A REDOX-FOCUSED GEOCHEMICAL SURVEY OF PHANEROZOICSOURCE ROCK-RESERVOIR SHALES FROM NORTH AMERICA
Abstract/Contents
- Abstract
- Source rock-reservoirs (SRR) are continuous-type hydrocarbon systems characterized by fine-grained facies that contain adequate organic matter (OM; typically >2 wt%) to generate and retain significant hydrocarbon¬ accumulations. It is clear from modern analogue studies that O2-deficient conditions favor preservation of qualitatively- and quantitatively-enhanced OM, with appreciable productivity and OM flux to the sediment required to establish and maintain these conditions. However, debates regarding controls on source rock quality have mainly focused on oxic versus anoxic conditions, and the implications of different anoxic redox states for exploration and production remain unexplored. Here, we present detailed multi-proxy sedimentary geochemical studies of major Paleozoic and Mesozoic North American SRRs to elucidate their depositional redox conditions. This is the first study focused on SRR geochemistry to use Fe-speciation – presently the only proxy able to independently distinguish anoxic conditions as ferruginous (H2¬S-limited) or euxinic (H2S-replete, Fe-limited) – coupled with total organic carbon (TOC) and redox-sensitive trace element proxies. These analyses demonstrate that SRRs were almost exclusively deposited under anoxic bottom waters, but that there is wide variance in the prevalence of euxinic versus ferruginous conditions. Specifically, in contrast to most modern analogue systems, many SRRs were deposited under dominantly ferruginous or oscillatory conditions. TOC is significantly higher under euxinic bottom waters, although sediments deposited under both redox states have economically appreciable levels. Differences in initial redox condition likely impact organic matter quantity and quality, the presence of carbonate and clay cements, and the abundance of authigenic phases (pyrite and toxic metals) that can cause environmental or engineering issues during production. Increased emphasis on how initial depositional conditions affect the properties of the sediment, and the downstream implications of these differences, will ultimately lead to better sweet spot targeting and higher resource extraction efficiencies than a ‘one-size-fits-all’ model.
Description
| Type of resource | text |
|---|---|
| Publication date | December 12, 2022 |
Creators/Contributors
| Author | Ritzer, Samantha |
|---|---|
| Advisor | Sperling, Erik |
Subjects
| Subject | Shale |
|---|---|
| Subject | Shale gas reservoirs |
| Subject | Geochemistry |
| Subject | Phanerozoic |
| Subject | Source Rocks |
| Subject | Geology |
| Genre | Text |
| Genre | Thesis |
Bibliographic information
Access conditions
- Use and reproduction
- User agrees that, where applicable, content will not be used to identify or to otherwise infringe the privacy or confidentiality rights of individuals. Content distributed via the Stanford Digital Repository may be subject to additional license and use restrictions applied by the depositor.
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 4.0 International license (CC BY-NC).
Preferred citation
- Preferred citation
- Ritzer, S. (2022). A REDOX-FOCUSED GEOCHEMICAL SURVEY OF PHANEROZOICSOURCE ROCK-RESERVOIR SHALES FROM NORTH AMERICA. Stanford Digital Repository. Available at https://purl.stanford.edu/sg024wg6109. https://doi.org/10.25740/sg024wg6109.
Collection
Master's Theses, Doerr School of Sustainability
View other items in this collection in SearchWorksContact information
- Contact
- sritzer@stanford.edu
Also listed in
Loading usage metrics...