Originally offshore meant islands in the open sea. However, in the field of crude oil and natural gas production offshore means the development of crude oil fields and gas deposits in the sea. Approximately 25 percent of the worldwide confirmed oil reserves are to be found in offshore deposits.
Drilling rigs are used for offshore exploration and production of crude oil or natural gas. Thanks to drilling platforms drilling and exploiting in the sea becomes possible; they develop the deposits in the sea and exploit them. Partially the drilling platforms are replaced by specialised production platforms.
The work on offshore platforms is determined by special directives for offshore – crude oil and natural gas activities with regard to environment management, health protection and work safety.