J = \frac{q}{|p_e - p_{wf}|}

where

The definition of flowrate  and formation pressure  may vary depending on application.

Overall concept is applicable to both producers and injectors but can be split into specific definitions:

J^{\uparrow} = \frac{q^{\uparrow}}{p_e - p_{wf}}

J^{\downarrow} = \frac{q^{\downarrow}}{p_{wf} - p_e}

The PI concept also applies to aquifer expansion:

J^{\downarrow}(t) = \frac{q^{\downarrow}(t)}{p(t) - p_{AQ}(t)}

where

See Also

Petroleum Industry / Upstream / Production / Subsurface Production / Subsurface E&P Disciplines / Production Technology 

[ Definition specifics on formation pressure and productivity index  ] [ Sandface Productivity Index ] [ Surface Productivity Index ] [ Specific Productivity Index ] [ Injectivity Index ] [ Field-average Productivity Index (Jr) ]