By Nick Cunningham The first and third-largest oilfield service companies in the world saw their earnings hit in the third quarter due to the slowdown in U.S. shale drilling. Schlumberger took a $12.7 billion impairment charge related to its North American business, a rather dramatic write-down. That led to an $11.4 billion loss for the quarter, the largest in the company's history. "That's a sizable writedown from pressure pumping business. That just tells you the state of the North American onshore market being pretty poor," said Anish Kapadia, founder of oil and gas consultancy firm AKap Energy. Halliburton also saw its earnings hit by the slowdown in shale drilling and the oilfield services giant shifted its focus to international markets as the signs of a shale rebound do not appear to be imminent. Rig counts have fallen sharply over the past year, down more than 20 percent from late 2018.