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Politics : Rat's Nest - Chronicles of Collapse -- Ignore unavailable to you. Want to Upgrade?

To: Wharf Rat who wrote (10741)	6/3/2010 9:36:29 AM
From: Wharf Rat	Read Replies (3) \| Respond to of 24231

What caused the blowout? Rock's summary... ROCKMAN on June 2, 2010 - 8:58pm FOR ALL NEWBIES 05 (question from previous thread) – For your benefit and that of other newbies showing up daily I’ll offer you my very biased conclusion of the primary cause of the blow out. The regulars can skip the rest of the story…they’ve heard already. I’ll make just one qualification and it’s a big one: IF THE INITIAL REPORTS ARE CORRECT. It will likely be at least 6 months but more likely a year before there’s official confirmation. The following are just my suppositions. But suppositions gleamed from 35 years as a petroleum geologist with a strong background in well site operations. That experience includes working on site on DW GOM wells as a pore pressure analyst. As a PPA I assisted the drillers in determining the magnitude of the rock pressure they had to deal with. BP drilled thru an oil reservoir at about 13,000’ below the sea floor. The pressure in the reservoir was around 14,000 psi (an educated guess). They ran steel pipe (casing) from the bottom of the hole back up to the wellhead at the sea floor. They then ran the drill pipe to the bottom of this csg string and pumped wet cement up between the csg and the rock. The purpose of the cement isn’t to hold the csg in place…it isn’t going anywhere. The purpose is to isolate the oil reservoir and keep it from flowing along the outside of the csg in either direction…up or down. It appears the cmt job failed to provide this isolation. Opinions vary but IMHO this is not the BIG SMOKING GUN. Cmt jobs fail all the time. You assume that during the course of drilling a well that you’ll have get a bad cmt job or two. That’s why you routinely test the cmt after a period of 18 to 36 hours. The primary and best cmt test is to apply pressure to it. The cmt has to hold a pressure greater than the reservoir pressure. If it doesn’t then you do a “squeeze job”: pump more cmt behind the csg and then test again. There is some question regarding the validity of the pressure tests BP conducted. Opinions vary but the cmt did fail…that’s why the well blew out. After BP decided the cmt job was sufficient they had to set cmt plugs inside the csg string as required by MMS regs. But before setting the upper cmt plug they began removing the heavy drilling mud (14.5 pounds per gallon) from the csg and the riser (the 20” tube that connected the wellhead to the drill rig 5,000’ above. They did this by going down into the csg with drill pipe and pumping seawater down. The seawater pushed the drill mud back up to the rig. The seawater weighs about 7.5 pounds per gallons. That means the pressure exerted at the bottom of the well was reduced considerably. So low this pressure wasn’t sufficient to keep the oil reservoir from flowing up. This is a normal procedure. Had the cmt job held all would have been fine. The bad cmt job allowed the oil reservoir to flow up the csg. Had they set the top cmt plug first the well would not have blown out when they displace the mud. Even with a bad cmt job a proper upper plug would have held the flow back. There are any number of circumstances when there’s a valid concern that some reservoir is flowing into a well that’s cased or still drilling. There’s a very basic protocol for checking to see if the well is “kicking (flowing upwards): you turn the mud pumps off and determine if there’s any drilling mud still flowing out of the well. There are some exceptions but in general a reservoir can’t flow up the well unless it pushes the mud out ahead of it. No flow returns and the well is static. Mud flowing out of the well when the mud pumps are off = something pushing it out. This is not an uncommon event. The drill crew has practiced “killing” the flow (stopping it) many times. First all the return lines are closed (shut the well in). Even if this doesn’t prevent the oil/NG from flowing all the way up to the rig it does prevent it from breaching the drill floor (this is the definition of a blow out). Once the well is shut in they can pump a “kill pill” (heavy drilling mud) down the well and put enough back pressure to stop the well flow. I could be wrong but the evidence seems to indicate that the hands on the rig weren’t monitoring the mud returns when they were displacing the mud. They didn’t see the well coming in (flowing) until it was too late and the oil/NG breached the drill floor and exploded. Why weren’t they closely watching the mud returns? I’ll skip that part of my already long store. When the well blew out every hand on the drill floor knew exactly what was happening at that point. They knew what was likely to happen. Every hand on the rig knows. The hands had two simple choices. Run and give up any chance of killing the well. Or stay in there and try to execute the kill procedure. The 11 hands that died took the second option. They were obviously “top hands”. That’s the highest title you can earn on a drill rig. Doesn’t seem like a very impressive title to most but in the oil patch it says everything you need to know about the guy working next to you. I’ll pass on the BOP failure. That’s a critical but separate issue. Just as the efforts to stop the flow since the rig sunk. Lot’s of folks on TOD better qualified to handle those discussions. Likewise other knowledgeable TOD folks have other interpretations of what caused the blow out. Listen to them all and you can come up with your own conclusions == widelyred on June 3, 2010 - 12:12am Permalink \| Subthread \| Parent \| Parent subthread \| Comments top Rockman, you've done an excellent job all along on this site and I applaud you for it. 30 years ago I was a roughneck, but a world of change has happened since then and I was just happy to get away from it. Per your note about a "top hand". I worked with a driller from Texas and there was a problem with the mud pump in a huge mud pit. He was standing next to me and handed me his hard hat and proceeded to DIVE into the pit! One of the other hands rushed up to me and asked where he went and I said, "I think he just committed suicide"! About a minute later, we see the submersible pump jump around a bit and it starts working again. Then we see the driller follow the power cable / guy wire assembly holding the pump hand over hand as he worked his way out of the pit. Astonished doesn't begin to describe what I was feeling. When he got back, looking like a creature from the brown lagoon, with slimy bentonite dripping off him I said, "What the hell were you thinking?" He replied that he'd never ask a hand to do something he wouldn't be willing to do himself, and he didn't think asking any of us to do what he'd just done would have even worked, we'd have probably died. THAT was just to keep circulation! What people lurking here don't realize is just how slick drilling mud is. He essentially dived into quicksand and his only hope of survival was to find the pump and use it to get back to land. He may not have been the brightest bulb, but he had more heart than I could ever muster in that profession. He knew how to be a "top hand". If he'd been on that DW rig, I don't doubt for a second he'd have tried to "get er done" no matter what. I too suspect BP cut one too many corners, but for all these folks beating them down, remember that BP acquired multiple companies along the way, including the so-called merger with Amoco. Amoco should have been the dominant company but BP has whittled them down over the years in political in-fighting. There are still a lot of Amoco hands left who are dismayed at what has become of their once proud heritage. I know one who is resigning over this, I'm sure there are more, they weren't involved at all but are ashamed of what has happened. Remember, fish rots starting at the head.