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The Devonian of Western and Central Australia consists of sedimentary rocks deposited in intracratonic basins. No igneous activity is known. Devonian rocks are scattered over more than one million square miles and fall into three divisions:5,000 to 10,000 feet of mainly Upper Devonian marine platform limestones and sandstones in the three western basins with laterally equivalent siltstone and shale in the Canning and Bonaparte Gulf Basins;Upper Devonian terrestrial fish-bearing quartz sandstone and associated siltstone and conglomerate in the Amadeus Basin (12,000 feet) and Dulcie (500 feet) and Toko (unknown thickness) synclines; andpoorly known probable Lower and Middle Devonian red-beds and evaporites in the Canning Basin (8,000 feet), barren quartz sandstone in the Amadeus Basin (3,000 feet), and vertebrate-bearing quartz sandstone in the Dulcie (1,500 feet) and Toko (500 feet) synclines.Except fr the Amadeus Basin, all these rocks are flat-lying to moderately tilted, and high-angle faults are the chief structural elements. Metamorphism is wholly absent except adjacent to major faults. Steep dips in the Devonian of the Amadeus Basin are related to folding. The rocks of the first division represent part of a depositional phase which continues into the Lower Carboniferous; divisions (ii) and (iii) are probably the end phases of depositional cycles which started before the Devonian.Interesting features of these rocks are the well-exposed and essentially undeformed carbonate reef complexes of the northern Canning Basin and the Bonaparte Gulf Basin, the thick Frasnian sandstones of the Bonaparte Gulf Basin, and the thick redbed-evaporite sequence of the southern Canning Basin. The reef complexes with their associated basinal facies provide prospects for petroleum production.

Rough Range No. 1 was the first well to be drilled for oil in Western Australia in the post-war period. It was spudded on September 5th, 1953. At a depth of 1100m, the well encountered a flow of oil at a rate of 500 bbls per day from the Early Cretaceous Birdrong Sandstone. This first discovery of flowing oil in Australia set off a boom in exploration for oil that rivalled the gold mining booms of the last century. The discovery well was drilled for a total of 20 months, encountering a section of Tertiary, Cretaceous, Jurassic, Permian, and Carboniferous -? Devonian rocks. By May 1955, when Rough Range No. 1 was terminated, a further seven wells had been drilled on the Rough Range Anticline and all were dry. Late in 1955, Rough Range -9 was drilled but also proved dry. Rough Range-10 was drilled less than 200m from the discovery well but only found a thin, non-commercial pay zone.Studies of the Rough Range structure, incorporating data from all of the wells and the intense seismic mapping of the feature show that the area of closure is very small and the total accumulation could not be more than 282,000 bbls of oil in place in the reservoir.Assuming a 30% recovery factor, the accumulation is capable of producing approximately 84,600 bbls. Of this, 16,900 bbls has already been produced in a 48-day production test of Rough Range-1 A in 1955. WAPET believes that the small remaining reserves, even at world parity pricing, are not economically viable.Although the small accumulation at Rough Range No. 1 was a disappointment to WAPET, this first post-war oil well proved to be a "lucky break" and a big stimulus for oil exploration in Australia.

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