As oil firms scrap dozens of billions worth of mega projects essential for supplies in decades ahead, fresh output from huge fields already being developed is set to weigh for many more months on an oil market struggling to shake off a glut. A collapse in oil prices over the past 20 months to below $30 a barrel has taken a heavy toll on production around the world, reversing spectacular growth in U.S. shale oil and halting plans to develop costly and complex fields deep in oceans or treacherous seas such as the Alaska Arctic. But companies that have been investing often more than $10 billion in projects that were approved in the first half of the decade, when oil fetched in excess of $100 a barrel, are pushing ahead with many […]