An ILS heuristic for the ship scheduling problem: application in the oil industry

Abstract

This paper addresses a real‐life rescheduling problem of a pipe‐laying support vessel (PLSV) fleet in charge of subsea oil well connections. The short‐term schedule of these vessels is subject to uncertainties inherent to its operations, resulting in ships idleness or delays in oil production. The objective of this study is to develop methods to support a Brazilian oil and gas company in overcoming impacts caused by operational disruptions, while reaching its planned production level. The PLSV rescheduling problem was treated as an identical parallel machine scheduling problem, where the machines represent the vessels and the jobs are the activities for the subsea well connections. We propose a mathematical programming model and a method based on the iterated local search (ILS) metaheuristic to solve the problem. This paper contributes to this by considering simultaneously setup times, machine eligibility, release dates, due dates, and machine availability. Both methods were applied on 10 instances based on real PLSV data. Taking into account an objective function that measures the operational impact on schedules, the ILS provided an average improvement above 91% in schedules when compared to the initial solution provided by the studied company. The ILS outperformed a mathematical programming model for the problem, in eight instances, within a 30‐minute execution time limit, fitting to the company process.

A biased‐randomized iterated local search for the distributed assembly permutation flow‐shop problem

“…The local search embeds a heuristic procedure; the perturbation and the acceptance criterion allow to explore the search space as well as to escape from local optima. The ILS metaheuristic has been applied in many optimization problems, such as vehicle routing problems (Juan et al., ; Pollaris et al., ; Brandão, ; Estrada‐Moreno et al., ), scheduling problems (Zohali et al., ; Cunha et al., ), facility location problems (De Armas et al., ), or inventory routing problems (Alvarez et al., ), among others. In particular, Stützle () and Juan et al.…”

The family traveling salesman problem with incompatibility constraints

“…This process of applying a local search procedure and a perturbation method is done iteratively during a fixed number of iterations. For more details and applications of ILS algorithms, see, for instance, Lourenco et al [15], Boussaïd et al [4], and Cunha et al [6]. Algorithm 7 shows the basic framework of the ILS algorithm.…”

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

“…In both papers, a Greedy Randomized Adaptive Search Procedure (GRASP) was applied. Also related to the PLSVs programming area, Cunha et al [ 18 ] carried out a study making an analogy between routing activities and scheduling activities in parallel machines. The objective is to reschedule the PLSVs aiming to minimize the impacts caused by operational disruptions.…”