As long as you have the grades, you should be able to get in. Now, keeping grades is something else. If you can keep your head in the books, you'll make it through, but it isn't a cake walk. Just remember that a little extra effort will pay off big, in the end. From day one, you'll see lots of engineering students that couldn't keep up with the curriculum, and they tend to go into Industrial Technology (ITEC), most of them are doing better than typical college grads.
When it comes to internships, not a problem. Career Services does a great job at getting lots of companies in, and getting nearly all petroleum students into summer jobs. I can personally attest to this, as I had internships at Exxon (2000) and Baker Hughes (2001 & 2002). When I graduated, I signed on with Baker Hughes and worked off-shore for three years. Following that, I went to New Mexico, Colorado, and Utah for five years with and oil company. Now, I've been in Houston for four years, working for a different oil company. The amount of living I've been able to have, by age 30, can't be rivaled by any other industry. The only professions that allow someone to move (see the world, etc) and experience life, as much as petroleum engineering, is the military or international business.
Trust me, while you may be held to oil & gas, you will never regret it. This is an industry that is already beginning to need more engineers than what are available. This demand will only increase, as years go by; just look at the Department of Energy's (DOE) statistics, the US is expected to be the largest producer of petroleum on Earth, by 2024. This isn't by producing what we have, its by producing what we can't get, yet. My company is a part of that, as much as anyone. We have found oil in an area that was abandoned over 40 years ago; we tried new completion techniques, and are making more oil than anyone in the Midwest. This is just one example of where petroleum engineers are the right choice.
If you live on campus (I did for all four of my years), you'll have a great time. The school does lots of activities to keep you engaged, and you'll find yourself going to lots of sporting events - they are both easy to get to, and are tons of fun. Live on campus, it's cheaper and you'll have a blast - just some advice, your second or third year, try to hire on as a Residence Advisor, you'll get free room and board (including meals) and it is a very rewarding job too. It really helps develop good social skills with all types of people.
As for party scene and girls, I can't say enough. I found myself in college and can tell you, by your sophomore year, you'll know the women's dorms like the back of your hand. There are too many gorgeous women at UL to try and write about - trust me, there are plenty, and they are typically very sweet. If you want to party, just know that there is a festival nearly every weekend, during the warmer months, so no worries.
Here's the point, you can't go wrong with Petroleum Engineering. You'll be culture shocked at first, but by the time you graduate, you'll be thankful for every second you had at UL. I say go for it, I did, and can't be more thankful and blessed for it.