Natural Gas Hydrate Injection In The Porous Medium Hot Water Decomposition Theory And Experimental Research

It' s reported that natural gas hydrates over the world contain total methane carbon 10~16Kg or methane gas 20x 10~15 m3, this amount equal twice total carbon reserves of coals, oils and natural gases etc conventional fossi fuels around the earth. Natural gas hydrate, which will replace the status of oil fenatural gas in the future, has been voted an important cleanly energy sources in 21 century when energy sources present austere emergencies. Great amount natural gas hydrates that exit in solid distributing widely in sediments porous medium which locate under the seabed more depth 300~500m ocean and in permafrost deposit on high-latitude. It presents immobile and impenetrabile for natural gas hydrates exit in solid, thus must be decomposed to release naturl gases . It' s impossible to exploit these solid samples for the poor technology condition these days.Natural gas hydrates that look like ice crystal are formed from gases or volatile liquid and water under a certain condition. The lower temperature and higher pressure must be required for natural gas hydrates extence, namely the phase equilibrium of natural gas hydrate exits steady. The infection on formation process of natural gas hydrates in porous medium has been analyzed from the condition of phase equilibrium in sediments and function of force: the curves of phase equilibrium shift to left exhibits lower temperature and higher pressure than the free exterior; and the radius of capillary is less, the clearer for infection of porous medium is. The induction time of formation for natural gas hydrate is abridged by experimental results, there exits no induction time to the formation process of natural gas hydrates from ice-form, but can form the symmetrical steady natural gas hydrates.The routine methods that based on phase equilibrium for decomposition of natural gas hydrates have been provided through the breakage to the curve of phase equilibrium: thermal stimulation method, depressurization method and chem. inhibitor method. The feasibility of hot water injection for natural gas hydrates has been given based on the advantage of decomposition for hot water injection. The mathematic models for dissociation of natural gas hydrates have been built from the three stages for dissociation of natural gas hydrates (the stage of hot water injection, the stage of dissociation of natural gas hydrates and the stage of exploitation gases). One-dimensional models of dissociation frontal brim fornatural gas hydrates have been established through this information, partial differential equations of mass transport, energy conservation and momentum conservation have been proposed and been solved through the finite difference for linear solution, and the flow charts for program alternate been drew. Parameters on models of dissociation have been drafted through utilizing the little C programs that author own wrote. The different infection on grain radius, temperature and velocity of injection to parameters have been analyzed, including the infection of velocity of injection shows more larger than that of temperature.In lab a set one-dimensional experimental device has been designed and built for the formation/dissociation of injection hot water on natural gas hydrates in porous medium by oneself. Natural gas hydrates are formed through admixtures of parts of quartz and ice-power under a certain condition in lab, this process of reaction is being inspected by thermocouple and resistance.(1)Error between drafting models and experimental data is presented only 8.21%, and disparity 1. 14min through analyses of data and draft theory.(2)To the little injection velocity 25ml/min, little infection to dissociation of natural gas hydrates happens for temperature; maximal error of experimental values shows 13. 71% and nearly overlaps on the curve drafted. But that of injection velocity presents larger than temperature and maximal error exits 27.273%, higher 14% than temperature.(3)Consistencies are kept between temperature and resistance to measure of the dissociation frontal brim for natural gas hydrates through analysis of data in experiments.