Exxon Mobil Corp said on Friday it doubled its first-quarter per-share profit, but the results fell short of Wall Street estimates, even excluding a $3.4 billion writedown from its withdrawal from Russia.

The top U.S. oil producer tripled the size of its buyback program, similar to other energy giants like France's TotalEnergies that are sending more cash back to shareholders. Exxon said it will repurchase up to $30 billion in shares by the end of next year, compared with its earlier estimates for $10 billion in repurchases.

"We'd be looking to get $15 billion done a year, again, looking to sustain the program kind of more consistently over this 2-year period," said Kathryn Mikells, Exxon's chief financial officer.

The company said net income rose to $5.48 billion, or $1.28 per share, in the three months ended March 31, compared with $2.73 billion, or 64 cents per share, last year.

Exxon, however, said it faced pressure on margins due to feedstock inflation. Heavy market volatility had negative effect on downstream results due to swift changes in prices between the time when feedstock was purchased and products were sold.

The company's refining division posted much weaker results from the previous quarter, with earnings of $332 million, compared with $1.5 billion in the fourth quarter. The company said the sharp rise in prices ended up costing $1.3 billion of "negative timing impacts," including $760 million in mark-to-market effects on open derivatives positions.

The company said those losses will be unwound when it makes certain physical sales.

Chief Executive Darren Woods said he expected higher refining margins to reflect in second quarter results, adding that margins would remain high this year and likely into the next.

Exxon has been trying to boost output in its primary development areas, the U.S. Permian basin, and in Guyana, the tiny South American nation that has seen windfall oil discoveries in recent years and where Exxon has two major offshore developments.

Exxon's output of crude and other liquids including bitumen and synthetic oil was 2.3 million barrels per day, a 5% drop from the previous quarter. Natural gas production fell by 1.5%.

Exxon's shares were down 0.6% to $86.72 in late morning trading.

The company's adjusted earnings per share came to $2.07, short of the Refinitiv consensus for $2.12 a share, while revenue came in at $90.5 billion, below the $92.7 billion consensus.

The results included a $3.4 billion after-tax hit on the oil major's Russia Sakhalin-1 operation, which it said it would exit on March 1, shortly after Moscow's invasion of Ukraine on Feb. 24.

Exxon's writedown follows others oil majors exiting Russia after the Ukraine invasion. BP PLC and Shell PLC have flagged up to $25 billion and $5 billion in writedowns from leaving their Russian businesses, respectively.

(Reporting by Sabrina Valle in Houston and Shariq Khan in Bengaluru; Editing by Arun Koyyur; editing by David Evans, Chizu Nomiyama, Louise Heavens and Marguerita Choy)