| 摘要 |
A tank contains both Zeolite and a hydrate in a gas chamber formed beneath a piston in the sample tank. Out of safety considerations, we avoid using source cylinders of nitrogen whose pressures exceed 4000 psi. Thus, the gas chamber of the sample tank is initially pressurized by the source cylinder to no more than 4000 psi of nitrogen at room temperature at the surface. Nitrogen gas is sorbed onto the zeolite at room temperature. As the tank is heated by being lowered downhole, nitrogen desorbs from the zeolite and the gas pressure increases. However, once this tank reaches a temperature high enough to release the hydrate's water of hydration, the released water is preferentially sorbed by zeolite, displacing sorbed nitrogen, and causing the pressure in the gas volume to increase even further. Because well temperatures are not high enough to desorb water from zeolite, any water sorbed onto a Zeolite sorption site will permanently block released nitrogen from resorbing at that site. The process of lowering the tank downhole provides the necessary heating to make the entire process occur. Thus, if returned to the surface at room temperature with the original gas-chamber volume, the tank's pressure would not fall back to the original pressure (e.g., 4000 psi) but would be at a substantially higher pressure (e.g., 6000 psi or more depending on the amount of Zeolite used and gaseous nitrogen gas released).
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