Experimental Study On Natural Gas Hydrate Formation In Icefilled Porous Media

Because of the shortage of energy,nature gas hydrate get more and more attention from all countries in the world,and its research has become one of the most important directions in today's energy field.A series of works had been conducted by scholars to explore its mechanism of formation.The formation of natural gas hydrate can be affected by various factors: not only pressure,temperature,reactant state and other basic factors have impacts on its formation,but surface additives,porous media,mechanical shock,light,electromagnetic waves and other external factors also have important influence.In this particle,a series of well-prepared experiments have been conducted to explore the effects of ice-filled porous media on the methane hydrate formation,especially the effects of ice-filled media's particle size and the volume ratio of media to ice.Then,some hydrate samples were researched by CT to analyze the state of methane hydrate in small particle media.The study found that both the media's particle size and its volume ratio with ice had important effects on the formation of hydrate.According to the experiments' results,when less media(Vmedia: Vice=0.36),big particle media has obviously positive effect on the process of hydrate formation while the effect become weak when media's particle size identical or slightly bigger than ice particles.when middle media(Vmedia: Vice=0.72),big particle media and small ones have obviously positive effect and the effect become weak when media's particle size identical to ice particles.when excessive media(Vmedia: Vice=1.08),big particle media and small ones have obviously positive effect and the effect become weak when media's particle size slightly bigger than ice particles.With the media proportion increase,small particle media and big particle media's positive effect become large.When the media particle size slightly smaller or bigger than ice particles,the effect first become large then become small with the media proportion increase,contrary to the media whose particle size identical to ice particle.In these experiments,small particle with less ratio media group has the maximum ice conversation rate,and the 0.6mm particle size with less media group has the minimal ice conversation rate.According to the analysis,the effect of ice-filled porous media on the formation of natural gas hydrate is mainly caused by the filling effect between porous media particles and ice particles.It have two main forms: non-reactive media particles' supporting effect as skeletons;the change of pore structure caused by the hydrate conversion of ice particles.Though the hydrate samples' CT figures,it was found that a small part of the media particles would gather in some aspects in the reaction process,which may cause error.