Authors / CoAuthors
Edwards, D.S. | Grosjean, E. | Kuske, T.J. | Chen, J. | Boreham, C.J.
Abstract
The Browse Basin lies offshore from Western Australia's Kimberley region and hosts vast accumulations of natural gas, some of which are rich in condensate, making it Australia's next major liquefied natural gas (LNG) producing province on the North West Shelf. The Ichthys accumulation is estimated to host 12.8 trillion cubic feet (Tcf) of gas and 527 million barrels (mmbbl) of condensate (condensate:gas ratio (CGR) 60 bbl/MMscf) representing the largest hydrocarbon accumulation with recoverable liquids found in Australia since the discovery of the Gippsland Basin and Barrow Island oil fields in the 1960s. Similar amounts of gas, albeit drier (CGR 2030 bbl/MMscf) are hosted within the Brecknock, Calliance and Torosa accumulations (cumulative 15.9 Tcf gas, 436 mmbbl condensate). Despite the extensive ongoing exploration activity and prior research interest [1, 2 and 3], the basin's petroleum systems (PS) have not been publically updated for a decade. Collating the existing molecular and isotopic datasets for the wet gases and associated hydrocarbon liquids, along with the biomarker and 13C/12C and D/H ratios of the n-alkanes for the crude oils, has enabled the origin and extent of the petroleum systems to be redefined. In doing so, it is apparent that the filling of the gas accumulations within the Caswell Sub-basin and along the Scott Reef-Brecknock trend is complex, with the component gases originating from multiple organic and inorganic sources. Differing degrees of biodegradation are observed in the Cornea and Gwydion oil and gas accumulations. Four preliminary petroleum systems are defined for known accumulations by their 13C n-alkane isotopic profiles (Figure 1). The PloverPlover PS is a basin-wide gas-prone system where the gas is reservoired within the Middle Jurassic Plover Formation (e.g. Brecknock-Torosa, Ichthys) and sourced from mixed terrestrial and marine organic matter deposited in fluvio-deltaic sediments. The Plover/VulcanVulcan PS occurs within the central Caswell Sub-basin at Ichthys and Prelude/Concerto and is a wet gas-prone system reservoired within the Upper Jurassic Brewster Member, upper Vulcan Formation. This PS has a more marine source affinity with the additional hydrocarbons probably being sourced from the lower Vulcan Formation. The Plover/VulcanPlover/Vulcan/Nome PS is a gas-prone system within the Heywood Graben. The complex reservoir at Crux is sourced from mixed terrestrial and marine organic matter deposited that may be sourced from within Jurassic sediments. The Echuca ShoalsHeywood PS is an oil- and gas-prone system (e.g. Caswell, Cornea and Gwydion) sourced by marine algae and bacterial remains within Lower Cretaceous sediments [2]. The oils and gases on the Yampi Shelf vary in their degree of biodegradation. Further work is in progress to confirm these petroleum systems and redefine their extent by correlating the wet gases and oils with their source rocks.
Product Type
nonGeographicDataset
eCat Id
82517
Contact for the resource
Custodian
Owner
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- PowerPoint
- ( Theme )
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- petroleum exploration
- ( Theme )
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- geochemistry
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- WAAC
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Geology
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- Published_Internal
Publication Date
2014-01-01T00:00:00
Creation Date
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Access - license
Use - license
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Purpose
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Lineage
Unknown
Parent Information
Extents
[-22.0, -12.0, 118.0, 128.0]
Reference System
GDA94 (EPSG:4283)
Spatial Resolution
Service Information
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Source Information
Data generated in GA Laboratories. Petroleum Systems created within the Browse CCS Project 118.0 128.0 -22.0 -12.0