The majority of the aoi prospects you speak of were purchased from 3rd rate venture micro caps for peanuts....most likely for good reason.  See, for example,  the purchase of AOS's 5 billion barrels (kenyan resources) for roughly CAD 3 million.  Blocks have been previously drilled in some cases without success:

http://www.nationaloil.co.ke/upstream/index.php?flag=upstream&ust=5