The failure to address net pay adequately leads to errors and incorrect conclusions in many important reservoir calculations. Many reserve estimates are based on volumetric mapping, for which estimation of net pay is fundamental. Depending on circumstances, a probabilistic approach might be appropriate for such mapping. There are, however, no industry guidelines regarding estimation and classification of net pay for scenarios where probabilistic procedures considered appropriate. The consensus of the ATW participants was as follows.
Net pay means different things to different people.
Current industry net pay cutoffs are largely subjective, object oriented, and based on local experience. There is no systematic industry guideline for selecting net-pay cutoff criteria. The workshop received high marks from the participants. All participants recognized that net pay is an important reservoir parameter that has not been adequately addressed in the petroleum literature, and the rationale for its computation needs to be fully disclosed. Moreover, industry guidelines for establishing net-pay cutoff criteria should be established.