Gas hydrate blockage removal using chemical injection in vertical pipes

Gas hydrates can cause restriction and blockages in pipelines. Therefore, if hydrates are identified as a potential challenge, a prevention strategy for hydrate formation and options for remediation of hydrate blockage are considered. The most commonly used means of blockage removal involves one or two sided depressurization with or without other options such as heating and injecting thermodynamic inhibitors. In this work, we report use of thermodynamic inhibitors to remove a hydrate blockage in a vertical pipe. The experimental work was carried out using a long, cylindrical, high pressure, vertical visual cell with full temperature gradient control. The pressure was kept relatively constant (± 5 bar) during multiple inhibitor injections and hydrate dissociation by batch removal of gas from the top of the cell. The results are presented in this paper including pressure response due to hydrate dissociation, reformation of gas hydrate, and possibility of ice formation as a result of gas hydrate dissociation.