http://www.energybulletin.net/node/20455
I was trying to find a good and simple geologic profile or boring log. Lots of technical stuff out there. This article is interesting in that it talks about efforts in 2006 at the leading edge of discoveries of these deep Gulf of Mexico oil finds. And talks a bit about the rock in the Gulf and the geologic history.
These wells drill into the deep (and therefore very old) rocks in the gulf. Even though they may talk about Tertiary “sediments” and oil “sands”, they are talking about sediments and sands that were laid down millions of years ago. They have undergone deep burial, compaction, tectonic plate motion (pressure), etc. They are now rock, like sandstone, shale and slate (from silty mud), limestone (from dead coral), etc.
Granted, the sea floor of the Gulf has a thick layer of loose sand and silt from the Mississippi river in it (thousand(s) of feet thick?? I don’t know). And the water pressure in that loose material can also play havoc with a drill hole. But BP’s problems are well below that layer.
The well was something like 25,000 feet deep as I recall. They are dealing with hard rock. Probably hard “salt” as well (as in rock - not table salt).
So the rupture in the well pipe is where? In the rock or above where the rock starts or both? You said the trouble is below the soft stuff. I’ve read conflicting info on that so I don’t know.
There’s also the issue of how much support is being provided now to the well pipe. Seems to me that the answer there would be not enough until you get to the rock so everything above it is not stable. Is that correct?