UPES

UPES has some of the best engineering courses that are known throughout the country. The industry-aligned approach is really one of a kind and brings out the best in petroleum engineering. For admission to UPES in petroleum engineering you need to meet the following the eligibility criteria:
Examination Pathway admissions through UPESEAT (Up to 80% of Seats):
Minimum 60% marks at Higher & Senior Secondary level (10th & 12th)
Minimum 60% aggregate in Physics, Chemistry & Mathematics at Senior Secondary level (12th)
Non-Examination Pathway admissions through JEE Mains Score (Up to 20% of Seats):
JEE Main Merit Pathway
Eligibility: Minimum 60% marks at higher & Senior Secondary level (10th & 12th) and minimum 60% aggregate in PCM at senior secondary level (12th class)
Cut off: 60 percentile score JEE Main
Board Merit Pathway We are opening this pathway for this session
Eligibility: Minimum 80% marks at higher & Senior Secondary level (10th & 12th) and minimum 80% aggregate in PCM at senior secondary level (12th class)
Since you got 86 in JEE Mains score and 91% in 12th in board exams you can apply through the board merit pathway. Alternatively, you can apply for UPESEAT and sit for examination. All admissions are merit based.

"UPES conducts a lot of entrance exams for a lot of courses. I think you are asking about UPES engineering entrance exam which is called UPES-EAT. Here a glance at UPESEAT:
UPESEAT can only be attempted by students with minimum 60% marks at 10th and 12th level with minimum 60% aggregate in Physics, Chemistry, and Mathematics. It is a Computer Based Test with a total of 200 questions with 1 mark each. The exam duration is of 3 hours. There are only multiple type questions and with no negative marking
UPESEAT Subjects are as follows:
Mathematics, Physics, Chemistry, English Language Comprehension & Current Affairs Awareness
Subject-Wise distribution of Marks are as follows:
Mathematics, Physics, & Chemistry 50 each
English Language Comprehension 30
Current Affairs Awareness 20
UPESEAT is attempted by thousands of students across the country so make sure your filling the form to secure a seat. You also asked about how tough the exam is well, there's no straight answer to the question because it depends on your preparation. If you are prepared enough, you will get a really good rank. So, focus on preparation and since it doesn't have negative marking, make sure to attempt every question. "