A study of adsorption of gases in tight reservoir rocks
In this work, we studied adsorption in tight porous solids using both experimental and numerical methods. We conducted adsorption experiments for geothermal reservoir rock samples and studied the scanning behavior of the steam sorption hysteresis loop. The results of the sorption experiments show that temperature has an important effect on desorption, such that hysteresis becomes more pronounced as the temperature increases. Using a pore network model to represent porous media we investigated adsorption-desorption processes over the range of the relative pressures, highlighting in particular capillary condensation. The numerical model incorporates recent advances from density functional theory for adsorption-desorption in narrow pores (of order as low as 1 nm), which improve upon the traditional multi-layer adsorption and Kelvin`s equation for phase change and provide for the dependence of the critical pore size on temperature. Comparison of the numerical results with the experimental findings showed a good agreement. The hysteresis in the adsorption-desorption cycle is interpreted in terms of blocking of larger pores, where adsorbed liquid is allowed to but cannot desorb, by smaller pores containing liquid that may not desorb. The hysteresis also increases if the porous medium is represented as a fractured (dual porosity) system.
- DOE Contract Number:
- FG07-90ID12934; FG22-93BC14899
- OSTI ID:
- 199456
- Report Number(s):
- CONF-951002--
- Country of Publication:
- United States
- Language:
- English
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