Athena SNE 3, page-5

10mc and @rae915
This is what the Oct Quarterly actually says:

"FAR believes there is additional net pay and resource potential not included in the preliminary assessment of contingent resource estimates for the SNE field. This includes thin bed reservoir sands that, recent detailed post well analysis has indicated encouraging reservoir characteristics.
Two wells in the appraisal program will be located to appraise the SNE field (SNE-2 and SNE-3 as shown in Figure 2). They are expected to intersect all potential reservoir zones and the wells will be flow tested (drill stem tested) and cored at certain intervals. Both of these wells will be logged, cored and flow tested as part of the evaluation program"

ie SNE 2 and SNE 3 between them are expected to intersect all potential reservoir zones (ie blocky sands, upper thinner sands and the "additional thin bed sands", not SNE3 alone as you selectively have it in your post. In any event, it is by no means clear whether the 15m upper pay interval tested at SNE 2 included the additional thin bed sands but even if it did the reported net pay was only 3.5m at the SNE 2 location.

So could SNE be holding 1 billion barrels of oil as a result of the "additional thin bed sands", the short answer is NO.

pj

ps
The longer answer is:
By way of example only, an assumed economically recoverable 4 meters net pay at a (generous?) 25% recovery (if that were possible) over a near maximum 100sq km from my oil in place calculations would equate to approximately 100mb and that assumes all sorts of stuff like continuity and averaging over the whole area. So I regret to say your number of 1 billion in relation to the possible impact of these sands is totally "plucked out of the air".