Ann: Significant Upgrade of Kingia Gas Discovery, page-369

More likely Day Traders just taking profits.

There are a heap of Day Traders out there who buy into oil exploration companies pre drilling and either sell into the hype a few days before drilling results are released or they sell once the results come out and they move onto their next target Company.
These traders have no intention of holding the Company shares for more than a few weeks.
They are in it for a quick buck and they move on.

That's why 90% of the time when good drilling results come out you are better off taking your profits within the first hour and buying the stock back a few days later at a lower price.
It doesn't always work but over time you should make a lot more money doing that (subject to your tax situation).