Christmas Tree
A Christmas tree is an assembly of valves, spools, chokes and fittings mounted on the tubing head of a completed well to control the flow of produced or injected fluids. A typical vertical surface tree includes lower and upper master valves, one or more wing valves leading to the flowline, a swab valve on top for vertical access to the well, and a choke to regulate flow rate. Hydraulically or pneumatically actuated master and wing valves serve as surface safety valves, allowing remote or emergency shut-in. Trees may be surface (dry) or subsea (wet), and vertical or horizontal in configuration. Surface trees are built to API Spec 6A and subsea trees to API Spec 17D. Selection parameters include rated working pressure, bore size, temperature class, material class, PSL, actuation type and connections to the wellhead and flowline.
Examples
- Single-completion surface tree on an onshore producer
- Water injection tree with actuated wing valve
- Horizontal subsea tree on an offshore field