Note: I am not a niger deltan

People live in those communities where the bulk of Nigeria's wealth comes from and if they are asking for 25% of what comes from there, it shouldnot be an hassle to concede it.

They live there
Already their sources of drinking water has been polluted
Their initial source of income i.e farming/fishing has been affected
They will still live there after there is no more oil and bear with the biohazards

Rather than deprive them, I recommend giving them what they want and the federal government should monitor the state expenditure to ensure the side effects of drilling is being catered for and a better life for its citizens. My take

http://www.solarnavigator.net/oil_rigs_deepwater_horizon_british_petroleum.htm

http://www.mnn.com/earth-matters/wilderness-resources/stories/the-13-largest-oil-spills-in-history