Changes

[[file:predicting-reservoir-system-quality-and-performance_fig9-22.png|300px|thumb|{{figure number|1}}Example reservoir cross section.]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-22.png|300px|thumb|{{figure number|1}}Example reservoir cross section.]]

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 macroporous or [[Wikipedia:Mesoporous material|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 macroporous or [[Wikipedia:Mesoporous material|mesoporous]] reservoirs; immobile water saturation is lower in macroporous rocks.