Changes

  | part    = Traps, trap types, and the petroleum system

  | part    = Traps, trap types, and the petroleum system

  | chapter = Petroleum systems

  | chapter = Petroleum systems

  | frompg  = 3-1

  | frompg  = 3-19

  | topg    = 3-34

  | topg    = 3-23

  | author  = Leslie B. Magoon, Edward A. Beaumont

  | author  = Leslie B. Magoon, Edward A. Beaumont

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch03/ch03.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch03/ch03.htm

  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

}}

}}

The Ellesmerian(!) petroleum system of the North Slope, Alaska, contains approximately 77 billion bbl of oil equivalent.<ref name=ch03r2>Bird, K., J., 1994, [http://archives.datapages.com/data/specpubs/methodo2/data/a077/a077/0001/0300/0339.htm Ellesmerian(!) petroleum system, North Slope, Alaska, USA], in Magoon, L., B., Dow, W., G., eds., The Petroleum System—From Source to Trap: [http://store.aapg.org/detail.aspx?id=1022 AAPG Memoir 60], p. 339–358.</ref> The age of the reservoir rock ranges from Mississippian to early Tertiary. Total organic carbon and assumed hydrogen indices from the marine shale source rocks indicate the mass of petroleum generated to be approximately 8 trillion barrels of oil<ref name=ch03r2 /> These estimates indicate about 1% of the generated hydrocarbons are contained in known traps. More importantly, the U.S. Geological Survey estimates another 1% is trapped in undiscovered accumulations in the Ellesmerian(!) petroleum system.<ref name=ch03r2 />

The Ellesmerian(!) [[petroleum]] system of the North Slope, Alaska, contains approximately 77 billion bbl of oil equivalent.<ref name=ch03r2>Bird, K. J., 1994, [http://archives.datapages.com/data/specpubs/methodo2/data/a077/a077/0001/0300/0339.htm Ellesmerian(!) petroleum system, North Slope, Alaska, USA], in L. B. Magoon, and W. G. Dow, eds., The Petroleum System—From Source to Trap: [http://store.aapg.org/detail.aspx?id=1022 AAPG Memoir 60], p. 339–358.</ref> The age of the reservoir rock ranges from Mississippian to early [[Tertiary]]. Total organic carbon and assumed hydrogen indices from the marine shale source rocks indicate the mass of petroleum generated to be approximately 8 trillion barrels of oil<ref name=ch03r2 /> These estimates indicate about 1% of the generated hydrocarbons are contained in known traps. More importantly, the U.S. Geological Survey estimates another 1% is trapped in undiscovered [[accumulation]]s in the Ellesmerian(!) petroleum system.<ref name=ch03r2 />

==Geologic setting==

==Geologic setting==

[[file:petroleum-systems_fig3-12.png|left|thumb|{{figure number|1}}Ellesmerian(!) petroleum system geographic extent. From Bird.<ref name=ch03r2 />]]

The North Slope evolved from a passive [[continental margin]] to a foredeep during the Jurassic. Prior to the Jurassic, Paleozoic and Mesozoic strata were deposited on a passive continental margin. They consist of [[Carboniferous]] platform carbonate rocks and Permian to Jurassic shelf to basinal siliciclastic rocks. The passive margin converted to a foredeep during the Jurassic and Cretaceous when it collided with an ocean island arc. The foredeep began to fill with sediments in the Middle Jurassic and continues to do so.

The foredeep basin fill consists of orogenic sedimentary materials eroded from the nearby ancestral Brooks Range that were deposited as a northeasterly [[Well_log_sequence_analysis#Parasequence_stacking_patterns|prograding]] wedge of non-marine, shallow marine, basin-slope, and basin conglomerates, sandstones, and mud-stones.

 

The foredeep basin fill consists of orogenic sedimentary materials eroded from the nearby ancestral Brooks Range that were deposited as a northeasterly prograding wedge of non-marine, shallow marine, basin-slope, and basin conglomerates, sandstones, and mud-stones.

 

==Petroleum system map==

==Petroleum system map==

[[:file:petroleum-systems_fig3-12.png|Figure 1]] shows the Ellesmerian(!) petroleum system geographic extent. The limit is determined by the extent of the contiguous active source rock and the related petroleum accumulations.

file:petroleum-systems_fig3-12.png|{{figure number|1}}Ellesmerian(!) petroleum system geographic extent. From Bird.<ref name=ch03r2 />

[[file:petroleum-systems_fig3-14.png|left|thumb|{{figure number|3}}Major structural-stratigraphic elements, the occurrence of oil fields, elevation of selected vitrinite reflectance values, and reflectance isograds. From Bird.<ref name=ch03r2 />]]

[[:file:petroleum-systems_fig3-12.png|Figure 1]] shows the Ellesmerian(!) petroleum system geographic extent. The limit is determined by the extent of the contiguous active source rock and the related petroleum [[accumulation]]s.

==Petroleum system maturity map==

==Petroleum system maturity map==

[[:file:petroleum-systems_fig3-13.png|Figure 2]] shows the thermal maturity of the two main Ellesmerian(!) petroleum system source rocks, the Shublik Formation and the Kingak Shale. Note that Ellesmerian(!) petroleum system traps (shown in [[:file:petroleum-systems_fig3-12.png|Figure 1]]) are mostly located above immature source rocks.

[[:file:petroleum-systems_fig3-13.png|Figure 2]] shows the thermal maturity of the two main Ellesmerian(!) petroleum system source rocks, the Shublik Formation and the Kingak Shale. Note that Ellesmerian(!) petroleum system traps (shown in [[:file:petroleum-systems_fig3-12.png|Figure 1]]) are mostly located above immature source rocks.

==Petroleum system cross section==

==Petroleum system cross section==

The cross section of the Ellesmerian(!) petroleum system ([[:file:petroleum-systems_fig3-14.png|Figure 3]]) shows major structural-stratigraphic elements, the occurrence of oil fields, elevation of selected vitrinite reflectance values, and reflectance isograds. For the location, refer to [[:file:petroleum-systems_fig3-12.png|Figure 1]].

file:petroleum-systems_fig3-14.png|{{figure number|3}}Major structural-stratigraphic elements, the occurrence of oil fields, elevation of selected vitrinite reflectance values, and reflectance isograds. From Bird.<ref name=ch03r2 />

[[file:petroleum-systems_fig3-15.png|thumb|{{figure number|4}}Analysis of the burial history chart of the Inigok 1 well. From Bird.<ref name=ch03r2 />]]

The [[cross section]] of the Ellesmerian(!) petroleum system ([[:file:petroleum-systems_fig3-14.png|Figure 3]]) shows major structural-stratigraphic elements, the occurrence of oil fields, elevation of selected [[vitrinite reflectance]] values, and reflectance isograds. For the location, refer to [[:file:petroleum-systems_fig3-12.png|Figure 1]].

==Burial history chart==

==Burial history chart==

Analysis of the burial history chart of the Inigok 1 well ([[:file:petroleum-systems_fig3-15.png|Figure 4]]) and other burial history charts indicates peak petroleum generation (the critical moment) probably occurred in Late Cretaceous time (approximately 75 Ma) in the western North Slope and in early Tertiary time (approximately 50 Ma) in the central and eastern part of the North Slope. Also, note the large increase in the rate of sedimentation during the Early Cretaceous.

file:petroleum-systems_fig3-15.png|{{figure number|4}}Analysis of the burial history chart of the Inigok 1 well. From Bird.<ref name=ch03r2 />

[[file:petroleum-systems_fig3-16.png|left|thumb|{{figure number|5}}(left) Biological marker analysis. From Seifert et al.<ref name=Seifertetal_1980>Seifert, W. K., J. M. Moldowan, and R. W. Jones, 1980, Application of biological marker chemistry to petroleum exploration: Proceedings of the 10th World Petroleum Congress, Bucharest, p. 425-440</ref> Courtesy World Petroleum Conference. (right) Carbon isotopic composition comparisons. From Sedivy et al.<ref name=ch03r9>Sedivy, R., A., Penfield, I., E., Halpern, H., I., Drozd, R., J., Cole, G., A., Burwood, R., 1987, Investigation of source rock–crude oil relationships in the northern Alaska hydrocarbon habitat, in Tailleur, I., Weimer, P., eds., Alaskan North Slope Geology: Pacific Section SEPM Book 50, p. 169–179.</ref> Courtesy Pacific Section of SEPM.]]

Analysis of the [[burial history chart]] of the Inigok 1 well ([[:file:petroleum-systems_fig3-15.png|Figure 4]]) and other burial history charts indicates peak [[petroleum generation]] (the critical moment) probably occurred in Late Cretaceous time (approximately 75 Ma) in the western North Slope and in early Tertiary time (approximately 50 Ma) in the central and eastern part of the North Slope. Also, note the large increase in the rate of sedimentation during the Early Cretaceous.

==Oil-source rock correlation==

==Oil-source rock correlation==

Biological marker analysis ([[:file:petroleum-systems_fig3-16.png|Figure 5A]]) from the main reservoir rock, Sadlerochit Group, of Prudhoe Bay field shows that the oil originated from the Shublik Formation, the Kingak Shale, and the Hue Shale. Carbon isotopic composition comparisons ([[:file:petroleum-systems_fig3-16.png|Figure 5B]]) indicate that Shublik and Kingak share similar ¹³C values with oil from the Prudhoe Bay field, whereas the Hue Shale does not.

petroleum-systems_fig3-16.png|{{figure number|5}}(left) Biological marker analysis. From Seifert et al.<ref name=Seifertetal_1980>Seifert, W. K., J. M. Moldowan, and R. W. Jones, 1980, Application of biological marker chemistry to petroleum exploration: Proceedings of the 10th World Petroleum Congress, Bucharest, p. 425-440</ref> Courtesy World Petroleum Conference. (right) Carbon isotopic composition comparisons. From Sedivy et al.<ref name=ch03r9>Sedivy, R. A., I. E. Penfield, H. I. Halpern, R. J. Drozd, G. A. Cole, and R. Burwood, 1987, Investigation of source rock–crude oil relationships in the northern Alaska hydrocarbon habitat, in I. Tailleur, and P. Weimer, eds., Alaskan North Slope Geology: Pacific Section SEPM Book 50, p. 169–179.</ref> Courtesy Pacific Section of SEPM.

</gallery>

[[file:petroleum-systems_fig3-17.png|thumb|{{figure number|6}}Events chart for the Ellesmerian(!) petroleum system. From Bird.<ref name=ch03r2 />]]

Biological marker analysis ([[:file:petroleum-systems_fig3-16.png|Figure 5A]]) from the main reservoir rock, Sadlerochit Group, of [[Prudhoe Bay field]] shows that the oil originated from the Shublik Formation, the Kingak Shale, and the Hue Shale. Carbon isotopic composition comparisons ([[:file:petroleum-systems_fig3-16.png|Figure 5B]]) indicate that Shublik and Kingak share similar ¹³C values with oil from the Prudhoe Bay field, whereas the Hue Shale does not.

==Petroleum system events chart==

==Petroleum system events chart==

[[:file:petroleum-systems_fig3-17.png|Figure 6]], an events chart for the Ellesmerian(!) petroleum system, indicates when its elements and processes occurred. The cross-hatched pattern shows the estimated time of the tilting of the Barrow Arch, which resulted in remigration of petroleum from older to younger (early Tertiary) reservoir rocks.

[[:file:petroleum-systems_fig3-17.png|Figure 6]], an events chart for the Ellesmerian(!) petroleum system, indicates when its elements and processes occurred. The cross-hatched pattern shows the estimated time of the tilting of the Barrow Arch, which resulted in remigration of petroleum from older to younger (early Tertiary) reservoir rocks.

{| class = "wikitable"

{| class = "wikitable"

|+ The Ellesmerian petroleum system{{update after}}

|+ The Ellesmerian petroleum system{{update after}}<ref name=ch03r2 />

|-

|-

! rowspan = 2 | Map ID || rowspan = 2 | Accumulation || rowspan = 2 | Res. depth (m) || rowspan = 2 |  Trap type || colspan = 2 | In Place || colspan = 2 | Cum. Prod. || colspan = 2 | Reserves

! rowspan = 2 | Map ID || rowspan = 2 | [[Accumulation]] || rowspan = 2 | Res. depth (m) || rowspan = 2 |  Trap type || colspan = 2 | In Place || colspan = 2 | Cum. Prod. || colspan = 2 | Reserves

|-

|-

! Oil (Bbbl) || Gas (Tcf) || Oil (Mbbl) || Gas (Bcf) || Oil (Mbbl) || Gas (Bcf)

! Oil (Bbbl) || Gas (Tcf) || Oil (Mbbl) || Gas (Bcf) || Oil (Mbbl) || Gas (Bcf)

| —

| —

| —

| —

|

| —

| ?

| ?

|-

|-

[[Category:Traps, trap types, and the petroleum system]]  

[[Category:Traps, trap types, and the petroleum system]]  

[[Category:Petroleum systems]]

[[Category:Petroleum systems]]