Energy firms pulled another 13 rigs from U.S. oil fields this week, the biggest drop in four weeks, data showed on Friday, showing that a near six-month slump in activity had yet to run its course despite a rebound in crude oil prices.  That was the 25th straight weekly decline, bringing the total rig count down to 646, the lowest since August 2010, oil services company Baker Hughes Inc said in its closely followed report.  However, in the Eagle Ford basin in South Texas, the nation's second biggest shale oil field, drillers added one oil rig in the third weekly increase in a row, bringing the total up to 90.  U.S. crude, also known as West Texas Intermediate or WTI, closed up $2.62, or 4.54 percent, at $60.30 a barrel. July Brent, meanwhile, was up $3, or 4.8 percent, at $65.53.  The market has been eyeing the U.S. rig count and the increases of a few rigs in some basins over the past few weeks ahead of next week's meeting of the Organization of the Petroleum Exporting Countries, which is to decide on crude production levels of its 12 members. OPEC is widely expected to keep its output levels unchanged to defend market share.  The Permian basin in western Texas and eastern New Mexico, the biggest and fastest growing U.S. shale oil play, meanwhile, lost one oil rig to 231, the lowest since at least 2011, according to Baker Hughes data going back to 2011. At least three other shale formations also lost one rig each this week.  Read More US oil production at 43-year high as OPEC prepares to meet  Since the number of oil rigs peaked at 1,609 in October, U.S. drillers have slashed spending, eliminated thousands of jobs and idled more than half of the country's active rigs as U.S. crude futures collapsed 60 percent from over $107 a barrel last June to a six-year low near $42 in March.  Since then, however, U.S. energy companies have started to return to the well pad as prices rebounded around 40 percent to over $60 earlier in May. Prices so far this week have averaged about $58 a barrel.
Oil prices extended gains after Baker Hughes reported that the weekly U.S. oil rig count fell for the 25th straight week.