The global glut of oil could push prices as low as $20 a barrel, according to a report Goldman Sachs released Friday.

The bank’s commodities team cut its forecast for average prices of U.S. crude in 2016 from $57 to $45, and said there was growing risk of a drop to $20.

Oversupply has sank oil prices in the last year, as Brent has plummeted from $120 a barrel in the middle of 2014 to $42 in August.

Goldman Sachs’ warning comes as oil producers remain unmoved by the falling prices. Next year, OPEC will pump even more oil, led by increased production in Saudi Arabia, Iraq, and Iran. Shale oil companies in the United States have also been stubborn as prices have dropped, mainly because the cost of production is now so cheap.

Because prices fell from about $100 per barrel last year, demand was strong this year, but that trend won’t continue, Goldman said.

For the worldwide surplus to end by late 2016, U.S. producers will need to reduce output by 585,000 barrels a day and other non-OPEC production must fall by another 220,000 per day, the report said.