An improved high-efficiency anti-agglomerant for avoiding hydrate flow barriers in high water-cut systems: flowloop investigation and mechanisms

In deepwater clean energy development (hydrates and natural gas), as well as carbon capture, utilization and storage (CCUS) technologies, the formation and aggregation of hydrates in high water-cut systems can create flow barriers and block pipelines or wellbores, causing economic losses even casualties. The anti-agglomerants (AAs) are known as both efficient and eco-friendly in preventing hydrate aggregation. However, due to the mass transfer promotion and low critical micelle concentration of AAs, they have not been widely used in industry. This study conducted a flowloop investigation on the evolution and prevention of hydrate flow barriers, and identified two primary hydrate blocking modes in high water-cut systems: rapid blocking (RB) by flocculated hydrates and gradual blocking by hydrate particle migration. Based on the cocamidopropyl dimethylamine’s features, an improved high-efficiency anti-agglomerant, CDPKO, was developed. CDPKO prevented the emergence of RB, effectively reduced the hydrate aggregates of 150–500 µm, and prolonged the sum of hydrate induction and blocking times by 53.5%–126%. The five micro mechanisms of CDPKO were elucidated: moderate foaming, promote adsorption, steric hindrance, break water cage, and mildly promote formation. When compounded with a thermodynamic inhibitor (ethylene glycol, 5–15 wt%), CDPKO can reduce the usage of ethylene glycol by 64%–80%, while maintaining the original prevention effect.