According to Tryoty's earlier (partly reposted below), Symon's figures would make the 18 EEZ prospects so far identified "high risk" structures on average.
FYI, Bayfisherii, my original posts on the subject were not well recieved here.
Ex-Tryoty:
"Prospect - a lead which has been fully evaluated and is ready to drill
Chance of Success - An estimate of the chance of all the elements (see above) within a prospect working, described as a probability. High risk prospects have a less than 10% chance of working, medium risk prospects 10-20%, low risk prospects over 20%. Typically about 40% of wells recently drilled find commercial hydrocarbons."