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{{publication
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Predicting the occurrence of oil and gas traps
| chapter = Predicting reservoir system quality and performance
| frompg = 9-1
| topg = 9-156
| author = Dan J. Hartmann, Edward A. Beaumont
| link = http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
==Archie and non-Archie rocks==
Choquette and Pray's<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> porosity types include two different groups of pore system shapes: petrophysically simple '''Archie porosity''' and petrophysically complex '''non-Archie porosity'''. In most cases, water saturation (S<sub>w</sub>) of rocks with Archie porosity can be predicted from log analysis using the Archie equation
:<math>\mbox{S}_{\rm w} = \left(\frac{1}{\Phi^{\rm m}} \times \frac{\mbox{R}_{\rm w}}{\mbox{R}_{\rm t}}\right)^{\rm 1/n}</math>
without modification. To predict water saturation in rocks with non-Archie porosity, we modify the Archie equation.
==Table of characteristics==
The table below describes pore system shapes and other important characteristics of Archie and non-Archie rocks (after .<ref name=ch09r12>Coalson, E., B., Goolsby, S., M., Franklin, M., H., 1994, Subtle seals and fluid-flow barriers in carbonate rocks, in Dolson, J., C., Hendricks, M., L., Wescott, W., A., eds., Unconformity Related Hydrocarbons in Sedimentary Sequences: RMAG Guidebook for Petroleum Exploration and Exploitation in Clastic and Carbonate Sediments, p. 45–58.</ref>
{| class = "wikitable"
|-
! Feature
! Archie
! Non-Archie
|-
| Pore system shapes
| Intergranular (found between rounded particles); interparticle
| Mold-like <break> </break>
* Intraparticle * Moldic * Shelter
|-
| Intercrystalline (found between angular particles)
| Vug-like <break> </break>
* Boring/burrow * Growth-framework * Fenestral * Vug/channel/cavern
|-
| Fracture-like <break> </break>
* Fracture * Shrinkage
|-
| Relationship of pore shape to rock particles
| Negative image of particles making up matrix
| Relates only indirectly to particles making up matrix
|-
| Pore connectivity
| Pore throats connect pores into regular networks
| Pores are irregularly distributed and can be either poorly or very well connected
|-
| [[Porosity]] reduction processes
| Grain coating or pore filling by calcite, silica, or dolomite
| Pore or pore throat filling by clays or other minerals
|}
==See also==
* [[Classifying pore systems]]
* [[Pore system fundamentals]]
* [[Pore and pore throat sizes]]
* [[Connectivity and pore throat size]]
* [[Classifying pore systems]]
* [[Determining pore throat size from Pc curves]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Predicting the occurrence of oil and gas traps]]
[[Category:Predicting reservoir system quality and performance]]