Oil prices have increased by more than 2% due to a growing number of disruptions to Nigerian production.
Brent crude futures were up 88 cents and traded at $48.71 per barrel, while US crude futures rose 85 cents at $47.06 a barrel, Reuters reported.
Disruptions in supply globally as much as 3.75 million barrels per day (bpd) have dented a glut, which has caused oil prices to fall by as much as 70% between 2014 and early 2016.
Goldman Sachs told the news agency: "The oil market has gone from nearing storage saturation to being in deficit much earlier than we expected."
Oil production in Nigeria fell at around 1.65 million bpd due to several militant attacks on oil facilities.
A new militant group called Niger Delta Avengers claimed responsibility for an attack recently on an offshore facility, which is operated by the US-based Chevron and Royal Dutch Shell.
In 2016, oil production in Venezuela has already fallen at least 188,000bpd.
Crude production in the US plunged to 8.8 million bpd, which is 8.4% below 2015 peak. OPEC produced 32.44 million bpd in April.
