Effect of the effective stress coefficient and sorption-induced strain on the evolution of coal permeability: Experimental observations

Zhongwei Chen, Zhejun Pan, Jishan Liu, Luke D. Connell, Derek Elsworth

Research output: Contribution to journalArticle

90 Citations (Scopus)

Abstract

Permeability is one of the most important parameters for CO2 injection in coal to enhance coalbed methane recovery. Laboratory characterization of coal permeability provides useful information for in situ permeability behavior of coal seams when adsorbing gases such as CO2 are injected. In this study, a series of experiments have been conducted for coal samples using both non-adsorbing and adsorbing gases at various confining stresses and pore pressures. Our observations have showed that even under controlled stress conditions, coal permeability decreases with respect to pore pressure during the injection of adsorbing gases. In order to find out the causes of permeability decrease for adsorbing gases, a non-adsorbing gas (helium) is used to determine the effective stress coefficient. In these experiments using helium, the impact of gas sorption can be neglected and any permeability reduction is considered as due to the variation in the effective stress, which is controlled by the effective stress coefficient. The results show that the effective stress coefficient is pore pressure dependent and less than unity for the coal samples studied. The permeability reduction from helium experiments is then used to calibrate the subsequent flow-through experiments using adsorbing gases, CH4 and CO2. Through this calibration, the sole effect of sorption-induced strain on permeability change is obtained for these adsorbing gas flow-through experiments. In this paper, experimental results and analyses are reported including how the impact of effective stress coefficient is separated from that of the sorption-induced strain on the evolution of coal permeability.

Original languageEnglish (US)
Pages (from-to)1284-1293
Number of pages10
JournalInternational Journal of Greenhouse Gas Control
Volume5
Issue number5
DOIs
StatePublished - Sep 1 2011

Fingerprint

effective stress
Sorption
sorption
Coal
permeability
coal
Gases
Pore pressure
Helium
gas
pore pressure
helium
Experiments
experiment
effect
coalbed methane
Flow of gases
gas flow
coal seam
Calibration

All Science Journal Classification (ASJC) codes

  • Pollution
  • Energy(all)
  • Industrial and Manufacturing Engineering
  • Management, Monitoring, Policy and Law

Cite this

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abstract = "Permeability is one of the most important parameters for CO2 injection in coal to enhance coalbed methane recovery. Laboratory characterization of coal permeability provides useful information for in situ permeability behavior of coal seams when adsorbing gases such as CO2 are injected. In this study, a series of experiments have been conducted for coal samples using both non-adsorbing and adsorbing gases at various confining stresses and pore pressures. Our observations have showed that even under controlled stress conditions, coal permeability decreases with respect to pore pressure during the injection of adsorbing gases. In order to find out the causes of permeability decrease for adsorbing gases, a non-adsorbing gas (helium) is used to determine the effective stress coefficient. In these experiments using helium, the impact of gas sorption can be neglected and any permeability reduction is considered as due to the variation in the effective stress, which is controlled by the effective stress coefficient. The results show that the effective stress coefficient is pore pressure dependent and less than unity for the coal samples studied. The permeability reduction from helium experiments is then used to calibrate the subsequent flow-through experiments using adsorbing gases, CH4 and CO2. Through this calibration, the sole effect of sorption-induced strain on permeability change is obtained for these adsorbing gas flow-through experiments. In this paper, experimental results and analyses are reported including how the impact of effective stress coefficient is separated from that of the sorption-induced strain on the evolution of coal permeability.",
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Effect of the effective stress coefficient and sorption-induced strain on the evolution of coal permeability : Experimental observations. / Chen, Zhongwei; Pan, Zhejun; Liu, Jishan; Connell, Luke D.; Elsworth, Derek.

In: International Journal of Greenhouse Gas Control, Vol. 5, No. 5, 01.09.2011, p. 1284-1293.

Research output: Contribution to journalArticle

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AU - Chen, Zhongwei

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