Deepwater Offshore Southwest
Palawan - A Petroleum Province Beckoning (?)
deepwater (800 meters and greater) portion of the South China Sea
immediately to the southwest of Palawan Island has promising
potential to host significant hydrocarbon deposits.
is located within an attenuated continental terrane that is widely
believed to have separated from the Eurasian mainland as a result of
the opening of the South China Sea oceanic basin. Integrated
gravity, magnetic and seismic studies support the hypothesis that
basement in the area is largely acidic or continental in
composition. Exceptions occur in narrow structural depressions or
troughs floored by dense and magnetic basement, which are
interpreted to overlie basement fracture zones.
sections demonstrate that the area comprises a rifted terrane
characterized by a series of fault blocks regionally tilted to the
southeast, some of which are affected by recent folding and
faulting, inversion and igneous intrusion. A Mesozoic to Tertiary
stratigraphic succession is predicted from offset wells, sequence
stratigraphy of regional seismic data, and regional correlation with
basins peripheral to the South China Sea, consistent with an
episodic marine rift basin model.
source rocks with sufficient thermal maturity are expected to be
present in Paleogene syn-rift clastics and carbonates, and in
Mesozoic deposits similar to those inferred to occur in the west
Palawan shelf, Reed Bank and other South China Sea rift basins.
Charge modeling has delineated a number of potential generative
basins which could have yielded or are still expelling hydrocarbons
from potential source facies. Potential reservoirs are sandstone
units of Jurassic, Early Cretaceous, Paleogene and Miocene age, as
well as limestones of Late Triassic, Eocene and Late Oligocene-Early
Miocene age. The basal Middle Miocene deepwater shale interval - the
regional seal in the west Palawan shelf - is anticipated to extend
laterally to the area. Intercalated fine clastic lithologies may
provide intraformational seals within the Paleogene and Mesozoic
of play concepts typical of marine rift basins have been identified.
These petroleum plays are associated with potentially large
structural traps such as basement horsts, basement-cored
folds/anticlines, tilted fault blocks, and stratigraphic traps such
as reefal buildups, wedgeouts/onlaps, and deltaic sand bodies.