Publication Name: Eastern Australian Basins Symposium III (EABS 2008)
Authors: K.C. Hill, K. Bradey, J. Iwanec, N. Wilson and K. Lucas
Date Published: September 2008
Number of Pages: 14
Abstract:
For 60 years oil companies blindly drilled the big surface bumps in the Papua New Guinea (PNG) fold and thrust belt and eventually found large oil and gas reserves that went on production in 1992. Since then we have greatly increased our understanding of the structural style in the fold belt, based largely on the drilling of over 250 wells and sidetracks, most with good tops, dipmeter and pressure data. Interpretation has been aided by improved seismic data and surface mapping, together with the acquisition and modelling of high resolution aeromagnetic data and of passive earthquake seismic data. Within basement, these multi-disciplinary techniques reveal large north–south-striking Triassic folds that influenced subsequent faulting, facies changes and reservoir compartments. Exploration for basement-controlled north–south faults down-plunge from the main producing fi elds is likely to yield signifi cant new hydrocarbon discoveries. Interpretation of seismic data, combined with reported analogue modeling of the PNG Fold Belt, indicates that early inversion faults were a prerequisite to substantial offset on thin-skinned detachments. These early structures probably trapped migrating hydrocarbons and may have shielded areas further south from hydrocarbon charge. Subsequent thin-skinned deformation decapitated the inversion crests, retaining the hydrocarbons in newly folded and thrusted hanging wall structures. There is considerable potential for new large hydrocarbon discoveries in deep inversion structures that have not been decapitated. Exploration for such structures will involve regional strike seismic lines to define the crest, and deep pockets to fund deep wells.