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West Natuna Basin is situated approximately in the middle between Malay Peninsula Basin and The Kalimantan Island which was developed in intracontinental rift-basin within the Sunda Platform. Major oil companies such as ConocoPhillips, Premier Oil, Gulf, and Petronas, have explored the southwest - northeast trending of very prolific basin and produced hydrocarbon.West Natuna Basin was formed during Eocene time which was characterized by SW-NE half-graben rifting. Tectonic quiescence was occurred in middle Oligocene to Early Miocene and followed by subsidence of the basin where abundance sediment of Keras and Upper Gabus shale were developed very well. Tectonic inversion was taken place in the middle Miocene that was identified by unconformity at Barat Formation and Intra Arang Formation. Significant inversion was occurred at the northern area of the West Natuna basin, while it was not occurred at the main area. The regional gentle subsidence was occurred during Middle Miocene when Muda Formation was deposited. The maximum subsidence was occurred close to the Malay-Indo border.Benua/Lama shale, Keras and Barat Formation was recognized as good source rock. Most of them was classified as type I kerogen of lacustrine shale. In this basin, oil window formed at depth 7000 ft. Lower Gabus Sandstone was recognized as reservoir which has 15-350 ft thickness, and the sandstone has good porosity ranging from 10%- 27%. The Gabus Sandstone represent at Anoa and KF Fields. Upper Gabus sandstones are primary reservoir for most fields in the West Natuna basin that were deposited in the distributaries channel, channel bars, and crevasse splay. This sandstone has porosity up to 30% in the upper part. The Barat shale overlaid Upper Gabus Formation where it would be sandy in the northeastern area and known as Intra-Barat sandstone. Lower Arang is also important reservoir with excellent porosity ranges from 26%-32% that was discovered in Belida, Belut, and Kakap fields. Middle Arang sandstone has porosity up to 32%, and is generally a good reservoir. Barat shale provided effective regional seal rock for Lower Gabus Sandstone. Greater thickness formed at the center of the basin and toward Malay Basin to the west (up to 1000 Ft). Widely spread of Arang shale in the basin also provides effective regional seal for Lower Arang Sandstone. Anticlines trap is favorable trapping because of tectonic inversion regime. Stratigraphic trap was also discovered in Belida field as crevasse splay and stratigraphic pinch out. Combination structural and stratigraphic trap is also formed in normal fault along southern part of the basin.Even though exploration has been done since 1970s, there are several parts of the basin which has not explored yet or unsuccessful exploration. This poster will describe how the structure or stratigraphic trap developed on those areas.