Changes

Pore systems are easily characterized by size using pore throat size. Pore throat sizes can be measured using [[capillary pressure]] curves. A capillary pressure curve is converted to a distribution profile of pore throat size, and a pore throat size that characterizes the rock is determined by picking a certain saturation level.

Pore systems are easily characterized by size using pore throat size. Pore throat sizes can be measured using [[capillary pressure]] curves. A capillary pressure curve is converted to a distribution profile of pore throat size, and a pore throat size that characterizes the rock is determined by picking a certain saturation level.

Which saturation level should we use? Work by Dale Winland and Ed Pittman<ref name=ch09r46>Pittman, E., D., 1992, [http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0002/0000/0191.htm Relationship of porosity to permeability to various parameters derived from mercury injection–capillary pressure curves for sandstone]: AAPG Bulletin, vol. 76, no. 2, p. 191–198.</ref> shows a statistical correlation between optimal flow through rocks and the radius of the pore throats when 35% of the pore space of a rock is saturated by a nonwetting phase during a capillary pressure test. They call the size of pore throats at 35% nonwetting phase saturation r₃₅, also called '''port size'''. Port size is convenient for characterizing the size of a pore system. Pore systems can be subdivided into “port types” by port size. (See [[Characterizing rock quality]] for a discussion of port size and r₃₅.) The table below shows port types and size ranges for those port types.

Which saturation level should we use? Work by Dale Winland and Ed Pittman<ref name=ch09r46>Pittman, E. D., 1992, [http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0002/0000/0191.htm Relationship of porosity to permeability to various parameters derived from mercury injection–capillary pressure curves for sandstone]: AAPG Bulletin, vol. 76, no. 2, p. 191–198.</ref> shows a statistical correlation between optimal flow through rocks and the radius of the pore throats when 35% of the pore space of a rock is saturated by a nonwetting phase during a capillary pressure test. They call the size of pore throats at 35% nonwetting phase saturation r₃₅, also called '''port size'''. Port size is convenient for characterizing the size of a pore system. Pore systems can be subdivided into “port types” by port size. (See [[Characterizing rock quality]] for a discussion of port size and r₃₅.) The table below shows port types and size ranges for those port types.

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