Abstract

In early 1992 an Australian International Development Bureau funded survey was conducted in the Philippines by the Australian Geological Survey Organisation in conjunction with the Philippine Office of Energy Affairs. Seismic, gravity, magnetic, bathymetric and geochemical data of NE Palawan, Cuyo Platform, Tayabas Bay and Ragay Gulf areas of the Philippines was collected using the Australian Research Vessel Rig Seismic.

The Palawan and Cuyo survey was a regional grid with line spacing of 5-10 km (Palawan) and 10-20 km (Cuyo). The object was to delineate potentially prospective and non prospective areas. Tayabas and Ragay survey which was more detailed was designed to infill and extend the existing grid.

The seismic data shows extensive structuring with deep depocentres of up to 6 seconds of layered sedimentary section. The major object was to improve the resolution of the seismic including deeper penetration and removal of the severe multiples. The greater clarity of the new sections and increased density of lines will allow better definition of leads

Geochemical anomalies were recognised in Palawan near the Roxas well site and in a separate anomaly 10-15 km NW of it. In Ragay Gulf there are many anomalies. Initial processing has confirmed that several are almost certainly of thermogenic origin.

In Ragay Gulf the oil and gas potential of the area appears high. The number of offshore seeps as well as onshore seeps on adjacent Bondoc and Bicol Peninsulas indicates there are mature generating source rocks with migration pathways to the surface. Potential traps abound. Reservoir potential is probably present in the several carbonate reefal buildups and in the sands of the clastic sequence.