tubing head[′tüb·iŋ ‚hed]
a device for mounting a tubing string at the head of a flowing or gas-lift well; it is also used for the conduct of various production operations.
The tubing head makes it possible to suspend several tubing strings (for the simultaneous working of two or more beds at the same time through a single borehole), to install blowout prevention equipment and to seal the annulus between the tubing string and the casing string. The tubing head has a lateral opening through which oil, water, gas, or air is fed into the annulus between the casing string and the tubing in order to carry out production processes, such as stimulation of a flowing well or washing-out of sand plugs. The tubing head is connected to the head of the casing string from below and to the Christmas tree from above.