As the hole gets deeper, the drill casings get narrower, the current casing size aims to take the hole to 3,600 metres depth before a smaller casing is set.
Drilling is targeting the Caley Member interval which is expected to be intersected at a depth of about 3,800 metres measured depth.
The primary objective for the Dorado-1 well is to assess the gas and liquids potential in the Caley Member interval.
The well is less than 20 kilometres from and updip of the successful Roc-1 and Roc-2 wells.
The Dorado structure at the Caley interval is estimated to contain a gross mean recoverable prospective resource of 545 billion cubic feet of gas and 30 million barrels of associated condensate.
This equals 125 million barrels of oil equivalent, gross, Pmean.
Drillong of the Phoenix South-3 well at the nearby Phoenix project is also underway and yesterday and update revealed it was at 4,634 metres measured depth.
It is also targeting the Caley Member and a closure that is estimated by Carnarvon to contain a gross mean recoverable prospective resource of 143 million barrels of oil equivalent.