Sammendrag
The daily transportation of employees with helicopters to and from the oil platforms is an important and difficult logistical operation in the offshore oil industry. This paper presents a model for the problem of selecting the optimal helicopter fleet composition and deciding which land bases to allocate the helicopters to as well as deciding whether opening additional hubs for refuelling is required. To capture the operational aspects of the operations, the routing of the helicopters is included as an element of the model. In this paper, we show why including routing is important to ensure a good fleet composition and helicopter allocation. The problem is denoted the base location and fleet composition problem (BLFCP) and a model based on a priori generation of flights is proposed. The test cases are based on estimates of the expansion into new oil-producing sectors outside the Brazilian coast as well as test cases based on the Norwegian expansion into the Arctic. In addition, different approaches for strengthening the formulation or otherwise improving the solution procedure are proposed. These include dynamically added constraints, symmetry breaking constraints, integer rounding cuts and various heuristic approaches to reduce the number of variables and constraints in the problem. The solution procedure proves efficient for realistically sized problems.