World Oilfield Forum
May be sorry later, but here goes........
The title says "What WE know", but it should say "What I think we know...."
What "We" know..........
1. It was technologically a tough well. If you have to set three full strings of casing and four drilling liners in a space of 13.000' (approximately), this is a tough well from an engineering and feasibility standpoint.
2. They shut the well in before it blew out...about two or three minutes before. I evidence the rapid gain in stand pipe pressure in the last two or three minutes. Nobody can explain that without telling me the well was shut in. They boys did what the well told them to do.
3. Displacing with sea water before setting the final cement plug was NOT a factor. They could have set it in mud, then pulled up above the plug and displaced with sea water. No biggie. Either way, in order to remove the riser, they had to displace the well before or after setting that final plug, or just pull the riser and let @ 2,350 bbls of synthetic oil based mud loose into the gulf.
4. Bottom hole pressure was @ 13.000 psi as evidenced by their TD mud weight of 14.0ppg and TD at @ 18,300 ft.
5. The tapered string of 7" on bottom and swaged up to 9 5/8" or 9 7/8" (whichever), was cemented in place with 51 bbls of cement. By my calculations, that was an excess over guage hole of 20 bbls. I have read recently that no caliper log was taken of the well as they depended on MWD and did not run an open-hole wireline log. That is anecdotal evidence read on the web, and not substantiated. So I don't really know if the hole was washed out 20 bbls over caliper. Gotta figger formation at that depth won't wash out that bad, but they did have three 15" triplex pumps on board. This is a "gray area" to me until I get more info.
Here's what I DON"T know.....
1. Did anyone note a discrepancy between the amount of sea water being pumped down the drill pipe and the associated returns? Unless you had a dedicated and monitored "second" surface system on the rig to do just that, then the answer would be that they could not track it barrel-for-barrel. But did someone see "something wrong" in the displacement? Nothing about the surface monitors submitted by Halliburton can track that, because it doesn't track what is being pumped to the work boat.
2. THE SINGLE MOST IMPORTANT UNANSWERED QUESTION.......When they set that final string of casing (after cementing) and lowered it into the seal assembly and released the 5,000' of drill pipe from the setting tool in the hanger......Did they have a way of monitoring the annular pressure outside that last string of casing? I don't know and haven't seen a diagram or picture of their wellhead configuration, but I cannot conceive of a configuration where after setting the casing, they couldn't monitor the backside pressure.
Your thoughts and comments are certainly appreciated.