海底输油管道泄漏检测及溢油水下扩散模拟技术研究

发布时间：2018-05-20 17:22

本文选题：海底输油管道 + 泄漏检测　；参考：《西南石油大学》2015年硕士论文

【摘要】：海底输油管道一旦发生泄漏溢油对海洋环境将产生十分严重的危害性,并且这种危害往往具有长期性。及时准确的泄漏检测方法和掌握水下溢油扩散规律能够为管道泄漏后现场应急策略制定提供必要的理论指导以及降低溢油对环境的损害程度。本文将在海底输油管道泄漏检测和水下溢油扩散两方面问题展开研究。针对海底输油管道泄漏检测问题,从流体动力学角度研究了管道泄漏的实质；基于流体动力学和热力学基本原理建立了泄漏检测数学模型,探索了有效的求解方法。实现了海底输油管道泄漏检测、泄漏定位和泄漏量预测的目的。最后开发了相应的海底输油管道泄漏检测软件。针对溢油在水下的扩散问题,分析了泄漏发生后溢油在水下扩散行为。将溢油扩散过程分为两个阶段。第一阶段是泄漏发生后较短时间内,溢油以射流形式进入海水中,此时溢油扩散主要受初始动量控制；第二阶段是溢油上升一定高度至到达水面,此时初始动量减弱,溢油受动量和海流等因素共同作用。建立相应的数学模型,其中控制方程引入多相流VOF模型和标准化的k-ε湍流模型。采用有限体积法离散控制方程,PISO算法进行流场计算。最后基于FLUENT软件对两阶段的溢油扩散行为进行模拟分析。通过以上研究得到的主要结论如下： (1)泄漏检测和定位方面：①确立了三种不同边界条件下的泄漏检测方法,通过传统特征线法实现管道的泄漏检测；②同时利用管道起终点的流量、压力和温度值基于改进后的特征线法,得到同一时刻两条沿线的压降曲线,两条压降曲线的交点即为管道泄漏点。 (2)泄漏量的计算方面：提出了阀门关断后泄漏的残油量计算方法,基于传统的特征线法引入关断的阀门边界和泄漏边界,再结合阀门关断前泄漏量的求解信息进行计算；而阀门关断前泄漏量是通过改进后的特征线法进行计算的。 (3)基于C#2010开发了海底输油管道泄漏检测软件,算例分析结果所呈现的规律符合泄漏事实,验证了模型和求解方法的正确性。 (4)模拟分析了溢油扩散第一阶段射流速度和泄漏孔径对溢油射流的影响：①随着泄漏孔径和射流速度增大,相同时间内喷射的油柱更长；②随泄漏孔径越大,喷射油柱直径越大；相同速度下油柱两侧由不出现卷流发展到有明显的卷流,然而射流速度低于一定数值后射流油柱两侧不会形成卷流；③随着泄漏孔径的增大射流油柱上半段由不出现颈缩段发展到有明显的颈缩段。 (5)模拟分析了溢油扩散第二阶段泄漏速度、泄漏孔径和海流速度对海底输油管道溢油扩散的影响：①油粒子数量越大水下污染范围越广,较大的海流速度、较小的泄漏孔径和较小的泄漏速度有利于水下油粒子的成长；②泄漏速度越大,溢油上浮到达海面的时间越短,水下污染程度越严重,泄漏速度越小在水下形成的油粒子数量越多,污染范围越广；③泄漏孔径越大,溢油上浮到达海面的时间越短,泄漏孔径越小形成的油粒子数量越多,水下污染范围越广；④海流速度越大,溢油上浮时间越长,水下污染范围越广,并且海流因素是影响水下溢油扩散范围的主要因素。
[Abstract]:Once the oil pipeline is leaked, the oil spill will be seriously harmful to the marine environment, and the damage is often long-term. The timely and accurate leakage detection method and the control of the rule of the underwater oil spill can provide the necessary theoretical guidance for the emergency strategy formulation after the leakage of the pipeline and reduce the oil spill to the environment. The damage degree will be studied in the following two aspects: leak detection and submarine oil spill diffusion.
In view of the leakage detection of submarine oil pipeline, the essence of pipeline leakage is studied from the hydrodynamic point of view. Based on the basic principle of fluid dynamics and thermodynamics, a mathematical model of leakage detection is established, and an effective solution is explored. The purpose of leakage detection, leakage location and leakage prediction is realized. The corresponding leak detection software for seabed oil pipeline has been issued.
In view of the diffusion of spilled oil under water, the diffusion behavior of spilled oil after leakage is analyzed. The process of spilled oil diffusion is divided into two stages. The first stage is a short time after the leakage occurs, the spilled oil enters the sea water in the form of jet, at this time the diffusion of spilled oil is mainly controlled by the initial movement, and the second stage is a certain height of the oil spilled up. To reach the water surface, the initial momentum is weakened, the oil spilled by the momentum and the current and other factors together. A corresponding mathematical model is established, in which the control equations are introduced into the multiphase flow VOF model and the standardized k- e turbulence model. The finite volume method is used for discrete control equations and the PISO algorithm is used to calculate the flow field. Finally, the two stage is based on the FLUENT software. The behavior of spilled oil diffusion is simulated and analyzed.
The main conclusions obtained through the above study are as follows:
(1) leakage detection and location: (1) the leakage detection method under three different boundary conditions is established, and the leakage detection of the pipeline is realized through the traditional characteristic line method; secondly, the flow, pressure and temperature value of the end end of the pipeline are based on the improved characteristic line method, and the pressure drop curve and the two pressure drop curve along the two lines at the same time are obtained. The intersection point of the line is the leak point of the pipe.
(2) the calculation of leakage amount: the calculation method of the residual oil amount of the leakage after the valve closing is put forward. Based on the traditional characteristic line method, the closed valve boundary and the leakage boundary are introduced, and the calculation of the leakage amount before the valve closing is combined, and the leakage amount before the valve closing is calculated by the improved characteristic line method.
(3) the leak detection software of the submarine oil pipeline is developed based on C#2010. The law of the example analysis results in the leakage fact, and verifies the correctness of the model and the solution method.
(4) the effects of the first phase of the spilled oil diffusion and the leakage aperture on the spilled jet are simulated and analyzed. (1) with the increase of the leakage aperture and the jet velocity, the oil column is longer in the same time, and the larger the diameter of the leakage hole, the larger the diameter of the injection oil column, and the flow of the oil column will not appear on the sides of the oil column to the obvious volume at the same speed. Flow, however, when the jet velocity is lower than a certain value, no coiling is formed on both sides of the jet oil column. 3. With the increase of the leakage aperture, the upper part of the jet oil column develops from the necking section to the obvious necking section.
(5) the influence of the leakage velocity of the second stage of spilled oil diffusion, the leakage aperture and the velocity of the sea current on the spilled oil diffusion in the submarine oil pipeline: (1) the larger the number of oil particles is, the wider the underwater pollution range is, the larger the velocity of the sea current, the smaller leakage aperture and the smaller leakage speed are beneficial to the growth of the underwater oil particles; the more leakage speed is, the more leakage speed is. The shorter the time of the oil spill to the sea, the more serious the underwater pollution is, the less the leakage speed is, the more the amount of oil particles formed under the water, the wider the pollution range; the longer the pore size is, the shorter the time for the spill to float to the sea surface, the smaller the amount of oil particles formed by the smaller pore diameter, the wider the underwater pollution range; (4) the ocean current The greater the speed, the longer the floatation time of oil spills and the wider the scope of underwater pollution. And the current factor is the main factor affecting the spread of underwater oil spills.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE88

【参考文献】