AT a time when it is obtaining publicity for all the wrong reasons, the Great Australian Bight has a new compamny to explore its potential.
Within days of BP announcing it was pulling out of the Bight, Australian junior Karoon Gas Australia Ltd announced it had beeen award of exploration permit EPP46 in the frontier area.
The permit covers 17,793 square kilometres in the Ceduna Sub‐Basin, offshore South Australia, an area Karoon says is one of the world’s last underexplored Cretaceous basins.
According to Karoon, the Ceduna Sub‐Basin hosts a massive Cretaceous delta system which the compan y believes has the potential to be a globally significant hydrocarbon province with world class potential.
Karoon’s initial three‐year firm commitment consists of acquiring an extensive 2D seismic survey over the permit area, a targeted 3D seismic survey and geotechnical studies. The indicative value of Karoon’s firm commitments is A$26 million or A$1,455 per square kilometre.
Exploration history in the Bight
Petroleum exploration in GAB has been active in three major cycles since the late 1960s to the present.
Approximately 100,000 line‐km of seismic data has been acquired and ten exploration wells drilled to date in the eastern part of the GAB.
Only four wells have been drilled in the Ceduna Sub‐Basin, and with the exception of Gnarlyknots‐1/1A, all drilling was focused in the shallower, flanking depocentres in shallower waters near the basin margin.
The deeper part of the GAB remains largely untested and is the main industry focus for the current exploration programmes.
All historical wells were drilled on 2D seismic data only, however since 2011, approximately 40,000 km2 of 3D seismic survey data has been acquired.
Exploration well Greenly‐1, located in EPP41 to the east of the Karoon’s permit, was drilled by BHP in 1993 to a depth of 4,860 mKB. The well encountered good quality sandstones of Cretaceous age with significant shows thought to be of Cenomanian‐Turonian age similar to source rocks dredged in 2007 by Geoscience Australia in the west of the Ceduna Sub‐Basin.
Exploration well Gnarlyknots‐1A, located in EPP44 adjacent to the west of the Permit, was drilled by Woodside in 2003 (50m to the SW of Gnarlyknots‐1) to 4,736mKB, approximately 1,500 metres above the targeted depth and abandoned due to adverse weather conditions. The well intersected only two of the five targets. While the well failed to discover significant hydrocarbons, a large sandstone reservoir of late Cretaceous age was intersected.