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Gas Hydrate Sloughing as Observed and Quantified from Multiphase Flow Conditions

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journal contribution
posted on 26.02.2018, 00:00 by Erlend O. Straume, Celina Kakitani, Luis A. Simões Salomão, Rigoberto E. M. Morales, Amadeu K. Sum
Sloughing of gas hydrates from deposits formed on the pipe wall is a phenomenon that can cause hydrate accumulation and blockage of the flow in oil/gas pipelines. While hydrate sloughing has been recognized as an important mechanism leading to hydrate blockage, its observation and measurements have not been reported. Experiments performed in a visual rocking cell to emulate multiphase flow conditions with a methane–ethane gas mixture, fresh water, and non-emulsifying oil or condensate as hydrocarbon liquid demonstrated that hydrate sloughing occurs at a wide range of subcooling and temperature gradient conditions. However, sloughing was not detected in a narrow operational window defined by both subcooling lower than 4 °C and temperature gradient in the cell lower than 1 °C. The potential existence of an operational window for conditions without sloughing might be valuable for the development of hydrate management strategies for blockage-free production.