Crude Oil Futures

In petroleum and natural gas extraction, a Christmas tree, or "Tree", is an assembly of valves, spools, and fittings, used for an oil well, gas well, water injection well, water disposal well, gas injection well, condensate well and other types of wells. It was named for its crude resemblance to a decorated tree. The other named for Christmas tree is Wellhead.

A wellhead is a general term used to describe the component that is used to suspend casing strings and provide sealing functionality for oil wells. Wellheads can be located on platforms, subsea or onshore.

A Wellhead system provides the following basic functionality:

1. support of the casing and tubing strings (the tubing string may also be suspended in the Christmas Tree);
2. provide a seal between the different strings and increasing allow for access to annuli between the different casing/tubing strings.

Wellhead system primary components:

• Casing head
• Casing spools
  
• Casing hangers
  
• Packoffs and isolation seal
• Bowl protectors
• Test plugs
• Mudline suspension systems
  
• Tubing heads
• Tubing hangers
  
• Tubing head adapters

Wellheads are cemented in place and are generally permanently kept in place, although in exploration wells they may be recovered for use again. Factors that affect wellhead configuration are pressure, temperature, location, well depth, well size, well purpose, expected well life, well control equipment interface, drilling method, etc.

A wellhead serves numerous functions. Some of these are:

1) Means of casing suspension. (Casing is the permanently installed pipe used to line the well hole for pressure containment, collapse prevention etc.)

2) Means of casing pressure isolation when multiple casing strings are used

3) Means of attaching during drilling

4) Means of attaching a tree for well control during production, injection, or other operations

5) Means of well access

6) Means of pump attachment

7) Means of tubing suspension (Tubing is removable pipe installed in the well)