High Quality Content by WIKIPEDIA articles! Shell Oil Company is the United States-based subsidiary of Royal Dutch Shell, a multinational oil company ("oil major") of Anglo–Dutch origins, which is amongst the largest oil companies in the world. Approximately 22,000 Shell employees are based in the U.S. The U.S. head office is in Houston, Texas. Shell Oil Company, including its consolidated companies and its share in equity companies, is one of America’s largest oil and natural gas producers, natural gas marketers, gasoline marketers and petrochemical manufacturers.