( see also Upstream @ Wikipedia )

The area of Petroleum Industry dealing with subsurface exploration, drilling and production of hydrocarbons.

Drilling is split into exploration drilling and production drilling which have some specifics.

Petroleum Production is usually split into two operational areas:

• Surface Production

and

• Subsurface Production

Production operations usually follow Production Strategy which is a part of Field Development Planning.

The Subsurface Production is split into three major areas of activities:

• Reservoir Study & Modelling

• Well & Reservoir Surveillance

• Well & Reservoir Management