Thermal stabilization of kerogen maturation over a finite reaction duration

Conference · Sun Apr 01 04:00:00 EST 1984 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6648252

Barker, C E

If a first order reaction can be assumed for kerogen maturation during burial diagenesis, then its reaction constant is k = -ln(f)/t, where f is the fraction of kerogen tranformable to hydrocarbon remaining after some functional reaction duration, t. The fraction of reactive kerogen is estimated from Tissot and Espitalie's model of vitrinite reflectance (R/sub 0/) evolution. A method for calculating the functional reaction duration is suggested by kerogen maturation experiments that show hydrocarbon generation proceeds by concurrent reactions with successively higher activation energies (E/sub a/), which at a given temperature: are already complete and not generating products; are generating significant products; or are slow and will not generate significant products in geologic time. The general correlation of R/sub 0/ with maximum temperature suggests that at a given temperature, only a limited suite of reactions control hydrocarbon generation, and increased time at the that temperature will not make the slower, (high E/sub a/) reactions geologically significant. Thus, the functional reaction to essentially complete hydrocarbon generation (to the 99% level). Geologic field data, and kerogen maturation experiments extrapolated to geologic time and temperature ranges, suggest this occurs in 10/sup 6/-10/sup 7/ years. When plotted on an Arrhenius diagram (ln k versus l/T), reaction rate constants calculated for 80 cases of kerogen maturation at maximum temperature show a strong linear relationship (r = 0.77). The pseudo E/sub a/ of the overall kerogen maturation reaction is about 9 kcal/mole, and its frequency factor is 10/sup -11/ sec/sup -1/. This curve provides a method of assessing maximum paleotemperature from R/sub 0/ if the kerogen has had sufficient time to stabilize.

• Research Organization: Geological Survey, Denver, CO
• OSTI ID: 6648252
• Report Number(s): CONF-8405216-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 68:4
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
DIAGENESIS
KEROGEN
MACERALS
MATERIALS
MATHEMATICAL MODELS
MATURATION
OPTICAL PROPERTIES
ORGANIC MATTER
PHYSICAL PROPERTIES
REFLECTIVITY
SURFACE PROPERTIES
TEMPERATURE EFFECTS