US Patent 10036214 Christmas tree installation using coiled tubing injector

A method and system for installing a Christmas tree in place of a blowout preventer on a wellhead. The donut in the wellhead BOP is landed using a coiled tubing injector. Then the wellhead BOP is removed and the Christmas tree is installed using the same crane that supported the coiled tubing injector. This employs the coiled tubing rig already in use at the well site for a previous operation, such as plug drilling or perforating and fracturing. Notably, the system provides a second seal, such as a ceramic disk, below the donut while the Christmas tree is installed. The tool string used to install the donut includes a safety union so that the tool string can be disconnected after the donut is landed and locked into place.