The Dimensionless Productivity Index as a General Approach to Well Evaluation

Abstract

Summary Petroleum-well performance and its evaluation are clearly some of the most important functions of modern production engineering. We present a general approach to the issue by employing the field-derived, dimensionless productivity index (JD), which we calculate from measured information including the production rate, reservoir and flowing pressures, and well and reservoir data. The JD is independent of well completion (i.e., it transcends the geometry), whether the well is under radial flow, is hydraulically fractured, or whether it is vertical or horizontal. The determined JDs are then compared against benchmarks we have developed for optimized production, such as the concept of unified-fracture design (UFD) or maximized horizontal well performance. We have developed deterministic methods for this analysis and new means to depict the results graphically. Such evaluations are important in concluding whether the well is underperforming or whether past engineering could have been improved and by how much. Decisions such as refracturing, the redesign and improvement of future treatments, and whether to fracture vertical or drill horizontal wells can be readily made.