卧底管—立管系统两相流特性研究

发布时间：2018-04-07 19:04

本文选题：气液混输　切入点：卧底管-立管系统　出处：《上海交通大学》2015年硕士论文

【摘要】：在海洋油气开发中,气液混输逐渐成为一种重要的油气运输方式,通常采用由卧底管和立管组成的管道系统进行油气资源的输送。由于气液两相间物性差异,导致运送过程中容易出现气液两相不规则流动的现象,其中以严重段塞流最为典型。严重段塞流会造成管道内压力、速度等参数发生剧烈波动,对管道系统和油气采集设备造成危害。随着油气开采不断向深海迈进,对严重段塞流现象的深入研究变得越发关键和重要。本文针对卧底管-立管系统,选取常见的垂直立管和悬链线立管两种管型,通过建立理论模型进行数值模拟计算,对气液严重段塞流特性及其变化规律进行研究,主要工作如下:对卧底管系统采用分层流理论模型,立管系统采用分相流理论模型,考虑立管内摩擦压降,结合漂移流速度模型,对初始条件提出一种不需要经验模型的方法,建立了卧底管-立管系统气液两相流动的一维瞬态理论模型。对下倾管-垂直立管/悬链线立管两类系统,结合文献中的实验结果,将数值模拟结果与实验结果进行对比,结果表明,对严重段塞流周期和压力波动幅值等,本文理论模型的数值结果与实验数据吻合良好。在此基础上,本文成功地模拟了四类流型,并将其细分为严重段塞流I型、II型、III型和稳定流型,得到了下倾管-垂直立管/悬链线立管两类系统的流型图,结果表明,严重段塞流I型主要出现在卧底管入口气液折算速度较低的工况下,而出现严重段塞流II型、III型工况对应的范围处于严重段塞流I型与稳定流型之间,可以将这两种流型视为过渡流型。根据严重段塞流I型的流动特性,对严重段塞流I型和严重段塞流II型的转换边界进行了修正,与Pots判定准则的对比结果表明本文提出的转换边界可以更好进行预测。最后,利用理论模型计算结果,进一步对严重段塞流压力波动与周期、立管内气液流动速度、含气率及质量分布特性等重要参数进行了分析,结果表明:严重段塞流现象会导致卧底管-立管系统内气液流动参数剧烈波动;严重段塞流I型压力波动、立管两端气液相速度和立管平均含气率变化的幅度均大于其它流型,且波动幅度最大的工况均在严重段塞流I型和严重段塞流II型的转换边界上;悬链线立管系统内的气液两相流动参数波动的剧烈程度要小于垂直立管系统,主要原因是悬链线立管的几何形式的不同。
[Abstract]:In the development of offshore oil and gas, gas-liquid mixed transportation has gradually become an important mode of oil and gas transportation, and the pipeline system composed of undercover pipes and risers is usually used to transport oil and gas resources.Due to the difference of physical properties between the two phases, the phenomenon of irregular gas-liquid two-phase flow is easy to occur in the transportation process, among which the serious slug flow is the most typical.Severe slug flow will cause severe fluctuation of pressure and velocity in pipeline, which will cause harm to pipeline system and oil and gas acquisition equipment.With the development of oil and gas production into the deep sea, it becomes more and more important to study the phenomenon of serious slug flow.In this paper, two kinds of pipe types, vertical riser and catenary riser, are selected for the underground pipe-riser system. The characteristics of gas-liquid serious slug flow and its variation law are studied by establishing a theoretical model for numerical simulation.The main work is as follows: the theory model of stratified flow is adopted for the underground pipe system, and the theory model of separated phase flow is used for the riser system. Considering the friction pressure drop in the riser and the drift flow velocity model, a method is proposed for the initial condition without the need of empirical model.A one-dimensional transient model of gas-liquid two-phase flow in an undercover tube-riser system is established.For the downdip pipe-vertical riser / catenary riser system, the numerical simulation results and experimental results are compared with the experimental results in the literature. The results show that, for the period of severe slug flow and the amplitude of pressure fluctuation, etc.The numerical results of the theoretical model are in good agreement with the experimental data.On this basis, four types of flow patterns are successfully simulated and subdivided into severe slug flow type I / II and steady flow patterns. The flow patterns of downdip pipe vertical riser / catenary riser are obtained. The results show that,The serious slug flow type I mainly appears under the condition of low gas-liquid conversion velocity at the entrance of the underground pipe, while the range corresponding to the serious slug flow type II type III condition is between the serious slug flow type I and the steady flow pattern.These two flow patterns can be regarded as transitional flow patterns.According to the flow characteristics of severe slug flow type I, the conversion boundary of severe slug flow type I and serious slug flow type II is modified. The comparison with Pots criterion shows that the proposed transfer boundary can be better predicted.Finally, based on the theoretical model, some important parameters, such as pressure fluctuation and period of serious slug flow, gas-liquid flow velocity, gas holdup and mass distribution in riser, are further analyzed.The results show that the serious slug flow will lead to the dramatic fluctuation of gas-liquid flow parameters in the underground pipe-riser system, and the variation amplitude of gas-liquid velocity at both ends of riser and the average gas holdup of riser is larger than that of other flow patterns, and the pressure fluctuation of type I in severe slug flow is larger than that of other flow patterns.The most fluctuating conditions are on the transfer boundary of severe slug flow type I and severe slug flow type II, and the fluctuation of gas-liquid two-phase flow parameters in catenary riser system is less severe than that in vertical riser system.The main reason is the different geometry of catenary riser.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE95;P756.2

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