Investigation on Hydrate Growth at the Oil–Water Interface: In the Presence of Wax and Kinetic Hydrate Inhibitor

In oil industry, the coexistence of hydrate and wax can result in a severe challenge to subsea flow assurance. In order to study the effects of wax on hydrate growth at the oil–water interface, a series of microexperiments were conducted in a self-made reactor, where hydrates gradually nucleated and grew on the surface of a water droplet immersed in wax-containing oil. According to the micro-observations, hydrate shells formed at the oil–water interface in the absence of kinetic hydrate inhibitor (KHI). The roughness and growth rate of hydrate shells were analyzed, and the effects of wax were investigated. In addition, vertical growth of the hydrate shell was observed in the presence of wax, and a mechanism was proposed for illustration. In the presence of KHI, small hydrate crystals formed separately at the oil–water interface instead of hydrate shells. The presence of KHI reduced the growth rate of hydrates and changed the wettability of hydrates. Moreover, the presence of wax showed no obvious effect on the effectiveness of KHI under experimental conditions.