Source rock quality determination from oil biomarkers I: A new geochemical technique
- Chevron Petroleum technology Co., San Ramon, CA (United States)
- Stanford Univ., CA (United States)
- Chevron Petroleum Technology Co., La Habra, CA (United States)
- Chevron USA, New Orleans, LA (United States)
Biomarker analyses of the Aspen Shale (Mowry Shale equivalent), Skully`s Gap, Wyoming, suggest that vital source rock properties (e.g., kerogen hydrogen-to-carbon [H/C] ratio, Rock-Eval Hydrogen Index (HI), and maceral composition) may be indirectly, yet quantitatively, predicted from the biomarker parameters measured in oils. A strong correlation exists between the {open_quotes}Homohopane Index{close_quotes} of Aspen source rock extracts and both the H/C ratio and HI of the associated kerogen (R{sup 2} = 0.93 and 0.83, respectively). The percentages of C{sub 30} and C{sub 28} 4-desmethyl steranes, relative to total extracted 4-desmethyl steranes, correlate with the percentage of marine-derived amorphous type II organic matter in the kerogen (R{sup 2} = 0.80 and 0.73, respectively), and with kerogen H/C ratio and HI (R{sup 2} = 0.89 and 0.88, respectively, for C{sub 30} steranes; R{sup 2} = 0.89 and 0.83, respectively, for C{sub 28} steranes). The ratio of 4{alpha}-methyl-24-ethylcholestanes to 3{beta}-methyl-24-ethylcholestanes in the extracts also correlates with kerogen H/C ratio and HI (R{sup 2} = 0.93 and 0.92, respectively). In contrast, the percentage of C{sub 29} steranes in the extracts correlates with the percentage of higher-plant-derived vitrinite in the kerogen (R{sup 2} = 0.69), and shows a negative correlation with H/C ratio and HI (R{sup 2} = 0.81 and 0.66, respectively). These relationships were used to determine indirectly the source rock kerogen properties of several Mowry-derived oils. Therefore, prediction of source rock properties from oils in vertically drained basins could prove extremely useful to explorationists seeking to identify the most oil-prone areas in regions such as the US Gulf Coast, the North Sea, the Beaufort Sea, and the Mahakam and Niger deltas. An example from the Beaufort Sea is given in this same issue.
- OSTI ID:
- 44963
- Journal Information:
- AAPG Bulletin, Vol. 78, Issue 10; Other Information: PBD: Oct 1994
- Country of Publication:
- United States
- Language:
- English
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