Natuna Sea and Sarawak Basin

The Natuna Sea area is the southern extension of the South China Sea, mainly in the Indonesian territory. This area is divided by two parts by Natuna Arch, namely West Natuna Basin which extend to Malay Basin in West Malaysia and East Natuna Basin which extend of Sarawak Basin in East Malaysia

The West Natuna Basin was formed as an intra-continental rift basin within the Sunda Platform, the southern margin or Eurasian Plate. The basin has undergone Eocene-Oligocene extension, followed by Miocene to present day contraction and inversion.

In Late Cretaceous-Early Eocene reconstruction, East Natuna Basin was part of a large fore-arc basin extending from offshore Veitnam, across Natuna Sea to Sarawak. The SW-NE trending structures in East Natuna Basin are controlled by extensional faults and half grabens similar to the ones found in West Natuna Basin, but the rift magnitude is generally less than the ones in the West Natuna Basin.



West Natuna Seismic Sections
Seismic reflection section over the Anambas graben. Tectonic inversion over the graben occurred during the Miocene. Brown marker is the top Oligocene, Gabu formaion wheras the blue marker represents the Pliocene unconformtiy after inversion. The bright spots near basement may represent lacustrine source rocks with high TOC. Source: Fenstein, 2000.

Play concepts for West Natuna basin (Netherwood R., 2000, after Fainstein and Meyer, 1988)












East Natuna Seismic Sections




Seismic reflection section of East Natuna. No inversion occurs in this area. Blu marker represents top of carbona te reservoirs. Bursa is an oil field and Alpha-D is teh giant Natuna gas field (source: Fainstein, 2000).










Play concepts for East Natuna basin (source: Netherwood R., 2000, after Fainstein and Meyer, 1998)








ION Geophysics acquired deep seismic in Natuna area. The sections go as deep as 40 km. Below are a map and a sample section from their brochure  

 

References:
Netherwood R., 2000, The Petroleum Geology of Indonesia, in: Blunden, T. (ed.), Indonesia 2000, Reservoir Optimization Conference, Schlumberger