PI and IPR Summary The ability of a well to produce fluids. The uses of the Productivity Index and IPR Curves Find the well’s potential, q’, the maximum production rate. Predict production rates for planning production schedules and sizing production equipment Reference point for the comparison of wells in a field. Find Flow Efficiency of the well to plan or verify completion techniques. During production monitoring to help diagnose production problems if any. Equipment or reservoir problem Selecting testing procedures to identify production problems. Comparing the PI of the field test to a calculated PI to verify reservoir properties or an indication of skin in the well. Productivity Index J Simplest of the methods, one production and pressure point and a straight line. But the least accurate for calculating the well’s potential, greater error as pwf is lower. Very good for calculating flow efficiencies, FE.IPR Curves A very high accuracy if obtained by using a multipoint production test data. For one point tests Vogel Method Reasonable accuracy for the plot and the potential. Problem is that good mobility data is needed for a calculated ideal curve and for future average reservoir plots. Fetkovich Method Not as accurate as Vogel. But because of the straight forward method easier for a quick calculation. Gas Wells Multi-point tests are the norm for gas wells. One-point test assumes a straight line at 45 degrees or an assumed value for the field. Pressure depletion gas wells have a constant productivity index, calculated using the square of the pressures. Flow Efficiency The Flow Efficiency of the well which is the ratio of the actual PI to the ideal PI is used to check if the well is a candidate for a work over to remove damage. Also it can be sued to verify a stimulation job. If FE < 1 possible damage, FE > 1 a stimulated zone.Nomenclature h thickness ft J Productivity Index bpd/psi k Permeability md L Length of Horizontal section ft p Pressure psi pwf Bottom hole pressure flowing psi ps Bottom hole pressure shut in psi pskin Delta pressure skin psi q Flow rate bpd qsc Flow rate gas mscfpd q’ Well potential bopd, mscfpd re radius effective ft reh radius horizontal effective ft rw radius wellbore ft s skin s’eq skin effective horizontal T Reservoir Temp Ro formation volume factor rb/stb viscosity