The Fault Block Model is an alternative simulation tool, developed with the purpose of forecasting well requirements and reservoir performance in strongly faulted, gas and gas-condensate reservoirs. This model is particularly designed to handle reservoirs where uncertainty related to gas communication between various compartment blocks of the field is pronounced, and thought to be the dominant source of reservoir uncertainty. The model can predict reservoir production scenarios. where errors attached to reservoir input data are presented as alternative production profiles, displaying uncertainty associated with business opportunities and risks (upside and downside forecasts). Based on geological characterization and fault seal analysis, the reservoir is divided into blocks. The model forms drainage volumes based on a statistical evaluation of the communication probability between neighbouring blocks. Uncertainty analysis is carried out using error propagation techniques, forming an optimistic and a pessimistic view of the reservoir. Production is simulated by a material balance calculation technique, producing the reservoir reserves through wells allocated to different drainage volumes. The Fault Block Model has proven to be an advantageous tool in the early stage field development of a North Sea gas-condensate reservoir where the effect of regional well location, number of wells and the optimum well production sequence have been studied. Production profiles from different well location strategies are investigated and various tests involving uncertainty in inter-block communication and in block volume are presented. Uncertainty analysis also includes suggestions on how to reduce reservoir uncertainty and recommendation for an optimum well location strategy.