Good questions. I remember reading that four of the top five producing fields are now in or thought to be in terminal decline.

I don't believe that the information coming out about Ghawar is believed by most experts to be credible, so I don't think you'll find anything that is too reliable. But the other fields should be easy for us to find.

I'll try to figure out where I read that info, and see if there are footnotes to sources.