In an abrupt turnaround, U.S. oil prices plunged 3.3 percent after gaining more than 1 percent Tuesday.
U.S. crude futures closed down 96 cents, or 3.26 percent, at $28.46 a barrel after earlier reverting to a discount to Brent prices.
Brent crude oil prices rebounded on Tuesday from a 12-year low after data showed Chinese oil demand likely hit a record high in 2015, but the recovery was not expected to last amid warnings that the market would stay oversupplied this year.
Analysts also attributed much of the bounce from under $28 a barrel to a brief short covering rally after oil prices crashed over 20 percent this year, triggering a record volume of short positions in the week through Jan. 12.
"It seems to be a healthy upside correction in an otherwise downtrending market," said Tamas Varga, oil analyst at London brokerage PVM Oil Associates.
Brent crude futures, the global benchmark, posted their strongest daily gains in four months, before easing back to trade up 32 cents, or 1.12 percent, at $28.88 a barrel.