Paper: Reservoir Pressure and Skin From Production Data Using the Resiprocal Productivity Index Method (The Intercept Method)

The reservoir average pressure can now be evaluated from routinely available rate and flowing pressure production data, using an extension of the reciprocal productivity index method. Traditionally, reservoir average pressure could only be determined from an extended duration build-up test. Especially in low permeability, stimulated reservoirs, that procedure generally tends to underestimate the pressure, due to practical limitations on shut-in times. In addition, an error in the reservoir average pressure determination results in an error in the computed skin for the well. However, this new procedure provides an independent evaluation of skin and pressure so that they are not dependent on one another. The theory for the method is explained and two example field applications are included.