Posted on 05/30/2010 4:31:55 PM PDT by Hojczyk
The Top Kill attempts have failed, and the Government has given its response.
He (President Obama) said US Energy Secretary Steven Chu was leading a team of "the world's top scientists, engineers and experts" in devising a contingency plan should the "top kill" attempt fail.
But while waiting for that, and for the Lower Marine Riser Package (LMRP), I thought I would spend a few paragraphs discussing why Top Kill may have failed as a substitute for my tech talk tonight; you can find that under the fold by clicking "there's more."
(Excerpt) Read more at theoildrum.com ...
This is going to take a long time resovlve.
I think Nemo should summon all the sucker fish and sea sponges to clean it up
What’s really happening in the Gulf Oil Spill
I appreciate all of the concern with the disaster in the gulf, but there is an awful lot of ignorance concerning the mechanisms both on ATS as well as the myriad of so-called experts in the MSM. I am posting this thread, since I have been in the oil business for over 30 years working as a petroleum engineer and have actually designed drilled and operated oil & gas wells. This explanation may get too technical, but at least it will expose and dissipate myths concerning this disaster.
Any oil well is drilled starting with a large diameter that at certain points in the process the large diameter holes are cased off with pipe and cemented in place for various reasons and the drilling is continued with smaller diameters until it reaches its objective. I will not go into all of the reasons pipe is run and a smaller diameter is initiated, take my word for it happens & is necessary.
The Horizon Explorer had several strings of pipes until the final 7” pipe was run (probably the 7” was run in 9 5/8” OD casing). The well is blowing out of the annulus between the 7” casing & the 9 5/8” casing. There is no flow inside the 7”. This casing has tools & check valves that prevent anything from flowing into it. The 7” was supposed to be cemented in place, but the well was starting to blow out during this process. So the cement was being diluted with oil & gas where it could not solidify and shut off flow from the reservoir @ 18,000+/- feet below the seafloor.
I will not go into the failure of the blowout preventer. Let is suffice to say it didn’t work as designed and with the flow coming out, the oil & gas flowed up the riser (the pipe that connects the wellhead to the drilling rig) and it was game, set & match.
When the rig sank the riser was still attached to the wellhead and fell over & split in a reported 3 places. It w as reported that 16.5 #/gallon drilling mud was in the riser and the well blew out when it was replaced with seawater. To understand the physics I will try to explain hydrostatic head. The pressure created from a column of fluid in an oil well is identical to the reason you have water pressure out of the tap at the kitchen sink. Water which weighs 8.33 #/gallon is put into a water tower 100’ up in the air. Fresh water has a hydrostatic head equal to .433 psi per foot of height. Therefore you get 43.3 psi at your shower head. If water weighed 16 #/gallon then you would have 86.6 psi in the shower. Similarly as an oil well is drilled there is a fluid known as “drilling mud” that is pumped into the drillpipe, through the drillbit & circulated back to the surface where it is screened to remove the soil dug out of the well. This “mud” is carefully monitored to make sure that if encounters oil or gas it is heavy enough to keep it from flowing into the wellbore. The well in question had to have 16.5 #/gallon mud weight to keep the oil & gas from flowing. The hydrostatic head of the mud of this weight as opposed to fresh water is .86 psi/ft. This means that the pressure in the oil reservoir encountered must be nearly 20,000 psi. ((18,000 + 5000) X .86). As the oil replaced the column of mud that would offset this bottomhole pressure it began flowing faster & faster into the annulus with more & more force as the weight of the 23,000 foot column of fluid became lighter & lighter. When the “company man” (the BP guy in charge) removed 16.5 #/gallon mud from the riser with 8.4 #.gallon sea water he immediately reduced the hydrostatic pressure 2000 psi & it was over.
Now BP is trying to recreate this heavy mud column to offset the bottomhole pressure to balance the well using the “top kill”. A “top kill” entails pumping weighted fluid into the top of the well and forcing the oil & gas back into the reservoir and filling the annular space with heavy mud creating a hydrostatic head equal to the reservoir pressure. The oil & gas are not flowing from a void in the earth it is flowing out of the tiny spaces between sand grains. There is a limit how fast the fluid will reverse & flow back into the formation sand. If the mud is pumped at a higher rate than the formation can absorb then the pressure increases and even the heavy mud may be inadequate to hold back the bottomhole pressure and when the pumps stop the mud starts flowing back. In addition, if the injection pressure gets too high it may exceed the burst strength of the casing in the well. If the casing splits & starts blowing out into the ocean bed the party is over, there is no way to control unless the flow in contained inside pipe. So the top kill is a precarious balancing act. To further complicate this situation it appears that 90% or more of the mud is not going down the hole, but is being spewed into the ocean. To get more down the hole one needs to pump at higher pressure which means increased rate which means more escapes instead of going down creating increased hydrostatic head to decrease the flow from the reservoir. The junk shot (rubber, golf balls, etc) is not to solve the whole problem; it is only to try to reduce the amount of mud that is escaping from the holes in the riser. They shut down periodically, to measure pressure to estimate how much is going down the hole & how much is being wasted. If the well initially flowed at 5000 psi & after a day of the “top kill” it’s flowing at 4000 psi then we have offset 1000 psi of the oil & gas with mud. If the mud weighs 16.5 #/gallon with a hydrostatic head of .86 psi/ft then we have successfully gotten 1200’ of mud column in the well if we assume only gas in the wellbore. It’s actually not this much. Having done “top kills” on land with varying degrees of success I can assure that its not easy under any circumstances much less those out here.
A “bottom kill” is vastly easier and is what the relief wells are about. Unfortunately for that to work the relief well must intersect an 8 ¾” diameter well bore 3 miles underground in the dark. It has been and can be done, but the deep intersection is necessary so that the enormous bottomhole reservoir pressure can be offset with heavy drilling fluid. The drilling mud will then displace the oil and gas from the bottom rather than try to force somewhere it doesn’t want to go. Once the heavy fluid balances the bottomhole pressure then cement can be put into place that once set up will end the need for the heavy fluid.
Link follows:
http://www.abovetopsecret.com/forum/thread576723/pg1
There is some darn good info on that site. I’ve been learning large amounts of stuff about the drilling process and the problems
One thing that bothers me is why can’t they at least continue pumping seawater into the manifold system instead of mud. It will at least lessen the flow of oil and with enough pumping capacity will lower the flow of oil considerably.
Thanks for the info -- very informative.
All of this destruction seems to be traceable to this one BP man. What do we know about him???
>> When the “company man” (the BP guy in charge) removed 16.5 #/gallon mud from the riser with 8.4 #.gallon sea water he immediately reduced the hydrostatic pressure 2000 psi & it was over.
I wonder how this is related to the initial report that the disaster was caused by a “burp” from the reservoir.
Regarding “top kill”, I envisioned the difficult task of preventing the high pressure oil from flowing through and around the injected heavy mud.
I would think that the FBI would be starting to do family and business tree lineages on everybody that was on that platform at the time.
Start with the deceased.
>> One thing that bothers me is why can’t they at least continue pumping seawater into the manifold system instead of mud.
Freezing ice cold sea water slush might even be better. Add chiller coils around the manifold and freeze it shut.
Very informative. Good read. Looks like a ‘bottom kill’ procedure might be something to try?
And here is why:
http://www.freerepublic.com/focus/f-news/2524241/posts
More brainstorming. See #10
I would think the oil may be a higher temperature than the sea water and thus prevent any freezing.
I’m interested in how the operation to cut the top off the BOP is going to work. My fear is the blade of the portable band-saw would become pinched as the weight of the cut-off section slowly settled on it. And if they WERE to successfully cut through it, what kind of side loads might fling the cut-off section in whatever direction, even towards the ROV. High drama, I must say.
I understand the Russians have nuked a half-dozen or so leaks, but this area has a fragmented seabed and that a nuke may not work.
It would be interesting to know whether the “company man” has more political or company connections than practical experience and knowledge, or if he is knowledgeable but let other priorities determine his decision.
The man who wrote this informative piece is one of countless others in the industry with practical experience who knows and understands what is happening in the Gulf. The fact that there was an argument with the company man is proof enough of that.
A little power is a dangerous thing in the wrong hands. We are learning every day, and in many ways, how dangerous a lot of power in the wrong hands can be.
They need to put crushed stone into that hole, that will block it up
As far as the blow out all I have are field rumors.
1) They pumped a poor cement design that was pumped while the well was basically already blowing out although it had not hit the surface.
2) They didn't change out the pipe rams to the 7". Pipe rams are slotted to wrap around the diameter of pipe in the blowout preventer. The diameter of the drill pipe was 5 1/2" to 6". Prior to running the 7" casing the rams are supposed to be changed out to the new diameter. There has been talk about the BOP shear rams and others, but no one has mentioned the satus of the pipe rams.
3) Unless you could get the nuclear weapon way down the hole, I can only surmise it would crate a bigger disaster.
4) The bottom kill is easier once you are there and have a pipe to pump mud & cement through, I didn't mean to imply hitting the target is easy. I've taken "kicks" and seldom got hysterical if I had pipe on bottom, because I can take pressure measurments and calculate what it takes to kill the well and can control circulating out the "bubble".
5) I need to emphasize that all of the kill procedures must be accomplished with out exceeding the burst pressure of the casing in place. This is waht happened in Santa Barbara in 1969. That idiot Red Adair instead of taking measuements just tied onto the wellbore and started pumping in & exceeded the burst pressure of the casing. After that happens the only solution is the relief well.
6) Again, we don't need to worry about the earth moving. Oil comes from the tiny pore spaces between sand grains. This reservoir is 18,000' deep, even if there is slight compaction due to reduced bottom hole pressure causing the sand grains to get closer together it will not effect the seabed.
7) The large spill in the time frame and concentrations we are seeing is comparable to the one in Mexico from Ixtoc. I'm not aware of the long term effects, however oil naturally seeps into the gulf. Roberto Debaca recaulked his ships from the tar on the beaches in Port Isabelle in 1519.
8) I have no way to estimate what rate the blowout is occurring. We do measure rates accurately when we know the diameter of the pipe and have a pressure up stream, then we can calculate. With irregular diameters of escape and no flowing pressure estimates its anybody's guess. The area of the spill on the surface is no help. A quart of oil on your swimming pool will look like the Exxon Valdez.
9) The experts comments that are mindless prattle are many. Bill Nye really galled me when he proposed that the drilling mud will plate out closing the diameter of the pipe. Drilling mud is a highly sophisticated fluid. What someone told Nye was about a property of mud where it forms a filter cake against a permeable membrane. The clay particles in mud are too big to go into the tiny spaces between sand grains and will not penetrate into the formation and will plate out forming an impermeable barrier to keep the mud from dehydrating. If there's no permeable barrier the mud will not plate out. Since he didn't understand this he postulated that the mud would plate out against impermeable steel.
continued ....
http://www.abovetopsecret.com/forum/thread576723/pg3
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