Oil prices may rise by 20 percent this year as energy producers outside the U.S. keep a lid on how much crude they pump, said analysts at Citigroup.

"With a continuation of the OPEC/non-OPEC producer deal in the second half of 2017 and the expected associated inventory draw-down, we expect oil prices to move above $60 a barrel by the second half of the year," the analysts said in a report obtained by CNBC.

West Texas Intermediate crude has doubled in price since reaching a bottom of about $26 a barrel in February 2016. The Organization of the Petroleum Exporting Countries, which includes major oil producers like Saudi Arabia, Iran and Venezuela, agreed last year to curb output and help stabilize prices.

Citigroup’s analysts had estimated in February that oil prices would rise to $70 a barrel this year as supply and demand levels continued to rebalance, CNBC reported.

U.S. energy production is the biggest risk to the bank’s price estimates. Fracking technology has revived American drilling in shale fields, and that may come “roaring back” this year, Citigroup said.

“Oil producers would need to extend the historic agreement to curb global overspply through and until the end of 2017 for oil prices to surge,” CNBC reported, citing the bank’s report, “amid concerns Russia is lagging behind on its pledged production cuts.”

OPEC agreed to cut output by 1.2 million barrels a day for the first six months of 2017, while 11 other non-OPEC countries including Russia agreed to limit supply. OPEC's 13 national ministers will next decide on May 25 whether to maintain their production caps. 

"Commodities stumbled through the first quarter following what was clearly the healthiest year for the sector since the decade began. In retrospect, part of the sell-off toward the end of the last quarter was too much froth in critical subsectors like oil, copper and iron ore. But signs of better performance are increasingly clear, despite major risks," Citi analysts said.

U.S. crude fell about 0.7 percent to $52.27 a barrel by mid-day Tuesday.

Shale production in May was set for its biggest monthly increase in more than two years, according to the U.S. Energy Information Administration, as producers boosted drilling activity.

May output is set to rise by 123,000 barrels a day to 5.19 million, according to the agency. That would be the biggest monthly increase since February 2015 and the highest monthly production level since November 2015, Reuters reported.

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