The Research On The Size And The Ascending Velocity Of Oil Drops Spilling From Tiny Holes Of Seabed Pipelines

The petroleum is an indispensable energy source for people's lives. Since the resource onland has become more and more little, exploitation and utilization of the petroleum of theocean has become more and more important. With the development of oil fields exploitationand industry, seabed pipeline has become so important that nothing can substitute. But there isa hazard in company with the process. The hazard is that the formation of cracks andcorrodible wormholes around the seabed pipeline and oil leakage from cracks and corrodiblewormholes underwater. Oil leakage underwater does not waste the resource only, but alsopollute the ocean environment. To weaken the effect of oil spills, it is necessary to make aresearch about the process of formation and rising of oil spills.Over the past two decades, over 50 oil spill models have been developed to predict thebehavior and fate of spilled oil. Almost all of these models have been concerned with surfaceor near surface spills, but there are few investigations and results about oil spills underwater.There are many former researches about gas bubble spills underwater. The paper applies thetheory about the formation of gas bubble spills underwater to the formation of oil drops.Based on the overall force balance acting on the oil drops and reasonable assumptions, asemi-empirical and semi- theoretical model is presented to predict the diameter of oil dropsafter the two stages in the process of formation. At the same time, the properties of oil areconsidered in the model, including density, surface tension force and dynamical viscosity.The paper discusses the effect of the properties of oil and other factors to the diameter of oildrops of two stages. According to the characteristic of oil jet, a new method is adopted to getthe critical flux on the base of the theory in the expansion stage and analyze the factors whichhave the effect on the critical flux.According to the characteristic of oil drops during the course of diffusion and drift, andbased on the overall force balance acting on the bubble and reasonable assumptions, asemi-empirical and semi- theoretical model is presented about the rising process of small oildrops. The rising process of oil drops is discussed on the foundation of rising model and getsthe ultimately constant velocity in the rising process of small oil drops. Also the paperpresents the method of getting the ultimately constant velocity in the rising process of oildrops which belongs to the medial scale and big scale of diameter.By the way of CCD, the paper simulates the formation process and rising process of gas bubble and oil drop which successive spill from seabed pipelines in aquarium. The diameterof oil drops and ultimately constant velocity of oil are got through the experiment. Comparingthe theoretical results with the experimental results of oil drops, they have a good agreement.And the paper also discusses the factors which have effect on the diameter and the ultimatevelocity of gas bubbles and oil drops in the experiment and provides foundation for improvingthe model of oil spilled underwater.