Let me put it as I would understand it if it being explained to...

Let me put it as I would understand it if it being explained to me. Firstly any dirt is a prospect but obviously some are better than others why because there is more information about them than others. So a patch of ground stuck between fore holes that have been drilled say at each of the four corners of a small lease and none had found oil or gas would be considered a poor prospect but no one could give an absolute guarantee that there was no oil in the middle of the lease could they, But they could give a good educated guess and how many companies would be likely to put money into drilling holes in the middle? So because we have a lot of indications of what is going on underground and they have some I think it’s 2D seismic CVN can make some guess to what’s there which means we have a good prospect. This does not make it an absolute it just lessens the risk. Think if you go into your back yard and dig a hole at one end and find clay the only real assumption to make is that your yard is made up of clay soil, then you go to the other end and dig again and find sand the assumption changes to 50% sand and 50% clay dig again find sand again the maths changes again. That’s why they start at the start with things like seismic and progress to drilling if warranted.
As for the buying the leases you don’t actually buy them it’s an auction and you tell the government what you will do in the way of development of those leases if they give them to you. So a lease with big potential would likely have Woodside of BHP or such say we will drill 3 or 4 holes and little CVN might say we will reprocess some seismic so the government wanting the area developed would give yes give the lease to the ones that would do the most with it no up font money to the government.
Hope that helps it is simplistic and you may see someone tell me I am wrong.