Quaternary volcanics in Southeast South Australia are the source of carbon dioxide encountered in some petroleum exploration wells in South Australia and Victoria. This carbon dioxide, within the hydrocarbon province of the Otway Basin, presents a risk for petroleum exploration. Evaluation is necessary of possible carbon dioxide migration pathways and traps associated with trends of volcanic centres and faulting. Detailed aeromagnetic and seismic surveys may enable delineation of intrusives and prediction of carbon dioxide migration pathways to reduce hydrocarbon exploration risk in the Otway Basin. It is recommended that a high resolution aeromagnetic survey be flown over the volcanic province using flight height 80-100 m, flight path direction northeast-southwest and flight line spacing 250-500 m. (author). 7 fig., refs.