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A Comparative Study Of Petrological And Geochemical Maturity Indicators In Mesozoic And Palaeozoic Sediments From Dullingar #1, Eromanga/Cooper Basin.

Wythe, Scott R.

Honours Degree, 1989

University of Adelaide

Abstract

A detailed petrological and geochemical study was made of sediments from the Dullingari #1 well in the southwest Eromanga/Cooper Basin in order to measure a range of maturity indicators, including the methylphenanthrene index (MPI), and to assess their usefulness in source rock evaluation.

Core samples, comprising organic-rich sediments of several different lithofacies and ranging in age from Cretaceous to Permian, were selected for solvent extraction and isolation of the saturate, aromatic and naphthenic hydrocarbon fractions. These fractions were submitted for GC and GC-MS analysis. Rock-Eval pyrolysis was also performed on the samples, along with an organic petrological evaluation and vitrinite reflectance measurements.

The vitrinite reflectance profile obtained was very similar to that of Kantsler and Cook (1979) and thus provided a good indication of maturity against which the other parameters could be assessed.

Tmax from Rock-Eval pyrolysis correlated reasonably well with vitrinite reflectance but was subject to variations in organic facies.

Maturity indicators derived from the saturate hydrocarbon fraction (e.g. n-alkane odd-even predominance OEP, pristane/n-C17) were found to be heavily influenced by variations in organic facies and could only be used in a qualitative fashion.

Australian School of Petroleum
THE UNIVERSITY OF ADELAIDE

SA 5005 AUSTRALIA

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