Dow e-minis were down 380 points, or 2.26 percent, with 99,258 contracts changing hands at 8:13 a.m. ET (1313 GMT). S&P 500 e-minis were down 45 points, or 2.27 percent, with 578,860 contracts traded. Nasdaq 100 e-minis were down 130.25 points, or 2.93 percent, on volume of 108,831 contracts.

Crude oil prices ended 2015 below $40 per barrel (b), the lowest level since early 2009. Spot prices for the international crude oil benchmark Brent averaged $52/b in 2015, 53% below the level in 2014 and 49% below the average price over 2010-14. Spot prices for West Texas Intermediate (WTI) crude oil were also down 53% in 2015 compared with 2014, averaging $49/b for the year.

"We will be more subtle in our approach and may gradually increase output," Qamsari said. "I have to say that there is no room to push prices down any further, given the level where they are."

While Iran enjoys the world's fourth-largest proven crude oil reserves and the world's second-largest natural gas reserves, its production and export potential has remained largely unutilized as a result of the nuclear related sanctions. The sanctions have had a major impact on Iran's energy industry and have caused a number of cancellations or delays in its oil and gas upstream projects.

Underground sites are slated to hold about 130 million barrels, which would account for nearly a quarter of the 550 million-barrel SPR target set by Beijing for 2020, according to local media and analysts.

“Given the volumes of gas shipped to Europe, the marginal cost of additional Russian gas is low and they should be able to compete with US LNG supplies,” said Malcolm Johnson, a Guildford, England-based faculty member of The Oxford Princeton Programme, an energy training provider. “However, it is clear that in certain countries there is a desire to diversify supplies for supply security.”

West Texas Intermediate crude for February delivery declined to $36.58 a barrel on the New York Mercantile Exchange, after falling 0.8 percent Monday. U.S. crude inventories are forecast to keep supplies more than 130 million barrels above the five-year seasonal average, according to a Bloomberg survey before government data Wednesday.

While tens of thousands of jobs have already been cut in 2015, more redundancies are expected this year as companies narrow their focus.

Moody’s last month also projected average prices of West Texas Intermediate crude at $40/bbl in 2016, $45/bbl in 2017, and $50/bbl in 2018. The 2016 price is down $8/bbl from the firm’s earlier forecast.

Iran's deputy oil minister for commerce and international affairs, Hossein Zamaninia, said Tehran had identified nearly 50 oil and gas projects worth $185 billion that it hoped to sign by 2020.