The petroleum geology of Cambodia has been studied less than has that of the neighbouring countries in Indochina. Nevertheless, the results of recent geological, remote- sensing and limited seismic investigations (the latter on the Cambodian Shelf area of the Gulf of Thailand) have allowed identification of sedimentary basins favourable for hydrocarbons exploration (both on- and offshore), and, consequently, the delineation of prospective areas. Six possibly oil- and gas-bearing basins have been identified, namely: the Siam (northern portion: in the Gulf of Thailand), Tonle Sap, Khorat (southern portion), Preah, Chung and Svairieng Basins.