In the industry of drawing oil and gas from inner cores of the earth, people are usually confused about the terms Well head Christmas tree. Are these two the same? There are times that Wellhead and Christmas Tree are two interchangeable words. But the truth is, these are different and separate pieces of the equipment.
In other words, you need a wellhead to use the Christmas Tree. But you can use it without the Christmas Tree when drilling. This is also similar when making surface wells which will usually require a pump. This will not be using a tree as well.
Which is Which?
A Christmas tree is a combination of valves, spools, and fittings which are used for an oil well, gas well, and also water well injection. It can also be used for water disposal well, gas injection well, and so on. It is named as such because of its resemblance to a well decorated Christmas tree. But in order for you to use it, you would need a Wellhead. The Wellhead is the part of the machine that is at the surface of a well which provides the structural as well as the pressure-containing interface that is used for drilling and production.
These two parts are working together to bring oil and gas to the surface. The Christmas tree is usually from blocks of steel with valves. Its primary function is to control the flow into and out of the well. A tree usually has additional functions like chemical injection points, pressure relief, monitoring points, and so much more.
The Christmas Tree Functions
The Christmas Tree has different functions. In producing wells, it injects chemicals, alcohol, or oil distillates to prevent or correct production issues. It also controls the injection of gas or water for from other wells in the area. The control system that is attached to the tree will control the downhole safety valve.
Different Parts of the Christmas Tree
If you know the different parts of these assemblies, it will help you differentiate the wellhead from the Christmas tree.
- The two lower valves of the tree are the upper and lower master valves. The lower master valve is manually operated while the upper master valve is hydraulically powered.
- The Hydraulic tree wing valves are kept it closed and can only be opened with hydraulic pressure.
- The right-hand valve is the flow wing or the production wing because it is used to take hydrocarbons to production facilities.
- The left-hand valve is the kill wing where it is used to inject fluids for corrosion inhibitors to prevent hydration.
- The valve at the top is the swab valve which is used for wireline and coiled tubing.
- The choke can either be stationary or adjustable to control the gas volume and to create a downstream pressure.
Now that you know the difference between the well head Christmas tree, you would be able to fully understand the functions of each and how it is used as one unit. Remember that a Christmas tree will not be used without the Wellhead.