Irina Gribkovskaia

Title of the talk: Transportation planning in upstream offshore energy logistics

Abstract: The talk presents results of the joint research on supply vessel activities and offshore personnel transportation planning arising in upstream offshore energy logistics, conducted at Molde University College-Specialized University in Logistics in cooperation with Norway’s largest energy company Equinor operating on the Norwegian Continental Shelf and worldwide.
Offshore supply logistics is rather complex. Installations are located at large distances from shore resulting in intensive long-haul maritime and aerial transportation activities generating significant logistics costs. To maintain planned activities at installations, transportation of cargo and personnel to and from offshore locations should be performed with high frequency and requires careful planning. There is a fleet of vessels and a fleet of helicopters serving a set of installations from a supply base and a nearby heliport. Usually, the weekly transportation demand to an installation is described through the number of vessel departures and the number of flights. Each vessel may sail one or more voyages during a week visiting several installations, while helicopters may have several flights per day with one or two stops. Supply vessel and offshore helicopter chartering and operating costs represent the major cost contributors to the upstream offshore logistics. Therefore, efficient planning of these fleets at the lowest possible daily rate, maximizing utilization and minimizing emissions are important objectives.
Because of the enormous shortage costs, the capability of fleets to meet the demand for transport capacity exactly when needed is a paramount objective. However, the offshore transportation is influenced by a number of uncertain factors. These are the uncertain weather conditions which often result in delays and cancellations, when servicing or landing at offshore installations may be impossible. Furthermore, the demands for supplies and personnel, especially during the exploration phase, are uncertain both in volumes and in time. Taking into account the fact that the supply process takes place in a highly uncertain environment and is associated with high transportation and shortage costs, logistics planners seek ways to provide a reliable, on-time, and cost-efficient transportation. In practice, for each period of stable demand, a fleet and its weekly schedule are created showing the vessel/helicopter resources and the scheduled voyages/flights, which are further operationally modified each day for the revealed demands from installations and known weather conditions.
For offshore cargo transportation, we present optimization models with heuristic solution algorithms for supply vessel routing and weekly sailing schedule planning for a deterministic case. For the construction of weekly sailing schedules under uncertain weather conditions we introduce an optimization-simulation method generating cost-efficient schedules with different predefined reliability requirements. To account for both demand and weather uncertainty, we present an algorithm which incorporates a metaheuristic generating vessel schedules with imposed reliability levels into a simulation model evaluating schedules’ performance with operational modifications caused by uncertainty. The algorithm applied iteratively for the increasing values of reliability level parameters yields a vessel schedule of least expected cost. For offshore helicopter transportation, we introduce a flight-based model for integrated weekly helicopter resource planning and assignment of flights to days and time slots, and a heuristic algorithm based on model decomposition.

Her recent 20 most cited works on offshore logistics planning are published in TRC, TRD, Omega, C&OR, EJOR, JORS, INFOR, AOR, etc. She has established international research networks in this field through contact with the largest offshore energy operators in Norway and Brazil giving her PhD and MSc students the opportunity to perform their research based on the up-to-date real problems in close cooperation with professionals from leading universities.