A wellhead is an equipment installed at the surface of a completed oil or a gas well that provides a structural and pressure containing interface for the drilling and production equipment. In other words, this object is installed where casings are terminated by hanging the casings using casing hanger and seals. It consists of following components:

·         Casing head

·         Casing spools

·         Casing hangers

·         Packoff seals, also called as isolation seals

·         Test plugs

·         Mudline suspension system

·         Tubing head

·         Tubing hangers and

·         Tubing head adapter

This equipment is used for various purposes such as:

·         Hanging or suspending casing by the means of casing hanger and seals.

·         It provides pressure seal as well as strength to hold the hanging weight of casings.

·         Provides a means of tubing suspension.

·         BOP is attached to the wellhead during drilling operations.

·         X-mas tree, also called as Christmas tree is attached to the wellhead during production of hydrocarbon streams.

·         All the well access for any workover operations is through wellhead.

 

Wellheads generally have the nominal diameter of 2, 3, 5, 10 and 15 inches and the working pressure ratings ranges from 2000 to 15000psi.