Dorado-1 spud date slips behind Phoenix South-3

July 31, 2017
The Perth-based duo of Quadrant Energy Ltd. and Carnarvon Petroleum Ltd. has decided to delay the drilling of the prospective Dorado-1 wildcat well in the Bedout sub-basin off Western Australia until mid-2018. It will now follow the group's second appraisal well on the Phoenix South oil and gas discovery.

Rick Wilkinson
OGJ Correspondent

The Perth-based duo of Quadrant Energy Ltd. and Carnarvon Petroleum Ltd. has decided to delay the drilling of the prospective Dorado-1 wildcat well in the Bedout sub-basin off Western Australia until mid-2018. It will now follow the group's second appraisal well on the Phoenix South oil and gas discovery.

The Quadrant-operated joint venture had planned to drill Dorado with a jack up rig during this year's second half but has now decided that there will be cost savings and more-efficient well operations in holding the well over to align with next year's Quadrant drilling program. This also will minimize exposure to the southern hemisphere cyclone season.

A jack up is still intended to be used. Dorado will target multiple stacked reservoirs within the prospective Calley formation, which has yielded gas and condensate in the Roc-1, Roc-2, and Phoenix South-2 wells.

The JV says the top Calley sand alone has the potential to contain a gross mean recoverable prospective resource of 545 bcf of gas and more than 30 million bbl of condensate.

The Phoenix South-3 appraisal is expected to spud during early 2018. Essentially it will be a redrill of the aborted Phoenix South-2 well, which was drilled last December.

PS-2, in WA-435-P, encountered a 39-m thick hydrocarbon-bearing zone with significant gas influx and elevated reservoir pore pressure at or near the Caley formation primary target.

However, the group was unable to assess up to 185-m thickness of additional potential hydrocarbon-bearing Caley reservoir below a 5,215-m well depth because of the higher-than-anticipated pressures.

The Phoenix South structure Calley reservoir is estimated to contain a gross mean recoverable prospective resource of 489 bcf and 57 million bbl of associated condensate. The condensate-to-gas ratio is high and adds value to the prospect.

In addition, the original Phoenix South-1 discovery well found oil in the stratigraphically higher Barret sandstone.

The JV says the primary objective of PS-3 will be to specifically evaluate the Calley interval that PS-2 was unable to fully penetrate and test.

The new well will be drilled with a semisubmersible drilling rig and tenders will be released within the next few weeks.

In the nearby Roc discovery, the JV has commenced pre-front-end engineering and design work, including detailed reservoir modelling, to determine the most appropriate development concept. The northern extent of the Roc reservoir will be a primary focus to provide greater certainty of the gas-condensate resource and reclassification of volumes into the proven category ahead of a final investment decision.

All the development scenarios being considered include options for tie-back of future discoveries and appraisal successes. These include the potentially larger Phoenix South field and the Dorado prospect.

Quadrant is operator with 80%. Carnarvon holds the remaining interest.