About 250 million years ago, at the end of the Permian period, something killed some 90 percent of the planet's species. Less than 5 percent of the animal species in the seas survived. On land ...

Some areas in the Permian have hit geological limits while others, yet to be drilled, are not expected to be as prolific as the prime Tier 1 acreage. Despite record U.S. crude oil production ...