A method of simulating a hydrocarbon reservoir is disclosed. A process-based model is generated that mimics a depositional process of the reservoir. The process-based model is analyzed to extract statistics of geometries of a body that forms part of the reservoir, and depositional rules of the body. An object-based modeling method is applied to construct multiple unconditional geologic models of the body using the statistics and the depositional rules. Training images are constructed using the multiple unconditional geologic models. Well data and gross thickness data are assigned into a simulation grid. A single multiple-point geostatistical simulation is performed using the training images. A three-dimensional (3D) reservoir model is constructed using results of the multiple-point geostatistical simulation.