dumgeek and others. I have found my way here as well after watching the footage the last few days. Cut/grind/saw off bolt heads. Throw away riser pipe stub. They cannot go for any quick stop on the oil, they have a 2 mile deep column, which, if 30,000 barrels/day is correct that is 6 cubic metres per second and if 9" is the pipe diam, it is going at 100m/s. Now, I am not sure if those flow rates are good, I am taking the figures put about elsewhere and maybe the pipe is significantly larger lower down, but even so that means that an impulse is required of 1,000,000 Newtons force for 16 seconds if that column is to be stopped. Stopping it quicker means a bigger force. The stopping process needs to take place over a longer period of time, then the forces can be manageable. What they need are some very long bolts, held in a hydraulic drive motor fixed on a steel plate which will form a cap. Bolts of different length so they can engage one at a time, in the poor seeing conditions. No nuts but a split and hinged, threaded collar snapped on below the flange. An alignment ring held at length of shortest bolt, to keep them all on the correct PCD. Engage each bolt and then run it down until the next, shorter bolt is at a height to be engaged. Same again, run down a bit more until all are engaged. Then drive down a bit more. Remove the temporary fixing to the alignment ring. Then drive down. Stop every so often to shear off the protruding bolt(s) below the collar before it makes contact with the BOP. Spend an hour or so driving the hydraulic motors turning the bolts, attached to the plate that will clamp on top. Just now I have sent a suggestion in with calculations and drawings. I am not sure it will ever see the light of day. That sawing yesterday was so painful to watch. I was amazed that the blade did not bend or run out more the number of times it was clamped up. No ROV driver could have done better, it was just the conditions.
And folks, I have really been impressed reading all the posts here. My hat off to you all for the many excellent comments. I hope the oil stops flowing soon.