US crude settles up 4%, at $45.72 a barrel

Oil prices jumped on Friday, snapping a 4-weeks losing streak, as the dollar fell on interest-rate uncertainty, lifting demand for dollar-denominated commodities from holders of other currencies.

U.S. crude settled up $1.76, or 4 percent, at $45.72 a barrel, marking its biggest daily gain since Feb. 12.

Brent's front-month May contract was up 1.6 percent at $55.20 a barrel, after a session low of $53.55. The contract is set for a 1 percent gain on the week after two weeks of declines.

U.S. crude's expiring front-month, April, rose $2.15 to $46.11 a barrel. The spread between April and nearby May, which will become the front-month for U.S. crude from Monday, was at just over $1 a barrel, indicating further gains for April before Friday's settlement.

Traders said U.S. crude was showing more momentum ahead of the expiration of its front-month contract.

Read More8 commodity trades on oil's slide

U.S. drillers cut the number of rigs drilling for oil by 41 this week to 825, the lowest total rigs since March 2011, oil services firm Baker Hughes said in a survey on Friday.

The number of oil rigs this week declined for a 15th week in a row, matching the longest streak for oil rig reductions set in March 2009.

The dollar was lower on Friday on expectations, spurred by a Federal Reserve statement on Wednesday, that U.S. interest rates will rise more slowly than expected.

The euro rose against the dollar after the leaders of Greece and Germany struck a conciliatory note over efforts to keep Greece in the euro zone.

Read More Gartman: Crude could hit $15. Here's why

Brent's spread with U.S. crude, one of the biggest volume trades in oil, was at around $8 a barrel, though technical analysts said it could blow out to above $30 over time.

Aside from the dollar and the oil rig count, traders were also watching intensive efforts by world powers to clinch a nuclear deal with Iran. Tehran plans to raise its oil exports, now curtailed by sanctions related to its nuclear program, once it strikes a deal.

Read MoreOPEC oil minister: We 'have no choice' on output

On Friday morning, the White House released the first set of federal rules for hydraulic fracturing, the well stimulation technique that has fueled a boom in U.S. natural gas and oil production.

The Obama administration will require companies that drill on federal lands to disclose the composition of fluids injected into wells to free hydrocarbons from underground basins. It also updated previous rules governing well construction and water disposal.