Definition - What does Wellhead mean?
A Wellhead is a structure that is installed at the top of a natural oil or gas well. Its main function is to ensure a safe operation and manage the flow of oil or gas from the well into the gathering-system. It is a system composed of valves, spools and assorted adapters that control the pressure of the production well. It acts as an interface between the surface facilities and the casing-strings in the wellbore.
Petropedia explains Wellhead
The main function of a Wellhead is to manage the pressure and flow of oil or gas. It also provides suspension to casing-strings and acts as an aid for attaching Christmas trees that are used to perform production operations. Additionally, it's used to carry the pressure inside those casing-strings.
After the wellbore is completed, it is used as a medium for injecting things inside the well and also to attach a pump to the wellbore. This device can vary in complexity and size according to the type of the well and its location such as land, offshore or subsea location. In an offshore location, the design of the device is more sophisticated so that it can handle bending loads, ocean currents and other loads.