Hi Subhashree, thanks for asking your query.

Your chances of getting into ONGC are high. Looking at previous years cutoff, cutoff score was between 500 and 700 for geology and geophysicist. I am sharing the link below, you can go through it and find the cut offs in previous years to get a fair idea about their recruitment:

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

Best of Luck!