2 seismic refraction surveys were carried out by the SA Department of Mines 27 miles north of Port Augusta for Santos, following the finding of traces of crude oil in Wilkatana 1, to investigate whether the possibility exists of a basement high over which Tertiary sands may be draped in anticlinal form [i.e. giving a potential structural trap for migrating petroleum]. The first survey, centered on Wilkatana 1, was designed to establish the direction and angle of dip of the basement. The second survey was subsequently located 4500 feet away in an updip direction. A limestone layer lying at 470 feet depth in the drillhole was not refracted, but basement depth was calculated to lie at between 540 feet and 720 feet. Further seismic interpretation was deferred pending making a velocity determination of the limestone.