Changes

In rocks with microporosity, capillary forces hold water tightly to rock surfaces, decreasing the effective size of the already small pore throats. Therefore, a greater buoyancy pressure is required for oil or gas to migrate. Micropore reservoirs have longer saturation transition zones than macro- or mesoporous reservoirs; immobile water saturation is lower in macroporous rocks.

In rocks with microporosity, capillary forces hold water tightly to rock surfaces, decreasing the effective size of the already small pore throats. Therefore, a greater buoyancy pressure is required for oil or gas to migrate. Micropore reservoirs have longer saturation transition zones than macro- or mesoporous reservoirs; immobile water saturation is lower in macroporous rocks.

In the example reservoir cross section in [[:file:predicting-reservoir-system-quality-and-performance_fig9-22.png|Gifure 1]], the rock in container 1 is mesoporous; the rock in container 2 is macroporous. Container 1 has a longer transition zone than container 2 because of this. Both containers have the same buoyancy pressure and free water level because the two containers are in pressure communication.

In the example reservoir cross section in [[:file:predicting-reservoir-system-quality-and-performance_fig9-22.png|Figure 1]], the rock in container 1 is mesoporous; the rock in container 2 is macroporous. Container 1 has a longer transition zone than container 2 because of this. Both containers have the same buoyancy pressure and free water level because the two containers are in pressure communication.

==Pore throat size sorting==

==Pore throat size sorting==

==See also==

==See also==

* [[Pore–fluid interaction]]

* [[Pore-fluid interaction]]

* [[Hydrocarbon expulsion, migration, and accumulation]]

* [[Hydrocarbon expulsion, migration, and accumulation]]

* [[Characterizing rock quality]]

* [[Characterizing rock quality]]