油气混输管道中天然气水合物的形成和堵塞过程研究

Research of natural gas hydrate formation and plugging in mixed transmission pipelines of oil and gas

关键词:  天然气水合物  生成  堵塞  黏度  压降  分层 

Key words:  natural gas hydrate  formation  plugging  viscosity  pressure drop  stratification

摘要:

为研究油气混输管道中天然气水合物的形成和堵塞过程,采用自行设计的高压环道装置,以去离子水、柴油、天然气为管输介质,在含水率70%、液相初始流量2 000 kg/h等条件下进行水合物堵塞实验。研究结果表明:实验时水合物在管道中各处同时生成,但初始生成量并不相同；在实验含水率70%的条件下,水合物主要在管道气相空间壁面和液相主体中生成；水合物的生成会导致管内流量降低,在未添加乳化剂的情况下,油水混合液会因流量的降低而产生分层,此时水合物颗粒集中分布在混合液下层,造成流体黏度和管段压降的急剧升高,进而引发管道堵塞。 

Abstract:

In order to investigate the hydrates formation and plugging in mixed transmission pipelines of oil and gas, a high pressure test loop is designed specially where natural gas hydrates are formed in diesel oil + water system with a water cut of 70% and an initial liquid flow rate of 2 000 kg/h. The experimental results show that hydrates form simultaneously in the whole pipeline, but the initial formation quantities are different. Tube wall and liquid bulk phase are the two places where hydrates mainly form at the experimental water cut. Without emulsifier, the oil/water emulsion separates at low flow rates. Hydrate particles distribute mainly in the lower liquid phase, which results in an incredible increase in the viscosity and pressure drop. Liquid stratification and the sharp increase in viscosity are the governing reason of plugging.