Oil price steadies decline after tumbling to the lowest level since before OPEC reached an output-reduction deal as U.S. shale confounds the producer group’s attempts to prop up prices.

Prices are approaching an 8 percent decline this week, bringing the U.S. benchmark crude back to levels last seen before the Organization of Petroleum Exporting Countries signed a six-month deal in November to curb production and ease a global glut. The drop in prices is being driven by expanding U.S. output and concerns that inventories haven’t declined as much as investors had hoped, even as OPEC and Russia signal that the output cuts should be extended.

OPEC’s curbs drove oil in early January to the highest since July 2015, encouraging U.S. producers to ramp up drilling. The result has been an 11-week expansion of American production, the longest run of gains since 2012. Prices are still more than 50 percent below their peak in 2014 when surging shale output triggered crude’s biggest collapse in a generation and left rival producers such as Saudi Arabia scrambling to protect market share.

“The faith in the OPEC and non-OPEC deal has just been obliterated. There are whispers and rumors out there that the deal won’t even get extended,” John Kilduff, a partner at Again Capital LLC, a New York-based hedge fund, said by telephone. “The proof just hasn’t been in the pudding in terms of this accord.”

West Texas Intermediate for June delivery rose 28 cents to $45.80 a barrel at 9:52 a.m. on the New York Mercantile Exchange, after dropping as much as 3.9 percent earlier. The total volume traded was 120 percent above the 100-day average. The contract fell 4.8 percent Thursday.

Brent for July settlement rose 44 cents to $48.82 after slumping as much as 3.6 percent earlier on the London-based ICE Futures Europe exchange. Prices are down 5.6 percent this week, heading for a third weekly decline. The global benchmark crude traded at a premium of $2.59 to July WTI.

Oil market volatility, as measured by the CBOE Crude Oil Volatility Index, jumped to the highest level since December, but at last looks like crude oil price steadies decline.

“There’s a lot of option-related activities so as the market falls through $45, the holders of short, put positions need to hedge,” said Mark Keenan, head of Asia commodities research at Societe Generale SA. “They need to sell futures, and that can drive some very significant and volatile moves through those levels.”

U.S. crude production rose to 9.29 million barrels a day last week, the highest level since August 2015, according to the Energy Information Administration. While OPEC is likely to prolong curbs for a further six months, American shale supply remains a concern, according to Nigeria’s oil minister.

OPEC will meet May 25 in Vienna to decide whether to extend the deal.

“There’s a disappointment that the production cuts we’ve seen from OPEC and others have not had any impact at this stage on global inventory levels,” said Ric Spooner, a chief market analyst at CMC Markets in Sydney. “The market seems to be much further away from a balanced situation than some had previously forecast. There is a possibility that oil could be headed to the low-$40s range from here.”

While energy consumers have benefited from lower energy prices, no one will be more pleased that the oil price steadies decline than U.S. producers who have frequently stated that oil prices need to be above $50 barrel to maintain production.