Changes

Rocks can be classified on the basis of their pore geometry into four major pore categories that can be divided into ten subcategories. Extensive experience and laboratory analysis show that these pore type categories have a particular behavior when interacting with fluids that can be used to predict the behavior of reservoir systems over time.  

Rocks can be classified on the basis of their pore geometry into four major pore categories that can be divided into ten subcategories. Extensive experience and laboratory analysis show that these pore type categories have a particular behavior when interacting with fluids that can be used to predict the behavior of reservoir systems over time.  

Pore geometry is categorized as intergranular, intercrystalline, [[vug]]gy/moldic, or fracture. [[Pore and pore throat sizes|Pore throat sizes]] are categorized into mega-, macro-, meso-, and micro-pore types. Combining both pore geometry and pore type into a classification scheme is an effective method of describing pore systems. For example, a very fine-grained sandstone might be classified as having intergranular mesoporosity or a limestone as having vuggy macroporosity.

Pore geometry is categorized as intergranular, intercrystalline, [[vug]]gy/moldic, or fracture. [[Pore and pore throat sizes|Pore throat sizes]] are categorized into mega-, macro-, meso-, and micro-pore types. Combining both pore geometry and pore type into a classification scheme is an effective method of describing pore systems. For example, a very fine-grained [[sandston]]e might be classified as having intergranular mesoporosity or a [[limestone]] as having vuggy macroporosity.

Table 1 describes a typical rock type for each pore type in the classification.

Table 1 describes a typical rock type for each pore type in the classification.

|Mega/macro || Clean, coarse sandstone or [[carbonate]] [[grainstone]] ||  

|Mega/macro || Clean, coarse sandstone or [[carbonate]] [[grainstone]] ||  

*Coarsely crystalline carbonate  

*Coarsely crystalline carbonate  

*Quartz- or carbonate-cemented coarse sandstone

*[[Quartz]]- or carbonate-cemented coarse sandstone

|| [[Chlorite]]- or [[illite]]-cemented (pore-lining) coarse sandstone || Connected vugs or vugs in a crystalline matrix || Fracture width >50µ

|| [[Chlorite]]- or [[illite]]-cemented (pore-lining) coarse sandstone || Connected vugs or vugs in a crystalline matrix || Fracture width >50µ

|-

|-

|Meso || Clean, coarse silt to very fine sandstone or carbonate grainstone ||  

|Meso || Clean, coarse [[silt]] to very fine sandstone or carbonate grainstone ||  

*Very fine to medium crystalline carbonate

*Very fine to medium crystalline carbonate

*Quartz- or carbonate-cemented fine to medium sandstone

*Quartz- or carbonate-cemented fine to medium sandstone

*Chlorite- or illite cemented (pore-lining) fine to medium sandstone

*Chlorite- or illite cemented (pore-lining) fine to medium sandstone

*[[Kaolinite]]-cemented (pore-filling) coarse sandstone

*[[Kaolinite]]-cemented (pore-filling) coarse sandstone

|| Poorly connected vugs or oomolds in a fine to medium crystalline matrix || Fracture width 5-50µ

|| Poorly connected vugs or [[oomold]]s in a fine to medium crystalline matrix || Fracture width 5-50µ

|-

|-

|Micro || Clean clay-size to fine siltstone or clay-size carbonate ||

|Micro || Clean [[clay]]-size to fine [[siltstone]] or clay-size carbonate ||

*Silt-size crystalline carbonate

*Silt-size crystalline carbonate

*Quartz- or carbonate-cemented silt to very fine sandstone

*Quartz- or carbonate-cemented silt to very fine sandstone