Abstract: Petroleum System Comparison of the Phitsanulok Basin, Thailand with the Tucano Basin, Brazil

Thornton, Scott E. - Kerr-McGee Corp.; Ivan Peixoto Costa and Luciano P. Magnavita - Petrobras/E&P

Comparison of a proven, producing Tertiary lacustrine petroleum system in the Phitsanulok Basin with an underexplored petroleum system in the Tucano Basin was executed to analyze risks and generate new ideas for exploration by analog comparison. Lake type appears comparable during source rock and reservoir deposition, with both basins parts of larger ?chains of lakes,? with southward tilting. Individual paleolakes were separated by strike-slip faults in the Phitsanulok Basin vicinity and several transfer faults in the Tucano Basin. Cessation of ?deep? lacustrine deposition was caused by tectonic drivers in both basins: 1) regional M. Miocene compression in the Phitsanulok vicinity created a southward tilt, causing the lakes to drain, and 2) onset of South Atlantic rifting caused the Reconcavo-Tucano-Jatoba Rift to ?abort? in the Early Aptian, with little subsequent sedimentation.

Significant structural inversion formed the best traps in both basins, with associated remigration common. While the Phitsanulok Basin was river-dominated with monsoonal lake level fluctuations, the Tucano appears to have experienced more wave reworking of shallow lacustrine sandstones due to larger paleolake size. Proven reservoirs in the Lan Krabu Fm. in the Phitsanulok have thin beds and high lateral connectivity, whereas the undertested multiple reservoirs in the Central Tucano Basin, are thicker and of variable connectivity. The most significant comparison of the two areas is the relative exploration maturity: mature in the Phitsanulok and immature in the Central Tucano.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil