Pattern of written test::
They were simply testing, how much familiar we were with the fundamental concepts of petroleum engineering. I GUESS they were watching everyone of us during the written technical carefully, and those who repeated the same habit of copying from others as most of us do in exams were marked and rejected.

Group discussion:

One should not aim at speaking more. Speak less but logically. 3 logical sentences are sufficient to make u qualify this round.

OGPA::
It had its own importance.Definitely it helps, if you have a good gpa. Everyone was asked to write his/her ogpa at the top of the written test paper. I GUESS they were asking the technical questions during the personal interview based on ogpa, like, tougher questions to those having higher ogpa.

Technical questions::

These were simple elementary/fundamental questions related to production, drilling and reservoir engineering.They asked to make some graphs, and write some equations as well.

HR questions::

They asked me about my family background, why am i interested in joining the company, where do i see myself 5 yrs down the line, what qualities do i think i have that will help me succeed in the professional life.

1) Try to develop a good understanding of the fundamentals of the subject.
2) Never try to copy anything from your friends in the written technical interview. They are always watching you. Also try to behave as decently and as friendly as you can with everyone (even your friends) during the entire process.
3) Mentally prepare yourself for the possible HR questions and counter questions which could be fired. Never try to boast of your family background. It would give a very negative impact. Rather, say that you have not so good family background.

around 40 people applied, and 5 got selected
my rank was 2nd.
I guess the following things worked in my favour:::
1) Good gpa
2) My summer intership project in the same company, which i did with full dedication.
3) Confidence.