Publication Name: The Sedimentary Basins of WA
Authors: K. A. R. Ghori
Publication Volume: 2
Date Published: December 1998
Number of Pages: 26
Reference Type: Book Section
Abstract:
Geochemical analyses confirm the presence of Silurian, Upper Devonian, Lower Permian and Upper Permian source rock intervals within the Carnarvon Basin.Oil-prone source beds within the Silurian Dirk Hartog Group on the Gascoyne Platform have fair to good generating potential (in Coburn 1 and Pendock 1) and are within the oil-window.
The Upper Devonian Gneudna Formation on the Gascoyne Platform contains the best oil source beds of the basin (up to 13.6% TOC and 40.1 mg/g S1+Sz). These source-beds are present in Barrabiddy 1A where they have excellent generating potential and are within the oil-window. In the Merlinleigh Sub-basin, however, the formation is immature in outcrop on the eastern margin and overmature along the western margin where it is deeply buried.
In the Merlinleigh Sub-basin the best source rocks are within the Lower Permian Wooramel Group, and are gas-prone with excellent to fair generating potential. In this sub-basin the group is marginally mature in the northwest and immature in the south. The only exception is in Kennedy Range 1 where an abnormally high thermal maturity is indicated. The next best Lower Permian source rocks are organicrich shales of the Byro Group.
Oil- and gas-prone source beds within the Upper Permian Kennedy Group of the Peedamullah Shelf have good to excellent generating potential in Candace 1 and Kybra 1, and are within the oil window.
Palaeotemperatures and petroleum expulsion peaked during the late Palaeozoic for the Dirk Hartog and Gneudna formations, and in the early Mesozoic for Permian formations. Therefore, Palaeozoic and lower Mesozoic traps, if present, will be the most prospective in the area.