Y. Bartov, D. Nummedal and R. Sarg - ceri-mines.org · Y. Bartov, D. Nummedal and R. Sarg The Colorado Energy Research Institute – Colorado School of Mines. Cole and Others, 1995.
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The Role of Lake Levels in Oil Shale Distribution
Y. Bartov, D. Nummedal and R. Sarg
The Colorado Energy Research Institute – Colorado School of Mines
Cole and Others, 1995
Cole and Doub, 1992
Fischer Assay
Study Question: What controls the distribution of oil shale in the basin?
Study approach:Analysis of the basins stratigraphy to identify the controls on oil shale deposits
Saline minerals
W NE
Sq 1
Sq 3
Sq 9
Sq 2
Sq 4
Sq 5
Sq 6
Sq 7
Sq 8
Gamma log signature in the Green River sequence
Sequences in the Green River FmW NE
Chronostratigraphic diagram
W NE
Typical sequences in the Green River Fm
Fresh water lake
Brackish lake
Saline lake
Margin Basin
Onlap position in the sequences
W NE
Subsidence rate
S N
Fresh water
Brackish low stand
Saline lake
High lake level – high salinety
Correlation of oil shale zones
Oil shale position in the sequences
W NE
Lake level
Oil ShaleSandSalt
Mudstone
Lake levels
Oil ShaleSandSalt
Lake level
Oxidation interface
Mudstone
Fresh water lakeLake levels
Lake level
Oil ShaleSandSalt
Lake level
Oxidation interface
Mudstone
Brackish lake Lake levels
Lake level
Oil ShaleSandSalt
Lake level
Oxidation interface
Mudstone
Saline lakeLake levels
Lake level
Oil ShaleSandSalt
Lake level
Oxidation interface
Mudstone
High salinity high lake levelsLake levels
Lake level
Oil ShaleSandSaltOxidation interface
Mudstone
High salinity high lake levelsLake levels
Conclusions
1. The Green River Lake in the Piceance basin experienced numerous lake level fluctuations which are expressed in 11 recognizable sequences.
2. Maximum water depth was at least 300 m during high lake levelperiods.
3. The lake evolved from fresh to brackish to saline. This enhanced water column stratification.
4. Oil Shale distribution in the basin was mostly controlled by lake levels that impact the salinity and the position of the oxidation zone in the water column.
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