Optimization in offshore supply vessel planning

Abstract

This paper considers the offshore supply vessel (OSV) planning problem, which consists of determining an optimal fleet size and mix of OSVs as well as their weekly routes and schedules for servicing offshore oil and gas installations. The work originates from a project with Statoil, the leading operator on the Norwegian continental shelf. We present both a new arc-flow and a voyage-based model for solving the OSV planning problem. A decision support tool based on the voyage-based model has been used by planners in Statoil, and cost savings from this was estimated to approximately 3 million USD/year. Weather conditions at the Norwegian continental shelf can be harsh; wave heights may limit both an OSV’s sailing speed and the time to perform unloading/loading operations at the installations. Hence, we analyze the weather impact on the execution of a schedule and propose robustness approaches to obtain solutions that can better withstand delays due to rough weather. Simulations indicate that such solutions both are more robust and have lower expected costs.