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DeepWater Horizon-- Digging for Facts
Various --- Oil Drum initially ^
| June 21, 2010
| Ernest at the Beach
Posted on 06/22/2010 12:09:14 AM PDT by Ernest_at_the_Beach
An attempt to look thru various sources and answer some basic questions .
1. Can we get a handle on a basic Fact ...What was the pressure at the bottom of the drilled hole in the formation ?
From the Oil Drum:
BP's Deepwater Oil Spill - Matt Simmons on Dylan Ratigan Today, Closing the Relief Ports, and Open Thread 2
Comment by avonaltendorf on June 8, 2010 - 12:06am
Thread Posted by Prof. Goose on June 7, 2010 - 9:00am
***************************EXCERPT*************************************
Comment by avonaltendorf on June 8, 2010 - 12:06am
I received a personal note, which I acknowledge gratefully.
Down to business. I agree with Matt Simmons and posted as much evidence as I could garner from publically available ROV feeds. We aren't being shown the IR or sonar images. Low res video is crap compared to what the ROV pilots and BP folks are looking at. Obviously USCG is in the dark or has been ordered to follow the White House playbook until they get a handle on how big a problem they have. In my view, it is a medium-sized problem, not quite as gigantic as Simmons suggested to Ratigan.
**********************************snip***********************************
Let's roll the movie back to the events of April 20. Simmons thinks that the reservoir pressure is 30,000 psi judging by the force of the blowout. This is clearly impossible. If true, it would have blown out immediately on penetration April 17. The scout ticket tells us that the pressure at the top of the reservoir was no greater than ~13,000 psi based on mud weight to control lost circulation:
LWD (RLL, BATSON, PWD) @17173, M 14.1, NO SWC, 9 7/8 LNR @14759-17168, LOT 15.9, LWD (RLL, BATSON, GEOTAP, PWD) @18260, LOST CIRC W/14.4 MUD, C&C SPTTD LCM
LWD=Logging While Drilling
RLL=Recorded Lithology Log with gamma ray and resistivity
NO SWC=No Side Wall Cores
PWD=Pressure While Drilling
LOT=Leak Off Test to measure strength of wellbore wall
At 18260 ft, Lost Circulation with 14.4 lb/gal mud, then Circulated and Conditioned the mud and Spotted a Lost Circulation Material pill to cure the losses. They had drilled into the top of the reservoir (gas cap) and mud started leaking away into the reservoir, because 14.4 mud weight was greater than the reservoir pressure. Assuming a vertical well, reservoir pressure was less than 14.4 x .052 x 18260 = 13768 psi, or mud would not have been lost.
It was a slow process of gas reaching bubble point plus a nonsense negative test ordered by Kaluza that sandbagged the drillers into displacing to seawater without watching mud returns or understanding what was happening. When a gas bubble formed it expanded rapidly as it travelled up the riser unopposed, blowing out the seawater and mud. It was followed by very light liquid and more gas. The BOP did not fire on EDS from the bridge because hydraulics were gone or malfunctioned, but there was mux control to one or both of the pods. Only when the rig sank and riser collapsed did the BOP see a "deadman" condition and attempt to shear the drill pipe -- except by then it was clogged with debris and couldn't shear or close fully.
Thus we have gas and light oil at low pressure spewing from the riser swivel. Below the BOP should be ~8,000 psi, which is sufficient to find paths of opportunity to nearby vents. However we have to keep in mind that collapsed casing and broken cement gives the reservoir a path to salt welds (thin mostly vertical remnants of salt withdrawl) and fractured slump faults. It is therefore possible that light oil at 13,000 psi could migrate updip miles away.
I posted such evidence as I found. It is not enough to prove anything, but convinced me that Simmons knows the deepwater GoM geology.
TOPICS: Business/Economy
KEYWORDS: deepwaterhorizon; oilspill
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To: Sender
":1)Hydrogen Sulfide (toxic, flammable) safe levels: 5-10 ppb tested: 1200 ppb 2)Benzene (toxic, carcinogen) safe levels:0-4 ppb tested: 3000 ppb 3)Methaline Chloride (toxic, flammable) safe levels:61 ppb tested: 3000-3400 ppb" This is ALL bullshit. 1.2 ppm of H2S is NOT harmful by any mechanism. Its one characteristic at the level is that it smells bad. Benzene is "slightly" carcinogenic. To develop the very rare cancer involved takes years-long exposure. And "methaline chloride" (correct spelling is "methylene chloride") is not found in oil at all. So if anyone says it is, they are lying in their eye teeth.
To: Ernest_at_the_Beach
does anyone know the inside diameter of the relief well pipe at the bottom where it is to intersect the current well?
22
posted on
06/22/2010 7:42:11 AM PDT
by
a real Sheila
(NOTHING makes SENSE anymore!)
To: justa-hairyape
Man, system is still very slow this morning...
Thanks for that link...
13,000 psi is looking very credible.
To: FreePaul; All
Thanks.....
This system is so slow,...I think I will turn to other things....
I am sure John is working hard to get the weekend troubles behind us.
To: a real Sheila
I do not know....I'll look later today on the Oil Drum after I get back from a dental appt.
Somebody may answer earlier.
To: Sender; CharlesWayneCT; Wonder Warthog
26
posted on
06/22/2010 2:48:55 PM PDT
by
Gondring
(Paul Revere would have been flamed as a naysayer troll and told to go back to Boston.)
To: Ernest_at_the_Beach
One hardly knows what to believe is the true condition at this well bore site. To many wide variance in pressure numbers and barrels per minute/hour/day being leaked at any given orifice or from the seabed, to know what to think at this point.
And as for the supposed huge oil plumes. What would keep the oil from rising to the surface based on the specific gravity of salt water verse oil.
To much does not seem to be accurate reporting.
27
posted on
06/22/2010 4:14:55 PM PDT
by
Marine_Uncle
(Honor must be earned....)
To: Ernest_at_the_Beach
The initial mud weight I recall was 16.8 lbs/gal. Doing the math, the hydrostatic from that mud weight before the riser was displaced is: 16.8*.052*18000=15724 psi at 18000 ft.
Displacing the riser would have dropped that hydrostatic (at full displacement with seawater) by (16.8-8.5)*.062*5000=2158 psi. which leaves 15724-2158=13566 psi of hydrostatic pressure at 18000, and the formation flowing. Formation pressure is somewhere between the two, because the riser was not yet fully displaced when the formation began flowing.
Pressure at the wellhead would be the difference between formation pressure and the hydrostatic pressure from the fluid column in the wellbore, and the question there remains one of how severely gas cut that column is. If the oil/gas mix has a weight of 5 lbs/gallon, the pressure at the wellhead would be from 13566-(5*.052*13000) to at the high end 15724-(5*.052*13000), or from 10186 psi to 12344 psi. It all depends on the gas cut in the fluid column and the density of the oil.
Keep in mind, there are a lot of dynamic factors ignored here, (sidehole friction, ECD, and any constrictions in the wellbore) this is just an offhand calculation of a range of static pressures, and not solid as fluid mechanics go.
28
posted on
06/22/2010 4:22:20 PM PDT
by
Smokin' Joe
(How often God must weep at humans' folly. Stand fast. God knows what He is doing.)
To: Ernest_at_the_Beach; AdmSmith; Berosus; bigheadfred; blueyon; Convert from ECUSA; dervish; ...
:’) Thanks Ernest_at_the_Beach. And happy belated birthday (hope I didn’t let any cats out of any bags).
29
posted on
06/22/2010 4:28:44 PM PDT
by
SunkenCiv
("Fools learn from experience. I prefer to learn from the experience of others." -- Otto von Bismarck)
To: SunkenCiv
To: Ernest_at_the_Beach
You are amazing! Thank you for generating the replies...
and happy birthday. ;o)
31
posted on
06/23/2010 12:04:47 AM PDT
by
dixiechick2000
(Remember November...I can see it from my house!)
To: dixiechick2000
Well,...thanks...not sure what I did.
Around here you just post something .... ping a few people.... and experts join in and supply info...
This "community" is amazing.
To: Sender
Today's Dialogue at the Oil Drum really gets into why 100,000psi is not the psi in the formation...
well's borehole pressure
*************************************EXCERPT*************************************
I have spent the past 30 min looking for a good ref for over burden the source of the well's borehole pressure and haven't located one.
A good rule of thumb is .45 psi per foot of depth for sea water column and .75 psi per foot for rock formation.
The oil/gas zone is permeable, that means there can be no differential pressure between 2 points in the permeable zone except for the differential depth. So yes it's like a tire, except when it's flowing, pore size changes flow rates within the formation but not greater than the initial pressure.
Believe rock he has good explanation.
We need to put this 100,000 psi nonsense to rest. It makes TOD look less than reliable for facts.
To: All
Let me add this...from the Oil Drum:
Halliburton docs, for reference (see Table 1.11 for pressure stats): http://tinyurl.com/33zsg9f
To: SunkenCiv; Marine_Uncle; BOBTHENAILER; Dr. Bogus Pachysandra; dixiechick2000; Smokin' Joe; ...
Update ping.....discussion today at The Oil Drum.
And data from the Halliburton plan for the well.
To: All
To: Ernest_at_the_Beach
I don't know the technical stuff about calculating the well pressure, but I know that it has to be above the water pressure a mile deep.
I have been wondering, how did the blowout preventer fail? Why is there no way to actuate a manual valve down there by a ROV?
It seems to me that the first requirement for this type of deepwater well would be to have redundant ways to shut it off.
But then, if they could shut it off, it might just blow the valve off the ocean floor and flow anyway.
38
posted on
07/03/2010 5:36:43 PM PDT
by
Sender
(It's never too late to be who you could have been.)
To: Ernest_at_the_Beach
Ecocentric Favorite Links
@import "http://cmads.time.com/ads/cm/css/article_feed_300x250.css";
To: Ernest_at_the_Beach
It’s funny reading the comments from TOD sometimes. It took a while for example for the commenters to realize that the whole analysis of the weight of the water/rock on the formation was NOT about pressurizing the formation, but was explaining that the formation couldn’t be at a much higher pressure than the weight or else it would fracture the rock and leak out.
You are working to hard in my opinion, but that’s because I’ve pretty much already accepted the 11,000 psi approximation as rational, and don’t feel like I have to keep re-justifying that when people speculated about 100,000psi pressures.
But I guess someone has to do it. I’m more focused on trying to keep people from turning their distrust of Obama into conspiracies about the government trying to hide oil under fresh sand, or the whole “corexit poison rain wipes out america’s breadbasket”.
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Chip -- Dig thru the doc and you'll find a pressure plot. From the log data they estimate the OBG (overburden gradient) to be around 16 - 16.3 ppg. They probably used the wire line density log to come up with a site specific OBG. You'll also notice the frac gradient is in the upper 15s. I suspect the low FG is why theyre setting csg just above the intersect: cut down the possibility of lost circulation.
ppg.http://energycommerce.house.gov/documents/20100614/BP-Production.Casing.TA.Options-Liner.Preferred.Long.Version.pdf