Got an offer from Kaduna NNPC refinery as casual worker and a post of Pupil (graduate) civil engineer at a construction company....

Which one should I go for pls advice?

Well, the better option should be the graduate civil engineering job. This gives room for future career prospects and job security which are key factors one should consider when accepting a job offer. Forget the huge pay that might come with the NNPC job. Remember you are going to be a casual worker and so the job security would be affected. Think of long term benefits rather than the short term gratifications

I think you should go for the construction company