Abstract Recent developments in structural modeling allow the detailed representation of the fault geometries, and their impact on reservoir behavior can be fully assessed. However, it is unclear how much the most advanced developments, such as sub-seismic fault and fault-seal modeling, contribute to a better understanding of a field. This study was designed to set up a workflow for assessing the impact of structural uncertainty and to test the workflow on a synthetic model to analyze the production response to this uncertainty. A synthetic oil reservoir model was built, using a simplified tilted block structure, which was then modified with different groups of faults, and three different sedimentary models for building the facies and property model. Two experiments were conducted, where both sedimentary model and structural settings would vary. Experiment 1 included the sedimentary model as a varied input, whereas experiment 2 focused on the structural factors in each defined sedimentary model. The models were built using a combination of RMS ™ and Havana software systems, and then the results were imported into a reservoir simulator, Eclipse ™ . Production results were extracted and analyzed using statistical methods, to determine the impact of each input variable. The results pointed out that apart from varying reservoir properties, some of the structural factors had a significant impact on production history (in particular fault-seal model and fault pattern). In addition, experiment 2 showed that different sedimentary settings do not respond in the same way to different structural settings, thus demonstrating the potential value of conducting this type of study in the early phases of field development.