PESA ACT/NSW Christmas Party

PESA NSW & SPE NSW Christmas Party

PHILIPPINES GEOLOGY AND PETROLEUM POTENTIAL

The petroleum potential of the Philippines has long been regarded by “industry experts” as average at best. The Philippines is a country with active crustal plate movements, subduction zones, regional wrench faults and active volcanoes located on the western edge of the Circum-Pacific “Ring of Fire”.

Geologically, the Philippines is the eastern rifted edge of Asia, which was initially separated by rifting and the development of the South China Sea commencing in the Eocene. Initial rifting resulted in the deposition of an Eocene clastic section, dominantly non-marine with extensive coal development.

The appearance of oceanic crust in the late Oligocene initiated the drift phase with development of extensive barrier and pinnacle limestone reefs on the upthrown sides of the large normal faults created by rifting. These Oligocene to Early Miocene reefs created the reservoir for many of the large gas fields discovered to date, eg Malampaya, which largely sourced the gas from the underlying coal measures. About 10 million years ago the Asian, Pacific and Australian crustal plates collided creating compression, subduction, regional wrench faults and volcanism. This tectonic activity caused regional uplift, particularly in the west of the Philippines centred on east Palawan and deposition of Early-Mid Miocene sedimentary deposits, dominated by an extensive deep water marine clastic section with excellent quality sandstone reservoirs. Waxy oils waxy with associated gas are the main hydrocarbon discoveries. These hydrocarbons have been sourced by both marine and non-marine organic matter.

The Late Miocene to present day sedimentary section is dominated by a thick section of marine marls and limestone reefs with associated volcanism adjacent areas of plate to subduction. The Tertiary to Recent geology of the Philippines is very similar to that recorded in Indonesia, Thailand, Vietnam and parts of offshore China. The Philippines experienced extensive petroleum exploration in the 1960s but concerted exploration efforts since then have been patchy. Whilst trap integrity is considered the main exploration risk, there is still excellent potential for oil and gas discoveries of significant size. Gas2Grid Limited has been active with onshore petroleum exploration in the Philippines since 2005 and the author since 1981.