Optimal policies for maintaining a supply service in the Norwegian Sea

This paper considers the real problem of determining an efficient policy for a supply operation in the Norwegian Sea, where a number of offshore installations are serviced from an onshore depot by supply vessels. The purpose of the study was to evaluate the effect on the total supply cost of having some or all of the offshore installations closed for service during night, and to determine an optimal routing policy. Six scenarios were developed, varying in the opening hours and the number of weekly services of the installations, as well as an algorithm to find an optimal routing policy (which vessels to operate and the coherent weekly schedules) for each of the scenarios. By also evaluating the qualitative aspects of the solution of each scenario, a routing policy was recommended, involving potential savings of 7 million dollars. The proposed policy has been implemented and the experience so far is good.