Migration (geology)

In geology and reservoir research, migration is the slow migration of hydrocarbons ( crude oil and natural gas ) from the bedrock - where it was formed and matured - into the later storage rock . It is an essential process for the formation of the deposits , but not yet fully understood in detail.

The formation and accumulation of hydrocarbons mainly takes place from biogenic material in marine deposits . When these become rock during diagenesis and the pressure increases due to new deposits or tectonic processes such as mountain formation, the formation water contained in the pores of the sediments is slowly squeezed out and flows off together with the hydrocarbons following the pressure gradient upwards. If the mixture hits reservoir rocks in suitable geological structures ( oil traps ), it collects there. If it is not retained, it can reach the surface of the earth and create special deposits there (for example bitumen or asphalt lakes such as La Brea Pitch Lake in Trinidad or the asphalt ponds of La Brea in Los Angeles ).

The migration of hydrocarbons should not be confused with the geophysical method of migration , which is used in reflection seismics during processing .

literature

• Dieter Richter: General Geology . 4th edition. Walter de Gruyter, 1992, ISBN 3-11-012242-1 ( p. 134 in the Google book search).