U.S. commercial crude oil stocks rose 1.994 million barrels to 359.092 million barrels for the reporting week ended September 7, according to data released Wednesday by the U.S. Energy Information Administration (EIA).

Analysts polled by Platts Tuesday expected U.S. crude stocks would decline by 3.25 million barrels during the reporting period.

EIA reports only a slight increase in Lower 48 crude oil production, up 8,000 barrels per day (b/d) to 5.062 million b/d, as the U.S. Bureau of Safety and Environmental Enforcement announced that 36.35.%, or about 501,683 b/d, of the U.S. Gulf of Mexico oil production remained shut-in as of September 7 due to Hurricane Isaac.

However, the build during the week that ended September 7 includes a 1-million-barrel crude oil loan to refiner Marathon Petroleum on August 31 from the U.S. Strategic Petroleum Reserve, according to EIA Analyst James Beck, after the refiner faced difficulties sourcing crude oil in the aftermath of Hurricane Isaac.

Backing out the Marathon loan, U.S. crude stocks remain amply supplied at 358.092 million barrels, and are just over 8% above the EIA five-year average.

The rest of the build last week was likely a product of higher U.S. crude oil imports, which rebounded, rising 530,000 b/d to 8.565 million b/d, and a 235,000 b/d decline in gross inputs to U.S. refineries, which fell to 14.594 million b/d, reflecting the fact that as of last week, Gulf Coast refineries were still not back to pre-storm operation levels.

Three of six refineries that were shut before the Hurricane Isaac returned to service ahead of the reporting period, totaling 514,700 b/d in capacity, according to EOXLive Analyst Tom Pawlicki. The remaining 632,000 b/d restarted in the middle of the reporting week, he added.

Gulf Coast crude stocks increased 548,000 barrels to 174.857 million barrels, according to data from the American Petroleum Institute, as imports rose 821,000 b/d to 4.453 million b/d. Gulf Coast refinery runs were still down, with gross inputs to Gulf Coast refineries down 225,000 b/d to 6.949 million b/d. Gulf Coast refinery utilization, accordingly, fell 2.6 percentage points to 79.6% of capacity.