The programme of work pursued over EPP 5 was as follows: Permit Year 1 - interpretation of 407 line km of regional reconnaissance 6 and 24-fold reflection seismic data recorded in the 1968-69 R 3 Marine Seismic Survey, plus the ongoing review and integration of previously acquired geological and geophysical data; Permit Year 2 - the acquisition, processing and interpretation of 435 line km of regional reconnaissance 24-fold reflection seismic data and some deep crustal seismic refraction profiles in the 1969-70 R 4 Marine Seismic Survey, using GSI's M/V Polaris; Permit Year 3 - the acquisition, processing and interpretation of 1159 line km of regional reconnaissance 24-fold reflection seismic data in the 1970-71 R 5 Marine Seismic Survey, using Western Geophysical's M/V Marchant III; - based on the new seismic work and other information, a regional geological review was performed to assess the area's sedimentation history and select potentially drillable traps; Permit Year 4 - the acquisition, processing and interpretation of 1084 line km of regional reconnaissance and semi-detailed (on a 5 km grid accuracy) 24-fold reflection seismic data in the 1971-72 R 6 Marine Seismic Survey, using GSI's M/V Dunlap. This survey aimed to define the orientation and fault pattern of structures found by previous seismic on the southern margin of EPP 5, which extend downdip principally into the deep water, continental shelf break region of EPPs 10 and 11; - seismic stratigraphic studies were undertaken to tie local seismic markers to broader basinal stratigraphic features, and the tectonic framework model for the permit was developed. No anticlinal closures had been identified, but two areas of likely stratigraphic wedge-out traps had been found, plus a possible normal fault-zone play located in 800-1000 feet water depth; - the decision was made to farm out a 50% interest in EPP 5 in order to fund further seismic and drilling investigation of the permit's deep water portion, so as to fully evaluate it and make optimum use of correlations to Shell's recently drilled Platypus 1 and Echidna 1 wells and onshore Eucla Basin geological information. The farmout proposal was offered to 26 companies in Australia and overseas; Permit Year 5 - no interest in Shell's EPP 5 farmout offer was received from any company approached, ostensibly because of the perceived high risk of drilling offshore stratigraphic traps, and the lack of available dip-fault or combination closures in shallow water that would be drillable with conventional rigs; - the acquisition, processing and interpretation of 402 line km of 24-fold detailed reflection seismic data in the 1973 R 7 Marine Seismic Survey, using GSI's M/V Eugene McDermott II, with the aim of verifying the structural viability of the Potoroo strong lead and another (Bunyip) to the east. Both leads were confirmed to prospect status, with Potoroo being judged as the more attractive of the two because it exhibited additional dip closure at all three mapped intra-Cretaceous levels; - a permit evaluation report was written for EPP 5 dealing with its geological setting, reservoir objectives, structure mapping, source rock identification and petroleum generation and migration possibilities; Permit Year 6 - the operator spent all of this year attempting to obtain a contract for drilling a deepwater well at the Potoroo Prospect. Logistic and technical hurdles held up the signing of a rig, since both existing rigs and those being built in the region were unavailable in the short to medium term and were also inadequate to the task without substantial design modifications; Permit Year 7 - the Potoroo 1 wildcat was drilled to economic basement at TD 2924 metres depth KB using Esso's anchored drillship Regional Endeavour, then was plugged and abandoned, having failed to encounter significant hydrocarbons. Despite the well's lack of success, it enabled good seismic marker ties to the Bight stratigraphic sequence to be achieved, assisting with seismic stratigraphic and depositional environment correlations to Cretaceous sediments deeper in the basin in EPPs 10 and 11, that were later mapped by Shell's R 8 and R 9 surveys.