WELLHEAD ASSEMBLY AND METHOD FOR AN INJECTION TUBING STRING

A wellhead assembly (10) for an injection tubing string is provided which allows a master valve to be closed without damaging the injection tubing si ring while still allowing for the use of a back pressure valve to isolate th e tree. Wellhead assemblies and related methods of the present invention inc lude a flange (15) adapted to be connected between a wellhead and a Christma s tree. The assembly also includes a mandrel (20) adapted to being inserted into the longitudinal bore of the flange, the mandrel having a port for comm unicating with an injection port which extends radially through the flange. The assembly further includes a hanger (25) adapted to connect to the upper end of the injection string, wherein the hanger is further adapted to land i n the longitudinal bore of the mandrel. The hanger (25) includes communicati on passageway for facilitating fluid communication between the port of the m andrel and the injection tubing string.