Acoustic emission and volumetric strain induced in coal by the displacement sorption of methane and carbone dioxide

作者：Majewska Zofia^*; Zietek Jerzy

来源：Acta Geophysica, 2008, 56(2): 372-390.

DOI：10.2478/s11600-008-0007-0

• acoustic emission
• carbon dioxide
• methane
• coal swelling
• coalbed methane
• sequestration of carbon dioxide

The aim of this study was to assess whether acoustic emission (AE) could carry information on preferential sorption/desorption of CH4 or CO2 in coal. AE and expansion/contraction of two nearly identical cylindrical coal samples were continuously monitored during displacement sorption experiments. One sample was subjected to presorption of CH4, followed by sorption of CH4/CO2 mixture. With the other one, presorption of CO2 preceded sorption of the mixture.
The results obtained are the following: first, AE and stain kinetics show that the affinity of the coal tested is higher for CO2 than for CH4; second, methane is preferentially desorbed after presorption of CH4 - sorption of mixture of CH4 and CO2; third, during displacement sorption, kinetics of AE and sample swelling/shrinkage bring out the importance of presorption and the sorbate used. It matters whether the coal is first exposed to CH4 or to CO2. The present study has demonstrated that injection of CO2 into the coal previously exposed to CH4 causes considerable swelling of the coal. On desorption after CH4/CO2 exchange sorption, initial shrinkage is followed by swelling of the coal.
These results could have implications for the sequestration of CO2 in coal seams and CH4 recovery from coalbeds (ECBM). Swelling/shrinkage of the coal matrix should be included in models used to predict coal permeability and gas flow rates. They also show that the AE technique can give more insights into coal matrix-gas interactions.

• 出版日期2008-6