A MULTIPLE-STAGE SIMULATION-BASED MIXED INTEGER NONLINEAR PROGRAMMING APPROACH FOR SUPPORTING OFFSHORE OIL SPILL RECOVERY WITH WEATHERING PROCESSES

摘要

As one of the most commonly used technologies in offshore oil spill response, skimming is facing challenges in recovering the spilled oil in the north region due to cold weather and harsh marine conditions. It is valuable to simulate and optimize the skimming process to improve efficiency of oil skimming during emergency response especially in harsh offshore environments. However, no studies have reported on integrating optimization and simulation approaches to support the offshore oil spill recovery by skimmers. This study developed a multiple-stage simulation based mixed integer nonlinear programming (MSINP) approach to provide sound decisions for skimming spilled oil in a fast, dynamic and cost-efficient manner, which is especially helpful to harsh environments. In the case study, regression models were developed to simulate the efficiencies of two drum skimmers based on the referenced performance tests. The models were further integrated with the optimization methods to determine the optimal strategy to achieve the maximum oil recovery with constraints of time and resources. The results indicated a 96% recovery efficiency based on the optimal settings. Furthermore, the approach was also tested with the integration of the oil weathering processes (e.g., evaporation, emulsification, and dispersion). The results indicated that with the consideration of evaporation and dispersion, in order to achieve the maximum oil recovery, the optimal setting for the oil recovery would be 5 sets of SK_1 and 15 sets of SK_2, yielding an oil recovery efficiency of 91.5%. The proposed approach was able to efficiently incorporate the regression models and optimization into the same framework and to support efficient skimming for offshore oil spills. The MSINP approach can timely and effectively support offshore oil recovery operations under dynamic conditions and therefore provide expeditious decision-making support during offshore oil spill response in harsh environments.