It can be a very labor-intensive task involving several different fields of science and elaborate equipment.
Petroleum geologists look at the structural and sedimentary aspects of the stratum/strata to identify possible oil traps or tight shale plays.
Petroleum geologists determine a prospect's viability looking at seven main aspects in conventional petroleum geology: These seven key aspects require the petroleum geologist to obtain a 4-dimensional idea of the subsurface (the three spatial dimensions, plus time).
Geophysical surveys show the seismology data of elastic waves, mainly seismic reflection.
More data may be obtained from the mudlogger, who analyzes the drill cuttings and the rock formation thicknesses.