Organic matter composition and thermal maturity evaluation of Mesoproterozoic source rocks in the Beetaloo Sub-Basin, Australia

Faiz, Mohinudeen; Altmann, Carl; Baruch, Elizabeth; Côté, Alexander; Gong, Shengkai; Schinteie, Richard; Ranasinghe, Padmasiri

doi:10.1016/j.orggeochem.2022.104513

Cited by 8 publications

(5 citation statements)

References 39 publications

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“…13). The discordance between apparently reliable maturity proxies in Velkerri source rocks have been discussed in other studies (Boreham et al, 1988;Faiz et al, 2016;Jarrett et al, 2019c) and suggest that the typical Tmax thresholds associated with the oil and gas windows may need refining for Precambrian organic matter. We speculate that the overall higher reactivity of bulk Precambrian biomass (Raiswell and Berner, 1986;Raiswell and Albiatty, 1989;Hieshima and Pratt, 1991), and specifically biomass with no terrestrial matter (Tegelaar and Noble, 1994), may be a significant factor for this discordance; this requires further research.…”

Section: Source Rock Characteristicsmentioning

confidence: 74%

A very unconventional hydrocarbon play: The Mesoproterozoic Velkerri Formation of northern Australia

Cox¹,

Collins²,

Jarrett³

et al. 2022

Bulletin

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The ca. 1.5-1.3 Ga Roper Group of the greater McArthur Basin is a component of one of the most extensive Precambrian hydrocarbon-bearing basins preserved in the geological record, recently assessed as containing 429 million barrels of oil and eight trillion cubic feet of gas (in place). It was deposited in an intra-cratonic sea, referred to here as the McArthur-Yanliao Gulf.The Velkerri Formation forms the major deep-water facies of the Roper Group. Trace metal redox proxies from this formation indicate that it was deposited in stratified waters, in which a shallow oxic layer overlay suboxic to anoxic waters. These deep waters became episodically euxinic during periods of high organic carbon export. The Velkerri Formation has organic carbon contents that reach ~10 wt%. Variations in organic carbon isotopes are consistent with organic carbon enrichment being associated with increases in primary productivity and export, rather than flooding surfaces or variations in mineralogy.Although deposition of the Velkerri Formation in an intracontinental setting has been well established, recent global reconstructions show a broader mid to low latitude gulf, with deposition of the Velkerri Formation being coeval with the widespread deposition of organicrich rocks across northern Australia and North China. The deposition of these organic-rich rocks may have been accompanied by significant oxygenation associated with such widespread organic carbon burial during the Mesoproterozoic.

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Section: Source Rock Characteristicsmentioning

confidence: 74%

A very unconventional hydrocarbon play: The Mesoproterozoic Velkerri Formation of northern Australia

Cox¹,

Collins²,

Jarrett³

et al. 2022

Bulletin

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“…Given that the collected rocks are Paleo-to Mesoproterozoic in age, the maceral alginite in this case is presumably derived from prokaryotic organic matter including filamentous cyanobacteria rather than algae. Inputs from modern eukaryotes, such as algae, were likely negligible at the time (Faiz et al 2022;Grosjean et al 2023).…”

Section: Source Rock Potentialmentioning

confidence: 99%

Source rocks of the Birrindudu Basin: perspectives from a new sampling program

Butcher,

Grosjean,

Palu

et al. 2024

Aust. Energ. Prod. J.

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The Paleo- to Mesoproterozoic Birrindudu Basin is an underexplored frontier basin straddling the Northern Territory and Western Australia, and is a region of focus for the second phase of Geoscience Australia’s Exploring for the Future (EFTF) program (2020–2024). Hydrocarbon exploration in the Birrindudu Basin has been limited and a thorough assessment of the basin’s petroleum potential is lacking due to the absence of data in the region. To bridge this data gap, a comprehensive analytical program including organic petrology, programmed pyrolysis and oil fluid inclusion analysis was undertaken on cores from six drill holes to improve the understanding of the basin’s source rock potential and assess petroleum migration. Organic petrological analyses reveal that the primary maceral identified in the cores is alginite mainly originating from filamentous cyanobacteria, while bitumen is the most common unstructured secondary organic matter. New reflectance data based on alginite and bitumen reflectance indicate the sampled sections have reached a thermal maturity suitable for hydrocarbon generation. Oil inclusion analyses provide evidence for oil generation and migration, and hence elements of a petroleum system are present in the basin.

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“…1 It has been observed that hydrocarbon gases with high maturity show partial reversal (i.e., δ 13 C 1 < δ 13 C 2 > δ 13 C 3 ) or total reversal (i.e., δ 13 C 1 > δ 13 C 2 > δ 13 C 3 ) in 13 C isotope, 2,3 contradicting with the kinetic isotope fractionation effect for hydrocarbon gas generation from the decomposition of organics. 4 Researchers have attributed such a 13 C reversal to several processes including the mixing of gases with different sources, 3,5−7 gas desorption and diffusion during accumulation, 8 and gas generation via water−hydrocarbon reactions induced by hydrothermal fluids. 9 As a ubiquitous substance, water may affect the generation of oil and gas in the thermal maturation of organic matter (OM).…”

Section: Introductionmentioning

confidence: 99%

Carbon Isotope Reversal Gas Generated in the Hydrothermal Experiments Involving 1-MNa and MnCO₃

Zhai

et al. 2023

ACS Earth Space Chem.

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To learn about the gas generation from water−mineral−hydrocarbon interactions, isothermal pyrolysis of 1-methylnaphthalene involving water (H 2 O) with and without rhodochrosite (MnCO 3 ) was conducted by a gold tube system at 330−450 °C and 50 MPa in this study. By determination of the yields of individual gas products, it was observed that the presence of MnCO 3 led to an apparent increase in the yields of hydrocarbon gases (C 1−5 ). The dryness (C 1 /C 1−5 ) of gas products in hydrothermal experiments with the mineral was much lower compared with that without the mineral. Kinetic calculations indicated that the presence of MnCO 3 reduced the activation energy for the generation of hydrocarbon gases at elevated temperatures. The higher isomeric ratios of hydrocarbons (i-C 4 /n-C 4 and i-C 5 /n-C 5 ) implied that water−hydrocarbon reactions in the presence of MnCO 3 should mainly occur via the ionic mechanism. It is noticed that hydrocarbon gases generated in the hydrothermal experiments with MnCO 3 show a partial reversal in the 13 C isotope (i.e., δ 13 C 1 < δ 13 C 2 > δ 13 C 3 ). Moreover, the presence of MnCO 3 led to the depletion of 2 H for methane. Therefore, it is reasonable that this mineral can control the mechanisms and C/H isotope fractionation for hydrocarbon gas generation from water−hydrocarbon reactions. Most importantly, our study may provide a possible interpretation for 13 C isotope reversal gas generated at high-over maturities in deep formations.

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Organic matter composition and thermal maturity evaluation of Mesoproterozoic source rocks in the Beetaloo Sub-Basin, Australia

Cited by 8 publications

References 39 publications

A very unconventional hydrocarbon play: The Mesoproterozoic Velkerri Formation of northern Australia

A very unconventional hydrocarbon play: The Mesoproterozoic Velkerri Formation of northern Australia

Source rocks of the Birrindudu Basin: perspectives from a new sampling program

Carbon Isotope Reversal Gas Generated in the Hydrothermal Experiments Involving 1-MNa and MnCO₃

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Organic matter composition and thermal maturity evaluation of Mesoproterozoic source rocks in the Beetaloo Sub-Basin, Australia

Cited by 8 publications

References 39 publications

A very unconventional hydrocarbon play: The Mesoproterozoic Velkerri Formation of northern Australia

A very unconventional hydrocarbon play: The Mesoproterozoic Velkerri Formation of northern Australia

Source rocks of the Birrindudu Basin: perspectives from a new sampling program

Carbon Isotope Reversal Gas Generated in the Hydrothermal Experiments Involving 1-MNa and MnCO3

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Product

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Carbon Isotope Reversal Gas Generated in the Hydrothermal Experiments Involving 1-MNa and MnCO₃