Submersible caisson for subsurface well completion

Claim 1

A SUBMERSIBLE ACCESS CAISSON FOR PROVIDING A BREATHABLE ATMOSPHERE SURROUNDING A WELLHEAD OF A SUBAQUEOUS WELL, SAID WELLHEAD BEING LOCATED BENEATH THE SURFACE OF A BODY OF WATER, AND FIXED ON A CONDUCTOR PIPE PROTRUDING A SUBSTANTIAL DISTANCE ABOVE THE MARINE BOTTOM, SAID ACCESS CAISSON CONSISTING OF: AN UPPER TUBULAR SECTION ADAPTED TO SLIDE OVER SAID CONDUCTOR PIPE AND SAID WELLHEAD; A SEALABLE HATCH MEANS IN THE UPPER END OF SAID UPPER TUBULAR SECTION; AN ENLARGED WORKING CHAMBER OPERATIVELY CONNECTED AT ITS UPPER END TO THE LOWER END OF SAID UPPER TUBULAR SECTION, SAID ENLARGED WORKING CHAMBER BEING ADAPTED TO PERMIT A WORKMAN TO MOVE AROUND SAID WELLHEAD WHEN SAID ENLARGED WORKING CHAMBER SURROUNDS SAID WELLHEAD; AND A SEALING MEANS OPERTIVELY CONNECTED TO THE LOWER END OF SAID ENLARGED WORKING CHAMBER, SAID SEALING MEANS BEING DESIGNED TO PERMIT SLIDING MOVEMENT BETWEEN SAID CAISSON AND AT LEAST A CONDUCTOR PIPE WHILE MAINTAINING A SUBSTANTIALLY WATERTIGHT SEAL THEREBETWEEN.