Christmas Tree (XT)

A Christmas tree (XT) is the stack of valves, spools, chokes, and fittings mounted on a wellhead to control flow from a completed oil or gas well. Subsea trees sit on the seabed and tie back to a manifold or riser; surface (dry) trees sit on a platform or jack-up deck. The assembly isolates the well, regulates production or injection rate, and provides access for wireline and intervention. The name reflects its branched profile. API Spec 6A and 17D govern surface and subsea tree equipment.