I have a friend in Houston, TX who is an investment banker. He  mentioned a 
project he was working on for purchasing 55 square miles of land in  Texas for 
oil drilling. I told him that I thought all the oil was gone from  Texas and 
this is his reply.
 
 
I might have thought the same thing.  I have a good  friend, a PHD 
Geophysicist and former professor of geology at the  University of Utah, who thinks that 
the oil and gas yet to be discovered is  equal to what has so far been found. 
 He bases his conclusion on what he  describes as the reality of geology vs. 
what geologists "thought" about  geology.  He says that based on the data and 
information  available 25 years ago anyone might conclude that the product yet 
to  be discovered was declining.  The reality is that there is a huge 
contrast  between the information available now about the subsurface vs. the  
thinking before the advent of the technologies we now use in the search for oil  and 
gas.  The new technologies show that what was thought to be true, is  not.
 
Most of the geophysicists I know say the same thing.
 
I might add that what I do is move the  risks of investment in the sector to 
the energy company - investors do not  participate; unless they choose to do 
so by investing in a completely  separate investment.  The goal is to invest 
and get capital back in a short  period of time - low  risk