What is driving up oil price?

I am puzzled with what is driving up oil price from 50 to 150 dollar per barrel in less than 2 year's time. Isn't the occupation of Iraq and Afghanistan serve to secure oil supply? Some factors that I can think of are:


1. increasing demand from China and india


2. reducing OPEC production


3. weakening of dollar


4. problem of Iran


However, I still cannot the impact because none of the above factors have changed so drastically in the last 2 years. Where can I find good resources to analysis this problem?What is driving up oil price?
I think we have a higher demand for oil now. What is driving up oil price?
all of those contribute somewhat. also, dont forget to include overall inflation, and envirnmental concerns and regulations that make procuring and producing oil more expensive.