The San Juan Basin extends 7,500 square miles across northwest N.M., and southwest Colo. Natural gas was first discovered here in 1921. Now a spry age of 104, it remains one of the nation’s oldest producing areas with sedimentary rock dating back to mid-Paleozoic times and a collision of supercontinents. ...

Might Texas-born Bob Simpson be looking to build back the Williston Basin powerhouse he created more than a decade ago? Back in 2010, the company Simpson founded in 1986—XTO Energy—merged with Exxon in a $41 billion all-stock deal pronounced one of the largest transactions in history for an independent oil and gas company. ...