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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 69 (1985)

Issue: 2. (February)

First Page: 247

Last Page: 247

Title: Molecular Thermal Maturity Indicators in Oil and Gas Source Rocks: ABSTRACT

Author(s): Joseph A. Curiale, Stephen R. Larter, Robert E. Sweeney, Bruce W. Bromley

Article Type: Meeting abstract


Detailed chemical parameters have been proposed as indicators of thermal maturity in oil and gas source rocks. Certain classical maturity parameters involving carbon preference indices and compound class ratios such as HC/EOM and EOM/TOC are infrequently used today, having been largely replaced by detailed molecular parameters. Among these parameters, the molecular distributions of metalloporphyrins, cyclic hydrocarbons, low molecular weight hydrocarbons, and gases are most commonly used. Recent instrumental advances have allowed the measurement of detailed molecular ratios in geochemical organic matter, stimulating the development of biologic markers, such as steranes, hopanes, and metallated tetrapyrroles, as thermal maturity indicators. Increased chromatographic resolu ion of source rock hydrocarbons has also promoted the use of low molecular weight hydrocarbons, methylphenanthrenes, and aromatized steranes as maturity indicators.

The future use of molecular thermal maturity indicators in source rocks is expected to increase significantly. In addition to further advances in understanding the significance of biologic marker hydrocarbons, metalloporphyrins, and thermally generated light hydrocarbons, the use of other nonhydrocarbons as maturity determinants will probably develop.

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Copyright 1997 American Association of Petroleum Geologists