Paper: THE RECIPROCAL PRODUCTIVITY INDEX METHOD, A GRAPHICAL WELL PERFORMANCE SIMULATOR

The ability to estimate descriptive engineering parameters, such as permeability, and to generate production forecasts and reserves based on those parameters, without the cost of fir11 numerical simulation or extended buildup tests, is provided by the Reciprocal Productivity Index graphical production analysis method. The method's theoretical basis arises corn the fact that traditional constant rate or constant pressure (potential) boundary conditions are sufficient, but that the necessary boundary condition only requires that the sandface transmissibility remain constant over time. With that difference, it is possible to accurately evaluate production histories, in which both the rate and pressure are varying over time, using traditional well testing methods. Examples for both oil and gas wells demonstrate the interpretive capability and limitations.