My best guess is that the cap was designed for the 9000 number and they're pretty happy with the true numbers.
Turbidites reservoirs are often "amalgumated" sands.
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Alaska_geo on July 17, 2010 - 1:34pm
I'm strongly suspecting that the reason the pressures are less than expected is because the Macondo well has been in communication with and draining a small compartment, rather that the entire accumulation. This reservoir is most likely composed of turbidite sands. Turbidites reservoirs are often "amalgumated" sands. That is they are deposited by a series of turbidity flows over some period of time. The sands may make one big pile, but are still individual sands. The pre-drill estimate of 50-100 million bbls is no doubt based on seismic data, which does a fair job of indicating the overall size of the sand accumulation. However, seismic is often too blunt a tool to image the individual turbidite sands that make up the whole sand accumulation.
In a compartmentalized reservoir, individual sands aren't well connected to one another. A well draining one sand may get little or no contribution from adjancent sands. In the normal oil field development and production situation a compartmentalized reservoir is a bad thing. It means more wells (hence more cost) are required to produce the field. In the present situation, compartmentalization may be a good thing. It means the last 80+ days of "production" may have drawn down the pressure in the compartment significantly from what was observed when the well was initially drilled.
You're leaving out the people who were talking about 70,000 psi. Good idea to leave them out.
The 9000 psi figure was from wireline downhole measurements made before the blowout.
"My best guess is that the cap was designed for the 9000 number and they're pretty happy with the true numbers."
Design max pressure for the BOP stack was 13000 psi.