The U.S. Energy Information Administration warned OPEC members might need to trim their budgets as oil prices continued their steady decline Wednesday.

"Further revisions to future budget plans may be required in many OPEC member countries, particularly [Venezuela, Iraq and Ecuador], because of lower oil prices and large uncertainty over future global economic growth and crude oil production levels," EIA said in a brief Wednesday.

Brent, the global oil price index, continued dropping in early trading Wednesday, down nearly $1 per barrel to $59.16 for the January contract. Brent prices this week fell below the $60 mark for the first time in more than five years.

A November decision by the Organization of Petroleum Exporting Countries to keep output steady at 30 million barrels per day sent oil prices reeling as markets are oversupplied. A glut of crude oil from North America, primarily from U.S. shale basins, is in part behind recent dynamics.

EIA said it expects Brent crude oil to sell for an average $68 per barrel next year, down from the $100 average expected for this year and $109 from 2013.

Based on its latest monthly market report, EIA said OPEC members, excluding sanction-strapped Iran, will earn 14 percent less in oil revenue year-on-year.

Oil prices are at the point at which some producers and drillers are starting to suffer, mostly notably Russia, where the value of the nation's currency is in a free fall. OPEC kingpin Saudi Arabia, however, was undeterred, rolling out a budget plan Wednesday that calls for "huge developmental projects and spending."

EIA warned the price pressure may spill over into the U.S. shale sector, though output for 2015 is still expected to eclipse 40-year records.