The number of rigs drilling for oil in the U.S. rose by 11 over the past week to 341, according to oil-field services company Baker Hughes Inc., BHI 1.26 % as oil prices were moved by the Brexit vote. The U.S. oil-rig count, viewed as a proxy for activity in the sector, has fallen sharply since oil prices began to drop in 2014. The number of U.S. oil rigs peaked in October 2014 at 1,609. The nation’s gas-rig count was down by one in the past week to 89. The U.S. offshore-rig count was 19, down two from last week and 10 from a year ago. Oil prices were up slightly Friday , after a topsy-turvy trading week influenced by Britain’s referendum vote last week. Many fear that other countries will follow the U.K.’s decision to leave the European Union, freezing investment and shrinking or slowing the global economy, […]