Optimization and Evaluation Experiment of Efficient Hydrate Anti-agglomerates Suitable for Gas-Water System

In the process of developing natural gas hydrates in the sea, the high-pressure and low-temperature environment near the mudline is prone to causing the decomposed gas and water to regenerate hydrates, causing pipeline blockage and reducing production efficiency. Traditional prevention methods for secondary hydrates often use methods such as excessive injection of thermodynamic inhibitors and electric heating, but they all have problems of low efficiency and high cost. At present, research on low-dose inhibitors (kinetic inhibitors, anti-agglomerants) has become a hot topic in this field. This study investigated the inhibition performance of a new type of anti-agglomerant suitable for gas-water system through high-pressure stirring vessels. Through experiments, a highly effective inhibitor suitable for gas-water system was selected as cocamidopropyl dimethylamine (PKO). The effects of mass fraction of PKO on hydrate induction time, formation rate, conversion rate, and torque were investigated. It was found that although it can significantly reduce the induction time of hydrates, increase the rate of hydrate formation, and promote its formation, the generated hydrates are loose, significantly reducing the torque of the stirring kettle. In engineering applications, it is manifested that under the action of PKO, the generated hydrates are dispersed and transported in the gasflow without agglomeration, effectively ensuring the safe and efficient transportation of the wellbore. At the same time, the improvement of hydrate conversion rate further improves the gas transportation capacity. Through further experiments, it was found that the mass fraction at which PKO can exert the optimal inhibition effect is the critical micelle concentration (CMC), and the inhibition mechanism of PKO in the gas-water system was revealed, providing a new prevention and control approach for the secondary hydrate blockage problem in the natural gas hydrate extraction process in the sea area.