After years of booms and busts that produced astronomical losses along with a whole lot of oil, the fracking industry seems to have found a sweet spot. It’s poised to generate more than $30 billion of free cash this year, a record, according to Bloomberg Intelligence. While that’s just a blip compared with the $300 billion that Deloitte LLP estimates the sector burned over the previous decade, it marks at least a temporary revival for an industry that a year ago had been largely written off by investors.