE OPERATING SYSTEM, GAS OR HYDRAULIC? SEEMS HALIBURTON WAS CEMENTING WHEN IT BLEW, ANY CHANCE THE CEMENT ENTERED THE BOP AND PLUGED THE SHEAR CHAMBERS? WITH CONNECTION TO THE SURFACE LOST, WOULD WATER PRESSURE ENTER BOP CONTROL LINES AND AFFECT THE ATTEMPT AT MANUAL OPERATION BY THE ROV?Posted 2 days ago. ( permalink )  dumbl1 says:I do not have a fraction of the knowledge of any of the engineers blogging here, but I have some questions. Apparently the survivors on the rig have submitted a report. Has it been published on the web?The early reports spoke of an explosion - presumably while cementing was in progress. Was the explosion the result of work being done on the rig or was it due to release of gas from the well? Could this have ruptured the waterproof tanks, causing the list and eventual sinking of the rig? If the explosion occurred first, could severe listing have broken the pipes before the BOP was activated. I understand the BOP is automatically activated and hydraulically operated. What triggers it and isn't there an indicator on the rig floor of the state of the valve - or did the explosion kill everyone in position to monitor or control what goes on at the wellhead? Posted 2 days ago. ( permalink )  10030854@N05.jpg?1184399948#10030854@N05" height="48" alt="view profile" width="48" style="border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-color: initial;" />ussnewyork says:What is the diameter of the casing above the seafloor BOP? Is there any wany to squeeze it together to stop the flow like a blind ram or Hydril? Is there any way to recharge the accumulator on the BOP? Horizon37 says:Halliburton had completed the cementing over a day before this happened, it's a 99.99% probability their activity had nothing to do with this accident, as the surface samples of the cement slurry had set as designed, in the time period they were design to. I am no fan of Halliburton as I worked for their competition for 25years, but to point the finger at them is unconscionable at best. Posted 2 days ago. ( permalink ) dumbl1 says:To Horizon37: Thanks for the technical insight about cementing, but I disagree that it's not the public's business to learn about an accident (or natural occurrence) that impacts the public's interest as much as this one has. Apparently, the government regulators don't have the sense to hire some knowledgeable engineers to confirm or question the companys' risk assessments and safety provisions before okaying something as tricky as deep-water drilling.Posted 2 days ago. ( permalink ) BOP2005 says:www.upstreamonline.com/live/article213497.ece Read the UPSTREAMONLINE article for information regarding BOP activation. Read further down for information re a RELIEF WELL and information regarding a capture dome.Seems the crew did indeed try to operate the BOP before evacuating the rig.Posted 2 days ago. ( permalink ) Horizon37 says:Here is a link to Halliburtons statement on their job on the well.  One man Band says:Any idea what the temperature of the oil at the BOP? Also, when cementing the pipe, how far down does the cement go. It seems that if the pipe above the BOP was full of cement the bend in the pipe would look different. The way it looks to me is that there is no cement at this point. Horizon37 do you have comment? One man Band says:BOP2005 any ideas of the temperature of the oil at this point?  s0ulsurvivor says:What about running a non-inflated balloon/bladder on the end of a flexible hose down the riser past leak three. Kind of like an inflatable cork. I'm certain the materials and knowhow are just waiting to intersect. I'm sure it could be fabricated and deployed via ROV quicker than a concrete dome.Posted 2 days ago. ( permalink ) Horizon37 says:One Man, The cementing operation would not have involved getting viable cement to the BOPs. I would estimate the oil temperature at the BOP stack is around 200degF. This was not a conventional casing job, it was a production liner, this is a smaller OD casing that relatively short in length and overlaps just the bottom portion of the larger casing.I will attempt a greatly simplified diagram here: |||||||||| BOPS.|..... | .|..... | .|..... | Casing .|..... | .|..... | .||... || Liner top .. Hanger packer & slips .||... || Liner Lap .||... || .||... || Bottom of casing . |... | . |... | . |... | Liner . |... | . |... | . |... | . |||||| Bottom of Well Posted 2 days ago. ( permalink ) One man Band says:Nice diagram, I got it. I was thinking of maybe using liquid nitrogen and pumping it into a sleeve or onton the pipe at the bend just above the BOP. Thinking that it would reduce the oil temp and make the oil thicker thereby making it more retrievable while the dome was being made. s0ulsurvivor I think that with the pressure coming out of the pipe and threading a bladder into the existing pipe might be like threading a needle while water is rushin through the eye. I had given the bladder idea some thought though. We use those in my line of work sometimes but not at high pressure and not with high temps. My background is structural engineering so we dabble in physics and mechancials a little bit. I do like the dome idea and will be watching it closely if it is utilized. This is intriguing to me. I like to solve difficult problems. Horizon37 any comments on the use of the nitorgen? |
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Tuesday, May 4, 2010
Deepwater Horizon Blowout Preventer and Comments
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bradridertx says:
Thanks for posting this info on the Deepwater Horizon. I'm a layman trying to get a handle on it and I really appreciate your help!
Posted 5 days ago. ( permalink )