消油剂分散作用对海上溢油行为动态的影响研究

Application of chemical dispersants to disperse the spilled oil is one of the most important countermeasures in marine oil spill emergency response. Since the dispersion effect of chemical dispersants will significantly change the oil spill behaviors such as dispersion, sedimentation, and the processes of transport and diffusion, while existing oil spill transport and fate models do not take account of the effects of chemical dispersants application, thus they can not provide enough scientific decision-making information during emergency response to marine oil spill accidents. In this project, firstly, a series of laboratory experiments of simulating chemical dispersant application to spilled oil on sea water will be conducted, to investigate the effects of different influencing factors (viscosity of spilled oil,thickness of oil slick, amount of dispersant, sea water temperature, wave action, etc) on the effectiveness of chemical dispersant and the resulting oil droplet size distribution in water column. On the basis of the experiment results and data collected, a quantitative dispersion effect model, which use the above influencing factors as input parameters, will be developed to predict the chemical dispersion effectiveness and oil droplet size distribution. Then the dispersion effect model will be integrated into a marine oil spill model that can simulate many behavior and transport processes (including advection, diffusion, evaporation, emulsification, dispersion, dissolution),to enable the oil spill model to simulate the effect of dispersant application. In the end, Dalian bay will be selected as study area, the integrated oil spill behavior and transport model will be used to simulate scenarios of different types of oil spill accidents with and without chemical dispersant application, so that to analyze and determine the rule of the effects of chemical dispersants application on the spilled oil behavior and transport in Dalian Bay marine environment. In all, the objectives of this project are to investigate the scientific usage of chemical dispersants and to develop new marine oil spill numerical prediction technology, so to form the basis for further theory research and practical application in the marine oil spill risk management and emergency response in China.

喷洒化学消油剂是应急处理海上溢油的一个重要手段。消油剂的分散作用会显著改变海面溢油的分散、沉降等行为以及输运扩散过程，而现有的海上溢油行为动态数值模拟未充分考虑消油剂的影响，难以为实际溢油事故应急提供科学合理的决策支持。本项目首先开展实验室模拟消油剂分散海面溢油的试验研究，分析溢油特性（油的黏度、油膜厚度）、消油剂用量及环境条件（海水温度、波浪作用）对消油剂分散效率和水中油滴粒径分布的影响，构建基于多影响因素的消油剂分散作用预测模型。并以分散效率和油滴粒径作为关键参数，集成建立考虑消油剂分散作用的海上溢油行为动态数值模拟模型。最后以大连海域为研究海区，通过对海上溢油事故和使用消油剂处理情景的数值模拟，分析消油剂分散作用对海上溢油行为动态的影响规律。本项目旨在探究溢油事故中科学使用消油剂和发展海上溢油预测预报技术，为提高我国海洋溢油污染风险管理和应急决策的理论研究与实际应用水平打下基础。

本项目通过理论和实验来开展消油剂分散作用对海上溢油行为动态的影响研究，并进行以风险评估为主的应用研究。主要研究内容包括模型构建、室内实验、模拟预测、风险评估等4个方面。（1）建立考虑消油剂分散作用的海上溢油行为动态数值模拟模型。该综合模型采用经典的Delvigne-Sweeney模型模拟预测海面溢油自然分散过程、分散效率和油滴粒径分布，采用基于量纲分析的多影响因素（波高、油膜厚度、油黏度、油水表面张力等）与油滴粒径分布之间的半经验模型来构建水面消油剂分散作用预测模型。这些理论模型利用文献报道的实验数据进行初步验证比较，并利用C++和Fortran编程技术实现软件化。（2）设计并建造1个用于溢油行为动态模拟的小型组合式环状水槽，配备造波、造流等功能。开展静水和动水环境中不同类型污染物（空气、自来水、原油）的水下浮射流试验（包括初步试验分析消油剂处理对水下溢油分散的影响），初步数值模拟结果显示模型具有较高准确性。（3）选取2011年我国渤海的一次典型溢油事故为泄漏地点，采用2012年的预报风场、流场数据，开展使用和未使用消油剂处理海面溢油的情景模拟，对比分析消油剂分散作用对海上溢油行为动态的影响。（4）构建综合随机和典型情景模拟的海洋溢油污染风险评估方法，并以渤海湾南部的2处港口码头、辽东湾中部1处海洋石油平台为例开展应用研究，以海面油膜最快到达时间、污染概率等指标评估了8个国家级海洋保护区遭受不同类型溢油事故的污染风险。此外，实现风险评估结果在业务系统平台中集成展示，探索研究成果的推广应用。前述项目研究成果，对发展我国海上溢油预测预报技术、提高我国海洋溢油风险管理和应急决策的理论研究与实际应用都有较高的参考价值。