Changes

|-

|-

|   Thin section petrography

|   Thin section petrography

| Mineral types and abundances; pore types and abundances; diagenetic sequence; texture (size, sorting)

| Mineral types and abundances; pore types and abundances; diagenetic sequence; texture ([[Grain size|size]], [[Core_description#Maturity|sorting]])

|-

|-

|   X-ray diffraction

|   X-ray diffraction

[[file:evaluating-diagenetically-complex-reservoirs_fig3.png|thumb|300px|{{figure number|3}}[[Porosity]]-permeability semilog crosspiot with samples coded according to grain size, clay content, and dominant agent of cementation.]]

[[file:evaluating-diagenetically-complex-reservoirs_fig3.png|thumb|300px|{{figure number|3}}[[Porosity]]-permeability semilog crosspiot with samples coded according to grain size, clay content, and dominant agent of cementation.]]

Sample sites for petrographic analysis are best selected on the basis of low magnification rock descriptions generated in step 1 and through examination of semilog porosity-permeability cross plots ([[:file:evaluating-diagenetically-complex-reservoirs_fig3.png|Figure 3]]) with values keyed to major categories of size, sorting, matrix content, cement content, or pore type, depending on their relative importance in a particular reservoir. Samples should be selected to span a wide range of porosities and permeabilities for each major type of reservoir rock (for example, sandstones that are dolomite cemented, anhydrite cemented, quartz-overgrowth cemented, or argillaceous).

Sample sites for petrographic analysis are best selected on the basis of low magnification rock descriptions generated in step 1 and through examination of semilog porosity-permeability cross plots ([[:file:evaluating-diagenetically-complex-reservoirs_fig3.png|Figure 3]]) with values keyed to major categories of [[Grain size|size]], [[Core_description#Maturity|sorting]], matrix content, cement content, or pore type, depending on their relative importance in a particular reservoir. Samples should be selected to span a wide range of porosities and permeabilities for each major type of reservoir rock (for example, sandstones that are dolomite cemented, anhydrite cemented, quartz-overgrowth cemented, or argillaceous).

Use of plug ends from homogeneous horizontal core analysis plugs for thin section, XRD, or SEM sample preparation allows for the development of quantitative relationships between data from these analyses and data from core analysis measurements. Plugs containing significant inhomogeneities, such as laminae of distinctly different grain size or degrees of cementation, should be avoided or else erroneous variance in the data set will tend to blur what otherwise might be easily recognizable clear-cut relationships.

Use of plug ends from homogeneous horizontal core analysis plugs for thin section, XRD, or SEM sample preparation allows for the development of quantitative relationships between data from these analyses and data from core analysis measurements. Plugs containing significant inhomogeneities, such as laminae of distinctly different grain size or degrees of cementation, should be avoided or else erroneous variance in the data set will tend to blur what otherwise might be easily recognizable clear-cut relationships.