Effect of Different Amino Acids on the Kinetic Characteristics of Hydrate Deposition in an Oil–Water Emulsion

In recent years, amino acids have garnered extensive attention as environmentally friendly, small-dose additives for modulating hydrate formation and aggregation behavior. Amino acids, due to their amphiphilic nature, can adsorb at the gas-liquid interface and on hydrate crystal surfaces, thereby modifying interfacial properties and influencing crystal growth patterns. In our measurements, the amino acids displayed a concentration-dependent "double effect". Small doses accelerated nucleation and early stage formation, whereas larger doses reduced the level of subsequent growth. In this study, the morphology of hydrate particles and the deposition process along the wall were investigated by using a high-speed video camera. This revealed the pattern of hydrate deposition on the wall in an oil-water system, and for the first time, a mechanism of hydrate deposition under various conditions (amino acid concentration, amino acid type, water content of the solution, and stirring rate) was proposed. Moreover, the initial water content of the system, by altering the interfacial state and mass transfer conditions, significantly impacted the nucleation rate and deposition mode of the hydrate. The deposition distribution and crystal morphology of the hydrate were also markedly influenced by the different stirring rates. Therefore, by precisely controlling the type and concentration of amino acids, the water content of the system, and the stirring intensity, it is possible to effectively promote hydrate formation while avoiding excessive deposition and to precisely regulate the particle size, dispersion state, and crystal growth mode of the hydrate. These findings offer a safer, more stable, and environmentally friendly strategy for preventing pipeline blockages and ensuring flow assurance.