Abstract: Petroleum Systems of the Papuan Basin, Papua New Guinea, and their Exploration Potential

R. L. Kaufman, J. C. Phelps

The Papuan basin of Papua New Guinea is a mature basin with a complex geologic history. The basin was initiated during Permo-Triassic rifting of the northern margin of Australia Passive margin sedimentation occurred until the Oligocene to Recent when the basin was compressionally inverted, resulting in the formation of the present-day fold and thrust belt. Numerous hydrocarbon fields, some commercial, occur in traps along the front of the thrust belt.

In mature complex basins such as this, it is critical to fully characterise existing petroleum systems as well as deliberately search for new systems. A recent systematic synthesis of the available geochemical data has defined three systems. Most important is the Jurassic system which is responsible for most of the oil and gas fields and all commercial production. Cretaceous and Tertiary systems, newly discovered in the basin, are based on detailed isotope and biomarker analysis of numerous oil seeps. These additional petroleum systems open up new plays for exploration.

To better define the pre-thrust basin geometry and help constrain the timing of hydrocarbon generation and migration, a series of palinspastically-restored cross-sections were constructed. Maturity modelling at different basin locations along these cross-sections evaluated the relative importance of two important scenarios: 1) pre-thrust generation from local kitchens behind the present thrust belt, and 2) syn-thrust generation by loading of stacked thrust sheets within the fold belt. The relative importance of re-migration from pre-thrust traps vs direct charging into present day fold belt traps was evaluated using oil composition data.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France