U.S. drillers add oil rigs for 18th week in a row -Baker Hughes

May 19 (Reuters) - U.S. energy firms added oil rigs for an 18th week in a row, the second-longest streak of weekly additions on record, as expectations of higher crude prices motivate drillers to boost monthly shale production to its highest level since mid-2015. Drillers added 8 oil rigs in the week to May 19, bringing the total count to 720, the most since April 2015, energy services firm Baker Hughes Inc said on Friday. The 18-week streak of rig inc