INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Remember Me

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.
Jobs from Indeed

Just copy and paste the

BP Gulf Coast Oil Spill Q/A

Share

BP Gulf Coast Oil Spill Q/A

(OP)
Informational and brainstorming thread about the recent coastal oil spill. Petroleum engineers' professional opinions greatly appreciated!

The story thus far:

Press release:
http://www.bp.com/genericarticle.do?categoryId=2012968&amp;contentId=7062470

Live cam:
http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/homepage/STAGING/local_assets/bp_homepage/html/rov_stream.html

Related articles:

http://www.cbsnews.com/video/watch/?id=6490509n&amp;tag=contentMain;contentAux

http://www.deepwaterhorizonresponse.com/go/site/2931/

http://www.api.org/Newsroom/safetyresponse/index.cfm

Some questions:

With the doubled pressure on the underwater rig (due to mud being pumped against the oil flow), could the structural integrity be weakened? What are some of the worst-case-scenarios if this were to happen?

What are some other methods to resolve the situation? Be it via relief well, junk shot, etc.

What are the long term effects on the surrounding area?

RE: BP Gulf Coast Oil Spill Q/A

Last question first. No one really knows for sure.  The thinking goes from complete loss of the Delta, if a storm comes in to a lot of habitat for sea creature and rookeries for birds.  The oil in open ocean is another unknown due to the quantities and where it goes. The Gulf can accommodate some oil as it does with the natural seeps.

The only real solution is the relief well. This can be troublesome as the 1979 Itox Blowout, BOP, took 9 months to completely seal and it was shallow enough for diver to work on the well head.  BP has acknowledged two heavy "junk hots" as well as smaller injections.

There was big worry that BOP had been damage by the collapsing riser but apparently was effected.  The biggest problem now is the pressure need will be too much for the kinked drilling riser. They only have two injection points to inject the mud into the BOP. I haven't heard what size these lines are. One is the coke line. BP still refuses to give the pressures involved in any aspect of the process.  One professor from a Texas school stated that that if will take 3000 ft of 16 pound mud to kill the flow.

RE: BP Gulf Coast Oil Spill Q/A

Hi unclesyd.
With the partially open BOP and the flow of oil, will that not act to vent most of any pressure rise the mud pumping may cause?
What is 16 lb. mud? 16 lb. per gallon? 16 lb. per liter?
Thanks.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

You can get live video of the BOP and surrounding areas at http://www.cnn.com/video/#/video/us/2010/05/28/vo.aerials.oil.rig.cnn . The link may change from time to time. When the camera is close to the BOP you will see the two injection pipes clearly, they look quite small. The idea seems to be that they pump so much mud in that the amount gushing from the BOP creates enough back pressure that some of the mud goes down the hole. Do that with enough mud for long enough, you should get an adequate column of mud in the hole. Please feel free to criticize this interpretation. I have never been near this type of well and I am just theorizing.

HAZOP at www.curryhydrocarbons.ca

RE: BP Gulf Coast Oil Spill Q/A

16 pound mud is 16 lb per gallon or about .83 psi/ft.  This would put 15,000 psi bottomhole.  The well blew out with seawater and was under control with normal mud.  This would lead one to believe that the bottom hole is between 9000 psi and 15,500 psi.  The 15000 psi is 1 psi/ft for the 13,000 feet of drill depth plus 2500 psi for the water pressure.

RE: BP Gulf Coast Oil Spill Q/A

Here is the scheme of things supposedly as it now stands.

http://www.reuters.com/article/idUSN2819681720100528?type=marketsNews

A strange place to find information.  Go down to the "Oil Drum" Leak header and read more.

http://www.petsstatus.com/archive/lower+marine+riser+package.html

BigInch
Here is primer on Drilling fluids.

Thanks for the analysis.  The CEO has been asked about some of the pressures involved several times and his comments are always that everyone is too busy to provide any outside information.

http://www.wdcexploration.com/what_we_do/pdf/drilling_fluid_fundamentals.pdf

Checkout BigInch's reply of May 29 @ 6:53 in thread311-2715: sun java cerificate is achivable in 3 months?.  One or two hard numbers from BP and his analysis would tell you exactly what's going on.  Apparently they are giving this information to anyone not even the US Government. Our government people at all levels measure the money received from the oil patch in barrels.

Early on in the reporting of this event there was an interview with a survivor of the accident who was in a position to give some of the preliminary events.  One of his comments was that some time before the event happened a mud pump operator reported that he was finding relative large chunks of rubber on his filter screens on the returning mud.   This gentleman said that this rubber could have only come from the "annular valve" at the top of the BOP.  As I understand it the purpose of this valve is to seal the annular space between a restricting bushing and the drill pipe when they want to shut the well off from the riser.  He stated that someone inadvertently pulled about 15' of drill pipe through the closed valve.  This valve acts like a hydraulic collet.

My in-laws who work offshore had been put under a "Don't Tell if Asked" policy.  To get close to the truth about about the events preceding the accident it would take a criminal indictment to get even half truths.   Have them brought before a Federal Grand Jury and have a jar of Petroleum Jelly on the table.

If you get a chance checkout the National Geographic Film. Right at the end you can briefly see a very large oil flow from the well head with an unbent riser.  It worries me if they cut the drilling riser below the kink they could possibly have this flow again.
If you listen to the comments and pay close attention to the events being recorded you will see that this was being treated as a shipbord/rig fire almost to the end, evidently no one wasted to say this was wild well on fire. The fire fighting crew from Holland was experts in shipboard fires. In fact you will note that they were preparing to salvage the ship.

Unclesyd,

rmw

RE: BP Gulf Coast Oil Spill Q/A

If I could get it right it might work.

Checkout BigInch's reply of May 29 @ 6:53 in thread311-271544: oil leak gulf of mexico.

The third heavy "Junk Shot" apparently has not worked. They are saying 24 hrs but have a news conference in one hour.

The reported potential of this reservoir is 50,000,000 barrels.  Also all the while this "Junk Shooting " was going on the flow of "hydrocarbons hasn't changed only a small change in the gas/oil ratio

RE: BP Gulf Coast Oil Spill Q/A

"Top Kill" has been killed!

RE: BP Gulf Coast Oil Spill Q/A

After "Top Kill" comes a plan to cut off the pipe at the top of the BOP and put a better funnel over it. I was wondering why they can't give the robots impact wrenches and unbolt the top. Then they could lower the next BOP down and bolt on top of the current BOP. Then close a few valves.

HAZOP at www.curryhydrocarbons.ca

RE: BP Gulf Coast Oil Spill Q/A

owg,
I have conveyed to my friends who have some contact with people on working site to look at hydraulic nut busters in lieu of any type wrench. This would do the same thing, but breaking the flange will still require the cutting of the drilling riser to take some pressure off the gasket.

To add another blowout preventer as I understand it will have to have it's separate support frame as the riser below the current BOP can't sustain the additional load.  Any larger leak would require that a vessels in the area where the oil surfaces would have to move due the possibility of fire where the oil surfaces.  I tried to get a number on this but had no luck.

I heard two comments yesterday and today that relieves some of the a big concern of mine.  Flow out of the riser is limited by the pressure drop taken in BOP stack.  I just hope it will not be the flow seen in Nat. Geo. Film during the filming of the drill ship fire.

RE: BP Gulf Coast Oil Spill Q/A

One of them brain thing A big question.  When this episode started there were three leaks one at top of the BOP still leaking, the second at the end of the broken drilling riser still leaking and the third at the end of drill pipe that they easily capped
The drill pipe goes through the BOP to some depth and would become a conduit for oil if as proposed they square off the Drilling Riser with a diamond wire saw. There is also a kink at the top of the BOP like the drilling riser that may have restricted the flow so they were able to cap it. I don't know the diameter of this drill pipe but I've heard 7" several times.

RE: BP Gulf Coast Oil Spill Q/A

Thanks to unclesyd for the very helpful responses. I was wondering if the drill pipe still goes through the BOP. Now I am wondering how the BOP was supposed to work. Are its functions 1) To provide a seal around the drill pipe? (There were reports about bits of rubber/sealant showing up in the mud. 2)To provide closure when the drill pipe is not in the way? 3)To provide closure around the annulus when the drill pipe is in the way? Thanks

HAZOP at www.curryhydrocarbons.ca

RE: BP Gulf Coast Oil Spill Q/A

The case is thus or somewhat similar.

If the drill pipe is still passes through the BOP there is a  rubber seal that can can be externally energized to seal the annulus at the top of the BOP. This valve can be used during any type of operation below the BOP.  There are a number of different variation of this valve.

Below this valves there can be a number of different type hydraulic valves that can be used to stop the flow if there is no drill pipe in the BOP.  If there is is drill pipe in the BOP there are pincher valves that are designed to pinch, not sever the pipe to stop the flow. If activated one has to pull the string of drill pipe to replace this section.

The last line of defense is the shear valve which which when activated will completely shear the drill pipe and shut the well in. This is the last resort. I don't know the configuration of the valve on the DWH BOP so I have no idea if they could have recover from the activation of this valve. It can be done on some BOPs but is very time consuming and expensive. Two BP wouldn't stand for as they had lost two months, getting in a hurry, will drilling this well.

The type of BOP used on this job is very complex in itself and with the controls.

The radiography accomplished right after the event was able to show that the pincher valves were partially closed.  The reported low hydraulic pressure reported early could account for this.

I've been told by several people in the business that the reason for the change from drilling fluid to salt water was money. BP would have been able to use this mud on another well saving a ton of money as the weight was 16 pounds, very costly.

RE: BP Gulf Coast Oil Spill Q/A

I am wondering why the depleted hydraulic pressure can not be rectified in the BOP.
With all the things that they can do with the remote operated vehicles, why can't they clamp and pierce a hydraulic line and increase the hydraulic pressure?
Is the BOP itself under designed and not able to function even with full hydraulic pressure?
Is anyone else starting to suspect that the BP honchos will still dismiss any idea that doesn't originate in house?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

They were able to hook up the two hoses for pumping the drilling fluid.  I see no reason why what your propose couldn't have been made to happened.  I've asked the same question to some people who work on these things everyday and have not gotten a full explanation of why not.

In the information being disseminated there has been mentioned about a hydraulic leak with nothing about where it was.  If it was on the servo circuit this could be a reason or the mention of a low battery which may have prevented the operation of a servo valve that would allow this to happen. If you check the interview with the rig electronics head you will hear that all the engines started sunning away very close to the time the gas first started escaping. This killed all the power on the ship and probably took out the BOP console on deck as they immediately lost dynamic positioning system which may have severed connections to the BOP.

On another discussion group a person with the handle "horizon 37" who if not part of the operation was very close to it said a good possibility was that the drill pipe was set with a joint in shear rams path and there wasn't enough power to shear it. This is quite plausible as the Williams interview on 60 minutes mentioned that the drill pipe had had been inadvertently raised about 15 feet.

Getting to the truth about what happened before and during the incident will be impossible as anyone in supervision will lie and the workers on deck can't say anything as they will be blackballed, probably their family too.

RE: BP Gulf Coast Oil Spill Q/A

I understood that the raised drill pipe incident was about one month previous and that is what may have trashed the inflatable annulus seal.
I understood from one of the interviews that the cementing crew tried to activate the missing annulus seal. I guess the regular crew didn't tell the cement crew;
"Oh, by the way, the annulus seal is trashed."
I have no idea of the separation of the hydraulic circuits on the BOP but the missing inflatable seal may have been responsible for the hydraulic leak and low pressure.
I don't know, I am asking. Please don't take my suggestions for fact. I'm asking questions based on a basic mechanical knowledge and bits and pieces of information gleaned from various press releases.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

I assumed that the engines were ingesting methane gas as the reason for the run aways. I was aghast that they would be running without automatic shut down flaps in the intake manifolds. Then we started to hear about BP's disregard for safe practice in general.
I am still some what aghast, but no longer surprised.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

That was my opinion also and the air intakes were inboard and evidently got the gas first.  There is one report that an attempt was make to start the backup generators and they wouldn't even turn over.  The report stated that an interlock had them locked out and couldn't be reset.

I was slightly in error about the shear rams on the BOP.  On this one there are two one and and one lower.  The top ram is supposed to shear the drill pipe and the lower to cut the casing and possibly squeeze the drill pipe.

Here is live feed of the bots working at the top of BOP stack.

http://www.livestream.com/wkrg_oil_spill

RE: BP Gulf Coast Oil Spill Q/A

I thought the engines would stall if they got nothing but fuel. I suppose the methane came in one side first and the engines ran richer and faster before stalling.

HAZOP at www.curryhydrocarbons.ca

RE: BP Gulf Coast Oil Spill Q/A

In the heavy oil fields,we are not allowed to drive a diesel pickup truck until it has been fitted with a shutdown flap valve because of a very small possibility of gas ingestion.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

Fascinating discussion!
Regarding the OPs last question, it's not just the local area that will be effected (though they will for sure hurt the most) but also a significant part of the lower US.  Consider that it will be August before the relief wells are in place.  Hurricane season starts today.  Hurricanes have been known to carry salt and plankton far inland, and Katrina went right up the Mississippi river valley and almost made it as far as Ohio before petering out.  Imagine our heartland getting rain after rain of oil on the crops.  And this is supposed to be an especially active hurricane season.
(Cue R.E.M. ITEOTWAWKI)

"Good to know you got shoes to wear when you find the floor." - Robert Hunter

RE: BP Gulf Coast Oil Spill Q/A

Anyone willing to listen to a bp executive not filtered through a government or media set of biases, might like to watch the video at http://bp.concerts.com/gom/kentwells_update24052010.htm

Kent Wells is a Sr VP of Exploration and Production for bp and his presentation has a bit of propaganda in it, but mostly he's trying to explain what is underway.  Unfortunately the video was made before the top kill evolution failed, but he does have a good explanation of what it is.

David

RE: BP Gulf Coast Oil Spill Q/A

For those who may have missed the link here is one of the live feeds from BP.  They getting ready to cut the drilling riser to shorten it prior to using the wire saw on same at the top of the BOP.

http://www.livestream.com/wkrg_oil_spill

RE: BP Gulf Coast Oil Spill Q/A

Thanks again to all the folks who provide answers to these dumb questions. One more - if the flange under the cut could be removed nut by nut, then bolting just one valve on top of the BOP might be able to control or stop the flow. And it would not be as heavy as a second BOP, so it may not need additional support.

HAZOP at www.curryhydrocarbons.ca

RE: BP Gulf Coast Oil Spill Q/A

I second the thank you.
Given BP's performance so far, cutting the riser scares the hell out of me. I'm glad I live 2000 miles away. My sympathies with those of you who are closer.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

As I understand it there is a piece of drill pipe, part of approximately 4000' total length hanging below the BOP, bent along with the riser.  There are several questions about this pipe, if they unbolt the flange, my first thought, they would still have he drill pipe hanging on at the kink. Is the drill pipe partially sheared our sheared enough to part and cause all manner of chaos.  Even in cutting the riser and drill pipe together they don't know how this pipe is supported.

The pucker factor is quite high on the rig.

RE: BP Gulf Coast Oil Spill Q/A

It looks like Poseidon is getting angry.
Taken from aboard the Discover Enterprise sitting on top of the event horizon.

They stated that the pucker factor is getting higher by the minute as no one knows the amount of gas they can expect when they start getting new riser working.

RE: BP Gulf Coast Oil Spill Q/A

i think I fixed the first link, the best.

RE: BP Gulf Coast Oil Spill Q/A

I'll bet the pucker factor on the rig is exceeded by the pucker factor in the head office.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

unclesyd, I was assuming they cut the pipe away before they unbolt the flange.

HAZOP at www.curryhydrocarbons.ca

RE: BP Gulf Coast Oil Spill Q/A

As I understand it they will not unbolt the flange. The LMRP will seal against the saw cut face on the drilling riser.  This is the primary reason for using the diamond wire saw.

This is a much smaller version of the type saw that cut the Russian submarine Kursk in two pieces to allow for the recovery.

RE: BP Gulf Coast Oil Spill Q/A

Is there any information out there on the quality of the stuff that is being recovered from the second cap. BP has announced that they will dispose of it by burning it. People are asking why not refine it. I would expect that the quality would be a lot better than skimmed oil, or tar balls. However it could have emulsifier, seawater, brine from the formation, and gas in it.

HAZOP at www.curryhydrocarbons.ca

RE: BP Gulf Coast Oil Spill Q/A

The quality is very good light sweet at 35 to 39 API and is being sent to be refined. They are going through the regulatory process to get an oil lighter from the North Sea permission to operate in the Gulf, it may take and act of Congress.  The Enterprise has only limited storage capacity and is flow limited by the amount of NG it can flare.
The net profits from the oil will go to the the Wildlife Groups, so said.

Unclesyd,
I was fine with your post till the last phrase.  I wish you'd said "net proceeds" instead of "net profits".  They're spending upwards of $100 million/day. They'll sell the oil for something like$500k/day.  The "profit" is a "loss".  The $500k will be going into the wildlife groups anyway. David RE: BP Gulf Coast Oil Spill Q/A Good catch... don't want the wildlife groups having to pay the difference! "Good to know you got shoes to wear when you find the floor." - Robert Hunter RE: BP Gulf Coast Oil Spill Q/A I've heard both and use net profits based on a statement that define the ammount the birds would receive. The description was a specific breakdown per bbl of oil recovered during this operation minus the usual deductions for lease royalties, which will have to be paid to the feds, some fee to Louisiana and a couple of others. If I recall the numbers$70.00 minus about $30.00 bbl. with$40.00 for Dawn dish washing liquid.
This is great if if it doesn't have to go through any of the Federal Agencies and each take pinch of the top.

I mention this on another post but there are 35 Federal agencies involved in anything that goes on and the majority have to sign off on anything before it goes to BP for approval.

There is some good reading on this site about the drilling and execution of Relief Wells.
It can induce a very large pucker factor

http://www.jwco.com/technical-litterature/tech.htm

RE: BP Gulf Coast Oil Spill Q/A

That would be "net proceeds" (i.e., sales price minus expenses and royalties).  I thought that's what you meant,  no one is making profit on this except the chemical salesmen (maybe that would be a good place to put some money?).

David

RE: BP Gulf Coast Oil Spill Q/A

Correct.

For any that miss it the Government has just put the flow rate at 20,000-40.000 bbls/day.

RE: BP Gulf Coast Oil Spill Q/A

Donm't forget there's the Oil Spill Liability Trust Fund, financed by a 5c levy on every bbl of oil imported or produced in the the US.  A sort of manditory insurance paid for by the oil companies for just this type of event.  Currently worth about \$1.5 billion

I don't know if it's been tapped yet, but if it hasn't BP could be a little irritated- it's like your car insurance not paying out if you have a crash becasue it was a Thursday...

RE: BP Gulf Coast Oil Spill Q/A

unclesyd- so at the upper bound, it's still smaller that Ixtoc-1, isn't it.

And what were the long term environemntal effects of that spill? Pretty minimal! And remember Pemex claimed soverign immunity (as it is goverenment owned) and refused to pay for the short term damage done to Texas beaches...

Sieze BP indeed!

RE: BP Gulf Coast Oil Spill Q/A

The real flow rate may be several times the Itox-1 average flow rate. bp may yet surpass the Itox-1 losses.
Even if they don't surpass Itox-1, they are stiil firmly in second place for all time oil spill disasters.
But wait, bp said that this has never happened before. If you are going to be a bp apologist, you shouldn't mention Itox. It doesn't look good alongside bp's denials of previous undersea accidents.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

Itoc 1 total flow over a ten month peroid was around 3,000,000 bbls covering 1,100 sq miles.  This blowout started at a very high flow rate and gradually tapper off due several different efforts to kill it.
It sure killed the red snapper fishing in the Bay of Campeche for about 5 years.

Just heard another blivit from the good old Coast Guard, remember the 1,000 bbl/day bunch,  saying the tar balls and oil washing up on on a 50 mile stretch of beach centered at Pensacola aren't from the DWH, BS.  The Brown mousse laying jsut off shore also cam from a fairy ship or Father Neptune.  The Brown mousse patches found inside the Perdido and Pensacola pass must be from alien space ships.

What bothers me is the big Mama Snapper, greater than 35 lbs will spawn in July and the fry will be in the water column for up to six months before they migrate to the bottom.  They can't win.  The only sea life than will move if they sense that their environment is becoming hostile are most of the shrimp species and squid, with the squid being the fastest to move.

I talked to my doctor who is an very accomplished Scuba Diver this morning to checkout what he had found when a group made a dive around a large patch of brown mousse about 13 miles off the beach.  He said that the oil extended down 60 feet and stayed about the same size of the visible spill on surface. The only difference noted was that the concentration tapered off somewhat toward the bottom. They got run off by the marine patrol as the area was said to be too dangerous.

RE: BP Gulf Coast Oil Spill Q/A

Thanks Syd
My comment was based on a rough estimate;
20,000 to  40,000 BPD times a possible 100 days.
The capture efforts will reduce the total lost in the ocean as opposed to the total well flow, and I hope that it is shut down in less than 100 days.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

waross- I'm not a BP apologist; I'm a professional drilling engineer in Aberdeen, watching this blowout with horror, and also getting irritated at the misinformation, assumptions, errors and ignorance being reported in the media.  Suff like accoustic BOP control systems being mandatory in Norway (they aren't); or the rig didn't have an emergency BOP control system (it had two: an EDS and a deadman switch) and so on.

I'm waiting for the full inquiry on this disaster to report- where did the kick come from?  Why did the BOP not close fully?  Why did the rig explode?  Why did the emergency BOP systems not funtion and so on before I say who's to blame.  Does that make a BP apologist?  Or does it make me someone who isn't making assumptions and rushing to conclusions?

This is the first deepwater blowout (defined as more than 1500ft water depth) in more than 30- 35 years of deepwater drilling and thousands of such wells.  It is the first major blowout in the GoM in almost 30 years and tens of thousands of wells.  If the Macondo blowout spills more than Ixtoc-1, it would still have a long way to go before surpassing either the first Gulf war spill or the Lakeview blowout.

RE: BP Gulf Coast Oil Spill Q/A

(on edit)  or on deaths, the Macondo blowout with 11 dead has a long, long way to go before surpassing the Alexander Kielland with 123 dead, or the Piper Alpha disater with 167 dead....

RE: BP Gulf Coast Oil Spill Q/A

Hi Nic.
First, although we do not agree, I respect you and your position. In a perfect world I would agree with you. But the world is not perfect. I expect to see bp's spin doctors and lawyers work as hard as they can to lessen bp's responsibilities and obligations.
And as for waiting for the inquiry and what facts are allowed to come out, bp's position may be even worse than we expected.
Case in point; The volume of the flow. I and others assumed that bp knew the volume of the escaping oil and were resisting publication of accurate figures for PR effect. We had many estimates putting the volume much higher than bp admitted. We had reports that a team of undersea scientists was enroute to accurately measure the spill volume and were turned away.
When bp started collecting more oil than their original estimate the amount reported as escaping, the goverment re-assesed the volume that was leaking.
When it became apparent that the surface facilities were inadequate to handle the volume that could be captured, it seemed that bp did not have any idea of the volume of the spill and had believed their own BS as well.
I think that we can safely assume that the BOP was in bad order.
As to why work proceeded with a bad order BOP, we will wait and see if that was incompetence in the matter of testing the BOP or willful disregard of safe operating procedures.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: BP Gulf Coast Oil Spill Q/A

Waross- metering of multiphase fluids is very very difficult, even on surface- generally the fluids are separated into liquid and gas and then indivudually metered.

My guess is that BP were working on what they thought the reservoir might deliver before they drilled it- ie "errrr, similar wells in this formation with a similar permeabilities produce about 2bbls/ psi of drawdown pressure below the reservoir pressure.... We know reservoir pressure in the Macondo well is xxxx psi as we measured it, but what's the pressure in the bottom of the well?  Well it depends on the fluids in the well, which are a mixture of oil and gas, but we don't know how much gas as we don't know the wellbore pressure.... And then there might (or might not, we're not really sure) be some back pressure due to restrictions in the riser and BOP and the holes the well fluid is flowing from.   Umm, let's estimate 2000psi of drawdown so that would give about 6000bopd"

I think the estimates were jointly produced by BP and bits of the US Government - the Coastguard and the NOAA- so I guess everyone involved reviwed the estimates and the assumptions.

Even the independent scientists have come up with 12,000- 19,000 bopd, which isn't a very accurate number (basically 15500bopd +/- 30%).  I've seen some riduclous numbers of 100,000bopd from the well(to put this in context, 100,000bopd is the production from a reasonable sized field with lots of wells).  Now we have an better number as BP are actually recovering a lot of the oil (but remember that they have also removed some of the flow restrictions inteh riser that may have been reducing the flow slightly).

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!