A surge in attacks on its facilities has forced it to cut back on production.
Armed groups in the Niger Delta, most prominently known as the Movement for the Emancipation of the Niger Delta (MEND), have sabotaged several supply pipelines owned by Shell and other oil operators in the region.
MEND emerged in early 2006 as the leading group calling for a greater share of Nigeria's oil revenue.
Besides attacking facilities, it has seized local and expatriate oil workers as hostages.
Overall, violence in the Niger Delta has reduced Nigeria's total production by a quarter in the past two years.