Unconventional Gas Potential in the Northern Territory, Australia: Exploring the Beetaloo Sub-Basin

Abstract

Despite unconventional targets being recognised across many Australian sedimentary basins, and the Energy Information Administration (EIA) estimating a technically recoverable shale gas resource of >400 tcf in Australia, there have been no definitive tests that prove any of these potential plays will flow gas at commercial rates. There have, however, been a number of technical successes reported from both shale gas and basin centred gas plays. Exploration activity has been concentrated across basins in central, northern, and north-western Australia. One of the emerging plays of particular interest is the Mesoproterozoic Velkerri Formation of the Beetaloo Sub-Basin (Beetaloo) in the Northern Territory (NT). The unique geologic history of the Beetaloo region has preserved source rocks from the Proterozoic, and been subject to relatively limited tectonic activity, while still burying and maintaining them within the gas window. This play has seen relatively consistent levels of activity over a number of years yielding encouraging positive results; including the successful hydraulic fracture stimulation and production test of the Shenandoah-1A well by Falcon Oil & Gas in 2011. Even though the hydrocarbon potential of the Velkerri Formation has been known from outcrop and both petroleum and mineral exploration wells drilled since the 1970s, Origin's exploration program in 2015 has provided new insights into the prospectivity of the play. Origin acquired extensive wireline data, sidewall core and full core data in addition to undertaking real time geochemical analysis of cuttings while drilling. These results indicate reservoir intervals contain gas bearing, quartz rich source rocks that are mature for gas over extensive areas providing an excellent exploration target with material volumetric upside. This paper provides insights into and results from an active exploration program in Australia's most prospective frontier basin for unconventional gas. The Mesoproterozoic age of the target source rocks makes the exploration unique but not without a number of technical and operational challenges.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016