Multistages hydraulic fracturing of horizontal wells has been an integral part of natural Canadian resources, such as shales and tight gas reservoirs. In the hydraulic fracturing process, long horizontal well divided into several stages to access much larger volume of oil and gas in low permeability/porosity formations. Then the hydraulic fracture fluid is pumped into each stage to initiate and propagate the fractures around the well which increase the porosity and permeability of the formation. Although, the technology has greatly improved in the past decade to enhance the production from unconventional reservoirs, still several uncertainties can cause failure. Therefore, without geomechanical considerations, the predicted design of hydraulic fractures may not be completely accurate. Then understanding the reservoir rock mechanics and their spatial heterogeneity as well as stress profiles have a major impact on the reliable decisions in fracturing design optimization. In most simulation models, geomechanical properties are assumed to be homogeneous throughout the reservoir. In this study, the heterogeneity of geomechanical properties is demonstrated by using geomodeling. A three-dimensional (3D) earth model was built by integrating both petrophysical and geological log data using more than 200 wells in the study area. Then, the state-of-stress prior to hydraulic fracturing is estimated by using geological log data to create a geomechanical model from near surface to below the Montney FormationFormation. The model includes dynamic elastic properties and rock strength property distributions in both vertical and horizontal directions within the reservoir. To determine elastic rock properties, changes in compressional and shear velocity through all the layers of the reservoir rock were taken into consideration. A workflow was developed to constrain well properties to derive realistic rock property values and distributions even in areas where only limited well log information exist. Then Petrel/Visage software package used to evaluate stress changes within the Montney FormationFormation.Since this formation has very low permeability with complicated geological settings, the knowledge of geomechanical and geological properties, stresses magnitude and orientation, completion and production data is essential to evaluate the fracture volume and conductivity. In this research study, we presented an unconventional reservoir simulator and the critical parameter to quantify multistage hydraulic fracturing in the Montney Formations. Data from a detailed core analysis and various field logs are used to achieve a history match of initial production data from the liquids rich Montney well production within the study field.