Reporting its Q4 and full-year results for 2021, oilfield services provider Schlumberger said it had closed the year with “great momentum.” Schlumberger (NYSE: SLB) reported Friday that pre-tax profits reached $2.37 billion (£1.75bn) in full-year 2021, reversing losses of $11.3bn (£8.3bn) the year before. Full-year revenue dipped slightly to $22.9bn (£16.8bn), from $23.6bn (£17.4bn) in 2020, though Q4 revenues rose to …