Integrating berth allocation decisions in a fleet composition and periodic routing problem of platform supply vessels

The aim of this work is to present mathematical models and a heuristic solution strategy to solve the heterogeneous fleet-sizing problem of platform supply vessels (PSVs) that support the offshore oil and gas exploration and production (E&P) activities. The problem considered in this research takes into account a novel characteristic related to the berth allocation problem of the supply base, which must be considered together with the decisions of selecting the departure days and the routes. The adopted solution strategy consists of sequentially solving models that capture different aspects of the problem, by starting with models that are simpler to solve. The solution found in one step provides a lower bound to the next step. This procedure was devised in order to reduce the search space and to speed up convergence. The proposed solution strategy was applied to real instances in Brazil, which has up to 79 offshore units grouped into clusters, with fair/acceptable results. The procedure allowed for assessing the impact of the number of berths on the fleet composition.