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The paper presents the experience of an accurate reservoir Development and Management for a viscous oil field and its benefits in terms of production. The Nikaitchuq field is located in the North Slope of Alaska. The production start up was in January 2011. The main hydrocarbon reservoir is a Cretaceous sedimentary series developed in a sand lobe environment within the Schrader Bluff formation. The structure is a monocline gently dipping to NE with a gross thickness of about 30-35 ft, the reservoir is composed by two main sand bodies. The oil presents different characteristics varying between 16°-19° API with associated viscosities in the range of 50-200 cP at reservoir conditions. The oil quality and drilling pad constraints defined a development scheme consisting of a water-flood linedrive with horizontal producers and water injection wells located side by side. Different well designs for producer wells have been implemented in time: single horizontal trajectory undulating between the two sands bodies in counterphase with the related water injectors; fishbone design with main borehole in the lower sand and multiple branches in the upper sand; multilateral counter-phase design with extended reach undulating dual laterals. As a result of the multilateral campaign, well productivity doubled with respect to the average before the intervention. A challenging horizontal reach/depth step-out ratio between 6.0 to 6.5 has been achieved, the lateral section lengths stand between 6,000 up to 18,000 ft. The completion string was equipped to provide the capability of integrating a complex reservoir monitoring plan including distribute temperature surveys, inflow control devices and polymer tracers. Nikaitchuq is a "Digital Oil Field" and a full set of monitoring activities are performed in real time from remote. With the aim to maximize production a set of future actions have been established: Intrawell tracers campaign for a comprehensive understanding of reservoir communication; EOR technologies to improve sweep efficiency. At present production is sustained by 23 producers and 18 injectors. The multilateral design is now standard practice for the remaining producers. Since the multilateral campaign started up the fieldwide production step-change was evident with a doubled oil rate in a six month timeframe. more...