Optimizing multiship routing and scheduling with constraints on inventory levels in a Brazilian oil company

Abstract

This study addresses a real-life multiship routing and scheduling application with inventory constraints that arises in pickup and delivery operations of different types of crude oil from various offshore oil rigs (platforms) to coastal terminals. Oil transportation largely results from the need to maintain inventories at each supply point (platform) between minimum and maximum levels, considering production rates in these operational points, and to meet demands of different oils in the terminals within the planning time horizon. Routing and scheduling of the available fleet aims to obtain solutions of minimum total costs, subject to various constraints such as the maximum volume of cargo carried on each ship, simultaneous cargo unloading in some terminals, conditions that rule ship docking in offshore platforms and terminal berths, among others. In this research, we modify and extend inventory constrained maritime routing and scheduling models to appropriately represent the problem of a case study at a Brazilian company and to solve small-to-moderate instances based on real data. We also present a matheuristic to deal with larger problem instances. Solution evaluation by company experts indicates that the model and this hybrid heuristic properly represent the problem and highlights the potential of their application in practice.

A continuous-time supply-driven inventory-constrained routing problem

“…Most work on the IRP includes extensions of the basic (demand-oriented) IRP to include multiple items [48,52,57] and heterogeneous fleet composition [21,40] . Other classifications include models with continuous time [1,3,4,7,21,35,54] , discrete time [e.g., [14,23,50] ] and both finite [8,16,46] and infinite planning horizons [42,59] . Work that is supply-driven is still relatively limited.…”

“…This assumption is also made in papers related to fuel transportation, in ch fuel is stored and transported in tanks [11,35,46,56] . Papers in which inventory levels are treated as continuous include [46,54] in maritime contexts and [58] in the liquefied gas industry.…”

Coastal Shuttle Tanker Scheduling Model Considering Inventory Cost and System Reliability

“…These characteristics of the system make the design of the shuttle tanker fleet more complicated. The crude oil produced in Chinese off-shore are waxy and have the physical property of high pour point and high viscosity, which require heating to prevent the crude oil from forming the gel [10]. Therefore, energy consumption is a significant factor in the operation cost for crude oil transfer and processing.…”

Optimization of the Use of Critical Resources in the Development of Offshore Oil Fields

“…This kind of activity is often related to sailing to refineries; it describes the transfer of crude oil from a discharging tanker to smaller vessels to make the tanker lighter. Stanzani et al [ 9 ] addressed a real life multiship routing and scheduling problem with inventory constraints that arises in pickup and delivery operations of crude oil from various offshore platforms to coastal terminals. MILP models were presented to deal with small-to-moderate instances; while a matheuristic was proposed to deal with larger instances.…”