A global crude oil deficit will develop before the end of this year, the chairman of Facts Global Energy consultancy Fereidun Fesharaki said Monday.

The sharp decline in oil prices since the fourth quarter of 2014 has had a significant effect on drilling in the United States. The number of active onshore drilling rigs in the Lower 48 states fell 78% (from 1,876 to 412) between the weeks ending on October 31, 2014, and April 15, 2016, according to data from BakerHughes. The decline in active rigs and well completions is projected to result in month-over-month onshore oil production declines of 120,000 b/d through September 2016.

A high debt-to-equity ratio can present challenges in the face of falling revenue, which most U.S. oil producers experienced in 2015 because of lower oil prices. A company agrees to the terms of a bank loan or bond issuance to fund projects with the expectation that its activities will generate sufficient revenue to service the debt and eventually repay it. Debt on the balance sheet implies future cash outflows. The need to service large amounts of debt as revenues declined made companies with high debt-to-equity ratios more vulnerable to losses than companies with less leverage in their capital structures.

Tehran is seeking to make up for lost trade to Europe following the lifting of EU sanctions imposed in 2011 and 2012, which deprived it of a market that accounted for over a third of its exports and left it relying completely on Asian buyers.

The Russian camp was locked in negotiations with the Saudis, Qataris and Venezuelans — a core group that had first backed the freeze in February.

Thousands of workers in six oil and petrochemical companies went on strike Sunday to protest proposed government cutbacks.

Industrial production—a broad gauge of output across U.S. factories, mines and power plants—decreased a seasonally adjusted 0.6% in March from the prior month, the Federal Reserve said Friday. Output has fallen for six of the past seven months. From a year earlier, industrial production decreased 2% in March. Manufacturing output, the largest component of the index, fell 0.3% in March.

Some 18 OPEC and non-OPEC countries, including Russia, had been meant to meet on Sunday morning in the Qatari capital of Doha and rubber-stamp a deal - in the making since February - to freeze output at January levels until October 2016.

Gas output from the top seven shale deposits will fall by 1.1 percent to 45.93 billion cubic feet a day from April, the biggest percentage decline since March 2013. The retreat is led by the oil-rich Eagle Ford deposit in Texas and the Niobrara shale in Colorado and neighboring states, where gas is pumped as a byproduct of crude extraction.

Crude oil production in May from the seven major US shale regions is expected to fall 114,000 b/d month-over-month to 4.84 million b/d, according to the US Energy Information Administration’s latest Drilling Productivity Report (DPR).