CNBC reports that the oil market is facing a "double crisis" with a collapse in the OPEC+ alliance affecting supply and the slowdown in the global economy crushing demand, oil guru Dan Yergin said.

"The breakdown of OPEC+ is only part of the picture," the vice chairman of IHS Markit told CNBC. "The big thing is the coronavirus and the showdown of much of the world economy."

Countries have implemented travel bans and instituted lockdowns to stem the spread of the virus.

"Cars not on the road, airplanes not in the air, factories not working, people not going to work," Yergin said. "We see, in this month of April that's coming, what could be a 20 million barrel a day decline in oil demand."

"It's unprecedented. That's six times larger than the biggest downturn during the financial crisis period (in 2008)," he added.

World oil demand in 2019 stood at around 99.67 million barrels a day, according to OPEC's estimate.

While demand is set to fall, major producers such as Saudi Arabia and Russia have announced they will increase supply in April after the OPEC+ agreement expires at the end of March.

"This is what people are now looking at ... where are you going to put all of the oil?" he asked. When oil storage runs out, prices could fall further, he added. "I think the prices that we're seeing, that you're talking about today are really precursors ... April is going to be a very difficult month."