Stable isotopic and molecular composition of desorbed coal seam gases from the Walloon Subgroup, eastern Surat Basin, Australia

Hamilton, Stephanie K.; Golding, Suzanne D.; Baublys, K. A.; Esterle, Joan

doi:10.1016/j.coal.2013.12.003

Cited by 100 publications

(104 citation statements)

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“…The origins of these gas content profiles were subsequently tested using stable isotopes of desorbed gases from three cored wells (Hamilton et al, 2014a). These wells exhibited positively parabolic δ 13 C-CH 4 profiles, with maxima in the stratigraphically central coal seams (Fig.…”

Section: Previous Workmentioning

confidence: 99%

“…This paper represents the culmination of a stepwise basin analysis project ultimately aimed at siting potential in situ bioreactor locations. The objectives of this paper are to: (1) further test hypotheses on gas distribution and origins raised in Hamilton et al (2012Hamilton et al ( , 2014a, using new gas and host coal isotopic data; (2) explore the timing of gas generation; (3) present a conceptual microbial methane exploration model for the eastern Surat Basin; and (4) suggest application of these results to MECoM exploration targeting, based on the known environmental requirements and limitations of methanogens and parallel work undertaken by The University of Queensland (UQ) (Australian Research Council (ARC) Linkage bioreactor project: LP100200730).…”

Section: Introductionmentioning

confidence: 99%

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Conceptual exploration targeting for microbially enhanced coal bed methane (MECoM) in the Walloon Subgroup, eastern Surat Basin, Australia

Hamilton

Golding

Baublys

et al. 2015

International Journal of Coal Geology

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Section: Previous Workmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Conceptual exploration targeting for microbially enhanced coal bed methane (MECoM) in the Walloon Subgroup, eastern Surat Basin, Australia

Hamilton

Golding

Baublys

et al. 2015

International Journal of Coal Geology

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“…This occurs as the continued preferential consumption of the isotopically lighter molecules during methanogenesis leaves a residual pool of isotopically heavier carbon in the remaining substrate (Conrad et al, 2011;Londry et al, 2008;Valentine et al, 2004). In natural samples, substrate depletion effects have been postulated to have occurred where the δ 13 C-CH 4 of biogenic CH 4 showed a thermogenic signature but molecular compositions and carbon and hydrogen isotope fractionations indicated a biogenic origin (e.g., Golding et al, 2013;Hamilton et al, 2014).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…3 Stable isotopes are a valuable tool for the identification of CH 4 gas origin and generation pathways (Flores et al, 2008;Hamilton et al, 2014;Kinnon et al, 2010;Strąpoć et al, 2007).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…Studies have documented that CO 2 reduction is the dominant pathway in the marine environment, while acetate fermentation is the major pathway in freshwater environments (Schoell, 1980;Whiticar et al, 1986). However, in coalbed environments, it has been recognized that the CO 2 reduction pathway predominates, even when the waters are quite fresh .Stable isotopes are a valuable tool for the identification of CH 4 gas origin and generation pathways (Flores et al, 2008;Hamilton et al, 2014;Kinnon et al, 2010;Strąpoć et al, 2007).The method has been used to evaluate CH 4 dynamics both in ecosystems and laboratory engineered systems. Organic matter degradation by microbial activity in an anoxic environment produces CH 4 depleted in 13 C relative to CH 4 produced thermogenically (Faiz and Hendry, 2006;Golding et al, 2013;Whiticar, 1999).…”

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Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Susilawati

Golding

Baublys

et al. 2016

International Journal of Coal Geology

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Carbon and hydrogen isotope compositions of CH 4 generated via methanogenesis in cultures of South Sumatra Basin (SSB) coalbed methane (CBM) formation waters grown on coal, acetate and H 2 +CO 2 were investigated. CH 4 production and molecular analysis confirmed the presence of active microbial communities that are able to convert coal into CH 4 using both acetoclastic and hydrogenotrophic pathways. The representative bacterial sequences were dominated by Bacteroidetes, Firmicutes and Deltaproteobacteria, while Methanosaeta and Methanosarcina were the most prevalent archaeal methanogens present in the cultures.CH 4 produced in this study's culturing experiments has δ 13 C values in the range of -50 ‰ to -20 ‰, with most values falling outside the current understanding of the carbon isotopic boundaries for biogenic CH 4 (-110 ‰ to -30 ‰). However, the corresponding apparent carbon isotopic α factor (α c = 1.02±0.006), and isotopic effect (ε c = -20.1 ‰ ±15.3) showed that CH 4 in SSB cultures was predominantly produced by acetoclastic methanogenesis, which is consistent with the results of molecular DNA analysis. In addition, the calculated contribution of CO 2 reduction from the δ 13 C values of coaltreated cultures was overall < 50 %, further confirming the high contribution of the acetoclastic pathway to CH 4 production in the SSB cultures. The outcome of this experimental study also suggests that δ 2 H-CH 4 values may not provide a reliable basis for distinguishing methanogenic pathways, while apparent carbon isotopic fractionation factor (α c ) and isotope effect (ε c ) are considered more useful indicators of the methanogenic pathway.The high δ 13 C-CH 4 values (>-30 ‰) and the dominance of Methanosaeta over Methanosarcina indicate that methanogens within the SSB cultures were operating at low substrate concentrations. An unusually positive δ 13 C-CH 4 suggests a substrate depletion effect, which is thought to be related to a decrease in the relative abundance of key bacterial coal degraders with formation water inoculum storage time. Closer observation of δ 13 C-CH 4 values during the growth of cultures within a single experiment also showed a 13 C-enrichment trend over time. At log phase of growth, the CH 4 produced was 13 C-depleted when compared to the stationary phase that also indicates substrate depletion effects. Finally, the δ 13 C-CH 4 values encountered in this study (as high as -20 ‰) highlight the possible positive extension of δ 13 C-CH 4 values of acetoclastic methanogenesis from those currently reported in the literature for natural and experimental samples (as high as -30 ‰).Keywords: Biogenic gas, coal, culture experiment, isotopic composition INTRODUCTIONArchaeal methanogens are the only known microorganisms capable of forming CH 4 . These strictly anaerobic microbes are restricted to utilizing simple compounds that contain no more than two carbon atoms. As such, complex organic compounds in anoxic environments (e.g., marine sediments, rice paddies, subsurface shales and coalbeds) ...

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Compositional data analysis as a robust tool to delineate hydrochemical facies within and between gas‐bearing aquifers

Owen

Pawlowsky‐Glahn

Egozcue

et al. 2016

Water Resources Research

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Isometric log ratios of proportions of major ions, derived from intuitive sequential binary partitions, are used to characterize hydrochemical variability within and between coal seam gas (CSG) and surrounding aquifers in a number of sedimentary basins in the USA and Australia. These isometric log ratios are the coordinates corresponding to an orthonormal basis in the sample space (the simplex). The characteristic proportions of ions, as described by linear models of isometric log ratios, can be used for a mathematical-descriptive classification of water types. This is a more informative and robust method of describing water types than simply classifying a water type based on the dominant ions. The approach allows (a) compositional distinctions between very similar water types to be made and (b) large data sets with a high degree of variability to be rapidly assessed with respect to particular relationships/compositions that are of interest. A major advantage of these techniques is that major and minor ion components can be comprehensively assessed and subtle processes-which may be masked by conventional techniques such as Stiff diagrams, Piper plots, and classic ion ratios-can be highlighted. Results show that while all CSG groundwaters are dominated by Na, HCO 3 , and Cl ions, the proportions of other ions indicate they can evolve via different means and the particular proportions of ions within total or subcompositions can be unique to particular basins. Using isometric log ratios, subtle differences in the behavior of Na, K, and Cl between CSG water types and very similar Na-HCO 3 water types in adjacent aquifers are also described. A complementary pair of isometric log ratios, derived from a geochemically-intuitive sequential binary partition that is designed to reflect compositional variability within and between CSG groundwater, is proposed. These isometric log ratios can be used to model a hydrochemical pathway associated with methanogenesis and/or to delineate groundwater associated with high gas concentrations.

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Stable isotopic and molecular composition of desorbed coal seam gases from the Walloon Subgroup, eastern Surat Basin, Australia

Cited by 100 publications

References 50 publications

Conceptual exploration targeting for microbially enhanced coal bed methane (MECoM) in the Walloon Subgroup, eastern Surat Basin, Australia

Conceptual exploration targeting for microbially enhanced coal bed methane (MECoM) in the Walloon Subgroup, eastern Surat Basin, Australia

Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Compositional data analysis as a robust tool to delineate hydrochemical facies within and between gas‐bearing aquifers

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