arckaringa basin, page-4

The bits that stood out to me concerned oil:

(My notes are in brackets)

In the "Source rocks" section:

"The Mount Toondina Formation and much of the Stuart Range Formation while immature, have high TOC values indicating good oil-prone source potential at depth. TOC ranges from 0.45 to 2.7% in Stuart Range Formation, and is as high as 5.95% in Mount Toondina Formation"

(TOC = Total Organic Carbon)

"In many areas depth of burial has not been sufficient for generation of hydrocarbons. Permian sediments are most likely to be thermally mature in southern deep parts of the Boorthanna Trough. In the Phillipson Trough a higher heat flow event 150 million years ago may have boosted maturity of the Permian sequence."

(My understanding is that the shallow depths mean Sapex won't find natural gas. Some consider the beds too shallow for oil too, but previous lease holders estimated there could be 900 million barrels)

In "Reservoirs and seals":

"Sandstone in the Mount Toondina Formation generally exhibits low porosity (6–9%). The Boorthanna Formation contains several thick units of porous and permeable sandstone (log porosity up to 13.5%).
Secondary vugular porosity and minor open parting along stylolites are observed in Cootanoorina Formation
carbonate. Stuart Range Formation and Bulldog Shale (Eromanga Basin) provide regional seals. Intraformational shale and siltstone in the Boorthanna and Mount Toondina Formations may locally provide seals."

(Reservoir: oil collects in porous sandstone or limestone.
Seal: impermeable rock that has prevented hydrocarbons escaping to the surface)

I have no expertise in this field and I'd like to see others' comments.

Macka