Enhanced microbial coalbed methane generation: A review of research, commercial activity, and remaining challenges

Daniel Ritter, David Vinson, Elliott Barnhart, Denise M. Akob, Matthew W. Fields, Al B. Cunningham, William Orem, Jennifer McIntosh

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

Coalbed methane (CBM) makes up a significant portion of the world's natural gas resources. The discovery that approximately 20% of natural gas is microbial in origin has led to interest in microbially enhanced CBM (MECoM), which involves stimulating microorganisms to produce additional CBM from existing production wells. This paper reviews current laboratory and field research on understanding processes and reservoir conditions which are essential for microbial CBM generation, the progress of efforts to stimulate microbial methane generation in coal beds, and key remaining knowledge gaps. Research has been primarily focused on identifying microbial communities present in areas of CBM generation and attempting to determine their function, in-situ reservoir conditions that are most favorable for microbial CBM generation, and geochemical indicators of metabolic pathways of methanogenesis (i.e., acetoclastic or hydrogenotrophic methanogenesis). Meanwhile, researchers at universities, government agencies, and companies have focused on four primary MECoM strategies: 1) microbial stimulation (i.e., addition of nutrients to stimulate native microbes); 2) microbial augmentation (i.e., addition of microbes not native to or abundant in the reservoir of interest); 3) physically increasing microbial access to coal and distribution of amendments; and 4) chemically increasing the bioavailability of coal organics. Most companies interested in MECoM have pursued microbial stimulation: Luca Technologies, Inc., successfully completed a pilot scale field test of their stimulation strategy, while two others, Ciris Energy and Next Fuel, Inc., have undertaken smaller scale field tests. Several key knowledge gaps remain that need to be addressed before MECoM strategies can be implemented commercially. Little is known about the bacterial community responsible for coal biodegradation and how these microorganisms may be stimulated to enhance microbial methanogenesis. In addition, research is needed to understand what fraction of coal is available for biodegradation, and methods need to be developed to determine the extent of in-situ coal biodegradation by MECoM processes for monitoring changes to coal quality. Questions also remain about how well field-scale pilot tests will scale to commercial production, how often amendments will need to be added to maintain new methane generation, and how well MECoM strategies transfer between coal basins with different formation water geochemistries and coal ranks. Addressing these knowledge gaps will be key in determining the feasibility and commercial viability of MECoM technology.

Original languageEnglish (US)
Pages (from-to)28-41
Number of pages14
JournalInternational Journal of Coal Geology
Volume146
DOIs
StatePublished - Jul 1 2015

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commercial activity
coalbed methane
Coal
coal
methanogenesis
biodegradation
Biodegradation
natural gas
microorganism
methane
Microorganisms
well
Natural gas
Methane
coal rank
formation water
Coal bed methane
coal seam
Geochemistry
bioavailability

Keywords

  • Coal
  • Coalbed methane (CBM)
  • Methanogenesis
  • Microbial community
  • Microbially enhanced coalbed methane
  • Stable isotopes

ASJC Scopus subject areas

  • Economic Geology
  • Geology
  • Stratigraphy
  • Fuel Technology

Cite this

Enhanced microbial coalbed methane generation : A review of research, commercial activity, and remaining challenges. / Ritter, Daniel; Vinson, David; Barnhart, Elliott; Akob, Denise M.; Fields, Matthew W.; Cunningham, Al B.; Orem, William; McIntosh, Jennifer.

In: International Journal of Coal Geology, Vol. 146, 01.07.2015, p. 28-41.

Research output: Contribution to journalArticle

Ritter, Daniel ; Vinson, David ; Barnhart, Elliott ; Akob, Denise M. ; Fields, Matthew W. ; Cunningham, Al B. ; Orem, William ; McIntosh, Jennifer. / Enhanced microbial coalbed methane generation : A review of research, commercial activity, and remaining challenges. In: International Journal of Coal Geology. 2015 ; Vol. 146. pp. 28-41.
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