EADINGTON, PETER, JOE HAMILTON, and MARK LISK, CSIRO Division of Exploration Geosciences, North Ryde, NSW, Australia; DENAH TOUPIN, and MARK PERSON, Department of Earth Sciences, The University of New Hampshire, Durham, NH; and DAVID WARNER, Santos Ltd, Adelaide, S.A., Australia

ABSTRACT: Hydrologic Controls on Petroleum Generation within the Cooper and Eromanga Basins, Australia: II Fluid Inclusion, Isotopic, and Geothermometric Data

Data from fluid inclusions, isotopic composition of diagenetic minerals, vitrinite reflectances and apatite fission track lengths are used to determine the thermal history, timing of hydrocarbon migration and sources of palaeo groundwaters within the Cooper and Eromanga Basins, Australia to provide observational constraints on mathematical modelling used by Person et al. (this volume) in assessing the importance of groundwater flow on oil and gas generation.

Vitrinite reflectances (Kanstler et al., 1983) indicate recent increases in geothermal gradients in the southern Cooper Basin. Apatite fission track annealing studies, also in the southern Cooper Basin (Gleadow and Duddy et al., 1986) indicate increased geothermal gradients in the last 10 My.

Fluid inclusions are used to determine the timing of oil migration and the salinity of paleo-pore waters from measurements of depression of freezing point. The fluorescence colors of oil in fluid inclusions are used to associate similar oils and delineate migration paths. Fuorescence colors of hydrocarbons differ in samples from reservoirs of different age. Fluid inclusion data indicate the timing of oil migration varies across the hydrologic system between recharge and discharge areas.

Differing isotope compositions between paleo pore waters and present day pore waters indicate that the present hydrology cannot be used as an analogue for the geological past.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.