Authors / CoAuthors
O'Brien, P.E. | Powell, T.G. | Wells, A.T.
Abstract
The Triassic to Jurassic rocks of Clarence-Moreton Basin contain abundant oil-proneorganic matter of terrestrial origin particularly in the Walloon Coal Measures and to a lesserextent in the Koukandowie Formation. This is reflected in petrographic composition, pyrolysisyields, elemental composition and extractable hydrocarbon yields. Maturation levels vary fromimmature to marginally mature in the west to overmature in the eastern part of the basin inNSW. Calculations based on Rock Eval data show that significant oil generation occurred ina narrow maturation range (0.8-1.0% vitrinite reflectance) and that migration has been highlyefficient. Potential reservoirs are present in quartzose sandstones in the KoukandowieFormation, Gatton Sandstone, Ripley Road Sandstone and Raceview Formations. Maturation modelling and fission track analyses indicate that hydrocarbon generation occurred in theperiod 80-100 Ma during a period of high heat flow when the Tasman Sea spreading ridgewas adjacent to the southeastern side of the Logan Sub-basin. Despite the abundance ofoil-prone source rocks, the basin is considered to be largely gas-prone because the drainageareas for most larger structural traps are overmature. The main difficulty in exploration ispredicting the distribution of porosity and permeability which varies because of bothdepositional facies and diagenesis, even in quartzose units. The area with the greatest hydrocarbon prospectivity is the New South Wales part ofthe Logan Sub-basin which has gas potential throughout and a chance of minor oil discoveriesalong its western margin. The northern Logan Sub-basin has some prospectivity for oil andgas and the Laidley Sub-basin has minor prospectivity for oil in the Raceview Formation.
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document
eCat Id
14624
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Keywords
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- GA PublicationRecord
- ( Theme )
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- petroleum geology
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
1993-01-01T00:00:00
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geoscientificInformation
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Record 1993/021
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