Hi Kalyani,

There are a number of public sector enterprises that recruit employees and particularly petroleum engineers through GATE. These companies are one of the most sought after and enjoy a goof overall reputation. Coming down to your specialistion, ONGC is a top recruiter from petroleum engineers. It is a Maharatna PSU which works in petroleum and natural gas production and is best suited for candidates like you. Then next comes HPCL which is Navrata company. Another company is MECL. 

As per specific course specialisation, these three are the top recruiters for petroleum engineers but for you reference, I would advice you to kindly go through the following link that I am attaching herewith. It will give you a detailed list of PSU companies and their discipline, therefore, please read it very carefully. 

Link - https://engineering.careers360.com/articles/psu-recruitment-through-gate

I hope this is useful to you, kindly follow up for any futher information or query. All the very best.