Abstarct: In the present thesis, application of data fusion approaches in determining productive zones is investigated. Conventionally, net pay zones (purest zones for production) are determined by selecting intervals with combination of high or low values of some petrophysical features. But here, for the first time three different methodologies are used for net pay determination. Methods used here are baxsed on Bayesian theory, fuzzy theory and diffusivity equation. The most advantage of all presented methods is determining productive zones fuzzily. Another advantage is to serve some methodologies, suitable for net pay determination in carbonate reservoirs (As a case study: Sarvak Formation). At the end, by combining outputs of used methods, a novel zonation for Sarvak Formation through the studied field is presented from the point of view of productivity.