Changes

[[file:migration-of-petroleum_fig7-3.png|300px|thumb|{{figure number|1}}Comparison of shale pore size with hydrocarbon molecule size. From Momper;<ref name=Momper1978>Momper, J. A., 1978, [http://archives.datapages.com/data/specpubs/geochem1/data/a034b/a034/0001/0000/t1.htm Oil migration limitations suggested by geological and geochemical considerations], in W. H. Roberts and R. J. Cordel, eds., Physical and Chemical Constraints on Petroleum Migration: AAPG Continuing Education Course Notes Series no. 8, p. B1–B60.</ref> courtesy AAPG.]]

[[file:migration-of-petroleum_fig7-3.png|300px|thumb|{{figure number|1}}Comparison of shale pore size with hydrocarbon molecule size. From Momper;<ref name=Momper1978>Momper, J. A., 1978, [http://archives.datapages.com/data/specpubs/geochem1/data/a034b/a034/0001/0000/t1.htm Oil migration limitations suggested by geological and geochemical considerations], in W. H. Roberts and R. J. Cordel, eds., Physical and Chemical Constraints on Petroleum Migration: AAPG Continuing Education Course Notes Series no. 8, p. B1–B60.</ref> courtesy AAPG.]]

Shale pore sizes range over five orders of magnitude and are about the diameter of the individual hydrocarbon molecules. This suggests many pore throats will be able to pass only the smaller hydrocarbon molecules due to physical restrictions (styric effects). Thus, the larger shale pores are supplied with full-spectrum hydrocarbons migrating directly from kerogen in contact with the pores. Larger shale pores are also preferentially supplied with the smaller paraffin and aromatics from the neighboring smaller pores. [[:file:migration-of-petroleum_fig7-3.png|Figure 1]] compares shale pore size with hydrocarbon molecule size.

Shale pore sizes range over five orders of magnitude and are about the diameter of the individual hydrocarbon molecules. This suggests many pore throats will be able to pass only the smaller hydrocarbon molecules due to physical restrictions (styric effects). Thus, the larger shale pores are supplied with full-spectrum hydrocarbons migrating directly from [[kerogen]] in contact with the pores. Larger shale pores are also preferentially supplied with the smaller paraffin and aromatics from the neighboring smaller pores. [[:file:migration-of-petroleum_fig7-3.png|Figure 1]] compares shale pore size with hydrocarbon molecule size.

==Trapping large molecules in shale==

==Trapping large molecules in shale==