The successful fracture stimulation and production test of the Amungee NW-1H well placed the Velkerri Shale play and the Beetaloo Sub-basin on Australia’s energy radar. The Velkerri Shale dry gas play is currently Australia’s most promising shale gas prospect; however, it is not the only prospect in the Beetaloo Sub-basin. Four additional potential plays have been identified, each with their own specific risk profile and relative benefits. These are the Velkerri Shale liquids rich gas play, the Kyalla Shale and hybrid liquids rich gas plays, and the Hayfield Sandstone oil/condensate play. Appraising each of these opportunities requires special attention to ensure efficient and appropriate deployment of capital. A framework approach allows for the high-level assessment and comparison of each of the discussed opportunities within the Beetaloo Sub-basin portfolio.

Origin Energy completed exploration campaigns in 2015 and 2016 in the Beetaloo Sub-basin of the Greater McArthur Basin in the Northern Territory, drilling three vertical wells and one horizontal well. These wells have provided a wealth of technical data to assist in the characterisation of the primary source rock reservoirs or ‘shale gas’ plays in the Basin – the Velkerri Formation Play and the Kyalla Formation Play. In this paper we demonstrate the presence of thick, gas saturated and over-pressured source rocks across the sub-basin. In addition to the drilling campaign, the multi-stage hydraulic fracture stimulation of the Amungee NW-1H horizontal well was completed in 2016 – this operation was unique as it represents the first horizontal stimulation operation in the Beetaloo Sub-basin and the longest ‘plug and perf’ type horizontal completion in Australia. Data from the extended production test of the Amungee NW-1H are critical from a technical and, potentially, economic and political perspective. In addition to the technical work program, Origin has undertaken preliminary environmental baseline studies and substantial stakeholder engagement. Ensuring environmental baseline data are available is key to demonstrating that onshore gas developments can be undertaken without adverse environmental outcomes, and also for gaining social acceptance. However, data and facts alone are not sufficient to build community confidence. Origin has engaged extensively with pastoralists, local communities and Traditional Owners to build direct relationships and partnerships that encourage acceptance of the gas industry’s ability to coexist and deliver mutual benefits to the businesses and communities of the Barkly region and the Northern Territory more broadly.

No abstract

The Hayfield Sandstone is a Neoproterozoic, 10–15 m thick, very fine- to fine-grained sandstone, interpreted to have been deposited in a shelfal-marine environment. The reservoir sandstone is characterised by high porosity and low matrix permeability, which is complimented by partially mineralised open fractures which may contribute significantly to overall system permeability. Hydrocarbon phase across the identified play fairway is interpreted to range from a gas with the potential for condensate and liquefied petroleum gas streams to a light, ~38 API gravity oil. The extent of the prospective play fairway and the distribution and connectivity of reservoir facies is poorly constrained due to a limited number of well penetrations and poor resolution 2D seismic data. From the wells drilled to date, the gross area of the prospective play fairway could be as low as 300 km2 or greater than 1500 km2.

Over the past decade, there has been a paradigm shift in the exploitation strategy in North American tight gas plays from vertical to horizontal wells. This shift has yet to occur in Australia. The Cooper Basin has vast amounts of contingent and prospective tight gas resources that have yet to be unlocked commercially. These resources continue to be developed primarily with hydraulic fracture stimulated vertical wells. Operators have yet to challenge the status quo and test the Cooper Basin tight gas potential with a drilled, completed and tested horizontal well. There are many advantages to horizontal well developments, from the ability to target a specific high graded reservoir unit to increased capital efficiency. Operators need to break away from convention and take a new approach to Cooper Basin tight gas exploration and development in the quest to demonstrate commerciality. A review of the inherent challenges in Cooper Basin gas field developments and the current exploitation strategies employed in analogous tight gas plays have been integrated to produce a pragmatic workflow to identify potential reservoir units that would benefit from a change in development strategy.