Extensive research has been conducted in numerous coalbed methane (CBM) basins; however, the Williston Basin (WB) remains largely unexamined due to the absence of CBM production despite large coal reserves. CBM in WB coalbeds has been reported, but there has been no systematic study on gas origin and distribution, or hydrogeochemical controls on gas generation to date. This study aims to determine differences in chemistry between groundwaters with and without the presence of CH₄ to better understand factors affecting CBM generation. Results reveal that shallow gas accumulations in WB coalbeds are microbial in origin and formed via CO₂ reduction. CBM is associated with Na-HCO₃ type groundwater with SO₄ concentrations<1 mmole/L due to cation exchange and sulfate reduction, respectively. These groundwaters occur in deeper units of the Fort Union Formation, underlying multiple coalbeds, suggesting that CH₄ is present in waters that have reacted extensively with formations containing low-rank (lignite) coals.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/228441 |
| Date | January 2012 |
| Creators | Pantano, Christopher Patrick |
| Contributors | McIntosh, Jennifer C., Ferre, Paul A., Meixner, Thomas |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | text, Electronic Thesis |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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