The oil & gas industry is composed of three major components:
The upstream industry finds and produces crude oil and natural gas. The midstream industry processes, stores, markets and transports commodities such as crude oil, natural gas and natural gas liquids. The downstream industry includes the oil refineries, petrochemical plants, petroleum product distributors and natural gas distribution companies.
All of these operations contain many processes that require monitoring of hazardous gases and vapors to protect personnel, product and facilities from accidental releases or leakage.