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Midale lithofacies and distribution (view source)
Revision as of 22:14, 31 January 2014
, 22:14, 31 January 2014Initial import
{{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
}}
==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.
==Reservoir SEM and [[capillary pressure]] curve==
The figure below 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 (r<sub>35</sub>) of the sample is approximately 3μ.
[[file:predicting-reservoir-system-quality-and-performance_fig9-99.png|thumb|{{figure number|9-99}}See text for explanation.]]
==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.
==Nonreservoir SEM and capillary curve==
The figure below 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 r<sub>35</sub> and r<sub>10</sub> values for the sample are 0.2 and 0.25μ, respectively.
[[file:predicting-reservoir-system-quality-and-performance_fig9-100.png|thumb|{{figure number|9-100}}See text for explanation.]]
==Facies tracts of midale vuggy beds==
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.
* Landward (now updip) from this facies tract, the reservoir grades into porous mudstone facies with scattered lenses of poorly developed, vuggy packstone facies.
* Still farther northeast but downdip from the truncation edge of the Midale, the rocks change facies into anhydrite.
==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.
==Weyburn well log==
The figure below is an example of log characteristics of Midale beds in a Weyburn field well. The well was continuously cored through the Midale interval. The brick pattern denotes packstone facies with vuggy and intergranular [[porosity]]; hachures indicate porous dolomitic mudstone facies. Log and core data for representative (if extreme) data points, numbered 1-8, also appear in Figures 9-102 through 9-104.
[[file:predicting-reservoir-system-quality-and-performance_fig9-101.png|thumb|{{figure number|9-101}}From .<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>]]
==See also==
* [[Evaluation of trap type]]
* [[Weyburn field location and trap problem]]
* [[Midale porosity, pore geometries, and petrophysics]]
* [[Effect of pore geometry on Sw in midale rocks]]
* [[Weyburn seal capacity]]
* [[Seal capacity and trap type]]
==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]]
| 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
}}
==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.
==Reservoir SEM and [[capillary pressure]] curve==
The figure below 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 (r<sub>35</sub>) of the sample is approximately 3μ.
[[file:predicting-reservoir-system-quality-and-performance_fig9-99.png|thumb|{{figure number|9-99}}See text for explanation.]]
==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.
==Nonreservoir SEM and capillary curve==
The figure below 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 r<sub>35</sub> and r<sub>10</sub> values for the sample are 0.2 and 0.25μ, respectively.
[[file:predicting-reservoir-system-quality-and-performance_fig9-100.png|thumb|{{figure number|9-100}}See text for explanation.]]
==Facies tracts of midale vuggy beds==
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.
* Landward (now updip) from this facies tract, the reservoir grades into porous mudstone facies with scattered lenses of poorly developed, vuggy packstone facies.
* Still farther northeast but downdip from the truncation edge of the Midale, the rocks change facies into anhydrite.
==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.
==Weyburn well log==
The figure below is an example of log characteristics of Midale beds in a Weyburn field well. The well was continuously cored through the Midale interval. The brick pattern denotes packstone facies with vuggy and intergranular [[porosity]]; hachures indicate porous dolomitic mudstone facies. Log and core data for representative (if extreme) data points, numbered 1-8, also appear in Figures 9-102 through 9-104.
[[file:predicting-reservoir-system-quality-and-performance_fig9-101.png|thumb|{{figure number|9-101}}From .<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>]]
==See also==
* [[Evaluation of trap type]]
* [[Weyburn field location and trap problem]]
* [[Midale porosity, pore geometries, and petrophysics]]
* [[Effect of pore geometry on Sw in midale rocks]]
* [[Weyburn seal capacity]]
* [[Seal capacity and trap type]]
==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]]