This is lovely. I commend your effort on this research. Keep it up man. As for the oil/gas, I think where they have edge is the exposure outside the shores of the country/continent. Man, those guys are high flyers when it comes to life offshore.
The main challenge is the black and white thing. They may pay well but I saw many of them complaining about the job satisfaction. The expatriates are not ready to transfer the knowledge, of course if Nigerians can do the job, they have to leave.
kudos