About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin


AAPG Bulletin, V. 90, No. 3 (March 2006), P. 387-403.

Copyright copy2006. The American Association of Petroleum Geologists. All rights reserved.


Evaluation of kinetic uncertainty in numerical models of petroleum generation

Kenneth E. Peters,1 Clifford C. Walters,2 Paul J. Mankiewicz3

1U.S. Geological Survey, 345 Middlefield Road, MS 969, Menlo Park, California 94025-3561; [email protected]
2ExxonMobil Research and Engineering Co., 1545 Route 22 East, Annadale, New Jersey 08801-0998; [email protected]
3ExxonMobil Exploration Co., 233 Benmar, Houston, Texas 77060; [email protected]


Oil-prone marine petroleum source rocks contain type I or type II kerogen having Rock-Eval pyrolysis hydrogen indices greater than 600 or 300–600 mg hydrocarbon/g total organic carbon (HI, mg HC/g TOC), respectively. Samples from 29 marine source rocks worldwide that contain mainly type II kerogen (HI = 230–786 mg HC/g TOC) were subjected to open-system programmed pyrolysis to determine the activation energy distributions for petroleum generation. Assuming a burial heating rate of 1degC/m.y. for each measured activation energy distribution, the calculated average temperature for 50% fractional conversion of the kerogen in the samples to petroleum is approximately 136 plusmn 7degC, but the range spans about 30degC (sim121–151degC).

Fifty-two outcrop samples of thermally immature Jurassic Oxford Clay Formation were collected from five locations in the United Kingdom to determine the variations of kinetic response for one source rock unit. The samples contain mainly type I or type II kerogens (HI = 230–774 mg HC/g TOC). At a heating rate of 1degC/m.y., the calculated temperatures for 50% fractional conversion of the Oxford Clay kerogens to petroleum differ by as much as 23degC (127–150degC).

The data indicate that kerogen type, as defined by hydrogen index, is not systematically linked to kinetic response, and that default kinetics for the thermal Previous HitdecompositionTop of type I or type II kerogen can introduce unacceptable errors into numerical simulations. Furthermore, custom kinetics based on one or a few samples may be inadequate to account for variations in organofacies within a source rock. We propose three methods to evaluate the uncertainty contributed by kerogen kinetics to numerical simulations: (1) use the average kinetic distribution for multiple samples of source rock and the standard deviation for each activation energy in that distribution; (2) use source rock kinetics determined at several locations to describe different parts of the study area; and (3) use a weighted-average method that combines kinetics for samples from different locations in the source rock unit by giving the activation energy distribution for each sample a weight proportional to its Rock-Eval pyrolysis S2 yield (hydrocarbons generated by pyrolytic degradation of organic matter).

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Protected Document: $10
Internal PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].