Three stratigraphic wells (Ooldea no. 1, Reid no. 1, and Reid no. 1A) were drilled by the South Australian Department of Mines during 1976 in an area that includes margins of the Officer, Arckaringa and Eucla basins. Principal objectives were to test the stratigraphy, and to identify seismic refractors, over mapped Bouguer gravity and magnetic anomalies. Of particular importance was identification of a seismic refractor with a velocity of 3.14 km/sec that was originally interpreted to represent Permian sediments. Subsequent drilling found it to originate within a ?Palaeozoic sandstone, siltstone and dolomite sequence. Ooldea no. 1 was drilled in an area of relatively high magnetic intensity and low Bouguer gravity. It penetrated 27 m of Miocene Nullarbor Limestone overlying 2 m of ?Tertiary claystone, overlying 223 m of ?early Palaeozoic sandstones, siltstones and dolomites and 35 m of ?Proterozoic sandstone and quartzite resting on crystalline basement. Reid nos. 1 and 1A were drilled in an area of relatively low magnetic intensity and high Bouguer gravity. They penetrated 33 metres of Eocene Wilson Bluff Limestone overlying 14.5 m of Eocene Pidinga Formation, overlying 175 m of ?early Palaeozoic sandstones and siltstones.