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Linda R. Sternbach1, John R. Conolly2
(1) Globex Energy, Houston, TX
(2) Petrofocus Pty. Ltd, Sydney, Australia

Abstract: Investigation of a Neogene Petroleum System in the Ragay Gulf, GSEC 76: A Frontier Province in the Philippines

Surface oil and gas seeps occur throughout the Ragay Gulf and its onshore margins, the Bondoc and Bicol peninsulas. Geochemical studies show that oil and gas has been generated from shales in the Early Miocene Vigo formation, which underlies younger Miocene carbonates and deepwater clastics in the offshore Ragay Gulf.

Seismic investigation shows that the Ragay Gulf consists of three major tectonic blocks: Anima Sola graben to the east, Burias High in the center and Bondoc sub- basin to the west. The Burias High is cored by thickened crust which remained uplifted and stable during deformation, and the high has been flanked by thick Miocene/Pliocene depocenters which contain possible fault-bounded hydrocarbon traps.

The hydrocarbon “kitchen” of the Bondoc sub-basin was tectonically deformed into an anticlinal trend during the late Miocene. This was driven by the compressive wrenching of the central Bondoc fault, a splay of the 1300 km-long Philippine strike slip fault, that bisects the Philippine islands. The whole region is tectonically active today, creating an active petroleum system with migration of oil and gas into Late Miocene/ Early Pliocene carbonate buildups. These carbonates include pinnacle reefs located on the flank of the Burias High, within the Bondoc sub-basin, and platform and reef deposits on the Burias High.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana