More than a year into the worst oil bust in a generation, companies keep tallying the carnage. Most of the industry’s third-quarter results will be reported over the next two weeks. Here are three numbers to watch: 1. Writedowns Southwestern Energy Co. set the tone on Oct. 22 with a $2.8 billion charge, twice as much as forecast by Barclays Plc. There’s more to come. Barclays predicted $20 billion in writedowns from six companies in an Oct. 21 report. That’s because some producers use an accounting method that requires them to take charges when estimates of future cash flow fall below the cost to acquire land and drill wells. Of the 61 companies in the Bloomberg Intelligence North American Independent Explorers & Producers index, 25 use that approach, including Devon Energy Corp., Apache Corp. and Chesapeake Energy Corp. 2. Cash Flow During the boom years, shale drillers spent far […]