While it’s not the base-case scenario, a failure to reduce production fast enough may require prices near that level to clear the oversupply, Goldman said in a report e-mailed Friday. The bank cut its forecast for Brent and WTI crude through 2016 on the expectation that the glut will persist on OPEC production growth, resilient non-OPEC supply and slowing demand expansion.

“The oil market is even more oversupplied than we had expected and we now forecast this surplus to persist in 2016,” Goldman analysts including Damien Courvalin wrote in the report. “We continue to view U.S. shale as the likely near-term source of supply adjustment.”

Goldman trimmed its 2016 estimate for West Texas Intermediate to $45 a barrel from a May projection of $57. The bank also reduced its 2016 Brent crude prediction to $49.50 a barrel from $62.

WTI for October delivery fell as much as 45 cents, or 1 percent, to $45.47 a barrel on the New York Mercantile Exchange and is heading for a weekly decline. Prices are down 14 percent this year. Brent for October settlement is 1.7 percent lower this week.

Oil in New York has slumped more than 25 percent from its June closing peak amid signs the glut will persist. Leading members of the Organization of Petroleum Exporting Countries are sustaining output, while Iran seeks to boost supply once international sanctions are lifted. U.S. stockpiles remain about 100 million barrels above the five-year seasonal average.

“We now believe the market requires non-OPEC production to shift from our prior expectation of modest growth to large declines in 2016,” Goldman said. “The uncertainty on how and where that adjustment will take place has increased.”

The U.S. pumped 9.14 million barrels a day of oil last week, almost 3 million barrels above the five-year seasonal average, according to data from the Energy Information Administration. While the EIA this week cut its 2015 output forecast for the nation by 1.5 percent to 9.22 million barrels a day, production this year is still projected to be the highest since 1972.

OPEC, the supplier of 40 percent of the world’s crude, has produced above its 30-million-barrel-a-day quota for the past 15 months. Iranian Oil Minister Bijan Namdar Zanganeh has vowed to increase output by 1 million barrels a day once sanctions are removed as the nation seeks to regain market share.