Brent crude for August delivery was up 28 cents, or 0.2%, at $115.88 a barrel at 0338 GMT. The contract settled down 1.7% on Tuesday.
The front-month contract for July delivery expired on Tuesday at $122.84 a barrel, up 1%.
U.S. West Texas Intermediate (WTI) crude rose 30 cents, or 0.3%, to $114.97 a barrel.
Both benchmarks ended May higher, marking the sixth straight month of rising prices.
EU leaders agreed in principle on Monday to cut 90% of oil imports from Russia by the end of this year.
