A Petroleum Engineer's Explanation

reply to post by Edrick

Again, many thanks for the earnest and well-informed replies..not just to my question but to others.
I have only one last comment re--the " nuke" option.

My thinking when I asked was that we must still have a couple " Davy Crocketts" in the arsenal..and if we don;t we certainly have allies and trading partners who do....Davy Crockett , you might ask?

"The smallest nuclear weapon the US produced was the "Davy Crockett" - a recoilless rifle round. It weighed about 51 pounds, was 16 inches long and 11 inches in diameter. It produced a variable yield of up to 1 kiloton. "

And what a few correspondents have told me is..that if the idea is to seal the well..it might be possible to ram such a device below the well cap and detonate.

But again...I am not a physicist nor an engineer and am, like most of us here, trying to find facts and fit them to theories...as we are all in this mess together.

Thanks.
Sincerely..and please keep posting!

Originally posted by Streetwise
"The smallest nuclear weapon the US produced was the "Davy Crockett" - a recoilless rifle round. It weighed about 51 pounds, was 16 inches long and 11 inches in diameter. It produced a variable yield of up to 1 kiloton. "

That was discussed earlier in the thread. The nuke would need to go deep in the hole, near the formation to seal it. If they could get something that deep they may as well just pump mud, that's what they plan to do with the relief well.

Besides 11" is too big, the casing is 7" so it would have to be about 6" diameter to fit that deep. Detonating at the sea floor would just make a crater and make the problem worse.

I know people like to talk about blowing stuff up because blowing stuff up is fun, but it's a really dumb idea in this case.

I had an interesting conversation with someone I've known for pretty much all of my life that has intimate knowledge of what's going on with DWH. I'm a gas processing person and I don't know a whole lot about drilling ops so if something is typed here that doesn't look right it's probably because my notes are bad. We talked about the probable cause of the various failures that resulted in the blow out. Almost all accidents are the result of human failure followed by mechanical failure. It sounds like this one is no different.

I hope BillyJack pops in and gives feedback on this.

From my notes (my comments are in () ):

The bottom rams on the BOP were not shear rams. They were test rams. This was done at BP's request. Not everyone on the rig knew this and when the blowout started the first set of rams actuated were the test rams and were incapable of holding back pressure from below.

They were running a negative pressure test and they didn't wait on cement. (Apparently there is a test to confirm that the cement job was good and MMS approved bypassing the test at BP's request.)

The cement job failed. (I have no clue what he meant by all that other than his final statement was that they thought that the well was sealed. Had they run a cement test they would have realized that it was a bad cement job.)

The 8" casing wasn't designed to hold the pressure that they are seeing and it failed.

At some point they were able to see inside the BOP. (I assume that was after the bent riser was cut off.) There were two pieces of pipe side by side inside the BOP. He stated that there was no way the shear rams could cut through that. He also said that the initial failure of the rams was "probably" related to the "sealant" (cement plug?) coming back up the well bore.

I forgot something.

The casing is damaged. Had the BOP worked as planned, because of the bad cement job the casing would have blown out deep and that would have caused untold problems. As it is, it's leaking under below ground. There is apparently a large crater around the well (unless I misunderstood him)

The relief well drilling is going very well. He predicted early July for them to begin the process of killing the well.

Originally posted by Mike6158
I had an interesting conversation with someone I've known for pretty much all of my life that has intimate knowledge of what's going on with DWH. I'm a gas processing person and I don't know a whole lot about drilling ops so if something is typed here that doesn't look right it's probably because my notes are bad. We talked about the probable cause of the various failures that resulted in the blow out. Almost all accidents are the result of human failure followed by mechanical failure. It sounds like this one is no different.

I hope BillyJack pops in and gives feedback on this.

From my notes (my comments are in () ):

The bottom rams on the BOP were not shear rams. They were test rams. This was done at BP's request. Not everyone on the rig knew this and when the blowout started the first set of rams actuated were the test rams and were incapable of holding back pressure from below.

I'll give you my thoughts till billyjack comes back

The test rams on the bottom is confirmed in the BP slides showing the BOP configuration in this thread:
www.abovetopsecret.com...





In fact there were undocumented changes to the BOP and they were still investigating that as of the date those slides were released. I'm sure there's a whole story in the undocumented BOP changes.

They were running a negative pressure test and they didn't wait on cement. (Apparently there is a test to confirm that the cement job was good and MMS approved bypassing the test at BP's request.)

The cement job failed. (I have no clue what he meant by all that other than his final statement was that they thought that the well was sealed. Had they run a cement test they would have realized that it was a bad cement job.)

Billyjack referred to the CBL test or cement bonding long, maybe that's the test you're referring to? Here's the cement slide:


They did some kind of U-tube test referenced there, but they never ran the CBL if that's what you are referring to.

And the casing test slide:

That shows a casing test also.

But it seems pretty clear that the cement job did not make a good seal like it's supposed to. Another site claimed they just used too little cement and that was the reason it failed, that they used the planned amount but the planned amount was insufficient.

The 8" casing wasn't designed to hold the pressure that they are seeing and it failed.

Well the cement bond between the 7-9" casing and the borehole wall failed. But this is the first I've heard about any casing failure, so I'm not sure about that. BP says the formation pressure was 12000 psi and billyjack said the casing was good to 15000 psi if I recall so there shouldn't be a reason for the casing to fail.

At some point they were able to see inside the BOP. (I assume that was after the bent riser was cut off.) There were two pieces of pipe side by side inside the BOP. He stated that there was no way the shear rams could cut through that. He also said that the initial failure of the rams was "probably" related to the "sealant" (cement plug?) coming back up the well bore.

That's interesting. I wouldn't have expected to see 2 pieces of pipe side by side in the BOP, unless one of the shear rams actually worked and did shear the pipe, and then later re-opened, that could allow the pipe sections to get side-by-side.

[edit on 13-6-2010 by Arbitrageur]

Originally posted by Arbitrageur

But it seems pretty clear that the cement job did not make a good seal like it's supposed to, that seems to be clear. Another site claimed they just used too little cement and that was the reason it failed,that they used the planned amount but the planned amount was insufficient.

The 8" casing wasn't designed to hold the pressure that they are seeing and it failed.

Well the cement bond between the 7-9" casing and the borehole wall failed. But this is the first I've heard about any casing failure, so I'm not sure about that. BP says the formation pressure was 12000 psi and billyjack said the casing was good to 15000 psi if I recall so there shouldn't be a reason for the casing to fail.

At some point they were able to see inside the BOP. (I assume that was after the bent riser was cut off.) There were two pieces of pipe side by side inside the BOP. He stated that there was no way the shear rams could cut through that. He also said that the initial failure of the rams was "probably" related to the "sealant" (cement plug?) coming back up the well bore.

That's interesting. I wouldn't have expected to see 2 pieces of pipe side by side in the BOP, unless one of the shear rams actually worked and did shear the pipe, and then later re-opened, that could allow the pipe sections to get side-by-side.

I stripped out the image links and some content so the post wasn't too long.

He said that there is a deep depression around the BOP and that the casing failed below ground. Beyond that I don't know other than I have seen reports of oil coming from places other than the BOP cap.

Link to ATS thread about this

As I understood him, they actuated the bottom ram first, it sheared the pipe but couldn't shut off so it failed and allowed continued back flow which brought the other section of pipe into the BOP beside the other piece of pipe.

The good news is that he said the relief well drilling is going well and they are only a few weeks out from killing the well.

[edit on 6/13/2010 by Mike6158]

[edit on 6/13/2010 by Mike6158]

[edit on 6/13/2010 by Mike6158]

reply to post by Arbitrageur


I really appreciate the pictures from BP that you are posting. This helps with obvious rookie mistakes by BP, but some of these are confusing where I don’t completely understand. I understand the LAP & UAP, this are what I call hydril type preventers that are composed of a rubber bladder like a balloon and will close around anything, but normally cannot hold back high pressures. In my experience certainly not 10,000 psi, but maybe they make them for offshore. I also don’t understand two sets of shear rams & I am surprised there are no blind rams. All shear rams cut things off drillpipe, casing etc., while blind rams are used to close when there are no pipes in the BOP. Glad to see that they had two sets of pipe rams, but the rams themselves can only close & seal around a specific diameter of pipe size. The same rams can’t close around 6 5/8” and also 3 ½”, so without specific diameters I still wonder what size pipe rams were there. I am still of the opinion that they didn’t have the right size pipe rams when it blew out. The fact that they release this diagram without specifying the size in place may confirm my suspicions and the fact that they said it only went to 6 5/8” when I thought they ran 7” casing may be proof that the pipe rams were not changed out. I’ve never heard of test rams, I test my BOP’s with the rams that I may have to use.

The real scary part is the cement job. First, assuming that they were drilling an 8 ¾” hole to run 7” OD casing then the theoretical annular volume is .0268 bbls/ft. If they circulated only 342 barrels before cementing that means that they didn’t even get bottoms up to the rig floor. 18000 times .0268 would require a volume of at least 480 barrels to see what was in the hole before starting cement. In addition, this annular volume is ideal theoretical, the actual hole drilled will have wash outs meaning that the actual volume to get fluid from the bottom of the hole to the surface will be larger. By the way, before I start cement and what is the norm is to get at least two bottoms up before cementing, so they should have circulated two bottoms up plus a safety factor or over 1000 barrels before cementing. In this environment with these pressures I might have been there a while before pumping cement. Keep in mind when we stop circulating with mud the effective circulating density of the mud is reduced. Without much ado the mud appears to weigh more while you’re pumping than when it stops. The well was dead & drillpipe was pulled from the hole & layed down, then casing was picked up and run so there had been no circulation from the bottom of the hole for at least 24 hours. All this time the bottom of the hole was filling with gas & apparently oil, that’s the reason we circulate when we get casing on bottom is to make sure the well is quiet before we pump cement. Cement can’t set up generally if it is dynamic (moving around). Now based upon the picture I start getting confused. They talked 60 bbls of cement which equals 2521’ of theoretical annular volume, yet they say top of cement was only 876’. To make this even more curious it was nitrified cement which probably means it should have covered even more of the annulus. The yield volume of foamed cement should even be larger. If this is the case then hole wash out bigger than 8 ¾” would mean the diameter was at least 50% higher than theoretical requiring a lot more volume to get bottoms up. It also doesn’t add up that they refer to lead cement. Cement jobs may be pumped as lead and tail, which means two different qualities and composition cement, was pumped, they didn’t break this down.
This is getting too long. Final concern is that they finished the cement job before they even had bottoms up once. Therefore the oil & gas that came up the hole was in theory in the riser above the BOP when they bumped the plug.

reply to post by Arbitrageur


Final Thoughts

the riser above the BOP when they bumped the plug and they had no way to know how bad of condition they were in since it would have taken at least another 100 bbls to get bottoms up. Add in that I am sure they had a pure nitrogen spacer in front of the foam cement further lightening the column then they were really screwed.

By the way, since they had 14#/gallon mud in the rat hole the reservoir pressure was probably closer to 13,000 psi. The 16.5# mud was pumped to equalize the effective hydrostatic head due to the nitrified cement weighing less than 14#/gallon.

reply to post by billyjack


A couple of things- He said "8" casing" when we were talking and he said test rams are just shear rams installed backwards so that they hold from the top down not from the bottom up.

After that we moved on to rain, baling hay, and other parts of life.

I was taking notes as fast as I could but some things could have been missed.

Just a question.

Wouldnt it be smarter to be spraying the oil with a congealer, instead of a dispersant.

Im thinking if all the oil globbed together it would be easier to recover. Floating masses could be hooked and scooped up. under water oil would come with it. Cleaning beachs would be a snap.

If a animal came in contact. It would act like a semi solid ground. Making it harder for the animal it get mired in it.
dont know if there is a product like this

Originally posted by vonrader
Just a question.

Wouldnt it be smarter to be spraying the oil with a congealer, instead of a dispersant.

Im thinking if all the oil globbed together it would be easier to recover. Floating masses could be hooked and scooped up. under water oil would come with it. Cleaning beachs would be a snap.

If a animal came in contact. It would act like a semi solid ground. Making it harder for the animal it get mired in it.
dont know if there is a product like this

There are natural oil seeps in the gulf of Mexico. Apparently there are microorganisms that "eat" the oil. I was thinking, why not spray the slicks with a liquid suspension of these cultured microorganisms? Probably because maintaining stockpiles of these living organisms for disaster control may be problematic but they might be able to engineer a rapid breeding approach to make them available in a week or so of a disaster.

The dispersants I've read about are apparently not environmentally friendly and may do more harm than the oil slick, so I'm not sure they are such a great idea.

reply to post by Streetwise

Again, many thanks for the earnest and well-informed replies..not just to my question but to others.
I have only one last comment re--the " nuke" option.

Yes, thank you!

And your welcome!


The Nuke option is a sort of "Last Resort" due to the complicated nature of deep well drilling... Allow me to explain.



Carbon is a light element... Silicon is heavier than Carbon.


Thus, our atmosphere contains carbon, while dense deep rocks are mostly silicon and other heavy elements or large molecules.

Carbon that is trapped in long chain molecules are heavier than the silica sand, or at least as dense as it, and thus, they "Sink" as soil deposits accumulate over the millinia.

The weight of the sand, soil, and rock above the carbon chains cooks them under pressure, added with the heat from subterranian magma pockets and all...


This makes the carbon form chains of hydrocarbons (from the water and such) which is the most efficient arrangement of those elements at those temperatures and pressures.


The oil is Trapped underneath Heavy, Solid Rocks... and above those, there is a decreasing density of sediment until you reach the ocean floor.

Now, given the pressure dynamics of fluids.... (Pressure to one point is distributed among the rest of the fluid relativley equally...) What you have is Miles of Rock, Clay, Sand, and dirt weighing upon this oil, and causing it's pressure to be REALLY HIGH.

The only problem is, that since it is a fluid, it rises through cracks and escapes the pressures of the rocks above, leaving nothing to support it....

And maybe even causing a collapse of the "Roof" structure of rock above the oil Well.


The current "Bottom Kill" plan, is to drill a well down INTO the hard rock (Near the oil pocket) and fill the original well with heavy drilling fluid from the bottom... establishing enough WEIGHT upon the bottom of the mud, that it equalizes the pressure, and the well stops flowing.


If they MISS (the relief well does not intersept the original well... then they might use a nuclear weapon to spill the leak.


The only problem is... that they will be setting off a nuclear explosion in the CEILING above this mammoth oil pocket.


If that Fractures.... Down to the Oil Pocket.....



Well... I don't think I need to draw you a picture or anything, but suffice it to say, that our itty bitty hole, would become great, big, and wide.


Hence.... Plan *B*

-Edrick (or perhaps C)

[edit on 14-6-2010 by Edrick]

reply to post by Mike6158


Forgive me if I have misunderstood any of the following, but I'm trying to get up to speed on this from a standing start....

According to the 60 minutes interview with Mr. Williams, the electronics and computer guy from the Deepwater Horizon, the annular at the top of the BOP had started to break up some time before the blow-out. He described chunks of rubber coming up to the rig with the drill fluid. Apparently it was the damaged annular that gave rise to the false readings on the pressure test.

The same interview describes (with a graphic) one of the rig workers nudging a lever and causing the pipe to be pulled back up through the BOP a short way. This meant that the shear rams in the BOP, when activated, were trying to close around a joint in two sections of drill pipe. Perhaps this is the two sections of pipe that Mike's contact spoke about. These wouldn't have been side-by-side, though, but one inside the other. This would also explain why the ROVs were unable to operate the rams manually.

Have I got that right?

Lastly, I would like to add my thanks to those of others for the people like Mike, Arbitrageur and Billyjack for elucidating some of the issues involved in this nasty business.

I'm keeping everything crossed for the relief wells to do their job.

reply to post by Karilla


I wish I had been able to talk with my contact a little longer and I wish that I had a better understanding of everything he said. My note taking was bad. For some reason I wrote LMRP??? but I don't remember what he said...

I am glad for BillyJack and Arbitrageur's feedback otherwise my notes wouldn't make sense at all.

I hope he was right about the early July time line for the relief wells. He should know. He's in Louisiana (or out in the GOM south of LA) this week. If I get to talk to him this weekend I'll try to feed the info back for clarification.

Originally posted by Arbitrageur
There are natural oil seeps in the gulf of Mexico. Apparently there are microorganisms that "eat" the oil. I was thinking, why not spray the slicks with a liquid suspension of these cultured microorganisms? Probably because maintaining stockpiles of these living organisms for disaster control may be problematic but they might be able to engineer a rapid breeding approach to make them available in a week or so of a disaster.

The microbe activity in the oily areas has increased, and is now is high enough that it is taking all the free oxygen out of the water. They need oxygen for the process of digesting the oil.
Maybe they should be working on a way to add more oxygen to the water so that the microbes can better "do their stuff".

A righands perspective is that all the things you have explained are correct,but you failed to mention that the focus of all of the procedural actions you describe correctly are designed to `save the viability of the well``,use your expertise to explain what would happen if you created a fracture in the formation of sufficient size and location to close in the well bore completely.

Explain that it would be efficient ,feasable,and should have been done already,there has to be a column of rock somewhere along the way that can be fractured.

Well dynamics only matter if you intend to CONTROL the well ,so you can utilise it as an asset.

If you dont care about the viability of the well in its totality,you seal the well bore permanently.Easy.

It sounds like the engineer took a pressure reading and noted a change in the downhole pressure so he adjusted his mudweight to compensate for the change as per standard operating procedure,in doing so he replaced his weighted mud with seawater and lost circulation,what the real question is ,is this,what were the three pressure readings prior to the one he lost it on.Why didnt he question the need to make such a drastic and sudden compensation.

We know he compensated according to the proper procedure for the pressure reading but we dont know why he didnt question the reading itself in comparison to earlier readings,thats his job,to make those correlations.

The well had been taking kicks earlier as the widow of one righand stated to the press.
They had had trouble maintaining circulation and control of the well.


WHY WASNT THE PRESSURE READING QUESTIONED AT SUCH A CRITICAL MOMENT.

This was the immediate cause of loss of circulation,but what caused the loss of the well was a human error of a different type,SOMEONE PULLED THE DRILL STRIGG UP THROUGH THE BOPS,after the bops had been closed,instead of before as should have been done..

reply to post by Edrick


Not all my questions are based on military-mindedness..although I do concede that it has at times been one of my perceived faults....that is, according to civilians...[ahem]

Anyway..it is comforting to know that I am not alone in wondering if the solution in the end may may be as.. or more ..drastic than the Deep Horizon event that caused this catastrophe

video.godlikeproductions.com...

Originally posted by Arbitrageur
I know people like to talk about blowing stuff up because blowing stuff up is fun, but it's a really dumb idea in this case.

video.godlikeproductions.com...

And it's getting so that I honestly don;t know who to believe anymore. What I DO know is that just letting this gusher continue to gush for the next 25 years is not an option.

So you guys involved in the industry, do you think there needs to be more regulation?

From what I have read, there doesn't seem to be a whole lot of effort to establish standard automated shutdown proceedures, or even standard procedures to drill these wells.

Considering the massive impact on numerous eco systems, and large numbers of people having their property destroyed by catastrophic environmental disasters, having rules that guide these operations are more important than traffic laws.