The R 10 Marine Seismic Survey was conducted during March, 1976 within EPPs 10 and 11 to detail the previously indicated Galah, Kookaburra and Rosella-Jabiru leads. This survey defined three structurally sound closures, Galah, Kookaburra East and Kookaburra West, while eliminating the Rosella-Jabiru lead as a viable exploration target. No other leads of sufficient potential size to offset the great water depths could be mapped from available seismic coverage on these permits. Detailed potential reserve evaluations of the three closures generated the following estimated middle rewards for both recoverable free gas and oil. Associated chance factors are shown in brackets: - GALAH - [gas] 451 x 10E9 cu. ft (0.047) [oil] 12 x 10E6 bbls (0.066). - KOOKABURRA WEST - [gas] 227 x 10E9 cu. ft (0.050) [oil] 6 x 10E6 bbls (0.062); - KOOKABURRA EAST - [gas] 221 x 10E9 cu. ft (0.054) [oil] 5 x 10E6 bbls (0.059); The great depths to the predicted reservoir (Platypus Formation) were thought by Shell to make the probability of gas filling only, much more likely. The distances from shore (greater than 250 km), water depths (greater than 1 000 m) and likelihood of poor reservoir development, coupled with the high chance factors and probability of gas filling, were regarded as considerably downgrading to the prospects identified within EPPs 10 and 11. It was therefore decided to surrender these permits prior to their entering the third permit year (first renewal) which commenced from 8th May, 1977.