In the current work multi variable stochastic

In the current work, multi variable stochastic approach was used for petrophysical interpretation of log data. Petrophysical evaluation results were modified and improved based upon the available core data, calcimetry results, geological information, and dynamic tests. Water saturation was calculated using formation resistivity data. Several equations are available for modeling water saturation. Some of the applicable models are Archie, Simandoux, Indonesian and Waxman-Smith. Although Archie is the most applicable water saturation model, it produces erroneous results in presence of clay SB705498 in the formation. Simandoux model is used to adjust the effect of dispersed shales. According to available image logs, Kangan and Dalan formations contain laminated shales. Therefore this model is not appropriate to be applied in petrophysical models of these formations. Waxman-Smith model has been constructed based on some parameters which these parameters should be measured in core analysis tests. These parameters were unavailable and this model could not be used in this study. The Indonesian model has been constructed based on propagation of electrical current in parallel circuits. This model is suitable for water saturation calculation in laminated shale layers. Therefore, this model (Eq. (1)) was found suitable for calculating water saturation from log data and diversity was applied in this study.equation(1)1RT=?maRw0.5+Vsh6−0.5VshRsh0.52Swnwhere RT is the electrical resistivity of formation, ? is porosity, “m” is cementation factor, “a” is a constant, RW is the water resistivity, Vsh is the volume fraction of the shale, Rsh is resistivity of the shale, SW is the water saturation, and n is saturation exponent.