The Exploration of and Lessons Learned From the Satyr and Achilles Gas Discoveries, WA-374-P, Carnarvon Basin, WA, Australia

Abstract

The Satyr and Achilles gas fields of the Carnarvon Basin, NW Australia, comprise gas filled fluvial and marginal marine reservoir sands within the Triassic Mungaroo Formation. Both discoveries are trapped in eroded Triassic horst structures, with the Satyr field also comprising overlying gas filled deepwater turbidite reservoir sands of the Cretaceous Lower Barrow Group in a counter regional-dip stratigraphic trap. The Achilles field has been defined by a single exploration well and four wells have been drilled to date on the Satyr structure, establishing a multi-Tcf gas resource that could serve as a development hub for other prospects in the area and which provide an important backfill or expansion opportunity for Chevron's major LNG projects in Australia. Discoveries were made in twenty three separate reservoirs, with the majority of the resource residing in three key intervals. Understanding the laterally variable fluvial and marginal marine reservoir intervals of the Mungaroo Formation and the restricted turbidite lobes of the Lower Barrow Group are critical to predicting future reservoir performance, development well planning, and continued exploration. Integration and analysis of 3D seismic, conventional cores, biostratigraphy, fluids, pressures and petrophysical logs within a structural-stratigraphic framework have provided key insights into reservoir parameters, vertical seals, and lateral continuity. This integrated interpretation framework positively impacted the delineation and assessment of both discoveries by providing robust correlations to other analogue reservoirs which in turn reduced uncertainty in key areas such as connectivity and property prediction. Quantitative seismic analysis of the rapidly varying reservoir units have been applied to post drill results for future development, well planning and to further refine pre-drill assessments and structural conformance on prospects in the surrounding area.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015