Wellhead equipment and Christmas tree are essential for oil and gas exploitation, composed of casing head, tubing head and Christmas tree, used to connect casing string and tubing string, and seal the annular spaces between all casing at all layers and between pipelines. In addition, it can be used not only to control wellhead pressure and adjust oil (gas) wellhead flow, but also for special operations, such as acid fracturing, water injection and testing, etc.
