Anti-agglomeration evaluation and Raman spectroscopic analysis on mixed biosurfactants for preventing CH4 hydrate blockage in n-octane + water systems

Hydrate formation and agglomeration in oil and gas pipelines is a serious safety and environmental problem. An eco-friendly and effective anti-agglomerant is a promising candidate to mitigate gas hydrate blockage risk environmentally and economically. This study evaluated the anti-agglomeration effect of mixed biosurfactants (rhamnolipid + trehalose lipids) through the torque changes during the CH4 hydrate growth process. The results showed that mixed biosurfactants greatly decreased the force needed for the system to be flowing. A surprising synergistic effect functioned for mixed biosurfactants, leading to the decease of dosage needed for anti-agglomeration. The CH4 hydrate formation kinetics was also studied, and the data revealed that mixed biosurfactants could fasten the gas dissolution process while did not greatly change the hydrate growth rate. In addition, the Raman spectra for CH4 hydrate formed with mixed biosurfactants were obtained and analyzed. It demonstrated that the added biosurfactants decreased the hydration number by increasing the small cage occupancy. Meanwhile, the hydrate surface became regular and smooth, which contributed to preventing hydrate blockage in oil and gas system.