At present, with the universal growth of population and industry, the need for fossil fuels, especially gas fuels, has become more prominent. On the other hand, the resources used, which are mostly conventional sources, do not meet global fuel needs. Hence, in recent years, the study and exploration of unconventional gas reservoirs have become very important in the economical view. Among the different types of unconventional gas reservoirs, the Tight Gas Reservoirs are more significant because of their more resource volume. The exploitation of these reservoirs is a bit complicated due to their low permeability. The more study on the uncertainty in hydrocarbon reservoirs especially in unconventional reservoirs can cause cost reduction, as well. 3-D petrophysical models of the hydrocarbon reservoirs contain their geological structures. Also, the reservoir parameters of the petrophysical models can be calculated using the Geostatistical methods in Geostatistical software. In this study, a 3-D petrophysical model of one of the unconventional reservoir has been constructed using petrophysical simulators. Then, the reservoir parameters, porosity, permeability, fluid (water) saturation, and above contact of fluid phase have been calculated using the Sequential Gaussian Simulation (SGS) as well as Multimin methods. As a result, all the petrophysical parameters mentioned above have been calculated in the three zones of the mentioned reservoir. While, the average porosity, permeability, and water saturation have been calculated as 0.114, 7.6, and 0.403 in the SGS method and 0.131, 8.8, and 0.470 in the Multimin method. It should be noted that some parts of this reservoir have unconventional reservoirs properties, but results presented in this study are for total parts of reservoir.