Study On Adhesion Effects Between Hydrate Particles And Droplets In The Presence Of Hydrate Inhibitors

Hydrate blockages during deepwater petroleum production is a major flow assurance problem.Hydrates can form when sufficient amounts of gas and water mix under appropriate pressure and temperature conditions.The modern strategy for hydrate mitigation has moved from total prevention to risk management,in which hydrates may be allowed to form as long as the hydrate formation does not lead to plugging.One key aspect leading to hydrate plugs is the agglomeration of hydrate particles.Reduction of the adhesion force between hydrates,or between hydrates and the pipeline wall,will likely reduce the plugging tendency of petroleum production systems.In this paper,hydrate particle-droplet adhesive force data were collected with a micromechanical force（MMF）apparatus.The effects of contact time,subcooling and hydrate inhibitors on interaction force were studied.On the basis of the pendular liquid bridge model,a new adhesive force model of hydrate-droplet.Results show that temperature and contact force are the important factors which affect the adhesion forces.The measured adhesion forces increase with the increasing temperature and contact force.The adhesive forces were predicted by theoretical model,which are in agreement with the experimental data well.Morphology change of hydrate particles and adhesive force between hydrate particle and droplet with thermodynamic inhibitors was investigated.At the same time,mechanism of thermodynamic inhibitors was analyzed.Experimental results showed that hydrate adhesion force between particles and droplets affecting by adding NaCl,CaCl₂,ethylene,etc.When the concentration was less than critical value,the adhesion force got smaller and smaller as concentration of linear inhibitors rose.When the concentration was higher than critical value,the adhesion force got higher and higher as concentration of linear inhibitors rose.For the same inhibitors,the critical value.got lower as the higher the temperature got higher.Morphology change of liquid bridge between hydrate particle and droplet with low dose inhibitors was observed.The adhesive force between hydrate particle and droplet was investigated.In this paper polyvinyl pyrrolidone（PVP）were used as kinetic inhibitors,and dodecyl benzene sulfonate and span80 were used as anti-agglomerant inhibitors.Experiment results showed that adhesion strength of hydrate particles and droplets inter-atomic forces effect is more obvious.The adhesion force got bigger as concentration of linear inhibitors rose.Hydrate adsorption on the surface of the particles and droplets,increasing the stability of the interface between hydrate particles and droplets.On the other hand,the droplets can spread throughout the hydrate particle surface,and converted into hydrate quickly.