Intelligent wells with inflow control valves enable flexible management of multiple reservoir intervals. In this paper, we describe model based optimization of inflow control valve settings for a producing North Sea field. A two step, non-invasive, iterative pattern search optimization algorithm is applied. The first step provides global search of the feasible region using a discrete genetic algorithm whereas the second step provides local search around the incumbent solution. To account for reservoir uncertainties, optimization is performed on a diverse set of history matched reservoir model realizations, within an automated framework. The results show a significant improvement in predicted reservoir production performance over the remaining life of the field.