Abstract: The emergency well-control vessel is capable of being moved above an offshore live oil or gas well, over which all normal controls have been lost. The vessel carries special purpose equipments and specially trained personnel for the purpose of bringing the erupted well under control, thereby stopping the pollution of the water body with the ejected formation fluids which form a so-called "plume". Such equipment is adapted to allow the vessel to move over and continue to dispel the plume while simultaneously attempting to regain control of the well. In one aspect, control of the abandoned wellhead and blowout preventers is established with divers working from the vessel or from an auxiliary craft. After control of the blowout preventer stack is confirmed and the same is fully operational, a kill string is lowered through the open blowout preventer stack and as deep down into the well as necessary.

Abstract: The method involves erecting a very large-diameter column from a plurality of buoyant columnar members at a selected site in a body of sea water. Each columnar member is floated erect to the site. The first or lowermost columnar member is pulled down and fully submerged to a predetermined depth over the site. The second columnar member is then positioned directly over the lowermost member. The lowermost member is allowed to move up and lift the second member out of the water. The two columnar members are securely interconnected to each other in a watertight fashion. The partial column is then pulled down to a fully submerged condition and the third columnar member is positioned directly over the second member. The partial column is allowed to move up and lift the third member out of the water. A secure watertight connection is made between the third columnar member and the second columnar member.