Effects of hydrate inhibitors on the adhesion strengths of sintered hydrate deposits on pipe walls

Interfacial Adhesion Forces of Hydrate Particles in the Presence of Hydrate Inhibitors

“…The interfacial tension of CP/water was 42.98 mN/m, which is close to prior reports of a CP/water interfacial tension of 48 mN/m. 35 The value was reduced to 38.21 mN/m with the addition of ethanol and increased to 43.80 and 45.21 mN/m with the addition of urea and NaCl, respectively. The small effect in interfacial tension is due to the fact that thermodynamic inhibitors are not interfacial active substances.…”

“…Embedding and sintering of the gas hydrate particles also have been observed in the work of Liu et al For CP hydrate with urea, the liquid bridge was relatively stable under the longer contact time and was not further converted into hydrate during the contact process (seen in Video 2). This is because the higher concentration of the thermodynamic inhibitor hinders the further conversion of hydrate, and the existence of a lubricant liquid layer makes the microstructure of the particle surface unable to be embedded with it . Although the early hydrate interparticle adhesion force increases due to the enhanced liquid bridge force, the thermodynamic inhibitors are more suitable for long-term anti-hydrate adhesion.…”

“…This is because the higher concentration of the thermodynamic inhibitor hinders the further conversion of hydrate, and the existence of a lubricant liquid layer makes the microstructure of the particle surface unable to be embedded with it. 35 Although the early hydrate interparticle adhesion force increases due to the enhanced liquid bridge force, the thermodynamic inhibitors are more suitable for long-term anti-hydrate adhesion. This is consistent with the experimental results of the rheological behavior of hydrate that the viscosity of the hydrate slurry first increased, then decreased, and finally tended to be flat in the presence of thermodynamic inhibitors.…”

“…Liu et al studied the effect of anti-agglomerant inhibitors (Span 80 and DBSA) on the adhesion strengths of CP hydrate. The results suggested that the interfacial tension of the oil–water interface was decreased, and an irregular geometry of the crystal morphology was formed after the addition of DBSA and Span 80, which led to a visible decrease in the contact area and a further decrease in the adhesion strength between hydrate and substrate . Delroisse et al studied the synergistic effects of quaternary ammonium salt (DA 50) and NaCl on the surface morphologies, wettability, and agglomeration of CP hydrate.…”

“…The results suggested that the interfacial tension of the oil−water interface was decreased, and an irregular geometry of the crystal morphology was formed after the addition of DBSA and Span 80, which led to a visible decrease in the contact area and a further decrease in the adhesion strength between hydrate and substrate. 35 Delroisse et al studied the synergistic effects of quaternary ammonium salt (DA 50) and NaCl on the surface morphologies, wettability, and agglomeration of CP hydrate. After the addition of NaCl, the hydrates formed a rougher surface, and the shell formed at the CP−water interface changed from water wettable to oil wettable.…”