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  = 9-115

  | topg    = 9-156

  | topg    = 9-116

  | 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

==Global climatic effect of cycles==

==Global climatic effect of cycles==

The earth's climate has ranged from times of cooler temperatures (icehouse) to times of warmer temperatures (greenhouse).<ref name=ch09r50>Read, J., F., Horbury, A., D., 1993, [http://archives.datapages.com/data/specpubs/resmi1/data/a067/a067/0001/0150/0155.htm Eustatic and tectonic controls on porosity evolution beneath sequence-bounding unconformities and parasequence disconformities on carbonate platforms], in Horbury, A., D., Robinson, A., G., eds., Diagenesis and Basin Development: AAPG Studies in Geology 36, p. 155–197.</ref> Continental glaciation characterizes icehouse conditions and causes large sea level changes because ice ties up large volumes of water. Sea level rises rapidly during glaciation and falls gradually during deglaciation. Sea level changes are small during greenhouse times because the ice volume was smaller.

The earth's climate has ranged from times of cooler temperatures (icehouse) to times of warmer temperatures (greenhouse).<ref name=ch09r50>Read, J., F., Horbury, A., D., 1993, [http://archives.datapages.com/data/specpubs/resmi1/data/a067/a067/0001/0150/0155.htm Eustatic and tectonic controls on porosity evolution beneath sequence-bounding unconformities and parasequence disconformities on carbonate platforms], in Horbury, A., D., Robinson, A., G., eds., Diagenesis and Basin Development: AAPG Studies in Geology 36, p. 155–197.</ref> Continental glaciation characterizes icehouse conditions and causes large sea level changes because ice ties up large volumes of water. Sea level changes are small during greenhouse times because the ice volume is smaller. Globally, sea level falls during glaciation and rises during deglaciation.  

The table below summarizes characteristics of fourth- and fifth-order sea level cycles during icehouse, greenhouse, and transitional periods.

The table below summarizes characteristics of fourth- and fifth-order sea level cycles during icehouse, greenhouse, and transitional periods.

{| class = "wikitable"

{| class = "wikitable"

|-

|-

! Characteristic

! Characteristic || Icehouse || Transition || Greenhouse

! Icehouse

! Transition

! Greenhouse

|-

|-

| Amplitude (m)

| Amplitude (m) || High (50–100) || Moderate (20–50) || Low (1–20)

| High (50–100)

| Moderate (20–50)

| Low (1–20)

|-

|-

| Dominant frequency (k.y.)

| Dominant frequency (k.y.) || 100 || 50 || 20

| 100

| 50

| 20

|}

|}

==Greenhouse vs. icehouse times==

==Greenhouse vs. icehouse times==

[[file:predicting-reservoir-system-quality-and-performance_fig9-80.png|300px|thumb|{{figure number|1}}From Read.<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> Courtesy SEPM.]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-80.png|300px|thumb|{{figure number|1}}Periods of icehouse and greenhouse conditions. From Read.<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> Courtesy SEPM.]]

The chart in [[:file:predicting-reservoir-system-quality-and-performance_fig9-80.png|Figure 1]] shows periods of icehouse and greenhouse conditions. Also shown are age and paleolatitudes of ice-rafted deposits (bar chart), net climate forcing CO₂+ solar luminosity (upper curved line), and the Vail sea level curve (lower curved line).

The chart in [[:file:predicting-reservoir-system-quality-and-performance_fig9-80.png|Figure 1]] shows periods of icehouse and greenhouse conditions. Also shown are age and paleolatitudes of ice-rafted deposits (bar chart), net climate forcing CO₂+ solar luminosity (upper curved line), and the Vail sea level curve (lower curved line).

==Regional climates==

==Regional climates==

Arid or humid conditions can occur simultaneously in different regions during icehouse or greenhouse periods. The aridity or humidity of a region strongly affects carbonate deposition and [http://wiki.seg.org/wiki/Dictionary:Diagenesis diagenesis]. For example, carbonates deposited under arid conditions tend to be associated with evaporites, and carbonate sequences are partly to completely dolomitized. In humid regions where rainfall is greater, carbonates are subject to greater dissolution; therefore, vuggy porosity and [http://wiki.seg.org/wiki/Dictionary:Karst karst] features are common.

Arid or humid conditions can occur simultaneously in different regions during icehouse or greenhouse periods. The aridity or humidity of a region strongly affects carbonate deposition and [[diagenesis]]. For example, carbonates deposited under arid conditions tend to be associated with evaporites, and carbonate sequences are partly to completely dolomitized. In humid regions where rainfall is greater, carbonates are subject to greater dissolution; therefore, vuggy porosity and [http://wiki.seg.org/wiki/Dictionary:Karst karst] features are common.

==Sea level and climate==

==Sea level and climate==

{| class = "wikitable"

{| class = "wikitable"

|-

|-

! Characteristic

! Characteristic || Tropical carbonate settings || Temperate carbonate settings

! Tropical carbonate settings

! Temperate carbonate settings

|-

|-

| Photic zone depth

| Photic zone depth || 20–30 m || 100 m+

| 20–30 m

| 100 m+

|-

|-

| Sedimentation rate

| Sedimentation rate || High in [[length::10 m]] or less of water, then rapid drop || Low but more constant in water [[length::100 m]] or deeper

| High in [[length::10 m]] or less of water, then rapid drop

| Low but more constant in water [[length::100 m]] or deeper

|-

|-

| Dominant fauna

| Dominant fauna || Reef-building assemblages (light-dependent biota) || Bryozoans, mollusks, forams, crinoids (biota not as light dependent)

| Reef-building assemblages (light-dependent biota)

| Bryozoans, mollusks, forams, crinoids (biota not as light dependent)

|-

|-

| Depositional topography

| Depositional topography || Reef-rimmed platforms || Gently sloping ramps on [[Well_log_sequence_analysis#Parasequence_stacking_patterns|prograding]] seaward-thickening sediment wedges

| Reef-rimmed platforms

| Gently sloping ramps on prograding seaward-thickening sediment wedges

|}

|}

* [[Predicting carbonate porosity and permeability]]

* [[Predicting carbonate porosity and permeability]]

* [[Carbonate facies]]

* [[Carbonate facies]]

* [[Carbonate diagenetic stages]]

* [[Carbonate diagenetic stages]]

* [[Early carbonate diagenesis]]

* [[Early carbonate diagenesis]]

[[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]]