To dampen the hysteria a bit:

As you move up to larger and larger areas, the effects get smaller / slower. So if Ain Dar / Shedgum drop by 4%, SA would drop by less as a result of the AD/S drop - perhaps 2%, and the world would drop by even less (less than 1%). So your statement is probably directionally correct, but is misleading in its implications.

CW
Global peak: 2007 - 2010
Global decline rate, Post peak: 2%
Economic response: Severe global recession, ~5 years, then slow recovery

To Dampen your enthusiasm a bit:

You would be correct if it were only Ain Dar/Shedgum in decline. And you would be closer if Ani Dar/Shedgum were declining by only 4%. However ALL Saudi existing fields are declining by an average of 8%.

One challenge for the Saudis in achieving this objective is that their existing fields sustain 5 percent-12 percent annual "decline rates," (according to Aramco Senior Vice President Abdullah Saif, as reported in Petroleum Intelligence Weekly and the International Oil Daily) meaning that the country needs around 500,000-1 million bbl/d in new capacity each year just to compensate.
http://www.eia.doe.gov/emeu/cabs/saudi.html

So your conclusion Hindmost, is totally misleading in its implications.

Ron Patterson