Experimental Investigation on the Formation and Agglomeration Characteristics of Methane Hydrate in Oil-Water System in Presence of Anti-agglomerants

Hydraflow technique has been proposed for the prevention of hydrate problems in the offshore oil and gas transportation. Therefore, it is of great significance to develop effective hydrate anti-agglomerants (AAs) and clarify the hydrate characteristics in the presence of AAs. In this study, the formation and agglomeration characteristics of methane hydrate in oil- water system in presence of the developed hydrate AAs was investigated using the high pressure stirring cell at the AA concentration of 0–2.0 wt% and water cut of 10–60%. For runs at the water cut of 30% and 60%, it was found that the agglomeration of hydrate exhibited two separate modes with the increase of hydrate volume fraction. At the low hydrate volume (usually <10%), the hydrate can be dispersed in liquid phase due to the dispersed hydrate particle, and the relative current slowly increased. The AA concentration has little influence on the hydrate agglomeration. Then with the proceeding of hydrate formation process, the agglomeration of hydrate can be significantly enhanced with the increase of hydrate volume fraction. In this stage, the agglomeration of hydrate can be significantly mitigated with the increase of AA concentration. Results showed that the hydrate induction time can also be prolonged by the addition of the developed AA. At the water cut of 60%, the addition of 0.5 wt% AA can delay the hydrate induction time by 9.1 h. In presence of 0.5 wt% AA and in the water cut range of 10–50%, the system with 40% water cut was found to be with the highest hydrate plugging risk. With the formation and agglomeration of hydrate, the relative current significantly increases by 16 times.