Abstract: Natural gas hydrates can readily form in deep-water oil production processes and pose a great threat to the oil industry. Moreover, the coexistence of hydrate and asphaltene can result in more severe challenges to subsea flow assurance. In order to study the effects of asphaltene on hydrate growth at the oil–water interface, a series of micro-experiments were conducted in a self-made reactor, where hydrates nucleated and grew on the surface of a water droplet immersed in asphaltene-containing oil. Based on the micro-observations, the shape and growth rate of the hydrate shell formed at the oil–water interface were mainly investigated and the effects of asphaltene on hydrate growth were analyzed. According to the experimental results, the shape of the water droplet and the interfacial area changed significantly after the formation of the hydrate shell when the asphaltene concentration was higher than a certain value. A mechanism related to the reduction of the interfacial tension caused by the absorption of asphaltenes on the interface was proposed for illustration. Moreover, the growth rate of the hydrate shell decreased significantly with the increasing asphaltene concentration under experimental conditions. The conclusions of this paper could provide preliminary insight how asphaltene affect hydrate growth at the oil–water interface.

Key words: Hydrate, Asphaltene, Interface, Growth, Shape

摘要： Natural gas hydrates can readily form in deep-water oil production processes and pose a great threat to the oil industry. Moreover, the coexistence of hydrate and asphaltene can result in more severe challenges to subsea flow assurance. In order to study the effects of asphaltene on hydrate growth at the oil–water interface, a series of micro-experiments were conducted in a self-made reactor, where hydrates nucleated and grew on the surface of a water droplet immersed in asphaltene-containing oil. Based on the micro-observations, the shape and growth rate of the hydrate shell formed at the oil–water interface were mainly investigated and the effects of asphaltene on hydrate growth were analyzed. According to the experimental results, the shape of the water droplet and the interfacial area changed significantly after the formation of the hydrate shell when the asphaltene concentration was higher than a certain value. A mechanism related to the reduction of the interfacial tension caused by the absorption of asphaltenes on the interface was proposed for illustration. Moreover, the growth rate of the hydrate shell decreased significantly with the increasing asphaltene concentration under experimental conditions. The conclusions of this paper could provide preliminary insight how asphaltene affect hydrate growth at the oil–water interface.

关键词: Hydrate, Asphaltene, Interface, Growth, Shape