hi,

see after completing diploma in petroleum you may apply for oil sectors like iocl, pgcl, haldia petrochemical as a field engineer,

some of the top colleges are,

DPC Polytechnic College, Tamil Nadu

Sri Rajiv Gandhi Polytechnic College, Tamil Nadu

Nandha Polytechnic College, Tamil Nadu

CPCL Velalar Polytechnic College, Tamil Nadu

NIMS Engineering and Technology School, Jaipur

VELS Institute of Science, Technology and Advanced Studies, Chennai