天然气水合物动力学抑制剂性能评价方法的现状与展望

添加动力学抑制剂(Kinetic hydrate inhibitors,KHIs)是一种经济、有效且非常具有前景的输气管道防天然气水合物(以下简称水合物)堵塞的解决方案,但目前KHIs在国内油气田中还没有得到大规模的应用,因而对其仍需加强开发和性能评价研究。为此,从水合物形成的原理出发,重新总结了KHIs的分类,并分析了过温压变化诱导时间法、晶体生长抑制法(Crystal Growth Inhibition,CGI法)、微观力法以及模拟循环管路法等13种水合物抑制剂性能评价方法的优缺点,形成了一套可以解决不同方法及设备之间评价效果可对比度差以及与实际应用效果差距大等问题的方法。研究结果表明:(1)水合物成核阶段的评价方法包括温压变化诱导时间法、可视观测诱导时间法、过冷度法;(2)水合物生长阶段的评价方法包括温压变化生长速率法、可视观测生长形态法、CGI法、微观力法;(3)成核和生成两个阶段共同的评价方法包括水含量法、组分变化法、微分扫描量热法、超声波法、激光法、电导率法等。并提出了KHIs评价方法的未来发展方向和建议:(1)把多种方法有机结合,多角度(声、光、电、热、力等性质)、多尺度(宏观、微观、介观、纳观等)、多指标(过冷度、诱导时间、生长速率等)及其组合评价将会成为未来更真实、更全面、更准确评价KHIs的发展方向;(2)应将更多的精力集中在KHIs的机理研究上,利用更多先进设备、设计相关实验,验证并发现其作用机理,以指导开发性能更优越的KHIs。

Present situation and prospect of performance evaluation methods for kinetic hydrate inhibitors (KHIs)

Kinetic hydrate inhibitors (KHIs) are a kind of economical, effective and promising technology to remove the blockage of gas hydrate in gas pipelines. So far, however, KHIs have not been applied extensively in domestic oil and gas fields. Therefore, it is in an urgent need to strengthen KHIs development and performance evaluation studies. In this paper, the classification of KHIs was summarized again based on the hydrate formation principles. Then, the advantages and disadvantages of 13 hydrate inhibitor evaluation methods were analyzed, e.g. KHI induction time influenced by temperature and pressure, crystal growth inhibition method (CGI), microscopic kinetics method and circulation conduit simulation method. And accordingly, a set of methods were developed which can improve the value for comparison between the evaluation results from different methods and equipments and reduce the gaps between evaluation and actual application results. And the following research results were obtained. First, the evaluation methods used in the stage of hydrate nucleation include KHI induction time influenced by temperature and pressure, visual observation for induction time method, and sub-cooling degree method. Second, the evaluation methods used in the stage of hydrate growth include the growth rates influenced by temperature and pressure change, visual observation for growth morphology, CGI method, and microscopic kinetics method. Third, the methods used in both stages include water content method, composition change method, differential scanning calorimeter method, ultrasonic measurement method, laser measuring method, electro-conductibility method and so on. Finally, the development directions and suggestions on KHIs evaluation methods were proposed as follows. First, many methods shall be combined organically. Multi-perspective (sound, light, electricity, heat, kinetics and other properties), multi-scale (macroscopic, microcosmic, mesoscopic, and nanoscopic) and multi-index (sub-cooling degree, induction time, growth rate) and their combination will be the future development direction of KHIs evaluation methods with more authentic, comprehensive and accurate evaluation. Second, it is necessary to pay more attention to investigating the mechanisms of KHIs and figuring out and verifying its mechanisms by using more advanced equipments and designing the related experiments to provide a guidance for the development of more superior KHIs.