A dual poroelastic model for CO2-enhanced coalbed methane recovery

Yu Wu, Jishan Liu, Zhongwei Chen, Derek Elsworth, Denis Pone

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Although CO2-enhanced coalbed methane (ECBM) recovery has been comprehensively investigated, the impact of coal matrix-fracture interactions on the evolution of coal permeability under in-situ conditions is still unclear. In prior studies on this issue, the influences of coal matrix-fracture interactions have not rigorously coupled with the binary gas transport system. In this work, general porosity and permeability models are developed to explicitly quantify the interactions between binary mixtures (CO2 and CH4) and dual solid media (coal matrix and fracture) under the full spectrum of mechanical conditions spanning prescribed in-situ stresses through constrained displacement. These models are implemented into a fully coupled finite element (FE) model of coal deformation, binary gas flow and transport in the matrix system, and binary gas flow and transport in the fracture system. The FE model represents important non-linear responses due to the effective stress effects that cannot be recovered where mechanical influences are not rigorously coupled with the binary gas transport system. The FE model is applied to simulate the results of a single well injection micro-pilot test performed in the anthracitic coals of the South Qinshui basin, Shanxi Province, China. The modeled CH4 production rates are in good agreement with the observed production history. In addition to this agreement, model results also demonstrate (1) CO2 injection increases the total pressure gradients; (2) as the CO2 injection progresses the partial CO2 pressure increases while the partial CH4 pressure decreases; (3) without CO2 injection the CH4 content at a specific point decreases almost linearly while with the CO2 injection the CH4 content at a specific point decreases exponentially; (4) without CO2 injection the CH4 production rate decreases linearly while with CO2 injection the CH4 production rate increases dramatically; (5) without CO2 injection coal permeability increases almost linearly while with CO2 injection coal permeability decreases near exponentially; (6) CO2 injection enhances cumulative CH4 production and the enhancement is proportional to the injection pressure; and (7) cumulative CO2 injection volume is also proportional to the injection pressure.

Original languageEnglish (US)
Pages (from-to)177-189
Number of pages13
JournalInternational Journal of Coal Geology
Volume86
Issue number2-3
DOIs
StatePublished - May 1 2011

Fingerprint

coalbed methane
Coal
coal
Recovery
gas transport
permeability
matrix
gas flow
Partial pressure
Flow of gases
Coal bed methane
in situ stress
Binary mixtures
effective stress
partial pressure
Pressure gradient
Gases
pressure gradient
Porosity
porosity

All Science Journal Classification (ASJC) codes

  • Fuel Technology
  • Geology
  • Economic Geology
  • Stratigraphy

Cite this

Wu, Yu ; Liu, Jishan ; Chen, Zhongwei ; Elsworth, Derek ; Pone, Denis. / A dual poroelastic model for CO2-enhanced coalbed methane recovery. In: International Journal of Coal Geology. 2011 ; Vol. 86, No. 2-3. pp. 177-189.
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A dual poroelastic model for CO2-enhanced coalbed methane recovery. / Wu, Yu; Liu, Jishan; Chen, Zhongwei; Elsworth, Derek; Pone, Denis.

In: International Journal of Coal Geology, Vol. 86, No. 2-3, 01.05.2011, p. 177-189.

Research output: Contribution to journalArticle

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