productivity ratio [´prä´dǝk`tiv·ǝd·ē ´rā·shō] PETROLEUM ENGINEERING 1. The amount of damage or improvement to reservoir formation permeability adjacent to the borehole (due to invasion or reduction of drilling mud present, drilling-fluid filtrate water, swollen clay particles, or salt or wax deposition). 2. The ratio of permeability calculated from the productivity index to the permeability calculated from reservoir buildup pressure. |