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ABSTRACT: Relationship Between Kerogen Composition and Hydrocarbon Generation Kinetics

NOBLE, R. A., and E. W. TEGELAAR, ARCO Exploration and Production Technology, Plano, TX

The kerogen composition of a global set of source rocks from a variety of depositional environments, tectonic settings and geological ages was examined using geochemical methods. Samples included organic rich sediments from open marine, marginal marine, fluvio-deltaic, inland swamp and lacustrine settings. Both "gas-prone" and "oil-prone" kerogen facies were represented, with Rock-Eval hydrogen indices of immature samples ranging from 150 mgHC/gC to over 900 mgHC/gC. Several samples represented pure endmember kerogens, consisting largely of a single polymeric substance of known biological origin (e.g., lignin, algaenan, cutan and polycadinane). Kinetic parameters for hydrocarbon generation were determined using a PYROMAT open system pyrolysis unit, resulting in distributed activation nergies and single frequency factors for each sample. Source rocks exhibiting similar kinetic behavior did not always have the same Rock-Eval characteristics and elemental kerogen composition. However, a good correlation was observed between molecular characteristics of the kerogen, determined by pyrolysis-gas chromatography (PY-GC), and the kinetic results. Moreover, the combined PY-GC and kinetics data for end-member kerogens provided a means to predict the kinetic behavior of kerogens made up of mixtures of preserved biopolymers.


AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)