Experiment Study On Formation Process Of CH₄/CO₂Hydrate In Quartz Sand Porous Media

The use of carbon dioxide to replace and mine NGH in permafrost regions can not only solve the energy problem, but also store CO2up as CO2gas hydrate. At the same time, this method can solve problems in environment.In this article, we use different silica sand with different size (14.2nm and26.7nm), different temperature and different pressure to generate CH4gas hydrate and CO2gas hydrate. We have done a series of experiments and found some features and laws as follows:(1) Above freezing point, whether in saturated or in unsaturated distilled water, the induction time generating CH4gas hydrate and CO2gas hydrate will become longer and longer with the decreasing pore size of silica sand. Under freezing point, the induction time generating CH4gas hydrate and CO2gas hydrate will increase with the decreasing pore size of silica sand. In certain range of pore size, smaller the grain and pore size is, longer induction time generating CH4gas hydrate and CO2gas hydrate needs.(2) Above freezing point and in saturated water, the average speed of generating CH4gas hydrate and CO2gas hydrate in silica sand with26.7nm pore size is0.0011mol/h,0.0025mol/h; the average speed of generating CH4gas hydrate and CO2gas hydrate in silica sand with14.2nm pore size is0.0014mol/h,0.0016mol/h. Above freezing point and in unsaturated water, the average speed of generating CH4gas hydrate and CO2gas hydrate in silica sand with26.7nm pore size is0.00030mol/h,0.0022mol/h; the average speed of generating CH4gas hydrate and CO2gas hydrate in silica sand with14.2nm pore size is0.0017mol/h,0.0019mol/h.(3) Under freezing point, the average speed of generating CH4gas hydrate and CO2gas hydrate in silica sand with26.7nm pore size is0.00019mol/h,0.0023mol/h; the average speed of generating CH4gas hydrate and CO2gas hydrate in silica sand with14.2nm pore size is0.000050mol/h,0.00053mol/h.(4) Above freezing point and in saturated water, the gas storage capacity of CH4gas hydrate and CO2gas hydrate in silica sand with26.7nm pore size is138.52L/L,29.94L/L; the gas storage capacity of CH4gas hydrate and CO2gas hydrate in silica sand with14.2nm pore size is176.93L/L,20.46L/L. Above freezing point and in unsaturated water, the gas storage capacity of CH4gas hydrate and CO2gas hydrate in silica sand with26.07L/L,19.59L/L; the gas storage capacity of CH4gas hydrate and CO2gas hydrate in silica sand with14.2nm pore size is162.93L/L,17.95L/L(5) Under freezing point, the gas storage capacity of CH4gas hydrate and CO2gas hydrate in silica sand with26.7nm pore size is12.31L/L,14.42L/L; the gas storage capacity of CH4gas hydrate and CO2gas hydrate in silica sand with14.2nm pore size is3.64L/L,3.83L/L. The innovation point in this article is:Using porous silica sand to simulate the existence of natural gas hydrate, we have done researches on the processes of generating CH4gas hydrate and CO2gas hydrate above freezing point and under freezing point separately, and reveal some features and laws on generating CH4gas hydrate and CO2gas hydrate.