How is Schlumberger's development? What are the advantages compared with PetroChina, CNOOC and Sinopec?

Schlumberger, right? Schlumberger is the world's largest oilfield technical service company, headquartered in new york, Paris and The Hague, with branches in more than 40 countries around the world. Founded in 1927, the company has more than 70,000 employees. In 2006, the company's profit was19.23 billion USD, making it one of the top 500 enterprises in the world. Schlumberger Technical Service Company (SIS) belongs to Schlumberger Oilfield Service Department and is recognized as the best software and service provider in the oil and gas industry.