Abstract An active exploration campaign in the Exmouth Plateau has yielded gas discoveries in a coeval wave-influenced delta and deep-water, sand-rich fan succession. Depositional elements were organized into clinoform seismic stratigraphic units that blanketed irregular topography created by extensional tectonics. Clinoform geometries revealed steady, rising and falling shelf-slope break trajectories. Slope successions associated with rising trajectories were devoid of deep-water feeder systems. In contrast, during steady to falling trajectories, the slope was characterized by numerous gullies. These gullies served as the main delivery system for sediment gravity flows into the basin. In some instances, an individual gully dominated and captured the flows of subordinate gullies and developed into a larger feeder system. The feeder systems were self-sourced and cannibalized the deltaic and slope successions through knickpoint retreat. Arcuate strandplains organized into wave-influenced cuspate lobes characterized the deltaic succession. Littoral drift was locally to the east. Delta front well information indicated excellent reservoir quality. Sedimentological analysis of core data indicated different depositional processes as a function of the clinoform geometries. High quality delta front sands were fed into the slope and basin floor as sediment gravity flows and deposited as coalescing sand-rich fans. The fan cores were composed of high-density turbidites that graded into debrites and linked debrites along the margins. The deep-water fans were of favorable to excellent reservoir quality.

Abstract The late Triassic Mungaroo Formation is a prolific gas-condensate reservoir along the landward margins of the Exmouth Plateau ( i.e. , Gorgon and Rankin trends). Recent exploration drilling has stepped outboard of these trends into the Exmouth Plateau adding calibration to an area of sparse well control. Reservoir units were primarily channelized complexes of variable widths and orientations within a large fluvial-deltaic complex that formed a thick (>2.5 kilometer) succession. Channel complexes were attractive exploration targets and have been the reservoirs of recent discoveries. Mungaroo channelized complexes were thick >10 meters, multistorey, and greater than 1 kilometer in width. Their depositional origins were considered either distributaries or channels within an incised valley. Reservoir characterization studies has provided ranges in the properties of the channels, internal reservoir architecture and expected facies distribution that allowed for gas initially in place (GIIP) and estimated ultimate recovery (EUR) calculations.