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Sequences during high-amplitude, high-frequency cycles (view source)
Revision as of 21:50, 31 January 2014
, 21:50, 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
}}
High-amplitude (60 to over [[length::100 m]]), high-frequency (fourth- and fifth-order) sea level fluctuations occurred during periods of global continental glaciation (Read, 1996). These icehouse periods were late Precambrian, Pennsylvanian to Early Permian, and Pleistocene.
==General characteristics==
The following are general characteristics of carbonate sequences deposited during icehouse conditions:<ref name=ch09r49>Read, J., F., 1995, Overview of carbonate platform sequences, cycle stratigraphy and reservoirs in greenhouse and ice-house worlds, in Read, J., F., Kerans, C., Webber, L., J., Sarg, J., F., Wright, F., M., eds., Milankovitch Sea-level Changes, Cycles, and Reservoirs on Carbonate Platforms in Greenhouse and Ice-house Worlds: SEPM Short Course 35, 183 p. Good summary of concepts of climatic effect on sea level cycles, carbonate deposition, and reservoir development.</ref>
* Flat-topped platforms with layer cake, 1–10-m-thick fourth-order sequences bounded by regional disconformities; sequences on platform margins shingled
* Ramp sequences highly shingled and erosionally bounded
* Pinnacle reefs and high-relief banks common on tropical platforms
* Tidal flat facies absent except adjacent to shorelines
* Deeper water facies juxtaposed with shallow-water facies and emergence features (except on the shallowest parts of platforms) because of large sea level changes
* Karstic sinkholes and cave systems extend down through several sequences
* Intense leaching/cementation (and sometimes dolomitization) possible because stillstands repeatedly localize paleowater tables
* Diagenesis usually complex because large sea level changes repeatedly cause large vertical and lateral [[migration]] of diagenetic zones
==Arid zone characteristics==
Carbonate sequences deposited in arid zones tend to have the following characteristics:<ref name=ch09r49 />
* [[Porosity]] plugged by caliche at sequence caps
* Below caliche cap [[porosity]] is intergranular in shoals and in nondolomitized build-ups
* [[Porosity]] is intercrystalline and remnant intergranular in dolomitized sequences that consist of inner platform highstand sabkha facies or late highstand to lowstand evaporite basin facies
==Humid zone characteristics==
Carbonate sequences deposited in humid zones tend to have the following characteristics:<ref name=ch09r49 />
* Single to multiple caliche zones at sequence tops if wet–dry seasons
* In a sequence package that lacks internal seals, the uppermost sequences generally have preserved intergranular porosity in contrast to lower sequences, which generally have moldic, vuggy, and cavernous porosity
* In a sequence package that contains internal seals, the upper part of each sequence can have preserved primary porosity because the seals protect the sediments from diagenesis
==High-amplitude sequences schematic==
The figure below shows (1) a typical succession of carbonate lithofacies sequences that formed during high-amplitude, high-frequency sea level fluctuations and (2) a corresponding sea level curve related to diagenesis. In this example, sequences lack internal barriers or seals to inhibit the vertical and lateral migration of the paleowater table; therefore, sequence sediments are subjected to a complex sequence of diagenetic events due to large-scale sea level fluctuations. If internal barriers were present, diagenesis would be lessened.
[[file:predicting-reservoir-system-quality-and-performance_fig9-83.png|thumb|{{figure number|9-83}}.]]
==See also==
* [[Predicting carbonate porosity and permeability]]
* [[Carbonate facies]]
* [[Carbonate diagenetic stages]]
* [[Early carbonate diagenesis]]
* [[Basics of carbonate porosity formation and preservation]]
* [[Sea level cycles and carbonate sequences]]
* [[Sea level cycles and carbonate diagenesis]]
* [[Sea level cycles and climate]]
* [[Sequences during low-amplitude, high-frequency cycles]]
* [[Sequences during moderate-amplitude, high-frequency cycles]]
* [[Predicting carbonate reservoir location and quality]]
==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
}}
High-amplitude (60 to over [[length::100 m]]), high-frequency (fourth- and fifth-order) sea level fluctuations occurred during periods of global continental glaciation (Read, 1996). These icehouse periods were late Precambrian, Pennsylvanian to Early Permian, and Pleistocene.
==General characteristics==
The following are general characteristics of carbonate sequences deposited during icehouse conditions:<ref name=ch09r49>Read, J., F., 1995, Overview of carbonate platform sequences, cycle stratigraphy and reservoirs in greenhouse and ice-house worlds, in Read, J., F., Kerans, C., Webber, L., J., Sarg, J., F., Wright, F., M., eds., Milankovitch Sea-level Changes, Cycles, and Reservoirs on Carbonate Platforms in Greenhouse and Ice-house Worlds: SEPM Short Course 35, 183 p. Good summary of concepts of climatic effect on sea level cycles, carbonate deposition, and reservoir development.</ref>
* Flat-topped platforms with layer cake, 1–10-m-thick fourth-order sequences bounded by regional disconformities; sequences on platform margins shingled
* Ramp sequences highly shingled and erosionally bounded
* Pinnacle reefs and high-relief banks common on tropical platforms
* Tidal flat facies absent except adjacent to shorelines
* Deeper water facies juxtaposed with shallow-water facies and emergence features (except on the shallowest parts of platforms) because of large sea level changes
* Karstic sinkholes and cave systems extend down through several sequences
* Intense leaching/cementation (and sometimes dolomitization) possible because stillstands repeatedly localize paleowater tables
* Diagenesis usually complex because large sea level changes repeatedly cause large vertical and lateral [[migration]] of diagenetic zones
==Arid zone characteristics==
Carbonate sequences deposited in arid zones tend to have the following characteristics:<ref name=ch09r49 />
* [[Porosity]] plugged by caliche at sequence caps
* Below caliche cap [[porosity]] is intergranular in shoals and in nondolomitized build-ups
* [[Porosity]] is intercrystalline and remnant intergranular in dolomitized sequences that consist of inner platform highstand sabkha facies or late highstand to lowstand evaporite basin facies
==Humid zone characteristics==
Carbonate sequences deposited in humid zones tend to have the following characteristics:<ref name=ch09r49 />
* Single to multiple caliche zones at sequence tops if wet–dry seasons
* In a sequence package that lacks internal seals, the uppermost sequences generally have preserved intergranular porosity in contrast to lower sequences, which generally have moldic, vuggy, and cavernous porosity
* In a sequence package that contains internal seals, the upper part of each sequence can have preserved primary porosity because the seals protect the sediments from diagenesis
==High-amplitude sequences schematic==
The figure below shows (1) a typical succession of carbonate lithofacies sequences that formed during high-amplitude, high-frequency sea level fluctuations and (2) a corresponding sea level curve related to diagenesis. In this example, sequences lack internal barriers or seals to inhibit the vertical and lateral migration of the paleowater table; therefore, sequence sediments are subjected to a complex sequence of diagenetic events due to large-scale sea level fluctuations. If internal barriers were present, diagenesis would be lessened.
[[file:predicting-reservoir-system-quality-and-performance_fig9-83.png|thumb|{{figure number|9-83}}.]]
==See also==
* [[Predicting carbonate porosity and permeability]]
* [[Carbonate facies]]
* [[Carbonate diagenetic stages]]
* [[Early carbonate diagenesis]]
* [[Basics of carbonate porosity formation and preservation]]
* [[Sea level cycles and carbonate sequences]]
* [[Sea level cycles and carbonate diagenesis]]
* [[Sea level cycles and climate]]
* [[Sequences during low-amplitude, high-frequency cycles]]
* [[Sequences during moderate-amplitude, high-frequency cycles]]
* [[Predicting carbonate reservoir location and quality]]
==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]]