Difference between revisions of "Midale water saturation and pore geometry"

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  | part    = Predicting the occurrence of oil and gas traps
 
  | part    = Predicting the occurrence of oil and gas traps
 
  | chapter = Predicting reservoir system quality and performance
 
  | chapter = Predicting reservoir system quality and performance
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  | frompg  = 9-1
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  | frompg  = 9-144
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  | topg    = 9-156
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  | topg    = 9-144
 
  | author  = Dan J. Hartmann, Edward A. Beaumont
 
  | author  = Dan J. Hartmann, Edward A. Beaumont
 
  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.htm
 
  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.htm
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  | isbn    = 0-89181-602-X
 
  | isbn    = 0-89181-602-X
 
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==Log response and s<sub>w</sub>==
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==Log response and S<sub>w</sub>==
  
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Variations in pore geometry have the expected effect on log responses and water saturations (S<sub>w</sub>). The Midale Vuggy in a cored field well consists of interbeds of packstone and mudstone. Below is a Pickett plot for the Midale Vuggy from an example well in Weyburn field. Data points cluster around higher resistivities for packstones (group A) and lower resistivities for mudstones (group B), reflecting the higher water saturations of the mudstones.
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Variations in pore geometry have the expected effect on log responses and [[water saturation]]s (S<sub>w</sub>). The Midale vuggy beds in a cored field well consist of interbeds of [[packstone]] and [[mudstone]]. [[:file:predicting-reservoir-system-quality-and-performance_fig9-103.png|Figure 1]] is a [[Pickett plot construction|Pickett plot]] for the Midale vuggy beds from an example well in Weyburn field. Data points cluster around higher [[Basic_open_hole_tools#Resistivity|resistivities]] for packstones (group A) and lower resistivities for mudstones (group B), reflecting the higher water saturations of the mudstones.
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[[file:predicting-reservoir-system-quality-and-performance_fig9-103.png|thumb|{{figure number|9-103}}. Copyright: Coalson et al., 1994; courtesy RMAG.]]
 
  
 
==Buckles plot==
 
==Buckles plot==
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As shown on Figure 9-102, mudstones (B) are micro- to mesoporous; packstones (A) are meso- to macroporous. The mudstones have more pores with smaller pore throats than the packstones. This means mudstones have greater pore surface area and higher immobile S<sub>w</sub>. As a consequence, S<sub>w</sub> values for mudstones are higher at any given elevation in the oil column.
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<gallery mode=packed heights=200px widths=200x>
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predicting-reservoir-system-quality-and-performance_fig9-103.png|{{figure number|1}}Pickett plot for the Midale vuggy beds from an example well in Weyburn field. Copyright: Coalson et al.;<ref name=Coalson1994>Coalson, E. B., S. M. Goolsby, and M. H. Franklin, 1994, Subtle seals and fluid-flow barriers in carbonate rocks, in J. C. Dolson, M. L. Hendricks, and W. A. Wescott, eds., Unconformity Related Hydrocarbons in Sedimentary Sequences: RMAG Guidebook for Petroleum Exploration and Exploitation in Clastic and Carbonate Sediments, p. 45–58.</ref> courtesy RMAG.
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Predicting-reservoir-system-quality-and-performance fig9-102.png|{{figure number|2}}Illustration of (A) packstones that are meso- to macroporous and (B) micro- to mesoporous mudstones. From Coalson et al.;<ref name=Coalson1994 /> courtesy RMAG.
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predicting-reservoir-system-quality-and-performance_fig9-104.png|{{figure number|3}}Buckles plot for the Weyburn well. Copyright: Coalson et al.;<ref name=Coalson1994 /> courtesy RMAG.
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</gallery>
  
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Following is a Buckles plot for the Weyburn well. The hyperbolic curves represent equal values of S<sub>w</sub> × Φ. Points from the same pore type that fall along a hyperbolic curve are at immobile S<sub>w</sub>. Curves with higher values represent higher immobile S<sub>w</sub>.
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As shown on [[:File:Predicting-reservoir-system-quality-and-performance fig9-102.png|Figure 2]], mudstones (B) are [[Wikipedia:Microporous material|micro]]- to [[Wikipedia:Mesoporous material|mesoporous]]; packstones (A) are meso- to [http://en.wiktionary.org/wiki/macroporous macroporous]. The mudstones have more pores with smaller pore throats than the packstones. This means mudstones have greater pore surface area and higher immobile S<sub>w</sub>. As a consequence, S<sub>w</sub> values for mudstones are higher at any given elevation in the oil column.
  
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On the plot, data for packstones (A), except for point 8, fall on a hyperbolic curve with a value between 100 and 300. This indicates these beds are at immobile water saturations. Point 8 is from a transition zone. Mudstones (B) also are at immobile water saturations but fall on a hyperbolic curve with higher numbers, between 1000 and 1300.
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[[:file:predicting-reservoir-system-quality-and-performance_fig9-104.png|Figure 3]] is a [[Buckles plot]] for the Weyburn well. The hyperbolic curves represent equal values of S<sub>w</sub> × porosity (Φ). Points from the same pore type that fall along a hyperbolic curve are at immobile S<sub>w</sub>. Curves with higher values represent higher immobile S<sub>w</sub>.
  
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[[file:predicting-reservoir-system-quality-and-performance_fig9-104.png|thumb|{{figure number|9-104}}. Copyright: Coalson et al., 1994; courtesy RMAG.]]
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On the plot, data for packstones (A), except for point 8, fall on a hyperbolic curve with a value between 100 and 300. This indicates these beds are at [http://petrowiki.org/Glossary%3AIrreducible_water_saturation immobile (irreducible) water saturations]. Point 8 is from a transition zone. Mudstones (B) also are at immobile water saturations but fall on a hyperbolic curve with higher numbers, between 1000 and 1300.
  
 
==See also==
 
==See also==
 
* [[Evaluation of trap type]]
 
* [[Evaluation of trap type]]
 
* [[Weyburn field location and trap problem]]
 
* [[Weyburn field location and trap problem]]
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* [[Middle lithofacies and distribution]]
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* [[Midale lithofacies and distribution]]
 
* [[Midale porosity, pore geometries, and petrophysics]]
 
* [[Midale porosity, pore geometries, and petrophysics]]
 
* [[Weyburn seal capacity]]
 
* [[Weyburn seal capacity]]
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* [[Seal capacity and trap type]]
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* [[Midale seal capacity and trap type]]
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==References==
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{{reflist}}
  
 
==External links==
 
==External links==
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[[Category:Predicting the occurrence of oil and gas traps]]  
 
[[Category:Predicting the occurrence of oil and gas traps]]  
 
[[Category:Predicting reservoir system quality and performance]]
 
[[Category:Predicting reservoir system quality and performance]]
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[[Category:Treatise Handbook 3]]

Latest revision as of 17:01, 12 April 2022

Exploring for Oil and Gas Traps
Series Treatise in Petroleum Geology
Part Predicting the occurrence of oil and gas traps
Chapter Predicting reservoir system quality and performance
Author Dan J. Hartmann, Edward A. Beaumont
Link Web page
Store AAPG Store

Log response and Sw

Variations in pore geometry have the expected effect on log responses and water saturations (Sw). The Midale vuggy beds in a cored field well consist of interbeds of packstone and mudstone. Figure 1 is a Pickett plot for the Midale vuggy beds from an example well in Weyburn field. Data points cluster around higher resistivities for packstones (group A) and lower resistivities for mudstones (group B), reflecting the higher water saturations of the mudstones.

Buckles plot

  • Figure 1 Pickett plot for the Midale vuggy beds from an example well in Weyburn field. Copyright: Coalson et al.;[1] courtesy RMAG.

  • Figure 2 Illustration of (A) packstones that are meso- to macroporous and (B) micro- to mesoporous mudstones. From Coalson et al.;[1] courtesy RMAG.

  • Figure 3 Buckles plot for the Weyburn well. Copyright: Coalson et al.;[1] courtesy RMAG.

As shown on Figure 2, mudstones (B) are micro- to mesoporous; packstones (A) are meso- to macroporous. The mudstones have more pores with smaller pore throats than the packstones. This means mudstones have greater pore surface area and higher immobile Sw. As a consequence, Sw values for mudstones are higher at any given elevation in the oil column.

Figure 3 is a Buckles plot for the Weyburn well. The hyperbolic curves represent equal values of Sw × porosity (Φ). Points from the same pore type that fall along a hyperbolic curve are at immobile Sw. Curves with higher values represent higher immobile Sw.

On the plot, data for packstones (A), except for point 8, fall on a hyperbolic curve with a value between 100 and 300. This indicates these beds are at immobile (irreducible) water saturations. Point 8 is from a transition zone. Mudstones (B) also are at immobile water saturations but fall on a hyperbolic curve with higher numbers, between 1000 and 1300.

See also

References

  1. ↑ 1.0 1.1 1.2 Coalson, E. B., S. M. Goolsby, and M. H. Franklin, 1994, Subtle seals and fluid-flow barriers in carbonate rocks, in J. C. Dolson, M. L. Hendricks, and W. A. Wescott, eds., Unconformity Related Hydrocarbons in Sedimentary Sequences: RMAG Guidebook for Petroleum Exploration and Exploitation in Clastic and Carbonate Sediments, p. 45–58.

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