1. n. [Well Testing]

The pressure that would be obtained if all fluid motion ceases in a given volume of reservoir. It also is the pressure to which a well will ultimately rise if shut in for an infinite period.

See: static pressure

2. n. [Production Testing]

A volumetric average of the pressure exerted by the fluids inside the reservoir at a specific depletion stage. Average reservoir pressure can be measured only when the well is shut in.