Changes

==Well-log cross section==

==Well-log cross section==

[[file:sedimentary-basin-analysis_fig4-48.png|thumb|{{figure number|6}}Well-log cross section of the ''Glob alt'' reservoir interval. After Armentrout et al.<ref name=ArmentroutEtAl_1991 /> Courtesy Springer-Verlag.]]

[[file:sedimentary-basin-analysis_fig4-48.png|thumb|300px|{{figure number|6}}Well-log cross section of the ''Glob alt'' reservoir interval. After Armentrout et al.<ref name=ArmentroutEtAl_1991 /> Courtesy Springer-Verlag.]]

[[:file:sedimentary-basin-analysis_fig4-48.png|Figure 6]] is a well-log cross section of the ''Glob alt'' reservoir interval; datum is a mudstone within the GA-2 sandstone (well locations are shown on [[:file:sedimentary-basin-analysis_fig4-46.png|Figure 1]]). All logs are spontaneous potential with true vertical depth displays. The GA-4 reservoir sand is below the displayed interval. Log profiles are annotated: arrow C = funnel-shaped, coarsening-upward sandstone; arrow F = bell-shaped, fining-upward sandstone; parallel lines B = blocky profile of relatively thick sandstones and thin mudstone interbeds.

[[:file:sedimentary-basin-analysis_fig4-48.png|Figure 6]] is a well-log cross section of the ''Glob alt'' reservoir interval; datum is a mudstone within the GA-2 sandstone (well locations are shown on [[:file:sedimentary-basin-analysis_fig4-46.png|Figure 1]]). All logs are spontaneous potential with true vertical depth displays. The GA-4 reservoir sand is below the displayed interval. Log profiles are annotated: arrow C = funnel-shaped, coarsening-upward sandstone; arrow F = bell-shaped, fining-upward sandstone; parallel lines B = blocky profile of relatively thick sandstones and thin mudstone interbeds.

==Net sandstone isopachs==

==Net sandstone isopachs==

[[file:sedimentary-basin-analysis_fig4-49.png|left|thumb|{{figure number|7}}Net sandstone isopachs for reservoir units of the ''Glob alt'' sandstone interval. From Armentrout et al.<ref name=ArmentroutEtAl_1991 />. Courtesy Springer-Verlag.]]

[[file:sedimentary-basin-analysis_fig4-49.png|300px||thumb|{{figure number|7}}Net sandstone isopachs for reservoir units of the ''Glob alt'' sandstone interval. From Armentrout et al.<ref name=ArmentroutEtAl_1991 />. Courtesy Springer-Verlag.]]

Well-log correlations within the ''Glob alt'' isochron thick show a succession of aggrading sandstone bodies ([[:file:sedimentary-basin-analysis_fig4-48.png|Figure 6]]). [[:file:sedimentary-basin-analysis_fig4-49.png|Figure 7]] shows net sandstone isopachs for reservoir units of the ''Glob alt'' sandstone interval. The stratigraphic succession from top to bottom reservoir sandstone is 1, 1.1, 2, 2.2, 3, and 4. Maps of each sandstone interval document lobate deposition within the minibasin. Individual lobe development shows compensation lobe switching as progressively younger deposits infill the mud-rich/sand-poor intralobe areas of the preceding lobe.

Well-log correlations within the ''Glob alt'' isochron thick show a succession of aggrading sandstone bodies ([[:file:sedimentary-basin-analysis_fig4-48.png|Figure 6]]). [[:file:sedimentary-basin-analysis_fig4-49.png|Figure 7]] shows net sandstone isopachs for reservoir units of the ''Glob alt'' sandstone interval. The stratigraphic succession from top to bottom reservoir sandstone is 1, 1.1, 2, 2.2, 3, and 4. Maps of each sandstone interval document lobate deposition within the minibasin. Individual lobe development shows compensation lobe switching as progressively younger deposits infill the mud-rich/sand-poor intralobe areas of the preceding lobe.

==Depositional model summary==

==Depositional model summary==

All the observations made from seismic profiles, isochron maps, seismic facies maps, well-log cross sections, cuttings, biofacies, and cores have been used to construct a depositional model for the ''Glob alt'' cycle of the High Island-East Breaks 160-161 minibasin. This model incorporates far-traveled gravity-flow sands that accumulated in a depositional thick, filling an upper-slope salt-withdrawal sea-floor low. Laterally shifting fan lobes resulted in a complex architectural framework (Figure 4-48). The profile pattern (Figure 4-47), combined with the mapped isochron and seismic facies pattern of Figure 4-46 and the net sandstone patterns of Figure 4-49, have been interpreted as minibasin basin-floor sheet sandstones, amalgamated-lobe sandstones, and leveed-channel sandstones by Armentrout et al.<ref name=ch04r7 />) (see Figure 4-48).

All the observations made from seismic profiles, isochron maps, seismic facies maps, well-log cross sections, cuttings, biofacies, and cores have been used to construct a depositional model for the ''Glob alt'' cycle of the High Island-East Breaks 160-161 minibasin. This model incorporates far-traveled gravity-flow sands that accumulated in a depositional thick, filling an upper-slope salt-withdrawal sea-floor low. Laterally shifting fan lobes resulted in a complex architectural framework ([[:file:sedimentary-basin-analysis_fig4-48.png|Figure 6]]). The profile pattern ([[:file:sedimentary-basin-analysis_fig4-47.png|Figure 3]]), combined with the mapped isochron and seismic facies pattern of [[:file:sedimentary-basin-analysis_fig4-46.png|Figure 1]] and the net sandstone patterns of [[:file:sedimentary-basin-analysis_fig4-49.png|Figure 7]], have been interpreted as minibasin basin-floor sheet sandstones, amalgamated-lobe sandstones, and leveed-channel sandstones by Armentrout et al.<ref name=ch04r7 />) (see [[:file:sedimentary-basin-analysis_fig4-48.png|Figure 6]]).

==Depositional model diagram==

==Depositional model diagram==

[[file:sedimentary-basin-analysis_fig4-50.png|thumb|{{figure number|8}}From Armentrout et al.<ref name=ArmentroutEtAl_1991 />. Courtesy Springer-Verlag.]]

[[file:sedimentary-basin-analysis_fig4-50.png|300px|thumb|{{figure number|8}}From Armentrout et al.<ref name=ArmentroutEtAl_1991 />. Courtesy Springer-Verlag.]]

[[:file:sedimentary-basin-analysis_fig4-50.png|Figure 8]] is a block diagram of the depositional model for the ''Glob alt'' reservoir interval. The model shows a 40-50-mi-long (60-80 km) transport system from a shelf-edge delta basinward to the East Breaks 160-161 minibasin. Depositional water depths exceeded [[depth::1000 ft]] (320 m) (upper bathyal), suggesting transport was by gravity-flow processes. Sandstone deposition in the minibasin may have resulted from subtle variations of sea-floor topography, perhaps related to early salt withdrawal.<ref name=ch04r53>Kneller, B., 1995, Beyond the turbidite paradigm: Physical models for deposition of turbidites and their implications for reservoir prediction, ''in'' Hartley, A. J., and D. J. Prosser, eds., Characterization of Deep Marine Clastic Systems: Geological Society, London, Special Publication 94, p. 31–49.</ref> Mass-wasting processes occurred on the slope well to the north of the field, as shown by slump facies on Figure 4-39. The areal extent of the basin-floor sheet is restricted by the areal extent of the East Breaks 160-161 intraslope minibasin.

[[:file:sedimentary-basin-analysis_fig4-50.png|Figure 8]] is a block diagram of the depositional model for the ''Glob alt'' reservoir interval. The model shows a 40-50-mi-long (60-80 km) transport system from a shelf-edge delta basinward to the East Breaks 160-161 minibasin. Depositional water depths exceeded [[depth::1000 ft]] (320 m) (upper bathyal), suggesting transport was by gravity-flow processes. Sandstone deposition in the minibasin may have resulted from subtle variations of sea-floor topography, perhaps related to early salt withdrawal.<ref name=ch04r53>Kneller, B., 1995, Beyond the turbidite paradigm: Physical models for deposition of turbidites and their implications for reservoir prediction, ''in'' Hartley, A. J., and D. J. Prosser, eds., Characterization of Deep Marine Clastic Systems: Geological Society, London, Special Publication 94, p. 31–49.</ref> Mass-wasting processes occurred on the slope well to the north of the field, as shown by slump facies on Figure 4-39. The areal extent of the basin-floor sheet is restricted by the areal extent of the East Breaks 160-161 intraslope minibasin.