Good question, seeing as there's a general perception that Nigerians based in Nigeria are largely incompetent and can't cut it in the developed world.
My thinking is, outside the people in the medical and scientific fields, there is a genuine opportunity for business professionals to internationalize their careers. Nowadays it is either giant corporations (Microsoft, Cisco, Oracle, Ericsson) or behemoth professional bodies (GSM Association, CIMA, ACCA, IIBA, PMI, etc) who are standardizing the corporate industry. Now certifications like Six Sigma, SOX, CFA, PMP appear to be far more valuable than a couple of masters degrees. Now you can easily get international jobs, plus even increase your local worth, if you can somehow prove certification and/or experience with any of the systems and processes midwifed by those organizations. So many people are even doing it. In Nigeria Ericsson is busting a lot of engineers out of the carriers and converting them to 'hired guns', contractors who work anywhere in the world, from Azerbaijan to Zimbabwe, for mouth watering fees (sometimes up to a thousand Euros a day).
My recommendation? To make your career truly international, it's a lot easier if you fall into any of these fields: finance, IT, engineering technology & applications (though this is debatable), operations and project management, business analysis and management. For these fields, irrespective of the nature of the organization where you work, you can still do something about moving your career ahead. So go for it, find a way to internationalize yourself by getting certified by a global body, and start to find out how to sell yourself in your field. It's the era of the mobile worker who may spend 8 weeks in Afghanistan and 12 in lagos, and get paid in those 8 weeks what some people get paid in 3 years, even in developed countries!