the key to blocking the well is to use one way technologies. basically, stuff you can put down there that wont be able to come back out (ever).
my idea to put a mount of sorts at the opening of the well (there is less pressure outside the opening) and then pull down a bunch of weights to gradually block it off more and more of the tunnel downward until it's sealed off.
the mount would be like a
grappling hook that collapses like an umbrella in order to fit in the well. when it gets to the bottom it would open and voila, you have a cable that you can pull things downward with. (one way technology)
however, to get it to the bottom you would need a weight to have gravity put it down (there's a lot of pressure pushing up!). you could put a
pincher claw at the bottom so that it would release the weight when it opens.
so now, you have the ability to pull/push objects down the well using a really really strong "rope" (see metal cable). to utilize the cable, you need to use something that works either like
cable/zip ties (you would need a fancy cable for that) or like a
chinese finger trap. i would go with the finger trap because it works using friction alone. (both are one way technologies)
for the objects you are pushing/pulling down, i would use a raw material that is heavy, really heavy... like lead and pull/push it down to where the opening is. however, the cable is just guide and momentary crutch for the objects going down. each object needs to have it's own "legs" that push outward as it's pulled/pushed down so that if/when the tension loosens it will dig into the sides of the well (one way technology) instead of come flying back out (
not a one way technology) of the well at a zillion miles an hour.
if you could get on of these objects (and several behind it) to block the well at it's opening, it's more likely to hold. after which time, fill the whole damn thing with cement if you want.
so yeah, that's my idea. it's simple, depends on
basic mechanics (very important when you have pressures and temperatures that warp materials) and should shit go terribly wrong it wont make the situation worse.
for the record, blowing shit up in or by and oil well is a hell of a retarded idea.
"the wisdom of the wise will perish, the intelligence of the intelligent will vanish."