NEW YORK—The sooner-than-expected startup of the extended Sunrise oil pipeline system in west Texas has shifted flows of crude and boosted inventories in Cushing, Okla., close to a one-year high, with traders now bracing for builds into next year.

Full pipelines have kept crude trapped in west Texas, but the startup of Plains All American’s (NYSE: PAA) extended Sunrise pipeline in November has helped send more crude from the Permian basin into Cushing, the delivery point for U.S. crude futures.

Stockpiles at Cushing hit 38.2 million barrels last week, the highest since January 2018, according to the U.S. Energy Information Administration (EIA). Before the most recent week, overall U.S. stockpiles increased for 10 straight weeks, fueling worries about a glut as oil prices have sagged.

Front-month U.S. crude for delivery in January traded as much as 25 cents per barrel lower than the second month last week, the biggest discount since November 2017. Trading in the spread typically reflects supply and demand at Cushing.

Sunrise is sending oil directly to the hub as well as serving nearby refineries which rely less on Cushing.

“We knew the startup of the line would have an impact, just how big was the question. And now it looks like the builds will keep coming into the new year,” one trader said.

Both Phillips 66’s (NYSE: PSX) 146,000-barrel-per-day (bbl/d) Borger, Texas plant and Valero’s (NYSE: VLO) 90,000-bbl/d Ardmore, Okla., facility, are sourcing more crude from west Texas, traders and analysts said. Overall, about 620,000 bbl/d flowed from the Permian to Cushing in November 2018, compared with about 480,000 bbl/d a year earlier, according to Genscape data.

The new Sunrise system currently moves about 300,000-350,000 bbl/d, of which about 120,000 bbl/d flows into Cushing while 100,000 goes to Valero’s Midwest refineries.

Phillips 66 declined to comment. Valero did not respond to a request for comment, though it noted on an earnings call in October that the startup of Sunrise will provide access to discounted Permian crude and be “a significant uplift” for the company.

Permian production has surged to a record 3.7 million bbl/d, helping boost overall U.S. output to 11.7 million bbl/d, making the United States the biggest oil producer worldwide. That growth had for a time depressed Permian prices, which hit a low of nearly $18 below U.S. futures, though that discount has narrowed to $8.50.

Traders also expect increases in Cushing stocks through year-end as Gulf refiners typically look to maximize stockpiles in Cushing because Texas charges a tax to keep those inventories on facility.

Onshore