That was way back in 2008, and many deadlines set by Nigeria's government to carry out the oil reforms have passed without action, creating uncertainty that has limited new investment, threatening future output.

The country has now launched a renewed reform bid, and there is reason to believe that this time it may be successful though various obstacles could again derail the plans.

Nigerian President Goodluck Jonathan last month sent a fresh version of sweeping legislation to parliament that would set out new fiscal terms for the industry and restructure the state oil company, among other measures.

The implications of the 223-page bill are immense in the OPEC member country that relies on the industry for some 80 percent of government revenue and where major firms like Shell, Exxon and Total pump crude for export.

"I think something's going to get passed before the end of the year," said Kayode Akindele of 46 Parallels investment firm.

"That's really out of necessity because we just can't have the situation we've had the last four or five years."

But a number of battles must still play out. Major firms argue that the fiscal terms are too harsh, there are concerns over powers granted to the oil minister, and a political tussle is expected over a fund for oil-producing communities.

Unrest in the oil-producing Niger Delta region has been sharply reduced following a 2009 amnesty deal, allowing output to return to more than two million barrels per day.