Because of the multiscaled character of fracture networks and their high degree of heterogeneity, characterization and modelling of fractured reservoirs requires different techniques to the well-established geostatistical methods derived for modelling rock heterogeneity. We have developed a method to improve the geological model used as an input of fractured reservoir fluid flow simulators, either in single or dual permeability simulations, as well as new specific procedures. The method is based on three nested models. The first, the ‘global geo-cellular fracture model’, considers fracture average property distribution at the scale of the reservoir. Location of the major faults as well as properties, such as horizon curvature, are taken into account. ‘The global discrete model’ considers the fault system at the same scale and algorithms generate realistic synthetic fault patterns using an object-orientated approach. The third model, the ‘local discrete model’, creates realistic synthetic fracture patterns at the decametre scale with another object-orientated procedure. These models are all constrained by hard data acquired from seismic, well imaging and logs. They can be constrained by output from deterministic approaches like structural evolution analyses and geomechanical modelling. Interrelationships between these models enable account to be taken of the complex interrelationships between fractures at different scales and rock material heterogeneity. Finally, this modelling approach makes the geological model used as an input of fractured reservoir fluid flow simulators more satisfying than conventional approaches.