Assessing the performance of commercial and biological gas hydrate inhibitors using nuclear magnetic resonance microscopy and a stirred autoclave

The formation kinetics of methane/ethane/propane hydrate in the presence of kinetic inhibitors was investigated using 1H nuclear magnetic resonance imaging (MRI) as well as a more-traditional method using a stirred autoclave. These studies were facilitated by fabricating a multi-drop insert for 1H NMR micro-imaging, which allowed the comparison of the performance of microliter quantities of several inhibitors simultaneously and under the same conditions. Both methods showed that hydrate nucleation and growth were delayed significantly in the presence of inhibitors, which included two biological inhibitors (antifreeze proteins) and a commercial inhibitor. The results demonstrate that MRI is a useful tool for the visualization and evaluation of the performance of kinetic inhibitors on mixed gas hydrate formation. The MRI technique should prove especially valuable in the case of analysis of potential inhibitors, pre-commercialization, which are available in only limited quantities, such as biological inhibitors. This technique may also find utility in the exploration of differences in inhibitor performance, which may suggest distinct mechanisms of inhibitor action.