【作者】 吕明琦；

【导师】 李巍；

【作者基本信息】 上海交通大学 ， 船舶与海洋结构物设计制造， 2012， 硕士

【摘要】 气液混输是石油与天然气工业中常见的一种输送方式。随着深海油气开发的逐渐深入,在海洋油气开采中,气液混输系统越来越多地开始采用水平-下倾-悬链线立管系统,它不仅包含有沿海底铺设的组合管道系统(水平-下倾管线),而且还包含有将油气资源从海底输送到海洋平台的悬链线立管系统。与纯粹的水平或垂直混输管道系统相比,在该种组合管道系统中气液两相流动特征要复杂得多,输运效果也与浅海油气开采作业中常用的垂直立管系统有所不同。严重段塞流即为该种管型中经常会出现的一种特殊有害流型。这是一种液塞长度可达一倍或几倍立管高度的流动现象,这种现象将造成管道压力剧烈波动、立管出口气液相流量随时间变化很大等有害后果,而对海洋油气开采系统带来诸多危害,对这种流动现象开展研究具有重要的理论和实际意义。在本文第一部分内容中,对水平-下倾-悬链线立管系统中气液两相流特性开展了实验研究。实验中,在水平管中形成了分层流、间歇流两种主要流态,立管中形成了严重段塞流、震荡流和间歇流三种主要流态,而严重段塞流又可细分为I型、II型和III型,通过实验得到了水平管和立管中的流型图。对严重段塞流的流动特性进行了实验研究和分析,结果表明:严重段塞流具有明显的周期性,周期随气液相折算流速增大而减小,压力波动幅度随气液相折算流速的改变而变化,最大值出现在严重段塞流I型到II型的转换边界上。严重段塞流的压力波动与气液相折算速度有重要关系,压力波动幅值随着气相折算速度的增加会出现先增大后减小的趋势,随液相折算速度的增加,在压力波动极值点左侧,较小的液相折算速度对应较大的压力波动幅值,在压力波动极值点右侧,较大的液相折算速度对应较大的压力波动幅值。在本论文第二部分中,针对气液混输管线与悬链线立管系统严重段塞流问题,采用严重段塞流形成条件一致的等效原则,发展了一种将三维管道系统等效为二维管道系统的计算流体力学(CFD)数值模拟方法。以文献中某水平/下倾管与悬链线立管组合系统为对象,结合其实验工况,数值模拟了该种管型下的严重段塞流现象,分析了其压力波动幅值及周期变化特性,数值模拟与文献所述实验结果一致,表明了该数值模拟方法的有效性。更多还原

【Abstract】 Gas-liquid mixed transportation is a method adopted normally in oil and gas industry. With the development of offshore drilling, a horizontal/declination pipeline- catenary riser system is often used to transport oil and gas resources from seabed to the platform. Compared with a horizontal/vertical pipeline system, gas-liquid two-phase flow is more complex for such a horizontal/declination pipeline-catenary riser system,and the transportation effect is different from a vertical riser normally adopted in offshore drilling.Severe slugging phenomenon is a special flow pattern occurred in such a system where the slug length may have several times of the riser’s height. As a result, severe slugging phenomenon is commonly encountered, causes drastic fluctuations for pressure and outlet flow, and then results in some harmful consequences. Therefore, investigation on such a flow phenomenon has of theoretical and realistic significance.In the first part of this thesis, the severe slugging phenomenon in a horizontal/ declination pipeline-catenary riser system was studied experimentally. The mechanism and flow characteristics of the severe slugging were analyzed. The main contents and conclusions are as follows:Two flow patterns are observed in the horizontal pipeline, including stratified flow and intermittent flow respectively. There are also three flow patterns in the catenary riser, including severe slugging,occasional flow and intermittent flow, where severe slugging can be divided into type I, II and III respectively. The flow pattern maps of the two-phase flows for the horizontal pipeline and catenary riser were also obtained.The flow characteristics of the severe slugging were analyzed. It was found that severe slugging is strictly cyclical, and the cycle length decreases with the gas and liquid superficial velocity increasing, the pressure fluctuations change with the gas and liquid superficial velocity change, and the maximum value of the pressure fluctuation occurs at the boundary of the severe slugging I and II.The pressure fluctuations are much related to the gas and liquid superficial velocities. The amplitude first increases and then decreases with the gas superficial velocity increasing. On the left side of the extreme points, smaller liquid superficial velocity corresponds to bigger pressure fluctuation amplitude,while on the other side,bigger liquid superficial velocity corresponds to bigger pressure fluctuation amplitude.In the last part of this thesis, Based on the consistence principle for the severe slugging formation condition, a CFD (computational fluid dynamics) method was proposed for numerically simulating the gas-liquid severe slugging in a pipeline-riser system by means of translating the 3D pipeline-riser system into a 2D equivalent one. Numerical simulations were conducted for the gas-liquid flow patterns of the severe slugging in a horizontal/declination pipeline-catenary riser system according to the experimental cases presented in the reference, and the pressure characteristics including period and its amplitude were analyzed due to such a severe slug flow, the numerical results are good agreements with the experimental ones in the refrence showing that the proposed method is effective.更多还原