Flooding in states in the oil-rich Niger Delta prompted Shell and French supermajor Total this week to declare force majeure on exports from Nigeria.
Osten Olorunshola, director of the Nigerian Department of Petroleum Resources, said a growing number of oil companies were blaming flooding for a slump in oil production from Niger Delta states.
"We have had a very unfortunate situation of flooding in the last couple of weeks and that certainly cut production by 500,000 barrels per day to 2.1 million bpd," his agency was quoted by the Platts news service as saying.
Nigerian crude oil production as of August was around 2.3 million bpd, a level Platts reported was 700,000 bpd higher than the previous month.
Nigeria is among the top oil exporters in the region. The U.S. Energy Information Agency reported last week that crude oil deliveries from Nigeria for July were down about 500,000 barrels compared to the same month last year.
Patrick Kulsen, an oil market analyst at PJK International, a research company in The Netherlands, told The Wall Street Journal that other markets were filling in the gap.
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