Monday, April 18, 2011

Comments on Macondo BOP's

Last month a report was issued regarding the BOP's on the ill-fated BP Macondo well.  One commenter noted that BP was faulting the BOP's, and went on to liken BOP's to the "rear guard" in a war zone:

Itsy bitsy problem doomed BP's well

The war zone analogy is a decent one for the handling of a difficult well. However, if you goof up your tanks, your troops and your artillery, and wait until the enemy is 100 yards away to call the rear guard ... you can guess the outcome.

A parachute might be an analogy for a blowout preventer. Although you function test both and check them regularly, you don't want to get yourself into an emergency situation where you have to use them. That is "Job One" you might say, namely staying out of that situation. Further, if you have to use them, you need to use them early. Waiting, and attempting to close a well flowing at a high rate could be likened to trying to open your parachute at 100 feet.

So, what are the tanks, troops and artillery in drilling and completing a well? There are many, and in drilling a well, you can "pull the plug on the war" at any time if you are prepared and do it soon enough. Among other things, you design your casing/hole size such that there is enough cement sheath to create effective cement isolation, which also requires the proper cement slurry and centralizing the casing in the hole. Then after the cement job - on a difficult, high pressure well - you stay "on guard" for "gas flow after cementing", ie when gas flows in due to the setting of the cement's removal of hydrostatic pressure - before the cement has set enough to contain it. Then you test your liner top, and you take action to fix any problem. Then you make good decisions about displacing the pressure controlling mud out of the well. Then if you decide to do that, you make sure you have a way to keep track of the mud coming out, versus the seawater going in, to make sure that the well is not "coming in". If the well starts to come in, or flow, you close the blowout preventer immediately and begin circulating the mud back in, then fix the problem that allowed the well to flow. You don't wait until oil and gas are seen at the surface to shut the well in; by that time, it may be too late - you're opening your parachute at 100'. Finally, and most importantly, you have a highly experienced, sufficiently rested person (one person) in charge at all times. All of the above are "standard operating procedures" in any well control manual. These procedures were developed beginning, say, in the 1950's. (The above is just an example, and it is only coincidental if it resembles some of what might have occurred on the Macondo well.)

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