Analysis Of Petroleum System And Resource Evaluation In Northern Carnarvon Basin,Australia

The Northern Carnarvon Basin,which lies in the North West Shelf of Australia,is a passive margin basin with the richest oil and gas resources in Australia.Based on the latest various geological data,this study attempt to analyze the petroleum geological features and petroleum systems in the basin,discuss the oil and gas distribution patterns,document the main factors controlling hydrocarbon distribution and erichment.Plays were used as the assessment unit to evaulate the undiscovered petroleum resources in the basin,and then the favorable exploration play fairways were delineated.The study results show that there are two petroleum systems: the Upper Jurassic Dingo and the Triassic Mungaroo petroleum systems.The discovered hydrocarbon accumulations were classified into nine plays based on the reservoir age and distribution.The hydrocarbon distribution is characterized by a stacking pattern of gas in the lower reservoirs and oil in the upper reservoirs,and oil in the inner fairways and gas in the outer fairways areally.Lower Cretaceous and the overlying strata in the central parts of the basin mainly host crude oil whereas the Triassic and Lower-Middle Jurassic in the surrounding structural highlands largely contain natural gas and condensate.The hydrocarbon distribution and enrichment are largely controlled by high quality source rocks,source kitchen adjacent to the uplifts,the effective regional cap rocks and the tectonic actitivities in the rifting phase.With the Monte Carlo method,the undiscovered petroleum resources were estimated to be about 26219.62 MMboe,of which 85.3% are natural gas.Four favorable play fairways were delineated and the most favorable one is the Triassic Mungaroo Play in the Exmouth Plateau.