Petroleum was discovered in 1929 after several fruitless attempts. Two men, F. F. Marriot and T. G. Cochrane, smelled oil near the Seria river in late 1926. They informed a geophysicist, who conducted a survey there. In 1927, gas seepages were reported in the area. Seria Well Number One (S-1) was drilled on 12 July 1928. Oil was struck at  on 5 April 1929. Seria Well Number 2 was drilled on 19 August 1929, and, , continues to produce oil. Oil production was increased considerably in the 1930s with the development of more oil fields. In 1940, oil production was at more than six million barrels. The British Malayan Petroleum Company (now Brunei Shell Petroleum Company) was formed on 22 July 1922. The first offshore well was drilled in 1957. Oil and natural gas have been the basis of Brunei's development and wealth since the late 20th century.