['Industry overview. Oil continues to provide over 90% of the energy used in transportation around the world. ... ', 'ConocoPhillips. As one of the largest exploration and production (E&P) companies in the world, ConocoPhillips (NYSE:COP) is a staple in the upstream segment of oil and gas. ... ', 'Royal Dutch Shell. ... ', 'ExxonMobil. ... ', 'Conclusion.']