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→Classes
==Classes==
==Classes==
The basis for the three classes of the depositional regime is the geometric arrangement of the facies resulting from depositional processes. The subclasses describe reservoir composition or lithology. Where described, trap styles can be listed based on the lithology or composition of the sealing rocks. The outline below shows the classes and subclasses of the depositional regime.
The basis for the three classes of the depositional regime is the geometric arrangement of the facies resulting from depositional processes. The subclasses describe reservoir composition or lithology. Where described, trap styles can be listed based on the lithology or composition of the sealing rocks. The outline below shows the classes and subclasses of the depositional regime.
{| class = "wikitable"
|-
! System || Regime || Class || Subclass || Style
|-
| rowspan = 11 | ''Stratigraphic'' || rowspan = 11 | ''Depositional''; Trap boundaries are created primarily by depositional processes and can involve igneous rocks as well as sedimentary rocks. Three classes are recognized, based on whether the trap involves an isolated reservoir, an updip pinch-out, or depositional relief on top of the reservoir. || rowspan = 3 | ''Isolated (local) depositional reservoirs''; Reservoir rock is partially or completely isolated by sealing rocks, which provide top, side, and often bottom seals. These traps are often of limited areal extent, with trap closure defined largely by reservoir distribution. || colspan = 2 | ''Sandstone reservoirs''; Partially or completely isolated by seal.
|-
| colspan = 2 | ''Carbonate reservoirs''; Partially or completely isolated by seal.
|-
| colspan = 2 | ''Igneous reservoirs''; Partially isolated by seal.
|-
| rowspan = 4 | ''Depositional pinch-outs''; Depositional processes form an updip pinch-out of permeable rock into impermeable rock. Trap closure is usually created by an updip re-entrant of the pinch-out boundary or by a combination of the pinch-out with other trap elements, such as tectonic nosing or hydrodynamics. Pinch-out boundaries typically involve top, side, and bottom seals. || colspan = 2 | ''Regional sandstone pinch-outs''; Regional updip pinch-outs of sandstone into an impermeable facies such as shale or anhydrite.
|-
| colspan = 2 | ''Local sandstone pinch-outs''; Local updip pinch-outs of sandstone into an impermeable facies such as shale or anhydrite.
|-
| colspan = 2 | ''Regional carbonate pinch-outs''; Regional updip pinch-outs of carbonate into an impermeable facies such as shale or anhydrite.
|-
| colspan = 2 | ''Local carbonate pinch-outs''; Local updip pinch-outs of carbonate into an impermeable facies such as shale or anhydrite.
|-
| rowspan = 4 | ''Depositional relief traps''; Process forms positive relief on top of the reservoir; this topographic relief between top seal and reservoir creates the trap closure. || colspan = 2 | ''Sandstone depositional relief traps''
|-
| rowspan = 3 | ''Carbonate depositional relief traps'' || ''Carbonate reservoirs sealed by shale''
|-
| ''Carbonate reservoirs sealed by tight carbonate''
|-
| ''Carbonate reservoirs sealed by evaporites''
|}
'''System:''' Stratigraphic
'''System:''' Stratigraphic