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Pc curves and saturation profiles (view source)
Revision as of 15:58, 14 February 2014
, 15:58, 14 February 2014→Pore throat size and saturation profiles
==Pore throat size and saturation profiles==
==Pore throat size and saturation profiles==
[[file:predicting-reservoir-system-quality-and-performance_fig9-22.png|thumb|{{figure number|1}}See text for explanation.]]
Water in the pore throats of rocks with macroporosity offers little capillary resistance to migrating hydrocarbons compared with the pore throats of rocks with microporosity. As a result, oil and gas migrate through a rock with macroporosity with minimal buoyancy pressure, i.e., hydrocarbon column. Macropore reservoirs have little or no saturation transition zone.
Water in the pore throats of rocks with macroporosity offers little capillary resistance to migrating hydrocarbons compared with the pore throats of rocks with microporosity. As a result, oil and gas migrate through a rock with macroporosity with minimal buoyancy pressure, i.e., hydrocarbon column. Macropore reservoirs have little or no saturation transition zone.
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 below, 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|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.
==Pore throat size sorting==
==Pore throat size sorting==