Thriving off oil

Both over the years and hearing stories about the "middle east" I have felt as though the middle east thrives off oil.  However when I was reading through the text book it was made very apparent to me that oil was the only thing that the middle east had.  If oil weren't as popular as it is today, the middle east, dubai and Iran would have virtually no money.  These countries are living off of something that is diminishing more and more every day which sets them up to completely run out fairly soon.  This is interesting to me because present day there is so much talk about these middle eastern countries, and the power that they hold because of how much land they have that is filled with oil.  The middle east participates the most out of any region of the world in the selling of oil, and its inevitable that they will run out pretty much wiping these countries off the list of "world powers".  There seems to be a trend when comparing the two maps.  Oil is located on planes that are very close to sea level.  Why is this the case? now that is a very tough question to answer and there would have to be some map of the geography of the middle east about 100,000 years ago to truly understand why this trend is present.  

One inconsistency that I noticed was how they called Iran one of the most important countries with oil even though when looking at the map which clearly shows where there are large oil fields, it seems as though oil is pretty scarce.  Im not to sure if this is just the book contradicting itself which happens fairly often, or it could just be talking more about the size and how much political pull Iran has, as opposed to how much oil it contains.