Kinetics of
Pure and Mixed CO2-CH4 Gas Adsorption on Crushed and
Sieved Coal from the
Blencoe, James G.1, Michael T.
Naney2, David R. Cole3, Jack Pashin4, Richard
E. Carroll4 (1) Oak Ridge National Laboratory, Oak Ridge, TN (2)
Electrochemical Systems, Inc, Oak Ridge, TN (3) Oakridge National Lab,
Oakridge, TN (4) Geological Survey of Alabama, Tuscaloosa, AL
A 60-gram sample of lightly crushed and
seived Black Warrior Basin, Alabama coal (1.2-2.0 mm size fraction) was
contacted with pure and mixed gases—CO2, CH4, a CO2-CH4 mixture (~50 mole %
CO2), H2O, and He—at 35 and 40°C, 324 < P(psi) < 497, to determine the
rates and magnitudes of gas adsorption. The sample was placed in a 1.2 liter
autoclave suspended in a 0.5 m3, cylindrical infrared oven. Temperature and
pressure were measured with ultra-high precision (T, ± 0.01°C; P, ± 0.05 psi)
and accuracy (T, ± 0.05°C; P, ± 0.1 psi) using high-quality thermistors and
pressure transducers.
Results of the experiments are very
systematic, indicating significantly different CO2, CH4, and CO2-CH4 gas
adsorption behavior for “dry” and water-saturated conditions. Key conclusions
that can be drawn from the work are: (1) Differential CO2/CH4 adsorption
kinetics will play a key role in CO2 sequestration/ECBM production in
subterranean coalbeds. (2) CO2 adsorption on dry and water-saturated coal is
much more rapid than CH4 adsorption. (3) Water saturation decreases the rates
of CO2/CH4 adsorption on coal surfaces, but it appears to have minimal effects
on the magnitudes of CO2/CH4 adsorption. (4) CO2/CH4 adsorption on coal
surfaces is not strongly dependent on formation temperature. (5) Experiments
with He suggest negligible adsorption of the gas on
coal surfaces.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California