Project Summary
Both ATP 539 and ATP 549 permits in Queensland are described as ‘greenfield’ areas containing larger, undrilled structural targets than their South Australian counterparts.
ATP 539 lies in a very strategic position on the western flank of the Queensland portion of the Cooper Basin, where it is well placed to receive hydrocarbons migrating to the west out of the adjacent basin deep (depocentre).
ATP 539, and the adjacent ATP 549 (West Block), contain the regional Curalle Anticline – a large structural high and regional focal point for migrating hydrocarbons from both the Arrabury Trough, to the south and southwest, and the Windorah Trough to the east. As shown in Gallery Picture 1 ATP 539 contains a number of prospects including Borva, Great Northern, Mianga, Copa South and several prospects located on the Curalle Anticline.
ATP 539 lies up-dip from the Inland Oil Field, the field testifying to the presence of commercial quantities of hydrocarbons in this portion of the basin. Previously, minor oil and condensate shows recovered from the Curalle-1 well indicated that hydrocarbons have also moved into the crestal areas of the Curalle Anticline, a trend which dominates the western margin of the Cooper Basin in the southern portion of the Permit.
Geological studies suggest that hydrocarbons migrating out of the deepest portions of the Cooper Basin would move up-dip and congregate in structures along the western flanks, such as occurred at the Inland Field. The occurrence of gas at McKillop-1 and a significant (50m interpreted palaeo-oil column) at Wyerie-1 in ATP 549, in locations structurally down-dip (lower) than the Curalle Anticline in southern ATP 539, also supports the concept that hydrocarbons have progressively moved westwards into higher structures in this area.
The Curalle Anticline was drilled early in the 1980’s by Delhi – Santos consortium on what is now considered a very loose seismic grid. New seismic data (Planet Downs Seismic Survey – see Picture Gallery 2) acquired in late 2004, and fully funded by Enterprise Energy N.L., confirm several nearby valid traps, including the Planet Downs Prospect which is down-dip and likely to have been preferentially filled before hydrocarbons moved into the trap tested by Curalle-1.
Curalle-1 recovered minor oil and condensate at the Adori Sandstone level, confirming movement of hydrocarbons into the crestal portions of the Curalle Anticline. Based on the new seismic data Curalle-1 is considered not to have been located in an optimal position.