AIM: The MESA Wallatinna Seismic Survey was programmed to provide sufficient new data on the eastern Officer Basin, together with petrophysics and petroleum geochemical updates, to stimulate renewed interest and reduce exploration risk such that in the near future a major exploration effort could be mounted by the private sector. The SAEI-funded Wallatinna grid linked seismic acquired in the mid-1980's in former PELs 29 and 30 by Comalco Aluminium Ltd (Exploration Div.) and Amoco Australia Petroleum Co., and was designed to investigate the southwestern extension of the Manya Trough and Marla Overthrust Zone in the eastern part of the basin where most of the oil shows have been recorded. In particular, the origin and structural position of the Middle Proterozoic Ammaroodinna Inlier in this region was to be delineated, and a reliable stratigraphic correlation between the potentially hydrocarbon-generative Munyarai and Manya Troughs was to be pursued. The additional biostratigraphic and petrophysical studies being undertaken of wells throughout the basin were intended to provide a more effective correlation of the Neoproterozoic succession, plus improved reservoir characterisation. The Wallatinna Survey was recorded over land held in freehold title by the Pitjantjatjara Aboriginal people, and was subject to an access agreement signed following substantial discussions with the landowners and the conduct of associated cultural investigations by their representatives and anthropologists. Aboriginal cultural topics, operational safety procedures and environmental issues formed the basis of a mandatory pre-survey induction course attended by all contractors entering the Aboriginal land, Anangu-Pitjatjantjara Council staff and MESA survey supervisors, which contributed to the successful and incident-free conduct of the work. METHODS: Survey dates: 13/8/93 - 25/9/93. Energy source: Vibroseis. CDP coverage: 12 000%. Recording mode: 240 channel digital - Geocor IV recorder. VP interval 20.0 metres, group interval: 20.0 metres. RESULTS: Nine 2D seismic lines totalling 378 line km were acquired by contractor Geosystems Pty Ltd, and then were processed in Brisbane by Digital Exploration Ltd, together with the reprocessing of another 7 lines (approx. 140 line km) of 1980s Comalco Exploration seismic (mainly thumper) data. Ground magnetics were also recorded every 20 metres along line 5 (62.5 km), with gravity readings every 200 metres, to cover potential plays along the boundary between the Manya Trough and Ammaroodinna High. These data were intended to complement the new seismic work, and will be integrated with future aeromagnetic surveys. Major thrust complexes generated by the Alice Springs Orogeny had been identified on previous seismic recordings along the Officer Basin's northeastern margin, and such thrust plays were a prime target of the Wallatinna interpretive work. The new data proved to be of sufficient quality to allow detailed seismic stratigraphic analysis, enabling the mapping of source-prone and reservoir-prone systems tracts. While the eastern Officer Basin is seen to be characterised by extensive thrust faulting in the cover as well as basement, it can also be seen that the Petermann Ranges Orogeny has caused local structural inversion prior to Cambrian deposition. Both the reprocessed Comalco and new MESA seismic data revealed a number of small to large ramp anticlines and partially eroded duplex structures. Although Permian erosion has locally breached some potential traps down to Middle Cambrian levels, reservoirs ranging from Neoproterozoic to Ordovician in age are largely preserved.