Neoproterozoic Salt Stratigraphy of the Amadeus Basin: A Comparative Analysis with the South Oman Salt Basin and Other Gondwana Salt Basins
Gonghua Fan, 2016
Honours Degree of Bachelor of Science (Petroleum Geology & Geophysics)
Australian School of Petroleum, The University of Adelaide
The Amadeus Basin is a slightly explored frontier basin in central Australia with proven hydrocarbon reserves. An intra-salt carbonate stringer play is speculatively present within the Neoproterozoic Gillen Formation. To date, only two wells (Magee-1 and Mt Kitty-1) have fully penetrated the Gillen Formation and reached the sub-salt strata. Due to this data sparsity, it is impossible to gain an accurate understanding of the salt stratigraphy of the Gillen Formation. By way of analogy, there exist numerous Gondwana basins that are similar in age and hydrocarbon potential to the Amadeus Basin. Among them, the prolific, well-established intra-salt stringer play in the South Oman Salt Basin may help shed some light on the uncertainties of the Amadeus Basin. However, before the analogue can be validated, a comparative study will be required to test the analogies between the basins.
This study utilised the publicly available well and seismic data of the Amadeus Basin to analyse the stratigraphy of the Gillen Formation. The stratigraphy is grossly composed of an upper carbonate section (the Upper Gillen), a middle salt section (the Gillen Salt), and a basal shale section (the Gillen Shale), with uneven thicknesses due to intense salt mobilisation. Two to four (possibly more) cycles of evaporite-carbonate sequences with variable thicknesses (10—180 m) were found to exist in the Gillen Salt, where an intra-salt carbonate stinger play was also tentatively shown to be present.
Built on the findings, together with information from existing literature, a comparison was made between the Amadeus Basin and the South Oman Salt Basin. Aspects such as palaeogeography, palaeoclimate and palaeobiology, tectonic evolution, and salt stratigraphy were reviewed and compared. Results show that the South Oman Salt Basin is highly likely to be a valid analogue for the Amadeus Basin in terms of the intra-salt carbonate stringer play. However, due to the remaining uncertainties in understanding the Amadeus Basin, the analogies should be further tested, and caution is to be taken when using the South Oman Salt Basin as an analogue.