Hi

Obviously go for CSE. CSE is a very mainstream course and actually taking up a mainstream course will help you to apply for a variety of jobs and is useful for further specialisation and higher studies. But that is definitely not possible in case of Petroleum Engineering. Because you have to end up at a Petroleum Industry. I believe you can yourself decide whichever will suit you more. Learning CSE has a wide scope and oppurtunities and certainlymore number of jobs.

Best of Luck.

Hope this helps.

Cheers!