A pump-jack near Guthrie, Okla., in September 2015. HONG KONG—While oil’s rise above $50 a barrel for the first time in seven months is a landmark for the market, analysts appear to have no clear idea how long this year’s crude rally might last. Brent crude, used to price much of the world’s oil, and West Texas Intermediate, the U.S. benchmark, both topped $50 a barrel Thursday before edging lower to $49.59 and $49.48 a barrel, respectively. The return of $50 oil is the latest development in a market that has confounded investors, producers and traders since a selloff caused by a global oversupply of crude began in 2014. Prices had fallen below $30 a barrel at the beginning of this year—a level not seen since early last decade—before mounting a recovery. Many analysts cite strong demand from major emerging countries such as China and India, coupled with supply […]