When an inner string is run in a deep-water application where the casing string exceeds the water depth and is across the sub-sea blow out preventer stack, a situation exists where a good control problem would be extremely dangerous. This is particularly true when running fill-up float equipment and where the casing string or the casing string and inner string cannot be shared by the sub-sea preventer system.
We now offer an Inner String Running Tool to provide a method of circulating fluid through the casing and to keep the casing string full. This Inner String Running Tool lands in a sub-sea hanger to provide an anchor and seal in the hanger. It also a method of sealing on the inner string so that mud can be circulated through the inner string, in the inner string/casing annulus or the casing/riser annulus.