Because the market currently prices oil much higher than natural gas, companies including Chesapeake Energy and EOG Resources have sped up the search for crude in basins like the Eagle Ford in Texas and the Bakken in North Dakota.
Although pipeline companies are rushing to build the capacity needed to transport the accompanying gas to market, their efforts have not caught up with the spike in wells drilled.
"The gas is worth very little in comparison to oil," Bruce Hicks, assistant director of North Dakota's state's oil and gas division, told Reuters. "This is an oil-driven play."
The number of rigs drilling for oil in North America has almost doubled from a year ago to 1021, according to a report from Baker Hughes oilfield equipment company.
The Texas Railroad Commission, which approves gas flaring permits, issued a total of 537 from September last year through this month, said agency spokeswoman Ramona Nye. That compares with 306 in all of fiscal 2010 and 107 in 2008.
The Eagle Ford shale had 56 active permits as of 22 July. Seventy-nine expired from September through June.
By comparison, the older Barnett Shale play in North Texas had no active permits and 33 expired in the same period.
In North Dakota, the amount of natural gas that is flared per day has increased 1200% since 2004, when Bakken development began its surge, and there have been relatively few complaints, Hicks said.
Centered on the city of Fort Worth, the Barnett is largely in urbanised areas, prompting tighter regulation limiting flaring. The Eagle Ford and Bakken are almost entirely in rural areas, where there is less objection to flaring wells.
Tom Smith of the Texas office of the consumer group Public Citizen said the practice pollutes the air and contributes to global warming.
"With our climate warming, we don't need to be adding fuel to the fire," Smith said.
Companies say temporary flaring is unavoidable, especially in fields like the Eagle Ford and the Bakken where the pipeline infrastructure is incomplete.
"Chesapeake flares natural gas on a case-by-case basis as needed, typically a few days," spokesman Silver Vasquez told Reuters in an e-mail. "The process is closely monitored in accordance with regulations."
Analysts agree flaring wastes a valuable energy source.
But companies as well as state officials, far from being careless about it, want to speed pipeline development to minimise flaring. Burned-off gas, after all, generates no revenue.
"They are just burning money," said Mike Breard, energy analyst at Hodges Capital Management in Dallas, but the situation limits the options.
"They are drilling so many wells down there, and the infrastructure just hasn't kept up, so you don't have any real choice," Breard said.