I believe that crude oil prices have hit rock bottom. I want to invest in it with the horizon of 5 years or more. I may withdraw money a lot before if I get a handsome return on it (like more than 20% annual return)

Which is the best way to invest in it? Is “DSP BlackRock World Energy Fund” good proxy for crude oil prices?

I am very much aware of impact of currency fluctuation on returns of fund and I have considered that risk as well.