U.S. crude oil stockpiles rose for a fifth straight week to the highest in more than a year, as production hit a record high and seasonal maintenance kept refining rates low last week, the Energy Information Administration (EIA) said Feb. 21.

Crude inventories rose 3.7 million barrels in the week to Feb. 15, to 454.5 million barrels, the highest since October 2017. Analysts polled by Reuters had forecast an increase of 3.1 million barrels.

U.S. weekly crude production edged higher to a record 12 million barrels per day (bbl/d), the data showed. Oil production has surged in the U.S., thanks to a shale revolution, vaulting the country above Saudi Arabia and Russia as the world's biggest producer.

"The continued surge in U.S. production stands as a bearish dynamic for market prices, especially as increasing volumes get sold abroad in a direct challenge to Saudi Arabia and Russia," said John Kilduff, partner at Again Capital in New York.

Net U.S. crude imports rose marginally last week by 69,000 bbl/d, as exports surged 1.2 million bbl/d to a record 3.6 million bbl/d, data showed.

Market participants had anticipated a jump in exports as shipments ramped up after fog disrupted loadings in the U.S. Gulf Coast a week earlier.

Refinery utilization rates remained unchanged at 85.9% of total capacity as refinery crude runs fell by 57,000 bbl/d, holding at their lowest since October 2017.

Crude stocks at the Cushing, Okla., the delivery point for U.S. crude futures, rose by 3.4 million barrels, the EIA said.

Analysts and traders attributed much of the increase in inventories at Cushing to ongoing seasonal maintenance work by refiners.

"The refinery runs obviously are down ... more than expected," said Phil Flynn, analyst at Price Futures Group in Chicago.

"But it's a reflection that maintenance season is in full stead right now, leading to lower demand for oil."

Gasoline stocks fell by 1.5 million barrels, compared with analysts' expectations in a Reuters poll for a 350,000-barrel drop.

Distillate stockpiles, which include diesel and heating oil, fell by 1.5 million barrels, vs. expectations for a 1.7 million-barrel drop, the EIA data showed.