Crude oil prices fell to a fresh six-year low Thursday, as traders found more reasons to worry about the global economy and fewer to think that the glut of oil might evaporate.

And Moody’s Investors Services warned the picture may grow bleaker, forecasting that oil producers need a price of about $51 per barrel of oil equivalent to keep their businesses from shrinking.

The U.S. price benchmark, West Texas Intermediate crude for delivery next month, fell $1.07 to $42.23 per barrel on the New York Mercantile Exchange. London-traded Brent crude, the international benchmark, fell 44 cents to $49.22.

Thursday marked the first time U.S. crude oil has ended daily trading below $43 per barrel since 2009, at the height of the global financial crisis. The price has fallen by about one-third from 2015 highs around $60, as China’s economy has weakened and global production has remained high. And oil has fallen from more than $100 since last summer.

“There’s simply too much supply,” said David Schiegoleit, managing director of investments at the Private Client Reserve of U.S. Bank in Los Angeles. “We see a lot more reasons for oil to continue to go down than we see a reason for it to go up.”

The return to six-year lows has turned up the heat on the already suffering energy industry.

On Thursday, Houston-based Hercules Offshore filed for Chapter 11 bankruptcy protection in a Delaware court while it moves forward with a planned restructuring of its finances.

Hercules’ court filings showed more than $1.3 billion in debt and about $546 million in assets. The company operates a fleet of 27 jack-up rigs, mostly in the Gulf of Mexico, and low oil prices have forced it to mothball nine rigs and to cut about 500 of its 1,800 workers this year.

The company said it expects to be in bankruptcy proceedings for 45 to 60 days and that it doesn’t anticipate halting daily operations.

Another Houston company, independent producer Energy XXI, said Thursday it will cut its 2016 capital expenditure budget to $140 million from the $640 million to $670 million it spent during the company’s 2015 fiscal year, which ended on June 30.

Despite slashing its spending budget, Energy XXI says it will pump 54,000 to 59,000 barrels of oil equivalent per day in its 2016 fiscal year, about the same as its prior year production rate of 58,900 barrels per day. Oil and natural gas liquids make up about two-thirds of its output estimates.

More producers could be forced to make similar cuts soon, according to a new analysis by Moody’s Investors Service.

It said Thursday that liquids-focused producers need to sell their barrels of oil equivalent for about $51 to be able to fund their operations and replace the reserves they’re producing. Including natural gas producers, Moody’s estimated the full cost of producing and replacing a barrel of oil equivalent is $42 per barrel.

Companies with high cost structures and high debt loads will need to find more costs savings or face a shrinking reserve base, said Gretchen French, an analyst at Moody’s.

“For many companies, they don’t have sustainable cost structures based on the historical data,” French said. “They can survive, but they may not survive at the same size.”

robert.grattan@chron.com

rhiannon.meyers@chron.com

Collin Eaton contributed to this report.