Drilling the wells that produce the world’s energy is a team effort. There are three main types of companies that collaborate in developing these energy sources — E&P companies, drilling contractors, and oilfield services and manufacturing companies. E&P companies seek the subsurface hydrocarbon resources, and thus oversee the well drilling process. They also manage hydrocarbon transportation, gas processing and, often, petroleum refining. E&P companies employ drilling contractors, which provide drilling rigs and crews. E&P companies also contract oilfield service companies for additional equipment and materials at the wellsite. Finally equipment manufacturers develop the rigs and gear needed drill and complete wells.

Together, these companies comprise the upstream oil and gas segment.