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ABSTRACT: The Greater Gorgon hydrocarbon system: predicting what works, what doesn't and understanding why, Australia

Sibley, David1, Fred Herkenhoff2, Dean Criddle2, and Mike McLerie2
(1) West Australian Petroleum Pty. Limited, San Ramon, Australia
(2) Chevron, San Ramon, CA

Between 1973 and 1999 West Australian Petroleum Pty Limited (WAPET) discovered seven major gas fields on the southern Rankin Trend. Recent exploration successes on Exploration Permit WA-267-P were the outcome of geologic and geophysical studies undertaken to gain a better understanding of the entire hydrocarbon system. These studies included key technical efforts in the following areas: 3D seismic interpretation, seismic attribute analysis and Monte-Carlo simulations to select exploration strategies involving multiple prospects and targets.

The first component of our exploration success is derived from the utilisation of seismic attribute analysis and integrated geologic studies to enhance our understanding of the key risk elements involved in each prospect: trap, reservoir, and charge. Seismic attribute analysis was the key tool used to locate probable gas reservoirs and integrated geologic studies increased confidence in the seismic predictions.

The second component facilitating WAPET's success comes from using our geologic model to further define risk, predicting probabilistic ranges of discovered volumes for all targets, and using the results to select exploration strategies. This methodology resulted in estimates of discovered HC OGIP and proba-bilities of exploration success which have proven accurate so far.

WAPET's comprehensive approach to exploration has been in-strumental in understanding and predicting why certain prospects are hydrocarbon bearing, and others are not. The recent out-comes observed at Geryon and Orthrus provides evidence that modern geophysical data, especially 3D seismic, combined with innovative strategies and leading edge technology can be used to define exploration reserves to high levels of confidence.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia