Brent crude prices, the benchmark for half the world’s oil, will weaken for a second year in 2014 as U.S. output expands and threats to Middle East and North African supply ease, the most-accurate forecasters said. Prices will average $105 a barrel in 2014, from $108.70 in 2013, according to the median of estimates from the seven analysts who most accurately predicted this year’s level in a survey last December. Brent averaged $111.68 in 2012. Global supply is expanding as the U.S. pumps oil trapped in shale-rock formations, driving domestic output to the highest in a quarter century and curbing demand for the crude priced off Brent. Iran , Iraq and Libya will also produce more in 2014, the forecasters said. While a second annual drop for Brent would be the first consecutive retreat since 1998, prices are still about 39 percent higher than the average over the past […]