Posted on 06/17/2010 11:05:41 AM PDT by Comrade Brother Abu Bubba
1. On a footage or day rate job, (this was a day rate, reportedly $1 MM/Day), the drilling contractor doesn’t do anything without operator approval or direction. (Questionable - reported that the semisubmersible TransOcean Deepwater Horizon was contracted on a day rate of around $530,000/day but about $26 Million Dollars over budget (AFE - Approved for expenditure)
2. There is no reason to believe the blow out preventer was defective. The probability of a similar result is high for any crew using the same casing and cement program that was used here.
3. The well was drilled to 18,360 ft and final mud weight was 14.0 ppg (lbs/gal). The last casing long string was 16 inch and there were 3 drilling liners (13 5/8”, 11 7/8” and 9 7/8”) with 3 liner tops. 16 inches is a massive annulus, with attendant massive forces. A 9-7/8” X 7” tapered casing long string was run to TD. Normal practice would be to run a liner with 9-7/8” liner top packer, followed by tieback string. Perhaps they ran the long string at the last minute to make up for being over time and budget? That would explain why there was no lock ring, since a last minute change would not allow time for fab or prep of a lock ring.
4. Apparently they had indications of mud losses, but efforts to control these were incomplete at best, and perhaps they decided to depend on the cement job to handle this for them.
5. This section of casing was cemented using only 51 barrels of nitrogen-aerated cement [UNBELIEVEABLE!, ON A POTENTIAL KILLER WELL LIKE THIS ONE], a product choice and volume that seems peculiar and “tricky”. Normal practice would be to pump heavy cement all the way back up to the seabed. Also, why nitrified cement? [POOR PRACTICE, ALSO REPORTEDLY ONLY UTILIZED 6 CENTRALIZERS ON THE LAST CASING STRING INSTEAD OF THE RECOMMENDED 21 BY HALLIBURTON]
6. The casing seal assembly was set in wellhead and pressure tested from above to 10,000 psi. Reportedly, a lock down ring was not run on the 9 7/8” hangar/seal assembly casing hanger, as stated above.
7. After only 16.5 hours after cementing, the casing string was pressure tested against the shear rams. Typically you wait 24 hours before pressure testing, because of the danger of expanding the casing and cracking the cement, causing a pathway up the annulus for gas. Were they trying to get off this hole? A negative test on the wellhead packoff was performed. No cement bond log was run, perhaps to save a few hours of precious rig time.
8. The rig crew HAD to believe that the well was successfully cemented, capped and secured at this point. No one would remove their heavy (14 ppg) drilling mud and replace with seawater [FATAL MISTAKE! The well was static with the 14 ppg mud in the hole, even without a proper cement job- Comrade Brother Abu Bubba] if they believed otherwise, and they did so before setting final cement plugs. Yet they did so less than 20 hours after primary cement job. At this point, they had NO effective barriers between reservoir and surface. They should have had at least 2 proven barriers. They chose the fastest way to displace the well with seawater, by pumping sweater down the drill string and sloughing the returns to a work boat, so you lose the benefit of monitoring influx via the pit level. All of this had to be operator mandated.
9. During the displacement failure, the casing collapsed or otherwise failed, causing the well to unload and ignite. According to the first photos, the crew was able to get the diverter closed since flames were shown coming out of diverter lines.
http://1.bp.blogspot.com/_udSTgadqhFc/S-uAQp9p7jI/AAAAAAAABbg/hQCGgca2Se8/s1600/Deepwater+well+casing.jpg
Not having a Nobel Prize, could someone direct me to a site that fully describes and illustrates the structure and processes required for deep watr drilling. All this “inside baseball” lingo concerning proper and improper pratices needs an accepted model of behavior to contrast to. Not being a oil guy, these posts are interesting but ultimately useless since we laymen have no way to digest and screen the comments for accuracy and common sense.
Link to original article seems broken.
OK, some of this is over my head, but the picture helps (thanks CD for putting it in-line!).
What is a “lock ring” and why would it be a bad thing not to have one? And the author seems to be saying that they did wrong by using cement with nitrogen mixed in, and using a 16” diameter pipe for too much length?
}:-)4
ping for later
It’s obvious that the hydraulic well head oscillator should have been engaged prior to pumping sea water in the diverter housing. /sarc
I think the BOP should have prevented a blowout.
Exactly! That is what caused the inertial pressure regulator to fail in the first place!
The BOP didn’t.
One wonders why the rush? I assume that project management has a bonus incentive to finish and being 26 mm over AFE already was about to lose any remaing bonus money. So the incentive was to finish quickly.
I think it says they were running a low-power test and deactivated a number of control safeguards and then tried to power up far too quickly...oh wait...wrong disaster. My bad.
This entire ordeal will be blamed on earthquakes and be classified as a natural disaster.
Here too.
I also agree that the well is likely unstable should they actually be able to cap it off at the top.
The "simple" solution to me is to drill a bunch of surrounding wells and pump them like H! to try to drop the local pressure at the surrounded bad boy.
2. There is no reason to believe the blow out preventer was defective. The probability of a similar result is high for any crew using the same casing and cement program that was used here.
What about the comment on 60 Minutes a few weeks ago from the chief electrical engineer about rubber from the top of the BOP being found in the circulating mud by the mud engineer? What about operational defects in the control system backups? Why did the shear rams fail to operate as designed?
Jeeeeeez, guy gets it wrong in the VERY FIRST POINT (AFE does not mean “approved for expenditure”). What else did he blitz?
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