Changes

==Diagenesis and rock fabric==

==Diagenesis and rock fabric==

The initial solid constituents of a carbonate rock normally determine its initial pore type and geometry and strongly influence diagenesis. Early pore space in carbonate rocks generally has fabric-selective characteristics; creation of late pore space does not.<ref name=ch09r10>Choquette, P., W., Pray, L., C., 1970, Geologic nomenclature and classification of porosity in sedimentary carbonates: AAPG Bulletin, vol. 54, no. 2, p. 207–250. Classic reference for basic concepts regarding carbonate porosity.</ref> Surface and shallow diagenesis mainly occurs in fabric-selective pore geometries that allow the greatest fluid flow (mostly interparticle or intercrystalline). Late-stage shallow diagenesis mainly occurs in nonfabric-selective pore geometries that allow the greatest fluid flow (mostly fracture related). Deep diagenetic processes can be both fabric selective (fluid flow through interparticle or intercrystalline pores) or nonfabric selective (compaction).

The initial solid constituents of a carbonate rock normally determine its initial pore type and geometry and strongly influence diagenesis. Early pore space in carbonate rocks generally has fabric-selective characteristics; creation of late pore space does not.<ref name=ch09r10>Choquette, P., W., Pray, L., C., 1970, Geologic nomenclature and classification of porosity in sedimentary carbonates: AAPG Bulletin, vol. 54, no. 2, p. 207–250. Classic reference for basic concepts regarding carbonate porosity.</ref> Surface and shallow diagenesis mainly occurs in fabric-selective pore geometries that allow the greatest fluid flow (mostly interparticle or intercrystalline). Late-stage shallow diagenesis mainly occurs in nonfabric-selective pore geometries that allow the greatest fluid flow (mostly fracture related). Deep diagenetic processes can be both fabric selective (fluid flow through interparticle or intercrystalline pores) or nonfabric selective (compaction).

==Fabric and nonfabric selection porosity==

==Fabric and nonfabric selection porosity==

The figure below shows fabric and nonfabric pore geometries and processes that create them.

[[:file:predicting-reservoir-system-quality-and-performance_fig9-74.png|Figure 1]] shows fabric and nonfabric pore geometries and processes that create them.

[[file:predicting-reservoir-system-quality-and-performance_fig9-74.png|thumb|{{figure number|9-74}}Modified.]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-75.png|thumb|{{figure number|2}}See text for explanation.]]

==Early diagenesis and pore-system quality==

==Early diagenesis and pore-system quality==

The diagram below shows the general pathways that different carbonate rock types might take during early diagenesis as their pore systems evolve. The parallel lines are contours of equal pore throat size. In terms of quality, points plotting along the contours represent rocks with equal flow characteristics (''see'' [[Characterizing rock quality]] earlier in this chapter). With the exception of the creation of connected vugs and dolomitized mudstone, carbonate rocks generally lose porosity and permeability as a result of diagenesis.

[[:file:predicting-reservoir-system-quality-and-performance_fig9-75.png|Figure 2]] shows the general pathways that different carbonate rock types might take during early diagenesis as their pore systems evolve. The parallel lines are contours of equal pore throat size. In terms of quality, points plotting along the contours represent rocks with equal flow characteristics (''see'' [[Characterizing rock quality]] earlier in this chapter). With the exception of the creation of connected vugs and dolomitized mudstone, carbonate rocks generally lose porosity and permeability as a result of diagenesis.

 

==Preserving pore systems==

==Preserving pore systems==