Gas diffusion behavior of coal and its impact on production from coalbed methane reservoirs

Mallikarjun Pillalamarry, Satya Harpalani, Shimin Liu

Research output: Contribution to journalArticle

165 Citations (Scopus)

Abstract

This paper discusses the results of an experimental study carried out to study and evaluate the sorption and diffusion properties of methane in Illinois basin coals. As a first step, sorption results were modeled using the Langmuir isotherm model and the Langmuir Constants were estimated. Next, the diffusion coefficient, D, was estimated by modeling experimental data using the unipore diffusion theory and Fick's law of diffusion. The results clearly indicated a negative correlation between D and pressure for pressures below 3.5. MPa. The overall trend of the variation was found to be bi-modal, its value remaining constant at high pressures, followed by a sharp increase below this critical pressure. Finally, a comparison of the sorption and diffusion results revealed that D depended on the surface coverage, which exhibits a positive relationship with pressure. The trend of diffusion variation with pressure appeared to be in good agreement with the results reported in the past studies using the bi-disperse diffusion model. The practical implication of the results is that the movement of methane is eased significantly at low pressures. Given the low in situ pressure typically encountered in the Illinois basin, this is a positive finding. Finally, this behavior may be responsible, at least in part, for the increased gas production rates encountered in the San Juan basin after several years of production.

Original languageEnglish (US)
Pages (from-to)342-348
Number of pages7
JournalInternational Journal of Coal Geology
Volume86
Issue number4
DOIs
StatePublished - Jun 1 2011

Fingerprint

coalbed methane
Diffusion in gases
Coal
coal
gas
sorption
Sorption
methane
basin
Methane
Fick's laws
Coal bed methane
gas production
low pressure
isotherm
experimental study
Isotherms
modeling
Gases

All Science Journal Classification (ASJC) codes

  • Fuel Technology
  • Geology
  • Economic Geology
  • Stratigraphy

Cite this

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title = "Gas diffusion behavior of coal and its impact on production from coalbed methane reservoirs",
abstract = "This paper discusses the results of an experimental study carried out to study and evaluate the sorption and diffusion properties of methane in Illinois basin coals. As a first step, sorption results were modeled using the Langmuir isotherm model and the Langmuir Constants were estimated. Next, the diffusion coefficient, D, was estimated by modeling experimental data using the unipore diffusion theory and Fick's law of diffusion. The results clearly indicated a negative correlation between D and pressure for pressures below 3.5. MPa. The overall trend of the variation was found to be bi-modal, its value remaining constant at high pressures, followed by a sharp increase below this critical pressure. Finally, a comparison of the sorption and diffusion results revealed that D depended on the surface coverage, which exhibits a positive relationship with pressure. The trend of diffusion variation with pressure appeared to be in good agreement with the results reported in the past studies using the bi-disperse diffusion model. The practical implication of the results is that the movement of methane is eased significantly at low pressures. Given the low in situ pressure typically encountered in the Illinois basin, this is a positive finding. Finally, this behavior may be responsible, at least in part, for the increased gas production rates encountered in the San Juan basin after several years of production.",
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Gas diffusion behavior of coal and its impact on production from coalbed methane reservoirs. / Pillalamarry, Mallikarjun; Harpalani, Satya; Liu, Shimin.

In: International Journal of Coal Geology, Vol. 86, No. 4, 01.06.2011, p. 342-348.

Research output: Contribution to journalArticle

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