Upstream (oil industry)

The upstream oil sector is a term commonly used to refer to the searching for and the recovery and production of crude oil and natural gas. The upstream oil sector is also known as the exploration and production (E&P) sector.

Major sectors of the oil industry
The oil industry is often divided into three major sectors: upstream, midstream and downstream. However, midstream operations are usually simply included in the downstream category.

Upstream sector
The upstream sector includes the searching for potential underground or underwater oil and gas fields, drilling of exploratory wells, and subsequently operating the wells that recover and bring the crude oil and/or raw natural gas to the surface.

Midstream sector
The midstream sector processes, stores, markets and transports commodities such as crude oil, natural gas and natural gas liquids (NGLs) such as ethane, propane and butane.

Downstream sector
The downstream  sector includes oil refineries, petrochemical plants, petroleum product distribution, retail outlets and natural gas distribution companies. The downstream industry touches consumers through thousands of products such as gasoline, diesel, jet fuel, heating oil, asphalt, lubricants, synthetic rubber, plastics, fertilizers, antifreeze, pesticides, pharmaceuticals, natural gas and propane.

Byproduct sulfur
Crude oil is a mixture of hundreds of hydrocarbons, including many which contain sulfur and refining the crude oil includes converting most of that sulfur into gaseous hydrogen sulfide. Raw natural gas also contains gaseous hydrogen sulfide and sulfur-containing mercaptans, which are removed in natural gas processing plants before the gas is distributed to consumers. The hydrogen sulfide removed in the refining and processing of crude oil and natural gas is subsequently converted into byproduct elemental sulfur. In fact, the vast majority of the 64,000,000 metric tons of sulfur produced worldwide in 2005 was byproduct sulfur from refineries and natural gas processing plants.