I’m a first time poster, so apologies if I hit the wrong button by mistake. I’m impressed by the knowledge shown in this thread, thanks.
To answer stompk at 11:34: There is no fluid communication route between a reservoir & the surface – reservoirs are created by fluids becoming trapped under some geological feature {which is why they can be found by seismic}. The reservoir pressure is caused by the overburden above – as a rule of thumb assume 0.45 psi/ft of vertical depth. However virgin reservoirs may be at much higher pressure than this – when drilling mud of 17 lb/gal is used, this implies that a reservoir pressure of 0.9 psi/ft is anticipated. Since a column of gas exerts very little psi/ft, & gas-free oil about 0.38 psi/ft, you can see that for a reservoir at 15,000 ft pressured at 0.9 psi/ft, the differential pressure between a mud column {well under hydrostatic control} & an oil column {well blowing out} is about 7,800 psi. Replace some of the oil with gas & the differential increases further. This is the drive behind the fluids escaping the well.
Reservoirs are not caverns, they are rock beds with porosity {like a sponge} between sand grains. Theoretical max porosity is about 26%, but 10% to 15% is more common. Only about 33% to 50% of fluid in place is ever produced, so there may be settling, but not usually collapse.
Hope this helps.
To Richard8000milesaway at 03:28 pm: They probably did not seek to sink the DWH – but it was too hot & dangerous to have anyone aboard controlling buoyancy in the hulls, the control systems would have been badly damaged & there was a lot of seawater being pumped onto the fires. But your thesis is correct – keeping the well flowing into the fire & burning would have stopped crude spilling into the ocean. This makes land blow-outs much easier to handle.