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Comparison of porphyrin and hydrocarbon biomarker data with other indicators of maturity and oil generation

Conference · · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)
OSTI ID:5866554
A single well in the San Joaquin Valley penetrates six Miocene shale formations through a depth interval of more than 10,000 ft. Eighty-three samples through the interval were analyzed by Rock-Eval to determine zones of maturity and oil generation. The maturity of select samples was also determined using porphyrins, steranes, and aromatic steroids. Rock-Eval T/sub max/ increases smoothly with depth through the interval, reaching 435/sup 0/C (the shallow limit of the oil window) at about 9500 ft. Increase in production index (S1/(S1 + S2)) and decrease in hydrogen index (S2/TOC x 100) indicate beginning of oil generation at about 10,000 ft and increasing generation with depth. The vanadyl porphyrin maturity parameter, C/sub 28/ETIO/(C/sub 28/ + C/sub 32/ DPEP) obtained by HPLC, shows a gradual increase with depth to about 10,000 ft and then a rapid increase to a maximum of 0.85 at 12,000 ft; the zone of rapid increase corresponds to the zones of maturity and of oil generation indicated by Rock-Eval parameters. The biomarker maturity parameters based on C/sub 29/ sterane isomerization and C/sub 29/ monoaromatic steroid aromatization showed a systematic increase through the interval. Isomerization and aromatization levels observed in these bitumens were comparable to local oils, thus confirming the top of the oil generation window.
Research Organization:
Chevron Oil Field Research Co., La Habra, CA
OSTI ID:
5866554
Report Number(s):
CONF-870606-
Conference Information:
Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 71:5
Country of Publication:
United States
Language:
English