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ABSTRACT: Sedimentology, Reservoir Potential, and Seal Integrity of the Pale Sandstone, Eastern Papuan Basin, Papua New Guinea

BOULT, PETER J., University of South Australia, South Australia, Austalia, GEORGE J. CARMAN, Department of Earth Sciences, Monash University, Clayton, Australia, and Austin Oil N.L., South Melbourne, Victoria, Australia, and SALLY E. PHILLIPS, Amdel Core Services Pty Limited, Frewville, South Australia, Australia

The Coral Sea syn-rift sediments exposed at the Aure scarp in the eastern Papuan basin include the Campanian Pale Sandstone, which is overlain by Paleogene Mendi Group limestone. These sediments have been mapped in stream outcrops and studied in the laboratory to assess sedimentary, reservoir and seal characteristics.

The Pale Sandstone reservoir is a fine- to coarse-grained, moderately sorted, mineralogically and texturally mature quartzarenite. Sediments were probably derived from the Paleozoic Omung metamorphics along the Kubor trend to the north. Deposition occurred on the northeastern, passive margin of the Australian craton in a fluvial to barrier island setting. Diagenetic alteration of the sands was minimal and appears to have been controlled by facies and lithological variations.

Measured sections of the Pale Sandstone are up to 190 m thick with a net/gross ratio of 90%. Petrological and core analysis studies indicate an average porosity of 20% and permeability of 750 md, with permeabilities up to 3.5 d over a 30-m interval at the top of the sand.

The basal Mendi Group seal is a transgressive systems tract comprising well-bedded micrite. Mercury injection/capillary pressure measurements on outcrop core plugs and cap-rock integrity sensitivity calculations, using fluid parameters from neighboring wells, confirm the limestone is capable of sustaining 50-1300-m oil columns for a reservoir depth of 2500 m. Fractures within the basal Mendi Group are nonpenetrative, were syntectonically annealed, and the sharp contact with the underlying Pale Sandstone suggests there will be no waste zone above this reservoir.

 

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)