Gas deposit is set of deposits of natural gas and condensate in a certain area, it usually occupies several hundred kilometers.
Gas deposits are divided into:
small – up to 10 billion m³ of gas;
average – 10 - 100 000 000 000 m³ of gas;
large – 100 - 1000 billion m³ of gas;
largest (giant) – 1 - 5 trillion m³ of gas;
unique (supergiant) – 5 trillion m³ and more.
Gas is extracted from the earth by operating gas wells and development system is determined by geological conditions of the deposit and economic calculations. They try to place wells evenly on all territory of a field for uniform drop in reservoir pressure in a deposit. Gas overflows between field areas, and also premature flood of a deposit are otherwise possible. Gas leaves a subsoil because in layer it is under pressure, multiply exceeding the atmospheric. Thus, the driving force is the difference between the pressures in the formation and a collection system. Calculation of produced natural gas is conducted in absolute figures for the losses (the so-called sales gas).
Natural gas production growth is ensured by new discoveries, involvement in the development of less rich deposits, improved technologies for the extraction and processing of raw materials using non-waste technology. Scale of natural gas production increases with the development of industrial production, technological progress and population growth.