A series of attacks on oil infrastructure in the Niger Delta has pushed Nigeria’s output of crude close to a 22-year low, according to Reuters data, putting intense pressure on the country’s finances. Shell workers at Nigeria’s Bonga oilfield in the southern Niger Delta were evacuated following a militant threat, a senior labour union official said yesterday. Attacks late last week forced Chevron to shut its Okan offshore facility, taking out 35,000 barrels per day (bpd).

Shell said the unrest had not yet impacted production, but its Forcados field is still closed and under force majeure following a February subsea pipeline attack, taking out 250,000 bpd. The violence has depressed production in Africa’s largest producer to roughly 1.69 million bpd this month, the lowest since at least June 2007, when production fell to 1.68 million bpd, according to International Energy Agency data.

A small reduction from any field would quickly send output to the next low, seen in August 1994, when it hit 1.46 million bpd, according to the IEA data. Read more about the Niger Delta unrest here.