Synonym: Formation = Formation unit
Locally agreed definition of one or more geological beddings which makes sense in the context of a particular subsurface study and reservoir model.
Formation units are usually identified and picked by geologist and petrophysicist based on the seismic survey and Reservoir Data Logs (RDL), usually Open-Hole logs.
See also
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology
[ Formation Tops ] [ Picking formation tops ]