Changes

The outline below presents the hierarchy and definitions for fluid-composition traps.

The outline below presents the hierarchy and definitions for fluid-composition traps.

'''Regime:''' Fluid-composition traps<br />

Result from a chemical property of the trapped oil or gas.

:'''Class:''' Viscosity traps

! Regime || Class || Subclass || Family

:Petroleum can be trapped by the presence of barriers created by highly [[Wikipedia:Viscosity|viscous]] oil ([[asphalt]], [[tar]]) or solid hydrocarbons ([[albertite]], [[gilsonite]], or [[grahamite]]).

::'''Subclass:''' Tar seals

| rowspan = 4 | ''Fluid-composition traps''; Result from a chemical property of the trapped oil or gas. || rowspan = 3 | ''Viscosity traps;'' Petroleum can be trapped by the presence of barriers created by highly [[Wikipedia:Viscosity|viscous]] oil ([[asphalt]], [[tar]]) or solid hydrocarbons ([[albertite]], [[gilsonite]], or [[grahamite]]). || ''Tar Seals'' || ''Bacterial degradation;'' Updip tar seal created by [[bacteria degradation]] of the hydrocarbons, preferentially removing the [[lighter fractions]].

:::'''Family:''' Bacterial degradation

:::Updip tar seal created by [[bacteria degradation]] of the hydrocarbons, preferentially removing the [[lighter fractions]].

| colspan = 2 | ''Disseminated;'' Tar or asphalt fills the pores of [[shale]]s, [[sandstone]]s, or [[carbonate]]s. These traps are often called [[tar sands]], [[oil shale]]s, bituminous sandstones, or bituminous limestones.

::'''Subclass:''' Disseminated

::Tar or asphalt fills the pores of [[shale]]s, [[sandstone]]s, or [[carbonate]]s. These traps are often called [[tar sands]], [[oil shale]]s, bituminous sandstones, or bituminous limestones.

| colspan = 2 | ''Veins;'' The solid, essentially infusible form of petroleum is called [[pyrobitumen]]. It occurs in veins [[length::1 mm]] to [[length::8 m]] across and appears to have been injected or is a dead seepage.

::'''Subclass:''' Veins

::The solid, essentially infusible form of petroleum is called [[pyrobitumen]]. It occurs in veins [[length::1 mm]] to [[length::8 m]] across and appears to have been injected or is a dead seepage.

| colspan = 3 | ''Coal-bed methane;'' [[Coal bed]]s trap large volumes of [[Wikipedia:Methane|methane]], where most is [[Wikipedia:Adsorption|adsorbed]] onto internal surfaces of [[micropore]]s or along [[cleat face]]s. [[Coalification]] generates methane along with water, [[Wikipedia:Carbon dioxide|carbon dioxide]], and [[Wikipedia:Carbon monoxide|carbon monoxide]].

:'''Class:''' Coal-bed methane

:[[Coal bed]]s trap large volumes of [[Wikipedia:Methane|methane]], where most is [[Wikipedia:Adsorption|adsorbed]] onto internal surfaces of [[micropore]]s or along [[cleat face]]s. [[Coalification]] generates methane along with water, [[Wikipedia:Carbon dioxide|carbon dioxide]], and [[Wikipedia:Carbon monoxide|carbon monoxide]].

==See also==

==See also==