Numerical Simulation Of The Spread-Diffusion Process Of Oil Spilled From Submarine Pipeline

Accompanied by the rapid development of offshore oil exploitation, submarinepipelines are used more widely as the main means of transporting the offshore oil andgas resources. And submarine pipelines will inevitably appear a variety of damagewhen they are in service. Therefore with the development of submarine pipelines, theprobability of oil spill will increase. What’s more, the oil spilled in deep sea willcause much larger pollution of water body than that occurred in the sea surface, whichwill result in serious impact and harm on marine life and the surrounding coastal cities.After the oil spills from subsea pipelines, it will directly affect the water quality, andendanger the marine life, damage the ecology of the sea during its rising process.Therefore, to study the transport and diffusion of submarine pipeline oil spill becomesincreasingly important and urgent.A brief overview of the research background is made in this paper, and then theresearch status of the oil spill and floating jet home and abroad is reviewed. Thespecific contents and conclusions of the research are as follows:1. Using Backhaus’ three-dimensional nonlinear numerical model, this papersimulate three-dimensional tidal current field of the northern South China Sea. Andthe model is validated by the measured data of three stations. The calculatedthree-dimensional tidal current field is using as the background flow field input ofthe submarine pipeline oil spill model.2. A submarine pipeline oil spill model simulating the transport and diffusion ofoil buoyant jet is developed by Lagrangian control volume method. And the model isverified by the experimental data given in the literature for four different ambientstatus including unstratified stagnant ambient, stratified stagnant ambient,unstratified flowing ambient, stratified flowing ambient.3. The model is applied in the oil spill from pipelines near Lufeng7-2oil field in the northern part of the South China Sea. The three-dimensional transport anddiffusion of oil spill is simulated in the density unstratified and stratified ambientrespectively. During the simulation several different situations of the spill oil areconsidered. The impact to the simulation result of different original spill angles andsurrounding ambient status is be analyzed. And the centerline of the spill oil and thearea of each horizontal profile are be simulated, too. Finally, the transport anddiffusion results of the oil spill are be modeled in stratified density ambient.4. The study results of the submarine pipeline oil spill show that: The mainfactor impacting the results of the oil spill model is the ambient flow distribution.And regardless of the oil spill time the minimum distance of the offset in horizonoccurs in vertical direction overflow, while the maximum distance in horizontaldownstream direction. What’s more, with the decrease of the initial oil spill angle,the time and the radius of spill oil reaching the sea surface will increase Thediffusion area of each layers is also subject to the combined effects of the ambientflow field and the initial oil spill angle, and the impact of spill angle at the same timeis affected by the tidal current field distribution. When the oil spill in densitystratified ambient, the buoyant jet will reach a terminal level, and then diffuse withthe ambient flow downstream without arriving at the sea surface in a relatively shortperiod of time. Therefore, even if there is no oil observed in the surface far from theoil spill location, the contamination of oil may still exist in the deep sea.By the study of the transport and dispersion model of the submarine pipeline oilspill, a clearer understanding of the affect extent of spill oil on marine water qualityand ecological environment will be showed, which can provide method and basis forthe evaluation of the oil spill harm to the marine ecological environment.