The Phoenix South Discovery: A New Hydrocarbon Province on the Northwestern Shelf of Australia

Abstract

The Phoenix South-1 discovery is located in the offshore Canning Basin (Bedout sub-Basin), approximately 180 km north of Port Hedland WA in 133 m of water. The area is very lightly explored, with a total of 7 wells and sparse seismic coverage over four permits covering more than 22,000 km². The acreage was acquired in a gazettal round in 2009 by Finder Exploration and Carnarvon Petroleum, and both Apache (the current operator) and JX Nippon farmed in in 2012, prior to drilling of the discovery well. The well objective was the Triassic Keraudren Formation and Locker Shale in a large, faulted anticlinal closure located 13 km southwest of the Phoenix-1 well. Phoenix-1 was drilled in 1980 by BP, with reported wet gas shows throughout tight sands in the reservoir objective. Phoenix South-1 was spud in May 2014 and reached a TD of 4595 m in late August. Drilling through the reservoir section was complicated by mechanical problems as well as by fluid losses, but the sands within the entire objective section to TD showed elevated C1–C5 gas readings and fluorescence, similar to the Phoenix-1 offset well. Initial LWD and wireline data were inconclusive, indicative of low-porosity sands and no clear hydrocarbon gradients. However, XPT pressure measurements indicated better than expected mobilities, and the use of Schlumberger's 3D Saturn radial probe proved critical in breaking through the filtrate and LCM lining the well bore into the oil-bearing reservoir. A total of six light, black oil samples were recovered from three zones, with API gravity of 45–48 degrees and gas-oil rations of 700–1200 scf/stb. Mobilities inferred from pressure build-up during oil sampling range from 100 to 460 mD/cP. Oils are significantly undersaturated and there is no indication of a primary gas cap. Preliminary geochemistry indicates a Lower Triassic, non-marine to marginal marine source. Commercial deliverability from the Phoenix South reservoir is a risk going forward due to the low porosity encountered in this well. However, the radial probe tests indicated much better than expected permeability, which may be further enhanced by the overall weakness of the reservoir rock. Furthermore, the discovery opens up an enormous area for oil exploration with a number of large, untested closures within the play fairway. New 3D and 2D seismic has been acquired and follow-up drilling is planned for 2015 and beyond.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015