The Components of an Oil Rig Wellhead

First it is important to understand what a wellhead is. Wellhead is the term given to the part of an oil  or gas well that is above ground. It helps to maintain the structure and pressure of the well drilling equipment beneath it. The wellhead provides the pressure seals and the suspension point for the casing strings. Casing strings are long sections of pipe that run through the whole length of the drill equipment and are cemented into place. Each casing string is typically around 40 feet in length and will have a male and a female connector at either end to allow them to be connected together to reach greater depths. The are fourteen standard casing diameters, from 4.5 inches up to 20 inches. The point of the casing strings is to protect or isolate formations adjacent to the wellbore

When drilling is underway, surface pressure is maintained via a blowout preventer. This prevents a well blowout. This is a massive surge of oil under high pressure. This can occur under water or underground, or above ground. If a blowout occurs above ground the oil can shoot very high into the air as the pressure is so high. This is costly for the rig owner, and can also cause environmental damage. It is dangerous for the workers and it can also destroy expensive equipment. The noise produced by a blowout can make workers go deaf. Oil is also highly flammable so there is a risk of fire too.  So you can see the importance the blowout proventer plays in the drilling process. To find out about our commitment to safety click here.

Once the well has been drilled, a Christmas tree is added tothe top of the wellhead; this has valves and choke equipment to control the flow of fluids through the well. The Christmas tree is so named as it vaguely resembles a decorated Christmas tree in its appearance. However these days, the construction and function of the Christmas tree has become far more complicated, that they no longer really resemble a real Christmas tree, however the name has stuck so it's here to stay. They are used in wells both under the sea and on the surface. They are usually used to control the flow of gas or oil out of the well, but they can also be used to control the flow of gas or water into a well that isn't producing during an attempt to enhance production rates of oil from other wells. The Christmas tree will also serve other purposes. There will be monitoring equipment to keep an eye on various measurements and levels, there will be facilities for adding chemicals to the well, and there will be pressure relief systems built in.

The wellhead is usually welded onto the uppermost casing string, so it becomes integral to the well itself. Wellhead components are expensive, so when the well becomes defunct the components may well be salvaged to be reconditioned and used for other drilling projects.