Shi Bohui, Ding Lin, Liu Yang, Yang Juheng, Song Shangfei, Wu Haihao, Wang Wei, Gong Jing
National Engineering Laboratory for Pipeline Safety, MOE Key Laboratory of Petroleum Engineering, Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum-Beijing Beijing 102249 People's Republic of China
RSC Adv. 2018 Mar 22;8(21):11436-11445. doi: 10.1039/c7ra13495a. eCollection 2018 Mar 21.
Hydrate risk management strategy has become a promising way of dealing with hydrates in subsea transportation pipelines in recent years. In this way, hydrates are allowed to form in the pipeline and are treated as a slurry flow with the help of anti-agglomerants. This work investigated the effect of hydrate formation on the flow friction factor in water in oil (W/O) emulsion systems. A series of hydrate formation and slurry flow experiments were conducted using a high pressure flow loop. Results show that the friction factor is in direct proportion to the volume fraction of hydrates formed, as it increases significantly after hydrate formation onset and then increases gradually with hydrate growing. A novel method is proposed in this work to amend the effective hydrate volume fraction and take into account the effect of hydrate agglomeration and water occlusion. In addition, it is found that the slurry flow velocity has a significant effect on the friction factor variation. As a larger flow velocity can lift the particles suspension height and cause the particles to be away from the pipe wall surface, so it gives a smaller friction factor by reducing the collisions between hydrate particles and the pipe wall surface. With the modified effective hydrate volume fraction and particle chord length distribution data, a model is proposed to estimate the hydrate caused friction factor in W/O emulsion systems, which shows a good prediction accuracy in 10% and 20% water cut conditions.
近年来，水合物风险管理策略已成为处理海底输油管道中水合物的一种很有前景的方法。通过这种方法，允许水合物在管道中形成，并在抗聚剂的帮助下将其作为一种浆体流来处理。这项工作研究了水合物形成对油包水（W/O）乳液体系中水的流动摩擦系数的影响。使用高压流动回路进行了一系列水合物形成和浆体流动实验。结果表明，摩擦系数与形成的水合物的体积分数成正比，因为在水合物形成开始后摩擦系数显著增加，然后随着水合物的生长而逐渐增加。这项工作提出了一种新方法来修正有效水合物体积分数，并考虑水合物团聚和水包藏的影响。此外，发现浆体流速对摩擦系数变化有显著影响。由于较大的流速可以提高颗粒悬浮高度并使颗粒远离管壁表面，因此通过减少水合物颗粒与管壁表面之间的碰撞而使摩擦系数变小。利用修正后的有效水合物体积分数和颗粒弦长分布数据，提出了一个模型来估算W/O乳液体系中水合物引起的摩擦系数，该模型在含水率为10%和20%的条件下显示出良好的预测精度。
