U.S. crude oil stockpiles rose last week to their highest in about a year and a half as imports increased, even as refiners sharply ramped up output ahead of the summer driving season, the Energy Information Administration (EIA) said April 24.

Crude inventories rose by 5.5 million barrels in the week to April 19, much more than analysts' expectations in a Reuters poll for an increase of 1.3 million barrels.

At 460 million barrels, crude stocks sit at their highest since October 2017, not including the Strategic Petroleum Reserve, but are at the five year average for this time of year.

Net U.S. crude imports rose last week by 877,000 barrels per day (bbl/d) to 7.1 million bbl/d, the heaviest week for imports since mid-February.

Crude production inched 100,000 barrels higher, back to its record high at 12.2 million bbl/d, the data showed.

Refinery crude runs rose by 505,000 bbl/d, EIA data showed. Refinery utilization rates rose by 2.4 percentage points to 90.1%, highest since early February.

"The refinery run uptick was probably supportive because we’re still going to need a lot of supply of gasoline based off the strong demand numbers we’re seeing. It’s a sign refiners are going to come out of maintenance," said Phil Flynn, analyst at Price Futures Group in Chicago.

Crude futures dipped after the data, with U.S. West Texas Intermediate down 37 cents at $65.94 per barrel by 9:45 a.m. CDT (14:45 GMT). International benchmark Brent crude fell 4 cents to $74.48 a barrel.

Gasoline stocks fell by 2.1 million barrels, compared with analysts' expectations for a 1 million-barrel drop, and are about 2% below the five year average for this time of year.

"Gasoline demand remains strong, ahead of the peak demand period, and that helped to drawdown gasoline inventories, which offsets some of the bearish pressure from the crude oil data," said John Kilduff, a partner at Again Capital Management LLC.

Distillate stockpiles, which include diesel and heating oil, fell by 662,000 barrels, vs. expectations for a 1.2 million-barrel drop, the EIA data showed.

Crude stocks at the Cushing, Okla., delivery hub rose by 463,000 barrels, the EIA said.