Multi-Depot Periodic Routing of Service Vessels with Time Windows in Offshore Oil Industry

To maintain oil production in offshore regions, National Iranian Oil Company periodically implements technical supports and well services on equipment installed in oil wellhead platforms by two types of service vessels (namely supporter vessels and mobile wellhead servants) belonged to different depots. But also mobile wellhead servants need to receive technical supports from supporter vessels in specific periods and within associated time windows. Number of service vessels in comparison with amount of service requirements is few, but instead their transportation costs are high. Minimizing the cost of transportation and also service shortages, we develop a mixed integer programming model and a heuristic algorithm to obtain an upper bound. We illustrate the performance of the algorithm by means of computational experiments on real life instances. Computational results show that the heuristic algorithm obtains a good upper bound in primary running iterations in a rather appropriate time compared to the existing algorithms.