SLB (formerly Schlumberger) is the world's largest oilfield-services company — the contractor that finds, drills, completes and produces the oil and gas that national oil companies and majors pump. It sells the four pillars of the well: reservoir evaluation, well construction, production systems and a fast-growing digital/AI platform business. After buying ChampionX (~$7.8B, 2025) it now also dominates production chemicals and artificial lift, and it controls the OneSubsea subsea joint venture.
The service company behind the barrel
SLB doesn't own the oil — it is the contractor producers hire to find, drill, complete and produce it. Steel, sand, chemicals and electronics flow in; reservoir, drilling, production and subsea services flow out to NOCs and majors, whose crude then feeds refiners and end markets.