hey,

ongc has job in various sectors, in engineering stream ongc hires electrical, mechanical, chemical,metallurgy and mining streams also. there is vacancy for IT and computer science professionals. students who are studying in bsc and msc  course in geography, can also join ongc as a geologist. so don't take engineering as a career choice to do job in ongc. if you are interested in chemistry based engineering stream than I would suggest you to take chemical engineering, keeping the idea of career growth and job demand.