Economic and Environmental Geology

Table. 1.

Table. 1.

Hydrocarbon gas compositions and carbon (δ13CCH4) and hydrogen (δDCH4) isotope ratios of coalbed methane in AA-1 core samples from the Asem-Asem Basin, Indonesia

Depth (mbs) Lithology Hydrocarbon gas composition (100%) CHC Stable isotopes (‰)
C1 C2 C3 C4 C5 C1/C2+C3 δ13CCH4 δDCH4
505.90∼506.60 coal 92.33 5.31 2.24 0.12 0.01 12.2 nd nd
507.10∼507.40 coaly shale 87.35 9.97 2.48 0.10 0.10 7.0 -58.8 -252.1
508.40∼508.50 coaly shale 94.24 4.51 1.21 0.04 0.01 16.5 -59.8 -252.7
514.35∼514.67 coaly shale 94.22 4.64 1.09 0.04 0.01 16.4 -59.7 -252.4
516.80∼517.10 coaly shale 93.41 5.38 1.16 0.03 nd 14.3 -59.1 -252.9
517.10∼517.37 coaly shale 95.29 3.65 1.01 0.05 0.01 10.1 -60.3 -252.3

Hydrocarbon gases were normalized to 100%. CHC; hydrocarbon index (C1/C2+C3, Kotarba and Rice, 2001). mbs; meter below surface. nd; no detection.

Econ. Environ. Geol. 2022;55:261-71 https://doi.org/10.9719/EEG.2022.55.3.261
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