Hello SAnkaran

Petroleum engineers are involved in the production and exploration of oil and gas. They also work with geo-scientists and other specialties.

Petroleum engineering needs a knowledge of many other disciplines such as geophysics, petroleum geology, formation evaluation, drilling, economics, reservoir simulation, reservoir engineering, well engineering, artificial lift systems, etc.

But i personally suggest you to please do not go for Petroleum Enigineering in your UG. These are the courses which is best suited for Post graduation. It is better to do a UG in core field like Mech or Civil and then optfor Petroleum Engineering in your PG.