The point you make are all very valid, and make the outlook very troublesome. I will address three regions in the next part which will encompass the reserve reporting issue. All these underestimates are reported as if they are based on technological advances, which they are mostly not. Since reserves seems to be reported more properly now (less is found so the data can't be that much obfuscated) and because past data is more properly assessed for most countries (at least in IHS Energy and WoodMackenzie databases) it would appear to me that reserve growth will decline as discoveries decline. Also more about this in the next parts.
Pardon my intrusion.
Given that this is a "Primer" it behooves us to provide some pointers for newcomers regarding what a "Reserve" number is to begin with.

  1. Wikpedia here tries to explain that reserve numbers have to do with what is "economically feasible" at a given time. If you want to better grasp that concept and differentiate between "reserves" and the total amount of oil that is actually down under, play this mind game: Instead of boring (drilling) a few thin pipes down into the ground after you have found a promising geological formation, you dig out the entire area to form a canyon that is 10x the size of the Grand Canyon, siphoning off all the oil you find as you dig. Of course the economic costs for such a method will be astronomical. In truth it is not "economically feasible". The reserve numbers will be significantly lower than actual oil below.
  2. News reporters generally don't know "Jack" s**t about what the word "reserves" means.
  3. Many a cornucopian fruit cake confuse growth of the human-generated reserve number with belief in abiotic oil.
  4. Wikpedia here provides a list of major fields and estimated recoverables. Included in their list is Ghawar.

We now return you to the regularly scheduled program.