For servicing offshore oil and gas wells, expensive submarines or fixed submersible work chambers or buoyant capsules have been proposed as illustrated in U.S. Pat. Nos. 3,638,720; 3,643,736; and 3,656,549, but which have not been too satisfactory. Workers in the chambers have had difficult times getting to the actual well and have had to resort to small submarines as shown in U.S. Pat. No. 3,469,627 or to skin diving as suggested by U.S. Pat. No. 3,664,423.
Offshore operations in deep water face the additional problem of collapsing of the shell when lowered to the sea bottom due to the high hydrostatic pressure thereon. Large submarine hulls with self-propulsion systems are very costly and dangerous because of the ever possibility of drifting into deep waters where the pressure is greater than what the submarines are structurally capable of withstanding.
Large diameter flooded bells or chambers are massive and expensive for being lowered over one of several wells for being pumped dry of sea water and pressurized with air for forming a working chamber therein as suggested in U.S. Pat. No. 3,656,549 referred to above, or U.S. Pat. No. 3,602,301.
If the sea or bottom water is muddy, either usual operations are suspended or the work is done blind and very slowly as the operators feel in the dark.