You searched for: “abiogenic theories
abiogenic theory (s) (noun), abiogenic theories (pl)
The theory that hydrocarbon deposits have a primarily non-biological origin.

According to this concept, such materials became trapped far below the earth's crust when the basic structure of the planet evolved, and have subsequently migrated into reservoirs and to the surface through openings in in the earth's crust.

Contrasted with the more generally accepted biogenic theory that hydrocarbon deposits derive from the remains of living organisms.