Fleet Sizing for Offshore Supply Vessels with Stochastic Sailing and Service Times

In this paper we address a supply vessel planning problem arising in servicing oil and gas offshore installations. Supply vessels provide offshore installations with necessary supplies on periodic basis from offshore supply bases according to weekly sailing schedules. The execution of weekly schedules during the year is affected by weather conditions influencing on sailing time and service duration at installations. When the contracted vessel cannot complete a voyage before the start of its next planned voyage, a vessel from the spot market is hired to perform it. Deciding on the number of supply vessels hired to perform operations from a supply base for a year ahead has a strong economic effect on the total annual vessel costs. We present a discrete-event simulation model for evaluation of alternative fleet size configurations taking into consideration uncertainty in weather conditions and future spot vessel rates. The model is validated and tested on real data. c © 2014 The Authors. Published by Elsevier B.V. Selection and peer-review under responsibility of the Organizing Committee of ITQM 2014.