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, 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 '''r'''₃₅, 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” in section C for a discussion of port size.) 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, 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 '''r'''₃₅, 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.) The table below shows port types and size ranges for those port types.

{| class = "wikitable"

{| class = "wikitable"

|-

|-

! Port category

! Port category

! Port size range (r35), μ

! Port size range (r₃₅), &mu;

|-

|-

| Mega

| Mega

| > 10

| >10

|-

|-

| Macro

| Macro

|-

|-

| Nano

| Nano

|

| <0.1

|}

|}