--> --> Maturation Profile at the Glyde Gas Discovery in the Southern McArthur Basin, Australia
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Previous HitMaturationNext Hit Profile at the Glyde Gas Discovery in the Southern McArthur Basin, Australia

Abstract

The Glyde gas discovery is situated within the Glyde Sub-basin of the Southern McArthur Basin in the Northern Territory. The McArthur Basin is an extensive Paleo- to Mesoproterozoic intracratonic basin of carbonate to siliciclastic sediments and lesser volcanic rocks. This basin has seen renewed oil and gas exploration activity in recent years, with operators targeting numerous prospective source rock formations. Within the middle McArthur Group, the Barney Creek Formation has been recognised for its hydrocarbon source and unconventional reservoir potential. To investigate the thermal and fluid flow history of the Glyde Sub-basin, organic matter Previous HitmaturationNext Hit (“in situ” solid bitumen reflectance – organic petrography) and illite crystallinity (001 illite peak at 10Å – X-ray diffraction) were determined in 26 drill cutting samples from two wells, Glyde-1 (vertical well) and Glyde-1 ST1 (lateral well). These samples are representative of the Barney Creek Formation. Reflectance values of the solid bitumens were then used to estimate paleotemperatures. Observations from organic petrography revealed the presence of lamalginite kerogen (hydrocarbon precursor), and solid bitumens, which indicate the production of oil. The solid bitumen reflectance values and paleotemperatures placed the maturity of the samples in the oil window passing to gas window in both wells. Very weak correlation between illite crystallinity and the organic reflectance data was found, which is possibly representative of hydrothermal fluid-to-rock interaction, due to the organic particles being affected faster than the growth of illite can occur. Nevertheless, reflectance values and illite crystallinity profiles of Glyde-1 showed an erratic behaviour with depth suggesting that thermal history was influence by factors other than regional basin subsidence. The same observations were found for the lateral well Glyde-1 ST1, implying lateral variations in the Previous HitmaturationNext Hit of the organic matter. These results suggest hydrothermal fluid interaction has influenced thermal Previous HitmaturationTop of the organic matter as expressed by the erratic character of the profiles. This type of study is fundamental to understanding hydrothermal influence on hydrocarbon accumulations in this region.