The collapse in oil prices has sent three-dozen companies into bankruptcy court this year—and that might not be nearly enough to balance the glutted market. Thirty-seven North American oil and gas producers havefiled chapter 11 cases in 2015, according to law firm Haynes and Boone LLP. The cases involve $13.1 billion in debt, and “industry and economic indicators suggest more producer bankruptcy filings will occur before the year is out,” the law firm said a report. More may well be needed to bring production back into balance with demand, some investors say. “There’s been more efficiency in the space than we all expected, and that’s helped current owners hold on a little longer,” said Rob Haworth, senior investment strategist at U.S. Bank Wealth Management, which oversees $126 billion. “We’re not seeing as much turnover in the oil patch as we’d expect, in terms of weak hands to strong hands. […]