Methane in Columbia River Basalt Aquifers: Isotopic and geohydrologic evidence for a deep coal-bed gas source in the Columbia Basin, Washington

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6060826

Johnson, V G ^[1]; Graham, D L ^[2]; Reidel, S P ^[3]

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1. Westinghouse Geosciences, Richland, WA (United States)
2. SEACOR, Tualitin, OR (United States)
3. Washington State Univ., Pullman, WA (United States)

Methane occurs as a dissolved constituent in groundwater from confined aquifers in the Columbia River Basalt Group, Columbia basin, Washington. Isotopic compositions of methane in groundwater indicate that the methane is a mixture of biogenic ([sigma][sup 13]C-CH[sub 4] to -88% and [sigma][sup 2]H-CH[sub 4] to -265%) and thermogenic ([sigma][sup 13]C-CH[sub 4] to -35%, and [sigma][sup 2]H-CH[sub 4] to -134%) components. Chemical and isotopic data are consistent with entrainment of deep, coal-bed generated methane in upwelling groundwater from below the Columbia River Basalt Group (>4 km) that mixes with near-surface groundwater. The areal distribution pattern of methane suggests that fault intersections are necessary for vertical migration of deep methane through the basalt. This study suggests that deep subbasalt coal-bed methane in the Columbia basin has infiltrated the shallow basalt groundwater system, and isotopic analysis of methane in groundwater from structurally favorable locations can be used to identify potential exploration targets. The wide areal distribution of methane in this large, relatively unexplored frontier province suggests economic gas reserves. 53 refs., 11 figs.

• OSTI ID: 6060826
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:7; ISSN 0149-1423
• Country of Publication: United States
• Language: English

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03 NATURAL GAS
METHANE
DISTRIBUTION
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RESOURCE POTENTIAL
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GROUND WATER
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SOURCE ROCKS
UPWELLING
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IGNEOUS ROCKS
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030200* - Natural Gas- Reserves
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