The 1st AAPG/EAGE PNG Geosciences Conference, PNG’s Oil and Gas Industry:
Maturing Through Exploration and Production

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Petroleum Prospectivity of the Fly Platform: Some New Perspectives

Abstract

New structural mapping using reprocessed seismic data has delineated prospective structures in several areas of the Fly Platform near the mouth of the Fly River, PNG. These features extend landwards towards an area where there is active oil seepage, the Panakawa Seep, today. A critical reassessment of all the wells drilled in this general area shows that many of the wells had strong indicators of oil and gas while drilling and most were not drilled on closed structures. The majority of wells were drilled before 1965 when there was either no seismic, refractions lines or minimal 2D seismic lines. A reassessment of the geochemistry of these wells indicates that the major source rocks are mostly Jurassic algae-rich shales with lacustrine affinities, not unlike the oil from the Panakawa Seep. The prospective structural traps should contain good reservoir quality quartzose sandstones of mainly Early Cretaceous and Jurassic age, and the traps are sealed by younger Cretaceous and Tertiary shales and marls. Migration pathways for gas and oil are provided by internal vertical migration through near vertical faults that extend into underlying source rocks. Some horizontal migration is also predicted as has shown to exist to set-up already discovered gas fields such as Puk Puk and Douglas. The key to finding gas and petroleum liquids in this region of the Fly Platform is dependent on good structural mapping along with predictive source migration pathways. Dry hole analysis studies have shown that in addition to Basement closure some essence of mapped closure is also necessary at the Base Carbonate level. Surface geochemical techniques followed by infill seismic will help identify the best prospects for drilling in a region where access by barge and land will enable exploration costs to be far lower than elsewhere in PNG. This paper will be illustrated with key seismic lines, cross sections and maps showing the prospective features.