NYIntensity wrote:
I'm interested in what you think might happen if one of these caverns collapses, Pat. Or how you think it *will* collapse. If the contents are under pressure and the contents are removed with no replacement, I can understand your fear of collapse. But they're being backfilled with saltwater, which, unless some crazy atmospheric anomaly occurs, is the same thing applying pressure from the outside. Oil is more dense than water but that just means that more water goes into the cavern.
I'm all ears to a lesson if I'm mistaken, but I think the fear of collapse is illogical.
denser items under solid pressure of rock acts like a rock. the layers of rock are compromised by the drilled holes, which weaken the system. put a piece of plywood over 2 2x4's 5 feet apart and walk across it. drill holes through it, roughly 1" in diameter, then cover them with wood filler. walk across it. it breaks.
conversely, step on an unopened pop bottle. it won't collapse. open it and then drink a swig or two. then close it. step on it. you'll collapse it a little. the pressure is changed and the seal has been compromised.
saltwater and oil are so completely different and act differently in their environments. throw in the compromised rock layers under millions of tons of pressure from the water.