Coordinates: 4°34′N 114°11′E / 4.567°N 114.183°E Rasau is an area in Brunei. The area contains one of the two oil fields of Brunei, the Rasau Field, and a small village, Kampong Rasau, which has a population of 103.
Rasau is located in the Belait district on the west bank of the Belait River south of Kampong Sungai Teraban, close to the district capital of Kuala Belait. It is one of the villages in Mukim Kuala Belait. It is located at 114°11′E longitude and 4°34′N latitude. To the north lies Kampong Sungai Teraban. The Malaysian state of Sarawak lies to the west and south with the Asam Paya oil field to the southwest. Across the Belait River to the east lies the southern portion of Kuala Belait and Kampong Sungai Duhon.
Rasau was historically one of the first stops on the Belait River upriver from Kuala Belait towards the former district administrative capital of Kuala Balai. It was founded further inland from the mouth of the Belait River and Kuala Belait for protection against pirates.
Commercial hydrocarbons were first discovered in Rasau in 1979, and production began in 1983. A blowout of one of the wells in the Rasau Field, Rasau-17 occurred in April 1989. The resulting fire lasted from 25 April to 8 May when it was finally extinguished.
Rasau gained prominence in the latter half of the 20th century when a bridge was built across the Belait River providing a route to Miri in Sarawak, Malaysia without the need for any ferry crossings across the Belait River. However, the bridge was not opened until after a family of Malaysians drowned at the ferry point during heavy rain.