Wednesday, September 8, 2010

Deepwater Oil Spill - a slight change in plan

I have not had a chance to read the BP report on the Deepwater Horizon disaster yet, and due to a couple of other activities (I returned to the USA today) have had only a limited amount of time to catch up on the current plans for abandoning the well, which were reviewed by Admiral Allen at his press conference .

One of the points that he mentioned however, that I thought might be worth discussing a little, is the plan to use the Development Driller II that is connected to the original well at the moment, to complete much of the plugging and abandonment procedures. I will go through that process again in a later post, but one of the things that the Admiral noted today was that the new process would be as follows:
If you remember, the DDII was drilling the second relief well. They came off of that wellhead and took the Blow Out Preventer, and that is the Blow Out Preventer that is now on the well. So they are hooked up to the new Blow Out Preventer over the well, just the same as the original rig would have been, had it still been there.

So they can go down through the well and perforate the casing above the cement and actually cement in the annulus from the top, because they're already there and available to do it. And then shortly thereafter, we will finish the relief well from the bottom with Development Driller III, which was always drilling the first relief well, and they'll do it on the bottom.

Now the point is that to gain access to the top of the cement that was pumped down the production casing, the DD2 is going to have to send tools down to the top of the projected cement and then perforate the casing to inject either mud or cement into that area of the annulus.

Here is where I have the current question. There was some 3,000 ft of drill pipe in the well below the original BOP, that wasn’t there when the BOP was removed. The question becomes, when did it fall into the well? Was it before the cement was injected (in which case the falling DP could have done some damage to the shoe, but all is now hidden, including the DP, in the cement injected) or did the DP fall later during the removal events that took the original BOP from the well.

In that case the DP could have fallen on top of the cement, could have damaged the casing in the process, and would, quite likely be distributed within the production casing so that it will make it difficult for the current operators to get their tool down to the required perforation and injection zone, with the DP in the way.

This could very well explain why they want to get the DP out of the hole using a fishing expedition, but it could be that they won’t find it, since it fell earlier and has been buried in the cement fill. At which point they can then proceed to do the final plug and abandon, following the path that the Admiral outlined. There is, however, no hurry at the moment, and the relief well could now not be completed until the end of the month.

For those wishing to read and comment on the report that BP have just issued on the originating events, that report can be accessed at the BP internal investigation website, and your comments are welcome.

1 comment:

  1. HO -- The full BP Internal Report with appendices is massive -- about 190 pages of text, 60+ MB. It will take some time to read it all.

    Looking at the executive summary, there is just a whiff of whitewash about it. No mention of BP's decision to start pumping the mud off the rig before the well had been securely suspended -- the BP-directed step which both denied the drillers the most obvious warning of an influx from the formation to the well and which removed their main method to control that influx.

    Also, read BP's description in Appendix F of the role of the all-powerful BP Company Man on the rig -- BP makes him sound like a junior observer, instead of being the ultimate decision-maker on the rig.