Diezani Alison-Madueke is the only women in Opec and the head of Africa's most powerful producer. Reports last year suggested that Abuja had also put her name forward as a contender to the lead the group and replace its long serving secretary general Abdulla Salem el-Badri who was due to retire in 2012. The largest producer in Africa, Nigeria has been hit hardest by the fall in prices and the rise of US shale oil. The country was once a major supplier to the US market but recently fell out of the rankings as more North American "tight oil" replaces the need for Opec. She faces huge challenges in Nigeria reviving the domestic oil industry and is likely to vote for a cut to push prices back to $100. Estimated production 2m bpd.