"estimates on wiki (for whatever that's worth...) are that Russia holds a little more than 3 times as much oil as China"
be careful when quoting reserves of oil or any other thing else in the ground - once it reaches a certain quantity they don't bother looking for several years. Especially when the price is low
Why would Saudi Arabia explore for more oil when they have 221 years of their annual consumption? I know for a fact that another Mid East country was drilling wells for gas in the early 00's and every time they found oil they just plugged it off as they had more than enough for decades. Both the the Russians and the Chinese can find a lot more if they are willing to pay a bit extra