Geochemical analysis (including biomarkers and isotopic data) of recovered oils, condensates and gases indicates that at least four hydrocarbon families are present in the Browse Basin (see Kennard et al. 2004).

1. An outer basin, relatively dry gas-prone system sourced from mixed terrestrial and marine organic matter within presumed Jurassic sediments (Scott Reef and Brecknock fields; condensate/gas ratio (CGR) around 10-20 BBL/MMSCF). The recent Argus gas discovery probably represents a northern extension of this system (CGR <20 BBL/MMSCF; Keall and Smith, 2004).
2. A central basin, wet gas/condensate-prone system, the source(s) of which has yet to be established (Brewster-Dinichthys-Gorgonichthys-Titanichthys Field and Adele-1; CGR about 60 BBL/MMSCF). The recent Crux gas discovery, interpreted to be sourced from mixed terrestrial and marine organic matter within Middle-Lower Jurassic Plover Formation source rocks in the Heywood Graben (Edwards et al., 2003), probably represents a northeastern extension of this system, but the gas is dryer (CGR 22-37 BBL/MMSCF; Kaoru et al., 2004).
3. An inner basin, oil (plus gas)-prone system sourced from predominantly marine algal and bacterial organic matter within Early Cretaceous sediments (Cornea and Gwydion fields, Caswell-2 oil accumulation and oil stains in Kalyptea-1).
4. An inner basin, high maturity dry gas-prone system (Macula-1) possibly sourced from Permian or Jurassic sediments.

Mature potential source rocks have been identified over much of the basin and are best developed within the Lower Permian, Jurassic and Lower Cretaceous sections. These source units underpin four major hypothetical petroleum systems [PDF_417kb] identified in the basin (Blevin et al., 1998b):

Early Cretaceous petroleum system (JPG 0.9MB)	Late Jurassic petroleum system (JPG 0.9MB)
Early-Middle Jurasic petroleum system (JPG 0.8MB)	Permo-Carboneferous petroleum system (JPG 0.9MB)

Publication:

Browse Basin high resolution seismic study. North west shelf, Austrlaia. Interpretation report.