U.S. Oil Fund (NYSEArca: USO) climbed over 2% in afternoon action Friday as crude futures topped $112 a barrel and notched a 30-month high.

Investors continued to worry about supply problems in Libya, sending crude to its highest intraday level since September 2008, according to reports.

“Traders are gearing up for further oil price upside,” a trader at SK Energy told Dow Jones Newswires.

The oil exchange-traded fund (ETF) came into Friday with a gain of nearly 13% so far in 2011.

“Although its tracking is not perfect, the simplest reason to own U.S. Oil Fund is that you believe oil prices are going up, as this fund aims to replicate the price performance of light, sweet crude oil delivered to Cushing, Okla,” said Morningstar’s Abraham Bailin in a recent analyst report on the $1.9 billion ETF.

“Keep in mind, however, that this fund will not track spot oil prices when the futures curve is behaving abnormally,” he added.

U.S. Oil Fund