2018 Release Areas

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Acreage Release 2018: Otway Basin

The Otway Basin is a gas producing hydrocarbon province that has enjoyed strong exploration and development activities since the commercial gas accumulations at Geographe and Thylacine were discovered in 2001. These successes were rapidly followed by the Casino discovery in 2002, and Blackwatch, Henry and Halladale in 2005. The discovery at Speculant in 2014 is the most recent to provide gas to the expanding energy market in south-eastern Australia. Despite its production status and long exploration history, large parts of the Otway Basin remain underexplored, especially those areas on the outboard part of the continental shelf and in the deep water areas represented by the Morum, Nelson and Hunter sub-basins.

Release areas V18-1, V18-2 and V18-3, Inner Otway Basin, Victoria

Highlights

Bids close on Thursday 18 October 2018 for Release Areas V18-1 and V18-2

Prequalification for Release Area V18-3 closes on Thursday 4 October with the cash bidding auction held on Thursday 7 February 2019

  • Producing gas province with ready access to an expanding infrastructure and growing southeast Australian energy market.

  • Close to the producing Minerva, Casino and Halladale–Speculant gas fields

  • Proven commercial gas accumulation at La Bella available for cash bidding

  • Mainly shallow water depths below 150 m

  • Further guidance available, refer to 2018 Special Notices

Release Areas V18-1 covering 4 graticular blocks, is located adjacent to Victoria’s Three-Mile Zone in the inboard of the Otway Basin. The area lies close to the producing Minerva, Casino and Halladale–Speculant gas fields (Figure 1, Figure 2).

Release Area V18-2 comprises 38 graticular blocks and covers large parts of the continental shelf. This part of the Otway Basin is only lightly explored and only a small number of exploration wells provide geological control (Figure 1).

Area V18-3 hosts the La Bella gas accumulation (Figure 1). The area covers three graticular blocks that represent the former retention lease VIC/RL7, and is released for cash-bidding.

Geological control is provided by the discovery wells of the surrounding gas fields, including Minerva, Casino, Henry, Netherby, Pecten, Martha, Blackwatch and Halladale. All gas accumulations in these fields are hosted by the Waarre Formation and related Sherbrook Group sediments (Figure 3), and this has remained the only successful play in the offshore basin to date. Slightly different facies associations were encountered in Geographe and Thylacine, related to a distinct sediment influx from the east during the Turonian.

Across the offshore gas fields, seismic data coverage, represented by multiple 3D surveys, is good. Further outboard, along the marine shelf, only 2D seismic surveys have been acquired (Figure 4) and Release Area V18-2 requires modern 2D/3D data sets.

Only four wells were drilled in Release Areas V18-2 and V18-3 (Table 1) with La Bella discovering sub-commercial volumes of gas. The shelfal platform offers opportunities to evaluate plays other than the Waarre Formation but lacks modern seismic data to evaluate the sequences within the Lower Cretaceous Otway Group and the lower Paleogene (Wangerrip Group) in which the onshore well Lindon 1 recorded minor oil shows.

Release Area V18-3 is represented by the La Bella gas accumulation and is offered for cash-bidding. La Bella 1 was drilled by BHP Petroleum in 1993 to test a mapped closure at the Waarre Formation level. The well encountered gas at two levels (15 m column in the Flaxman Formation, 65 m column in the Waarre Formation) which, according RFT pressure readings, are not in communication. Gas in place was initially estimated at 210 Bcf, but because the discovery was made before Australia’s gas market was deregulated, the well was plugged and abandoned as a sub-commercial gas discovery. WHL Energy Ltd, the most recent operator and holder of the retention lease, estimated the resource to contain 158 PJ (149 Bcf) of natural gas (WHL Energy Ltd, 2012). The current gas supply situation in southeastern Australia provides incentive for the development of the La Bella gas field.