Research Of The Methane Hydrate Formation Characteristics In The Porous Environments

As a new energy source,natural gas hydrate has the advantages of large reserves,high calorific value and low combustion pollution.It is considered to be the most environment-friendly fossil energy with exploitation value in the 21 st century.It is formed by water molecules and small molecular weight gases at low temperature and high pressure.Under natural conditions,the vast majority of hydrates are distributed in the pores of the seafloor sedimentary layer and the terrestrial tundra,and have great prospects for exploitation and application because of their abundant reserves.Therefore,understanding the formation and occurrence characteristics of natural gas hydrate in pore environment is of great significance for the exploitation and utilization of hydrate resources in China.It is of practical significance to simulate the formation of hydrate under natural conditions under experimental conditions for ore-forming mechanism exploration and exploitation as well as industrial application of hydrate.Based on this,the effects of porous media particle size,surface properties and additives on hydrate formation rate and phase equilibrium were summarized,and the distribution of hydrate formation in porous media under different experimental conditions and several thermodynamic theoretical models were discussed.In addition,for the problem of slow hydrate formation rate in pure water,we mixed the different-sized porous media with SDS solution.And the hydrate formation rate,gas storage capacity and formation distribution in this complex system were studied.For the influence of surfactant species on hydrate formation in pore environment,the experiment of hydrate formation in the complex systems consisted of SDS,SDBS and AEO solution and alumina particles were carried out.The results showed that under the condition of pH vlaue,the active groups ionized by anionic surfactant SDS and SDBS solution can significantly improve the gas storage capacity of the formed hydrate.Finally,the effect of silica sand particle size and saturation on hydrate formation in a compound system of silica sand and SDS solution with particle sizes of 100,150,200,300 and 400 mesh were studied.And by observing the distribution of the formed hydrate in the silica sand bed,the formation mechanism of hydrate in this complex system was proposed.Results showed that the presence of SDS in the complex system weakened the effect of particle size on the rate of hydrate formation and could greatly promote the formation of hydrates;With the increase of saturation,the inhibition of hydrate formation by small particle size silica sand was more obvious.In silica sand beds with different saturations,the expansion of the liquid volume when hydrate formed and the capillary forces produced by the pores of the particles led to the migration of the liquid phase,which caused a great difference in the distribution after the hydrate formation.Through the experiments of hydrate formation under different experimental conditions in the pore environment,knowing the effect of the different particles and surfactant types on the hydrate formation,and the research of rapid hydrate formation technology in the complex system consisted of the porous media and the surfactant,not only can provide theoretical support for the exploitation and utilization of the hydrate resource under natural conditions,but also can promote the industrial application of the hydrate method for storage and transportation of natural gas,which is of great importance to the industrial utilization.