In the presence of free water, and under certain conditions of temperature and pressure, low-molecular-weight hydrocarbons species, such as methane and ethane, CO2 and H2S may form crystals of gas hydrate. These crystals may accumulate and cause partial or complete plugging in the pipeline. Thermodynamic hydrate inhibitors (THIs) work to extract water and inhibit the formation of gas hydrate crystals. In some applications, only methanol was found able to clear and “dissolve” gas hydrate plugs. The challenge with methanol is it has a low flash point temperature. The main objective of the current work is to develop a high flashpoint treatment for dissolving in-place gas hydrate plugs in pipelines. Methanol has a very low freezing point (-90°C) and it is completely miscible with water. Different formulations were identified while considering parameters such as miscibility with water, freezing point, viscosity and availability. The performance of these formulations was evaluated using a see-through gas hydrate cell and compared to methanol. Several solvent- and aqueous-based treatments met the flash point requirement and were found successful to dissolve hydrate plugs at similar or lower dosage and within the time window given by the field (2 hours). These formulations will not only work as a dissolver but also as an inhibitor to prevent the formation of hydrate downstream. The developed formulations enable safer operations in the field.

Dual functioning dissolver and inhibitor for gas hydrate deposits

ACS Fall 2020 Virtual Meeting

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