Published classification schemes for hydrocarbon traps concentrate on the mechanisms that caused the traps to be formed. These schemes are of great value in exploring for analogs. However, traps formed in very different ways may have the same trapping mechanism (i.e., the means by which the oil is held in the trap).

A new scheme is proposed in which traps are classified by trapping mechanism. One-seal traps are those in which closed contours exist at the base of the top of the sealing sequence. Poly-seal traps are those in which closed contours do not exist on a single sealing surface (the base of the top seal). A secondary subdivision is by the relationship of the sealing surfaces to the sealing lithologies (e.g., conformable, unconformable, tectonic, or facies change), and a third subdivision is by the sealing sequence itself.

The risk of success or failure of the trap is carried entirely by the efficiency of the sealing surfaces, which is determined by the nature of the surfaces and the sealing lithology.