A system and method identify hydrocarbon productive reservoir zones using Monte Carlo numerical analysis to account for uncertainties in log measurements and petrophysical parameters. Random errors inlogging tool responses and core measurements, as well as reservoir heterogeneity, are incorporated in a Monte Carlo simulation to output appropriate petrophysical models to calculate statistical distributions for saturation and permeability to define productive zones, non-productive zones and zones of undetermined productivity as a basis of deciding whether additional logging, core sampling or well test data are needed to reclassify the undetermined zones as either productive or non-productive. As uncertainties are quantified in the analysis, the degree of certainty in determining productiveand non-productive zones is known and can be used to decide whether to further test, stimulate or abandon reservoir zones.