Wall Street JournalOPEC-US Oil Tussle Takes Toll on NigeriaWall Street JournalLONDON—The escalating duel surrounding U.S. and OPEC oil production has ensnared Nigeria's energy sector, highlighting a challenge for the petroleum cartel ahead of its meeti …

Wall Street JournalNigerian Oil Hurt by Tussle Between OPEC and USWall Street JournalOnce a highly desired, easy-to-refine product, Nigeria's oil is now hard to sell. In 2014 it fetched more than $2 a barrel more than the global benchmark, Brent crude, …