Abstract

The Cooper-Eromanga petroleum system, located in central Australia, contains the most prolific onshore oil fields in Australia. Approximately 32×10⁶ m³ (200 MMSTB) of recoverable oil with minor amounts of gas have been discovered in the Cooper-Eromanga petroleum system to date. Hydrocarbon accumulations occur in Eromanga Basin reservoirs ranging from Late Cretaceous to Early Jurassic in age within structurally controlled anticlinal traps, with the majority of accumulations sourced from underlying Cooper Basin rocks of Permian age. Investigation of essential elements and processes operative within the Cooper-Eromanga petroleum system provides a new perspective on understanding synergistic relationships between key components of the system. Spatial positioning of Permian source beds relative to Jurassic and Cretaceous reservoirs places strong emphasis upon effective lateral and vertical migration processes for significant accumulation of hydrocarbons throughout the system.

The critical moment of the system has been interpreted to be 90 Ma, at the end of Late Cretaceous sedimentation and immediately prior to Tertiary tectonism. Analysis of spatial and temporal elements of the system has identified pre-Tertiary structural trap development, effective lateral and vertical migration of hydrocarbons and post-Tertiary preservation of accumulations as major controlling factors on Eromanga Basin accumulations. On the basis of migration and entrapment processes, which vary significantly across the system, different play concepts can be identified in the Cooper-Eromanga Basin petroleum system. Further evaluation of these complementary plays is anticipated to create new opportunities for future exploration of the system.