In the oil and gas industry, the upstream sector refers to the exploration and production (E&P) of crude oil and natural gas. This includes activities such as searching for oil and gas reserves, drilling wells, and extracting the crude oil and natural gas from the reservoirs.

Upstream services in the oil and gas industry include a range of activities that support the exploration and production process, including:

• Geological and geophysical surveys to identify potential oil and gas reserves
• Drilling services, including well planning, wellbore design, and drilling fluids management
• Production services, such as artificial lift systems, well testing, and wellhead maintenance
• Reservoir engineering, which involves monitoring the reservoir and optimizing production from the wells
• Environmental and safety services, including spill prevention and response, safety audits, and environmental impact assessments

The upstream sector is a complex and capital-intensive part of the oil and gas industry, involving significant investment in equipment, technology, and expertise. Many companies specialize in providing upstream services to oil and gas exploration and production companies, including major oilfield services companies like Schlumberger, Halliburton, and Baker Hughes.