hi !!

Sincerely, choice of specialization after finishing a civil engineering degree is usually influence by a number of factors.

Although, oil and gas engineering is lucrative and you can get enough money to pay your bills but do you have the required passion to keep you motivated when you face tough times? Secondly, I may be wrong but I think oil and gas engineering is too narrow because if you don't get a job in an oil company as fast as you expect then you might blame yourself eventually.

I agree that there are a lot of structural engineers out there but the profession is not common in actually sense since it is a broad field and you can easily change your direction when you feel like. For instance, as a structural engineer, you can either work in consultancy offices like Arup, Hydra, Jacobs, etc. or construction company like AECOM (Tishman and Hunt), STRABAG, Grupo ACS, etc. or as computational mechanist in top firm around the world, or as  faculty member (if you are smart, intelligent, love teaching, and have passion for research).

Hi

which specialization have you thought of ?

which are the ones causing conflict in your mind?

Do let me know so that I may suggest you one of the two

also you should see the scope of the fields respectively and also the placement scope from the college you are pursuing 

All the best toyou