Dispersion coefficients are determined, and entry/exit
effects
during gas displacement experiments in porous media are characterized.
Two methods are proposed for measuring concentration breakthrough
profiles: using an X-ray scanner for internal core measurements and
a Raman spectrometer for postcore measurements. The experimental setup
includes a coreflooding system with X-ray scanning capabilities and
a high-pressure Raman probe. A description of the data processing
of X-ray and Raman signals to derive concentration profiles and calculate
mixing coefficients is presented. Results from the experiments are
discussed, including mixing coefficients for CO2 displacing
CH4 and CH4 displacing CO2, and their
variations with pressure, temperature, and flow velocity. Dispersion
coefficients are found to be higher with CH4 as the displacing
fluid compared to CO2, suggesting higher mixing during
gas injection in underground gas storage with a CO2 cushion.
The study extends the analysis to the structure promising for underground
storage in Poland, analyzing dispersion coefficients and other parameters
for gas injection and production scenarios. The proposed methods show
promise for characterizing mixing processes and optimizing UGS operations,
with potential applications in studying other gases such as higher
hydrocarbons or H2 for future energy developments.