Mid-Triassic play opportunities, NW Australia

Quadrant’s two-well campaign “Phoenix South-3” and “Dorado-1” in the Roebuck basin has focused the eyes of Australia’s oil and gas industry onto the region’s Middle Triassic play. Spectrum’s MC3D seismic coverage offshore Western Australia provides both a local perspective via the Phoenix 3D dataset and also a regional viewpoint via larger 3D projects such as nearby Zeester 3D.  Additional, Multi-Client 3D Broadband reprocessing projects and extensive Multi-Client 2D coverage together allow the play’s potential to be understood across the entire North West Shelf.

The Phoenix South-3 appraisal well started drilling mid-April should reached the main target, the Caley Sandstones in the Middle Triassic first.  It is currently at 5,041 m (as of 29 June 2018) having passed through intervals just above where oil bearing sands were recognised in the Barret and Hove Members during the drilling of Phoenix South-1 and 2. This time, however, the main objective is the underlying gas-condensate Caley Member intersected by Phoenix South-2 but not properly evaluated due to the higher than expected pressures. Thirty-nine metres of reservoir was drilled below 5,176 m but, due to the borehole design and safety concerns, no further drilling or formation evaluation could occur (Carnarvon press release 19 Dec. 2016). The results do however support the presence of a reservoir with porosity and permeability’s that can support high flow rates and the possibility of multiple sealed packages or 185 m of additional potential hydrocarbon bearing reservoir. Barring a surprisingly poor result this appraisal should prove up enough reserves to make the Phoenix development truly viable and confirm the Caley Sandstone as a play with great potential.

Dorado-1 spudded in early June will test the play up-dip, located 35 km south of Phoenix South-3 and 19 km SW of the Roc Caley Sandstone discovery. It does however now look like Dorado-1 will win the  race with drilling completed in the 12-1/4” section down to approximately 3,637 m MD and the 9-5/8” liner being set over the coming days before drilling ahead into the Caley Member at around 3,800 m MD. Phoenix South-3 is currently running about a week behind Dorado-1 at 5,041 m, almost to the final casing point above the Caley (Carnarvon press releases 22/29 June 2018). A good result here would pivotal moment with the underlying Crispin and Milne Members also offering further upside potential.

Spectrum’s Multi-Client seismic data library offers the opportunity to follow these exciting developments and gain an insight into this rapidly evolving series of plays in the Middle Triassic that have been previously poorly defined and under-explored in the region.

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