The evaluation of the risk associated to a development plan taking into account reservoir uncertainty has become a standard procedure. The integrated dynamic simulation of different assets considering mutual dependencies due to the production network is nowadays a standard procedure too. Integrated Asset Models (IAM) are usually simulated with a deterministic approach (one production profile for each network scenario). A methodological approach to take into account uncertainties together with different development scenarios (network and pipeline characteristics, infill wells, work-over...) is described in this paper. Reservoir numerical models have to be simplified (material balance models instead of full 3D simulations) to manage probabilistic simulations directly in the network facility model. The main phases of the methodology are: -Understanding of the asset and its model -Definition and evaluation of reservoirs and asset uncertainties -Simplification of full 3D reservoir models with material balance -Montecarlo simulation via spreadsheet -Statistical analysis of the resultsAn easy interface link has been developed to manage input and output in an uncertainty environment. The IAM is simulated by applying the standard software used in the company. The interface is able to set as uncertainty any input data defined in the models. This work-flow was applied on a dry gas offshore asset, which exploits many reservoirs (including multi-stacked sands) tied back to a central processing facility through a common pipeline network. The applied methodology proved to be manageable in terms of CPU time, effective and reliable.