Geology and Petroleum Potential of Ragay Gulf, Tayabas Bay, Northeast Palawan Shelf and Cuyo Platform, Philippines

The Philippines is currently energy deficient and there is a continuing dependence onimported petroleum for many industries, especially in the transport sector. TheGovernment of the Philippines has therefore decided to actively promote oil and gasexploration in the country, encouraged by recent studies and exploration resultssuggesting that potential oil and gas reserves exist in offshore Philippine basins. TheDepartment of Energy (DOE) has identified tectonic complexity and lack of geoscientificinformation as contributing to the low level of petroleum exploration in the majority ofthe thirteen identified offshore basins. The Government has therefore requestedAustralian assistance in the form of a comprehensive offshore seismic survey in selected,potentially oil-bearing, basins.
The survey project undertaken from September 1991 to June 1994 had two mainobjectives:
- to upgrade the knowledge of petroleum pro spectivity of selected areas in thePhilippines and to promote potential opportunities for future Philippines - Australiajoint venture exploration; and
- to assist the Philippines Government in acquiring the skills necessary to acquire andinterpret seismic data and other petroleum-related information, and use these to focusfuture petroleum exploration in Philippine waters.
The project was funded by the Australian International Development Assistance Bureau(AIDAB), and involved staff of the Australian Geological Survey Organisation (AGSO) working in co-operation with staff from the Philippine DOE. Data were acquired usingthe Australian geoscientific research vessel, Rig Seismic, during a forty-five day cruise from late March to early May, 1992. The survey resulted in 2750 line km of new seismicand magnetic data, and nearly 5000 km of geochemical, gravity and bathymetric profilingdata. The work was undertaken in four areas: Ragay Gulf and Tayabas Bay (offshoresoutheast Luzon), and the Northeast Palawan Shelf and Cuyo Platform (northeast ofPalawan).
Interpretation of the survey data has indicated that the survey was successful in its mainobjectives. The new seismic shooting achieved penetration to depths greater than thosepreviously reached, thus allowing improved definition of key horizons and structuralfeatures. In the Ragay Gulf, major fault systems controlling the distribution ofhydrocarbon traps are now better understood and have been mapped more accurately. Animportant limestone formation containing possible petroleum source and reservoir rocks,the Late Oligocene to Early Miocene Panaon Limestone, was shown to be much moreextensive than was thought of before. The formation also included reefal deposits whichmay provide attractive targets for future exploration by oil companies. Three separatesource 'kitchens' where petroleum source rocks are sufficiently deeply buried for oil andgas generation to be occurring, were identified in the Ragay Gulf area. Structural leadscontaining potentially commercial quantities of hydrocarbons were identified in eight areasof the basin. These were mapped with sufficient accuracy to estimate likely reserves.

Tags: Earth Sciences, GA Publication, Published_External, Record, geology, petroleum exploration, seismics
Organization: Geoscience Australia Data