Subsea tree is an assembly of valves, spools and fittings for an oil well. The operation of subsea tree is to both prevent the release of oil or gas from an oil well into the environment and also to direct and control the flow of formation fluids from the well. When the well is ready to produce oil or gas, valves are opened and the release of the formation fluids is allowed through a pipeline leading to a refinery, or to a platform or to a storage vessel. It is also used to control the injection of gas or water injection application on a none-producing well in order to sustain producer volumes.