CARNARVON Petroleum Limited and its JV partner Quadrant Energy have made a significant oil discovery with the Dorado-1 well off the north-west coast of Western Australia.
While the Dorado exploration well was testing what was largely expected to be a gas prospect, light oil has been recovered from excellent reservoir containing a gross hydrocarbon package of 96.1 metres and a net pay thickness of 79.6 metres in highly porous and permeable Caley Member sands.
The results were confirmed after wireline testing was undertaken after the at the Dorado-1 well was drilled down to around 4,044 m Measured Depth MD in 8-1/2” hole. Currently the well is still in a hydrocarbon bearing column.
Carnarvon managing director Adrian Cook said the result is transformational for the company.
“This is a significant discovery given the quantum of the net pay thickness, the quality of the oil and the extremely good reservoir characteristics,” Mr Cook said.
“Currently, we estimate the net oil pay is around 80 metres, with more drilling still to come this is very exciting for Carnarvon Petroleum. “With multiple targets still left, the focus now is to complete the drilling program through the Baxter, Crespin and Milne Members.
“In April we highlighted the possibility that the Dorado structure could contain a substantial oil accumulation. Given this outcome has now occurred, Carnarvon will make an assessment of and issue a revised volume estimate as soon as we possibly can once drilling operations have finished.”
Excitingly, an additional hydrocarbon accumulation has been observed in the Baxter Member, with drilling and evaluation still to be completed in that section of the well.
Drilling through the Caley Member, logging while drilling tools indicated a sandstone reservoir section with elevated gas readings and increased resistivity, indicating the presence of hydrocarbons. Given the significance of these results, it was decided to bring the proposed wireline program forward.
At the completion of drilling, at around 4,050 metres Measured Depth, the well had yet to encounter water saturated sands and all sands were hydrocarbon charged.
The wireline logging tools have confirmed the well encountered a total gross Caley hydrocarbon package of 96.1 metres True Vertical Thickness (TVT) with a net oil pay of 79.6 metres TVT.
Excellent reservoir characteristics were interpreted from the logging with average porosity of around 20% with hydrocarbon saturation of 82.5%.
Permeabilities ranged between 100 to 1,000 millidarcy in the Caley hydrocarbon zone.
The high quality of the reservoir was further reinforced by the rapid time taken to extract the oil samples and the high mobility recorded while undertaking formation testing.
A number of oil samples were extracted in the Caley sandstone interval with a very light oil being recovered to surface. Estimates of the oil characteristics from the rig indicate a 49.60 API oil.
Following the completion of the wireline formation evaluation, the well will be deepened to approximately 4,550 metres MD to evaluate the newly discovered Baxter sand and the secondary targets in the Crespin and Milne.
Carnarvon had previously disclosed prospective resources for Dorado of 545 Bscf of gas and 30 million barrels of associated condensate (being 125 million barrels of oil equivalent (boe).
Carnarvon has also previously noted that there is a possibility for the structure to contain a substantial oil accumulation. Given the oil discovery outcome in this well, Carnarvon said it will issue a revised volume estimate as soon as it can following the completion of drilling, which will be a contingent resource of oil.