Undiscovered Oil and Gas of New Guinea, Papua Barat, Seram and Timor-Leste

The eight conventional assessment units in New Guinea, Papua Barat, Seram and Timor-Leste. USGS map.

The estimate

Using a geology-based assessment method, the U.S. Geological Survey estimated means of 1.8 billion barrels of oil and 129.5 trillion cubic feet of gas that are undiscovered but technically recoverable, in eight assessment units within New Guinea (both Papua and Papua New Guinea), Papua Barat, Seram and Timor-Leste. Papua, Papua Barat and Seram are part of Indonesia.

F95 means a 95-percent chance of at least the amount shown; F5 is defined the same way. All results are fully risked.

A complex region

The region's tectonic history is described as one of the most complex in the world: movements of the Australia, Pacific and Philippine plates; several phases of subduction that closed ocean basins; arc-continent and microcontinent collisions; and regional extension from trench roll-back.

The assessment focuses on the petroleum systems along the Australian plate's northern and northeastern passive margin:

• Gondwana: from 90 to 45 million years ago, Australia was still joined to Antarctica, and a broad passive margin formed along Gondwana's northern edge.
• Breakup and collision: about 45 million years ago, Australia separated and moved northeast. In the latest Miocene and Pliocene it began colliding with the Sepik, Weyland and Melanesian arc terranes and microcontinents in the northeast, and with the Banda arc to the south.
• Thrust belts and basins: that squeeze built the Papua New Guinea Thrust Belt, the Papua-Lengguru Thrust Belt, and the foreland basins beside them — the Papua Platform, Arafura Platform and Bintuni Basin. The Salawati Basin may have formed through movement along regional wrench faults. Collision with the Banda arc built thrust belts and foreland basins on Timor-Leste and Seram, where regional extension also played a part.
• Source rocks: organic-rich rocks laid down in the Mesozoic along the passive margin were later buried under stacked thrust sheets, heating them enough to generate oil and gas.

The petroleum system

The USGS defined a single Mesozoic–Cenozoic Composite Total Petroleum System: oil and gas that may have come from Triassic, Jurassic and Cretaceous passive-margin source rocks, and from Neogene foreland-basin source rocks buried deeply enough during mountain building. Triassic and Jurassic organic-rich shales are most often cited as the likeliest sources, mainly on the evidence of oil geochemistry; Cretaceous and Neogene sources, known from little data, may matter locally.

• Generation: oil and gas formed from marine source rocks, possibly as early as the Late Cretaceous, peaking during late Miocene–Pliocene burial in the thrust belts and foreland basins.
• Traps: they migrated into structural traps in the four thrust-belt units, or into structural and stratigraphic traps in the foreland basins.
• Reservoirs: Jurassic to Cretaceous marine sandstones, Paleogene and Neogene carbonate platform-margin rocks, and shallow- to deep-water marine sandstones.
• Losses: oil and gas generated before Neogene thrusting may have been lost or remigrated, as the many oil and gas seeps in this region attest.

A generalized cross section of a thrust belt and its foreland; the dashed line marks the boundary between the thrust-belt and foreland assessment units. USGS figure, modified from Argakoesoemah (2018).

Results by assessment unit

The assessment's inputs are summarized in the fact sheet and in Schenk (2022). More results: the USGS Energy Resources Program.

Sources

Based on the USGS Eastern Asia Assessment Team (Christopher J. Schenk, Tracey J. Mercier, Marilyn E. Tennyson, Geoffrey S. Ellis, Cheryl A. Woodall, Phuong A. Le, Heidi M. Leathers-Miller and Ronald M. Drake II), "Assessment of Undiscovered Conventional Oil and Gas Resources of New Guinea, Papua Barat, Seram, and Timor-Leste, 2020," Fact Sheet 2022–3046, U.S. Geological Survey; a work of the United States government in the public domain. The results table and the figures are taken from the fact sheet's PDF.