What people should also consider is that the 10 largest...

What people should also consider is that the 10 largest producing fields supply approx. 19mmbls per day. They were discovered between 1922 and 1982 (average 1963). These fields are all in decline and when a field goes into decline they decline quickly. However, with water flooding and gas injection their production rates have been propped up, so not falling as fast as they would under natural conditions. Also, the operators have been putting more and more wells on these fields to replace declining production from older wells. This might be okay in the short term but medium to longer term it damages the fields and mitigates ultimate recovery rates. How long this lasts is anyone's guess.

There is a lot of speculation about Ghawar in SA but nobody really knows how quickly this is declining because the Saudis won't release any figures on production. They are however feverishly flooding the field with water to keep the ROP up. But sooner or later the water cut is going to become to great.

Have a look at this link http://www.energydigital.com/utilities/2676/Top-10-oil-producing-fields-in-the-world