Abstract: A method and system of subsea intervention comprises lowering one or more assemblies of intervention equipment into the sea. Underwater marine units (such as remote operated vehicles or small submarines) may be employed to connect the assemblies to each other and to the subsea wellhead equipment. The subsea wellhead equipment includes a carrier line spool (e.g., coiled tubing spool, wireline spool, slickline spool) and equipment to inject a carrier line from the carrier line spool into the subsea well. The carrier line spool can be located underwater, such as on the sea floor or positioned above the subsea wellhead equipment. The carrier line spool can also be located on a sea vessel. Also, to switch tools, a carousel system having multiple chambers containing different types of tools can be used.

Abstract: Well surface equipment is provided to seal around the outer surface of portions of tool sections as the tool sections are assembled or disconnected in a portion of the well surface equipment. The portion of the well surface equipment is isolated from wellhead pressure to enhance well operator control during assembly or disassembly of a tool string. Also, if a fluid path is opened up due to activation of the tool string (such as initiation of a detonating cord that is placed in the fluid path), a barrier mechanism is actuated to block fluid communication through this fluid path so that a portion of the well surface equipment can remain isolated from wellhead pressure to enable convenient retrieval and disconnection of tool sections.