基于CFD的深水钻井溢油事故定量风险评估

针对深水钻井作业过程中的井喷溢油问题,基于计算流体力学(CFD)方法,通过UDF函数给定海流流剖面、波浪入口边界条件和海水静压分布情况,结合标准k-ε方程,采用VOF模型实现对油、气、水三相自由面的追踪,建立了溢油扩散事故数值仿真模型,评估深水条件下溢油扩散危害区域,研究海流流速、溢油量对原油扩散的影响。结果表明,海流流速和溢油量是原油扩散行为和危害区域分布范围的重要影响因素。

CFD-based quantitative hazard assessment of oil spills in deepwater drilling

The present paper is aimed to propose an improved CFD-based quantitative hazard assessment of oil spills in deep-water oil drilling practice.As is known,with the rapid development of offshore oil and gas exploitation,oil spill accidents have ever increased significantly,one of which was the deepwater horizon accident in the Gulf of Mexico.The accident demonstrates that offshore oil spills can likely cause serious damages to ocean environment as well as human casualty,in addition to fishing and tourism.In order to effectively control such events and provide in-time technical assistance to save the oil wells and clean-up the water-contamination,it is of great emergency to master and control the regularity of the ocean movement and the rudimental cause leading to the oil spills,and in turn to be able to forecast the accurate trajectory of oil movement beneath the sea.Computational Fluid Dynamics(CFD) proves to be an invaluable tool for analysis of the dispersion of oil spills.However,most studies that have ever done mainly focused on the surface or shallow water oil spills,and seldom can we find qualified high-level researches on the deepwater oil spill.Therefore,we have developed a CFD-based numerical simulation model to analyze the dispersion of deepwater blowout and the influence of the seawater current and the oil flux to the oil dispersion.To be exact,the problem involves sea current profile,wave boundary condition and the static pressure of the seawater.It is just because of the above said factors involved,this paper adopts a standard two-equation model of k-ε and the three phase(oil,water and air) volume of fluid(VOF) model to trace the free surface among the oil,the gas and the ocean water.The environment factors are set by the UDF function.The dispersion simulation model of oil spills consists of two steps: the first step of the two is to simulate the environment factors of the wind,the sea current and the sea wave,by using the software FLUENT,and the second step is to make the coupled simulation of the environmental factors and the oil spill dispersion situation,by introducing a jet inlet boundary condition.The results of our simulation show that the flowing rate of the ocean-water current and the oil spill flux are the two key factors of oil dispersion process and the regional oil distribution.Besides,oil tends to be broken into small droplets at a certain water-level,and then diffuse in the downstream direction and in the vertical direction under the influence of seawater current and buoyancy,while the spill zones tend to expand gradually.Thus,it can be seen that the research results of this paper can serve as a valuable reference to prediction of the hazardous zones and corresponding emergency rescue measures to be taken.