I am not sure if Ind Sys Engin can get u into Oil n Gas.

I've not seen any job openings in O&G that requires ISE. Mostly just civil, elec, mech & chemical.

If u r gg into engineering, better to go into the 'traditional' engineering. Otherwise when u graduate, u might be in for a rude awakening. Better to play safe if you still dunno what u wan.