Despite extensive oil exploration in"Western Australia over the past 12 years no commercial oil fields have yet been found. A total ' of 66 test wells have been drilled throughout the State but only Rough Range No.s.. 1 and 1A have produced oil in significant quantities. Active oil exploration is now in progress in the" Canning, Carnarvon, Perth, Bonaparte Gulf and Officer Basins. Test wells have been drilled' in ,all of these except the Officer Basin, where the subsurface stratigraphy is still unknown. Large .areas of the other four have hot yet been drilled. It, is- probable that. commercial oil deposits will eventually be found' in these basins as they contain thick marine sequences, and have structures 'suitable for.,the. entrapment of oil. .