| Single-point tests are usually simple productivity tests that typically involve a measurement (or estimate) of initial or average reservoir pressure and a measurement of flow rate and flowing bottomhole pressure (which can be estimated from flowing surface pressure) at stabilized producing conditions.<ref name=pt09r1>Allen, T. O., Roberts, A. P., 1978, Production Operations, Volume 1 : Tulsa, OK, Oil and Gas Consultants International, 225 p.</ref> From these data, the productivity index, PI, can be calculated as follows: | | Single-point tests are usually simple productivity tests that typically involve a measurement (or estimate) of initial or average reservoir pressure and a measurement of flow rate and flowing bottomhole pressure (which can be estimated from flowing surface pressure) at stabilized producing conditions.<ref name=pt09r1>Allen, T. O., Roberts, A. P., 1978, Production Operations, Volume 1 : Tulsa, OK, Oil and Gas Consultants International, 225 p.</ref> From these data, the productivity index, PI, can be calculated as follows: |