Saudi Arabia increased crude oil production by 658,800 barrels a day in March to an average of 10.294 million a day, according to data passed on to the Organisation of Petroleum Exporting Countries (Opec) secretariat in Vienna.
That figure stands at about half the daily production from the Bakken shale formation in North Dakota, among the fastest-growing regions for shale drilling in the US, Bloomberg reported.
However, Opec data showed an increase of about half the amount reported by Saudi Arabia. Saudi output rose by 346,800 barrels a day in March to 10.01 million a day, according to data the oil cartel said was compiled from "secondary sources".
Opec pumps a third of the world's oil. The cartel, in a report published on 16 April, said its total oil production rose by 810,000 barrels a day in March to 30.79 million a day.
The Saudi boost was enlarged by higher output from Iraq and a partial recovery in Libyan production.
Opec's research department said: "Higher global refinery runs, driven by increased seasonal demand, along with the improvement in refinery margins, are likely to increase demand for crude oil over the coming months.
"Given expectations for lower US crude oil production in the second half of the year, these higher refinery needs will be partially met by crude oil stocks, reducing the current overhang in inventories."
The Saudi output figure was in line with a level of 10.3 million a day announced by oil minister Ali Al-Naimi on 7 April, when he reiterated that Opec will trim output to rebalance the global market only if other producers share the burden.
The Bakken formation pumped 1.1 million barrels a day in February, according to data from the North Dakota Industrial Commission.