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| | part = Critical elements of the petroleum system | | | part = Critical elements of the petroleum system |
| | chapter = Sedimentary basin analysis | | | chapter = Sedimentary basin analysis |
− | | frompg = 4-1 | + | | frompg = 4-93 |
− | | topg = 4-123 | + | | topg = 4-93 |
| | author = John M. Armentrout | | | author = John M. Armentrout |
| | link = http://archives.datapages.com/data/specpubs/beaumont/ch04/ch04.htm | | | link = http://archives.datapages.com/data/specpubs/beaumont/ch04/ch04.htm |
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| | isbn = 0-89181-602-X | | | isbn = 0-89181-602-X |
| }} | | }} |
− | Overburden rock is the total stratigraphic section above the [[source rock]].<ref name=ch04r61>Magoon, L., B., Dow, W., G., 1994, The [[Petroleum system]]: AAPG Memoir 60, p. 3–24.</ref> The thickness and age of overburden rock provides a history of the rate of burial of a source rock toward and through the increasing temperature domains of the basin. This includes the range of temperatures necessary for cracking kerogens into hydrocarbons. | + | Overburden rock is the total stratigraphic section above the [[source rock]].<ref name=ch04r61>Magoon, L. B., and W. G. Dow, 1994, The Petroleum System--From Source to Trap: [http://store.aapg.org/detail.aspx?id=1022 AAPG Memoir 60], p. 3–24.</ref> The thickness and age of overburden rock provides a history of the rate of burial of a [[source rock]] toward and through the increasing temperature domains of the basin. This includes the range of temperatures necessary for [[cracking]] kerogens into hydrocarbons. (See also [[Kerogen type and hydrocarbon generation]].) |
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| + | Because the depth to the probable [[source rocks]] of the East Breaks 160-161 field hydrocarbons is unknown, multiple working hypotheses must be considered. Four intervals of identified source rock are reported by Gross et al.<ref name=ch04r40>Gross, O. P., K. C. Hood, L. M. Wenger, and S. C. Harrison, 1995, Seismic imaging and analysis of source and migration within an integrated hydrocarbon system study, northern Gulf of Mexico basin: Abstracts, 1st Latin American Geophysical conference, p. 1–4.</ref> ([[:File:Sedimentary-basin-analysis_fig4-5.png|Figure 1]]) and are plotted on [[:File:Sedimentary-basin-analysis_fig4-45.png|Figure 2]]. Also plotted is the speculated middle Miocene source rock of Dow et al.<ref name=ch04r29>Dow, W. G., M. A. Yukler, J. T. Senftle, M. C. Kennicutt, and J. M. Armentrout, 1990, Miocene oil source beds in the East Breaks basin, Flex-Trend, offshore Texas: Proceedings, Gulf Coast Section SEPM 9th Annual Research conference, p. 139–150.</ref> Gross et al.<ref name=ch04r40 /> consider the petroleum of the East Breaks area to have been sourced by [[Jurassic]] marine mudstones for the oil and [[Paleogene]] marine mudstones for the gas. Alternatively, Dow et al.<ref name=ch04r29 /> suggest middle [[Miocene]] marine mudstones as the probable source rock, although Taylor and Armentrout<ref name=ch04r93>Taylor, G. S., and J. M. Armentrout, 1990, Rock geochemistry and relationships to produced oils from upper Pliocene turbidites, High Island area, Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 9th Annual Research conference, p. 151–161.</ref> believe the source rock facies to be older than the Miocene slope mudstones. |
| + | |
| + | <gallery mode=packed heights=300px widths=300px> |
| + | File:Sedimentary-basin-analysis_fig4-5.png|{{figure number|1}}Map of hydrocarbon types based on analyses of more than 2000 oil, 600 gas, and 1200 seep samples correlated to specific source rocks. Modified from Gross et al.<ref name=ch04r40 /> |
| + | File:Sedimentary-basin-analysis_fig4-45.png|{{figure number|2}}Time scale from Haq et al.;<ref>Haq, B., J. Hardenbol, and P. R. Vail, 1988, Mesozoic and Cenozoic chronostratigra- phy and cycles of sea-level change: SEPM Special Publication 42, p. 71–108.</ref> DOW represents source rock, generation, and critical moment estimates.<ref name=ch04r29 /> |
| + | </gallery> |
| | | |
− | Because the depth to the probable [[source rocks]] of the East Breaks 160-161 field hydrocarbons is unknown, multiple working hypotheses must be considered. Four intervals of identified source rock are reported by Gross et al..<ref name=ch04r40>Gross, O., P., Hood, K., C., Wenger, L., M., Harrison, S., C., 1995, Seismic imaging and analysis of source and [[migration]] within an integrated hydrocarbon system study, northern Gulf of Mexico basin: Abstracts, 1st Latin American Geophysical conference, p. 1–4.</ref> (Figure 4-5) and are plotted on Figure 4-45. Also plotted is the speculated middle Miocene source rock of Dow et al.<ref name=ch04r29>Dow, W., G., Yukler, M., A., Senftle, J., T., Kennicutt, M., C., IIArmentrout, J., M., 1990, Miocene oil source beds in the East Breaks basin, Flex-Trend, offshore Texas: Proceedings, Gulf Coast Section SEPM 9th Annual Research conference, p. 139–150.</ref> Gross et al.<ref name=ch04r40 />) consider the petroleum of the East Breaks area to have been sourced by Jurassic marine mudstones for the oil and Paleogene marine mudstones for the gas. Alternatively, Dow et al.<ref name=ch04r29 />) suggest middle Miocene marine mudstones as the probable source rock, although Taylor and Armentrout<ref name=ch04r93>Taylor, G., S., Armentrout, J., M., 1990, Rock geochemistry and relationships to produced oils from upper Pliocene turbidites, High Island area, Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 9th Annual Research conference, p. 151–161.</ref> believe the source rock facies to be older than the Miocene slope mudstones.
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| ==Rate of accumulation== | | ==Rate of accumulation== |
− | Accumulation of overburden above these five potential source rocks is shown by a dashed line on the events chart (Figure 4-45), indicating no specific rate of accumulation until the interval of late Pliocene to Recent sedimentation where rate variation is shown as defined by Piggott and Pulham.<ref name=ch04r75>Piggott, N., Pulham, A., 1993, Sedimentation rate as the control on hydrocarbon sourcing, generation, and migration in the deepwater Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 14th Annual Research conference, p. 179–191.</ref> Figures 4-32 and 4-33 indicate a major increase in rate of sediment accumulation occurred 6 Ma, which would accelerate burial of potential source rocks into the thermal zone for hydrocarbon generation. | + | <gallery mode=packed heights=300px widths=300px> |
| + | File:Sedimentary-basin-analysis_fig4-32.png|{{figure number|3}}Rock thickness vs. time plot for nine key wells south of east- ern Louisiana within the area of the 6–4 Ma [[depocenter]]. After Piggott and Pulham;<ref name=PP>Piggott, N., and A. Pulham, 1993, Sedimentation rate as the control on hydrocarbon sourcing, generation, and migration in the deepwater Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 14th Annual Research Conference, p. 179–191.</ref> courtesy Gulf Coast SEPM |
| + | File:Sedimentary-basin-analysis_fig4-33.png|{{figure number|4}}Rock accumulation rates for the Green Canyon 166 No. 1 well, as a histogram (lower graph) and as a set of burial history curves (upper graph). After Piggott and Pulham;<ref name=PP /> courtesy Gulf Coast SEPM. |
| + | </gallery> |
| + | Accumulation of overburden above these five potential source rocks is shown by a dashed line on the events chart ([[:File:Sedimentary-basin-analysis_fig4-45.png|Figure 2]]), indicating no specific rate of accumulation until the interval of late [[Pliocene]] to [[Holocene]] sedimentation where rate variation is shown as defined by Piggott and Pulham.<ref name=ch04r75>Piggott, N., and A. Pulham, 1993, Sedimentation rate as the control on hydrocarbon sourcing, generation, and migration in the deepwater Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 14th Annual Research conference, p. 179–191.</ref> [[:File:Sedimentary-basin-analysis_fig4-32.png|Figures 3]] and [[:File:Sedimentary-basin-analysis_fig4-33.png|4]] indicate a major increase in rate of sediment accumulation occurred 6 Ma, which would accelerate burial of potential source rocks into the thermal zone for [[Petroleum generation|hydrocarbon generation]]. |
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| ==Amount== | | ==Amount== |
− | Drilling has documented that the East Breaks depocenter in the vicinity of the 160-161 field contains at least [[depth::15,000 ft]] (5000 m) of late Miocene to Recent sediment (Figure 4-43). Dow et al.<ref name=ch04r29 />) use this thickness in calculating [[maturation]] and generation models. The thickness of overburden rock for any one of the older potential source rock intervals will be greater than [[depth::15,000 ft]] (5000 m), but the exact amount is highly speculative. | + | [[File:Sedimentary-basin-analysis_fig4-43.png|thumb|300px|{{figure number|5}}North–south seismic section through the East Breaks 160-161 intraslope [[minibasin]], showing the location of the East Breaks 160-161 field.]] |
| + | |
| + | Drilling has documented that the East Breaks [[depocenter]] in the vicinity of the 160-161 field contains at least [[depth::15,000 ft]] (5000 m) of upper [[Miocene]] to [[Holocene]] sediment ([[:File:Sedimentary-basin-analysis_fig4-43.png|Figure 5]]). Dow et al.<ref name=ch04r29 /> use this thickness in calculating [[maturation]] and generation models. The thickness of overburden rock for any one of the older potential [[source rock]] intervals will be greater than [[depth::15,000 ft]] (5000 m), but the exact amount is highly speculative. |
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| ==See also== | | ==See also== |
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| [[Category:Critical elements of the petroleum system]] | | [[Category:Critical elements of the petroleum system]] |
| [[Category:Sedimentary basin analysis]] | | [[Category:Sedimentary basin analysis]] |
− | [[Category:East Breaks minibasin|Overburden]] | + | [[Category:East Breaks]] |
| + | [[Category:Treatise Handbook 3]] |