This quote from Maugari is very strange. Original oil has got to refer to "Original Oil in Place" - OOIP. The Saudi's have a graph in their "Response to Simmons" presentation showing it growing steadily and linearly since the Saudi takeover to about 700gb IIRC. Add on another 200gb of al-Naimi handwaving and you have 900gb of OOIP. But there is no way this could possibly be considered reserves - that implies 100% recovery rate. Even the most optimistic projections are not claiming more than 60%-70% recover from Saudi Arabia (which would be double the industry average). Is Maugari confused, or deliberately misleading?

How could you possibly recover 100%?  Dig shafts into Ghawar and mine the stuff?
Mike Lynch floated that idea once. Oil mines were common in the early days of oil. That was Colonel Drake's original plan too. He was going to mine the oil, but then he decided to drill for it instead.
http://www.sjgs.com/history.html
There was a thought to do this with some of the shallow oil sands around Bakersfield.  The problem comes from the volatiles that would escape and have a quite negative environmental impact.
As I understand it, Saudi Arabian official reserves have always run about 2 times what they have numbers on at any given minute.