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Thermal maturation of Eagle basin, northwestern Colorado

Conference · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:5160398
Mean random vitrinite reflectance (R/sub m/) was measured on 120 surface samples from Lower Pennsylvanian through Upper Cretaceous rocks in the Eagle basin for the purpose of mapping thermal maturity. The Eagle basin is a trough that formed during the Pennsylvanian between the ancestral Front Range to the northeast and the ancestral Uncompahgre uplift to the southwest. For comparative purposes, the stratigraphic section in the basin was divided into four intervals, each with a range of R/sub m/ values; 2.70-3.70% for Lower Pennsylvanian rocks, 0.70-2.30 for Middle Pennsylvanian rocks, 0.80-1.50 for Upper Pennsylvanian-Triassic rocks, and 0.60-1.70 for Cretaceous rocks. R/sub m/ values decrease from Lower Pennsylvanian rocks to Cretaceous rocks throughout the basin. Variability in R/sub m/ values within each stratigraphic interval may be due to structural deformation, variations in source material and depositional environment, and spatial and temporal fluctuations in geothermal gradients. R/sub m/ values indicate that most of the Middle Pennsylvanian and Upper Pennsylvanian-Triassic rocks are in the oil window (0.60-1.35%) and gas window (0.75-3.0%). Although R/sub m/ values indicate that Cretaceous rocks are in the oil and gas windows, geochemical data suggest that mainly gas would be generated.
Research Organization:
Geological Survey, Denver, CO
OSTI ID:
5160398
Report Number(s):
CONF-860624-
Conference Information:
Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:5
Country of Publication:
United States
Language:
English