Pressure gauges are an integral part of controlling both static and dynamic wellhead pressure.
Static wellhead pressure is gauged in abandoned wells and depends on reservoir pressure, well depth, and density of the filling medium. Numerically it is equal to the difference between the reservoir pressure and hydrostatic pressure of the liquid column from wellhead to reservoir.
Dynamic wellhead pressure is measured in an operating well and depends on the same parameters as the static pressure, as well as the well rate or injection agent flow rate. It also depends on the pressure in the pipeline near the well, and on the pressure differential in the shut-off elements of the wellhead fittings.