Changes

==Influence of grain size on porosity and diagenesis==

==Influence of grain size on porosity and diagenesis==

Sorting and grain size are textural parameters that intuitively might seem to have the same effects on the porosity of a reservoir system sandstone. Studies show, however, that porosity is largely independent of grain size for unconsolidated sand of the same sorting.<ref name=ch09r5>Beard, D., C., Weyl, P., K., 1973, [http://archives.datapages.com/data/bulletns/1971-73/data/pg/0057/0002/0300/0349.htm Influence of texture on porosity and permeability of unconsolidated sand]: AAPG Bulletin, vol. 57, no. 2, p. 349–369.</ref> Size does affect permeability; the finer the sand, the lower the permeability. [[Permeability]] indirectly affects porosity through diagenesis. Stonecipher et al.<ref name=ch09r60>Stonecipher, S., A., Winn, R., D. Jr., Bishop, M., G., 1984, Diagenesis of the Frontier Formation, Moxa Arch: a function of sandstone geometry, texture and composition, and fluid flux, in McDonald, D., A., Surdam, R., C., eds., Clastic Diagenesis: AAPG Memoir 37, p. 289–316.</ref> suggest that slow fluid fluxes, resulting from low permeability, promote cementation; rapid fluxes promote leaching. In rapid fluxes, solutes do not remain in pore spaces long enough to build local concentration that promotes precipitation of cement. In slow fluxes, they do. Also, size affects the surface area available for diagenetic reactions: the finer the grain size, the greater the grain surface area for a volume of sediment or rock.

Sorting and grain size are textural parameters that intuitively might seem to have the same effects on the porosity of a reservoir system sandstone. Studies show, however, that porosity is largely independent of grain size for unconsolidated sand of the same sorting.<ref name=ch09r5>Beard, D., C., Weyl, P., K., 1973, [http://archives.datapages.com/data/bulletns/1971-73/data/pg/0057/0002/0300/0349.htm Influence of texture on porosity and permeability of unconsolidated sand]: AAPG Bulletin, vol. 57, no. 2, p. 349–369.</ref> Size does affect permeability; the finer the sand, the lower the permeability. [[Permeability]] indirectly affects porosity through diagenesis. Stonecipher et al.<ref name=ch09r60>Stonecipher, S., A., Winn, R., D. Jr., Bishop, M., G., 1984, [http://archives.datapages.com/data/specpubs/sandsto2/data/a059/a059/0001/0250/0289.htm Diagenesis of the Frontier Formation, Moxa Arch: a function of sandstone geometry, texture and composition, and fluid flux], in McDonald, D., A., Surdam, R., C., eds., Clastic Diagenesis: AAPG Memoir 37, p. 289–316.</ref> suggest that slow fluid fluxes, resulting from low permeability, promote cementation; rapid fluxes promote leaching. In rapid fluxes, solutes do not remain in pore spaces long enough to build local concentration that promotes precipitation of cement. In slow fluxes, they do. Also, size affects the surface area available for diagenetic reactions: the finer the grain size, the greater the grain surface area for a volume of sediment or rock.

==Influence of sorting on porosity==

==Influence of sorting on porosity==