Effect of Wax on Cohesive Behavior of Gas Hydrate under High Pressure

In the deep-sea crude oil pipeline, the formation of hydrates and the deposition of wax will cause pipeline blockage under adverse conditions. Moreover, the interaction of wax and hydrates will lead to a higher tendency of pipeline blockage, which will pose a huge threat to the transportation of crude oil on the sea floor. In order to clarify the effect of wax on cohesive behavior of gas hydrate, the gas hydrate particles were used as experimental particles to measure the adhesion force between particles in the wax-free system and the wax-containing system directly, and then, the effect of wax on the adhesion force between particles was compared and analyzed. The results showed that wax can destroy the shell structure of hydrate particles, resulting in easier formation of liquid bridges and significantly enhanced adhesion force. Therefore, the adhesion force in the wax-containing system would be significantly greater than that in the wax-free system. In addition, by comparing the adhesion force of different hydrate particles in contact with wax particles, it was found that under high pressure, the precipitation of wax may first cause the agglomeration of CH4 hydrate. Finally, by analyzing the adhesion force and particle morphology at different wax concentrations, the influence mechanism of wax on hydrate cohesion behavior was proposed. This study provides a theoretical basis for eliminating or reducing the blockage of deep-sea crude oil pipelines.