Unconventional Resource Potential of the Taroom Trough in the Southern Surat-Bowen Basin, Queensland, Australia

Abstract

The Bowen-Surat Basin is a well-known petroleum province, with a long history of conventional oil and gas production, primarily from Mesozoic reservoirs. It contains two active petroleum systems which, in the area of ATP 840P within the Taroom Trough, contain condensate- and gas-mature source rocks. The Blackwater Source system includes source rocks of the marine Back Creek Group, and coals and carbonaceous shales of the Blackwater Group. Both source rock intervals are mature to overmature for oil and gas generation throughout the Taroom Trough. Terpane and sterane biomarkers and isotopic data show the major source of conventional oils in Permian-Jurassic reservoirs in the basin to be the Blackwater Group. The Triassic Snake Creek Mudstone was deposited in a lacustrine environment, and is the second source interval. It contains Type II/III kerogen that is mature for oil and gas generation. A number of over-pressured unconventional tight sand reservoir targets lie adjacent to these mature source intervals, and are generally gas-charged where penetrated. These reservoir intervals include: • Triassic Showgrounds Sandstone; • Triassic Intra-Rewan sandstone; • Permian Kianga Formation, Tinowon Sandstone and Back Creek Group. Together, these reservoirs host significant prospective gas and condensate resources. Estimates of Hydrocarbons Initially-In-Place (HCIIP) within ATP 840P in the Taroom Trough are: • Gas Initially-In-Place (GIIP), most likely estimate of 2085 billion cu m (74.0 Tcf); • Condensate Initially In-Place (CIIP) most likely estimate of 879 million cu m (5.53 billion barrels). Natural fracturing may enhance reservoir quality within these units, and they also may be good candidates for fracture stimulation in vertical or horizontal wellbores. Comparisons with productive analogue plays in other areas of the world suggest that the chance of discovery of gas-condensate reserves within block ATP 840P is high, and that drilling and completions methods can be developed to extract them economically. Excellent comparisons can be drawn between the Lower Rewan / Kianga formations of the Bowen Basin and stacked fluvial successions of the Williams Fork Formation in Piceance Basin, as well as Cretaceous targets in the Deep Basin of western Canada. Permian Tinowon sandstones compare well with the prolific Montney Formation of western Canada.

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