Authors / CoAuthors
Radlinski, A.P. | Edwards, D.S. | Boreham, C.J.
Abstract
Small angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) are used to directly detect the processes of hydrocarbon generation in the 10 nm to 10 μm size pores in carbonate and siliciclastic rocks which contain no land-plant material suitable for conventional maturity determination by vitrinite reflectance. The method takes advantage of the pore-size-specific variation of neutron scattering contrast between the solid rock matrix and pore-space content with depth, which is caused by thermal maturation of organic matter through the oil and gas generation windows. SANS and USANS measurements were performed on bedding plane-orientated core slices, extracted from a series of 10 to 12 depth intervals for three wells, CKAD0001, MacIntyre 1 and Baldwin 1 in the southern Georgina Basin, central Australia. The depth intervals, intersecting the organic-rich basal ‘hot’ shales of the middle Cambrian Arthur Creek Formation, were selected based on Rock-Eval pyrolysis data. SANS and USANS results indicate that oil generation has occurred in the past in nano-sized pores in rocks that are now at depths of around 538.4 m in CKAD0001 and 799.3 m in MacIntyre 1. Furthermore, in the CKAD0001 well, the oil-wet pores extend into the larger pore-size range (at least up to 10 μm) due to the efficient expulsion of oil. At around 880 m in Baldwin 1, the influence of pyrobitumen reverts pore space from gas wet to oil wet. These hydrocarbons have remained in situ since the Devonian when the Neoproterozoic to Paleozoic section was exhumed in the Alice Springs Orogeny and subsequently eroded, preserving only remnants of the once extensive basin sediments.
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document
eCat Id
110782
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- Georgina Basin
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- Arthur Creek Formation
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- Small angle neutron scattering (SANS)
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- Ultra small angle neutron scattering (USANS)
- Australian and New Zealand Standard Research Classification: Fields of Research
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- Earth Sciences
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- Published_External
Publication Date
2017-11-20T05:21:35
Creation Date
2017-05-17T00:00:00
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geoscientificInformation
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[-90, 90, -180, 180]
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