U.S. shale drillers that proved resilient during the oil downturn face a new test in 2017: Can they make money producing more now that prices have stabilized? The price of crude is hovering just below $55 a barrel—the level many energy companies said they needed to make a profit—and that is setting off a race to drill again. Producers boosted U.S. oil output to nearly 9 million barrels a day, pumping an extra 500,000 barrels a day in…