U.S. oil producers are grappling with geological limits to production growth as the country's top oilfield ages and produces more water and gas and less oil - and may be nearing peak output. The ...

The Permian is pumping 6.5 million barrels per day (bpd), a record level and nearly half the all-time high 13.5 million bpd of crude that the U.S. produced in December. But the Permian is flagging.