Flowing wellhead equipment provides mechanical support, pressure sealing, and flow control at the top of an oil or gas well. The main assemblies include casing heads, casing spools, tubing heads, tubing-head adapters, and Christmas trees.
Casing Head and Tubing Head
The casing head supports the casing string and seals the annulus between casing strings. The tubing head supports the tubing hanger and provides access to the tubing-casing annulus. Both components must be selected according to pressure rating, bore size, material class, temperature class, and product specification level.
Production Tree
A production tree controls the flow of oil or gas from the well. It normally includes master valves, wing valves, swab valves, chokes, gauges, and outlets. The tree may be flanged or studded, and it can be arranged for standard, low-temperature, or sour-service conditions.
Correct installation is essential. Sealing surfaces, ring grooves, studs, nuts, gaskets, and valve operation should be inspected before pressure testing. After installation, the wellhead should be maintained according to operating pressure, production medium, and service environment.
For international projects, wellhead equipment is commonly specified to API 6A with clearly defined pressure rating, material class, temperature class, product specification level, and performance requirement.
