For Big Oil, the U.S. tax overhaul is turning out to be a mixed bag, especially for companies that drill overseas. Two weeks after President Donald Trump and congressional Republicans passed a sweeping rewrite of the tax code that cuts corporate rates, drillers are finding other changes that are less of a boon. BP Plc and Royal Dutch Shell Plc offered a preview recently, saying they may write off as much as $4 billion in tax assets as a result. Caps on debt-interest payments and cuts to deductions from previous years’ losses may hurt companies building capital-intensive projects with borrowed money. And other provisions, including time limits on expensing exploration, could hem in drillers with long-term projects, including Exxon Mobil Corp. and Chevron Corp. That may […]