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Line 31: − When a reservoir has formed in a trap and has come to pressure equilibrium with the water in the aquifer, the pore pressure of the hydrocarbons at different depths in the reservoir plot along a steeper gradient than the water gradient. The figure below shows this relationship. − + + +
Hydrocarbon expulsion, migration, and accumulation (view source)
Revision as of 21:21, 10 February 2014
, 21:21, 10 February 2014→Buoyancy pressure profile
==[[Buoyancy pressure]] profile==
==[[Buoyancy pressure]] profile==
[[file:predicting-reservoir-system-quality-and-performance_fig9-15.png|thumb|{{figure number|9-15}}. Copyright: Coalson et al., 1994; courtesy RMAG.]]
[[file:predicting-reservoir-system-quality-and-performance_fig9-15.png|thumb|{{figure number|2}}. Copyright: Coalson et al., 1994; courtesy RMAG.]]
When a reservoir has formed in a trap and has come to pressure equilibrium with the water in the aquifer, the pore pressure of the hydrocarbons at different depths in the reservoir plot along a steeper gradient than the water gradient. [[:file:predicting-reservoir-system-quality-and-performance_fig9-15.png|Figure 2]] shows this relationship.
The pressure contrast between the hydrocarbon gradient and the water gradient at a given depth in the reservoir (height above free water) is the buoyancy pressure (P<sub>b</sub>). The longer the column, the higher the P<sub>b</sub> at the top of the column.
The pressure contrast between the hydrocarbon gradient and the water gradient at a given depth in the reservoir (height above free water) is the buoyancy pressure (P<sub>b</sub>). The longer the column, the higher the P<sub>b</sub> at the top of the column.