Changes

  | 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

  | frompg  = 9-1

  | frompg  = 9-139

  | topg    = 9-156

  | topg    = 9-141

  | 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

==Productive facies==

==Productive facies==

The Midale in the Weyburn area is carbonates and evaporites deposited near a low-energy shoreline on a marine ramp. The main producing carbonate facies (“vuggy pack-stone” facies) is shoal deposits of fossiliferous, peloidal, ''Ortonella''-bearing nodular wacke-stones to grainstones. The principal occluding cements are sparry calcite and anhydrite.

The Midale in the Weyburn area is carbonates and evaporites deposited near a low-energy shoreline on a marine ramp. The main producing carbonate facies (vuggy packstone facies) is shoal deposits of fossiliferous, peloidal, ''Ortonella''-bearing nodular wacke-stones to grainstones. The principal occluding cements are sparry calcite and [[anhydrite]].

==Reservoir SEM and capillary pressure curve==

==Reservoir SEM and capillary pressure curve==

[[file:predicting-reservoir-system-quality-and-performance_fig9-99.png|300px|thumb|{{figure number|1}}Petrophysical characteristics of the main Weyburn reservoir facies: ''Ortonella''-bearing vuggy wackestones to packstones.]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-99.png|300px|thumb|{{figure number|1}}Petrophysical characteristics of the main Weyburn reservoir facies: ''Ortonella''-bearing vuggy wackestones to packstones.]]

[[:file:predicting-reservoir-system-quality-and-performance_fig9-99.png|Figure 1]] shows the petrophysical characteristics of the main Weyburn reservoir facies: ''Ortonella''-bearing vuggy wackestones to packstones. The sample is macroporous, its pore system dominated by large pores and pore throats. The capillary pressure curve shows relatively low entry (and presumably breakthrough) pressure. The port size (r₃₅) of the sample is approximately 3μ.

[[:file:predicting-reservoir-system-quality-and-performance_fig9-99.png|Figure 1]] shows the petrophysical characteristics of the main Weyburn reservoir facies: ''Ortonella''-bearing vuggy wackestones to packstones. The sample is macroporous, its pore system dominated by large pores and pore throats. The [[capillary pressure]] curve shows relatively low entry (and presumably breakthrough) pressure. The port size ([[Characterizing_rock_quality#What_is_r35.3F|r₃₅]]) of the sample is approximately 3μ.

==Nonproductive facies==

==Nonproductive facies==

The main nonproductive updip carbonate facies (“porous mudstone”) is locally laminated and burrowed peloidal lime and dolomite mudstones to wackestones. These tighter rocks originated on a low-energy to restricted shelf and in lagoons.

The main nonproductive updip carbonate facies (“porous [[mudstone]]”) is locally laminated and burrowed peloidal lime and [[dolomite]] mudstones to wackestones. These tighter rocks originated on a low-energy to restricted shelf and in lagoons.

==Nonreservoir SEM and capillary curve==

==Nonreservoir SEM and capillary curve==

[[file:predicting-reservoir-system-quality-and-performance_fig9-100.png|300px|thumb|{{figure number|2}}Petrophysical characteristics of the main nonreservoir facies in the field: lime and dolomite mudstones to wackestones. ]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-100.png|300px|thumb|{{figure number|2}}Petrophysical characteristics of the main nonreservoir facies in the field: lime and dolomite mudstones to wackestones. ]]

[[:file:predicting-reservoir-system-quality-and-performance_fig9-100.png|Figure 2]] illustrates the petrophysical characteristics of the main nonreservoir facies in the field: lime and dolomite mudstones to wackestones. The sample pore system consists of fine intergranular and unconnected vuggy pores and pore throats. The capillary pressure curve shows the higher entry pressure of the nonreservoir facies compared to the reservoir facies. The r₃₅ and r₁₀ values for the sample are 0.2 and 0.25μ, respectively.

[[:file:predicting-reservoir-system-quality-and-performance_fig9-100.png|Figure 2]] illustrates the petrophysical characteristics of the main nonreservoir facies in the field: lime and dolomite mudstones to wackestones. The sample pore system consists of fine intergranular and unconnected vuggy pores and pore throats. The capillary pressure curve shows the higher entry pressure of the nonreservoir facies compared to the reservoir facies. The [[Characterizing_rock_quality#What_is_r35.3F|r₃₅]] and [[Weyburn_seal_capacity#Winland.27s_r10|r₁₀]] values for the sample are 0.2 and 0.25μ, respectively.

==Facies tracts of midale vuggy beds==

==Facies tracts of Midale vuggy beds==

The Midale Vuggy beds contain three facies tracts that parallel the paleo-shoreline (northwest).

The Midale vuggy beds contain three facies tracts that parallel the paleo-shoreline (northwest).

* In and downdip from Weyburn field, the rocks consist primarily of the vuggy packstone facies, although there are numerous thin interbeds of porous mudstone facies.

* In and downdip from Weyburn field, the rocks consist primarily of the vuggy packstone facies, although there are numerous thin interbeds of porous mudstone facies.

==Overlying and underlying beds==

==Overlying and underlying beds==

The beds overlying the Midale Vuggy, i.e., the Midale Marly beds, consist almost entirely of the porous mudstone facies. The beds underlying the Midale Vuggy are tight carbonates and evaporites.

The beds overlying the Midale vuggy beds, i.e., the Midale marly beds, consist almost entirely of the porous mudstone facies. The beds underlying the Midale vuggy beds are tight carbonates and evaporites.

==Weyburn well log==

==Weyburn well log==

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file:predicting-reservoir-system-quality-and-performance_fig9-101.png|{{figure number|3}}example of log characteristics of Midale beds in a Weyburn field well.<ref name=ch09r11>Coalson, E., B., Hartmann, D., J., Thomas, J., B., 1990, Applied Petrophysics in Exploration and Exploitation: Notes from short course sponsored by Univ. of Colo.–Denver, var. pages.</ref>

file:predicting-reservoir-system-quality-and-performance_fig9-101.png|{{figure number|3}}example of log characteristics of Midale beds in a Weyburn field well.<ref name=ch09r11>Coalson, E. B., D. J. Hartmann, and J. B. Thomas, 1990, Applied Petrophysics in Exploration and Exploitation: Notes from short course sponsored by Univ. of Colo.–Denver, var. pages.</ref>

file:predicting-reservoir-system-quality-and-performance_fig9-102.png|{{figure number|4}}Crossplot of routine core porosity and permeability from Midale in an example well at Weyburn field. From Coalson et al., 1994;{{citation needed}} courtesy RMAG.

file:predicting-reservoir-system-quality-and-performance_fig9-102.png|{{figure number|4}}Crossplot of routine core porosity and permeability from Midale in an example well at Weyburn field. From Coalson et al.;<ref name=Coalson1994 /> courtesy RMAG.

file:predicting-reservoir-system-quality-and-performance_fig9-103.png|{{figure number|5}}Pickett plot for the Midale Vuggy form an example well in Weyburn field. From Coalson et al., 1994;{{citation needed}} courtesy RMAG.

file:predicting-reservoir-system-quality-and-performance_fig9-103.png|{{figure number|5}}Pickett plot for the Midale vuggy beds from an example well in Weyburn field. From 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.

file:predicting-reservoir-system-quality-and-performance_fig9-104.png|{{figure number|6}}Buckles plot for the Weyburn well. From Coalson et al., 1994;{{citation needed}} courtesy RMAG.

file:predicting-reservoir-system-quality-and-performance_fig9-104.png|{{figure number|6}}Buckles plot for the Weyburn well. From Coalson et al.;<ref name=Coalson1994 /> courtesy RMAG.

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==See also==

==See also==

* [[Weyburn field location and trap problem]]

* [[Weyburn field location and trap problem]]

* [[Midale porosity, pore geometries, and petrophysics]]

* [[Midale porosity, pore geometries, and petrophysics]]

[[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]]