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Figure 1. Index map of Denver basin with study area.
Figure 2. (see animation of Figures 2, 5-12, 17-20, and 25) Structure contour map on top of Codell Sandstone Member of Carlile Formation. Production as follows: Wattenberg field--Lower Cretaceous, J Sandstone; Spindle field--Upper Cretaceous, Terry and Hygiene sandstones; other fields--Upper Cretaceous, mainly from the Codell Sandstone.
Figure 3. Cretaceous strata, Denver basin (from Porter and Weimer, 1982); radiometric age dates taken from Fouch et al. (1983). Refer to Figure 4 for subdivisions of Benton Shale.
Figure 4. North-south electric log section A-B of the lower 900 ft (275 m) of Cretaceous strata drilled in general Wattenberg area.
Figure 5. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of J Sandstone. Contour interval is 25 ft (7.6 m). Triangular symbols outline wells used for J Sandstone core study.
Figure 6. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of Mowry Shale. Contour interval is 10 ft (7.6 m).
Figure 7. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of Graneros Shale. Contour interval is 25 ft (7.6 m).
Figure 8. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach of Greenhorn Formation. Contour interval is 25 ft (7.6 m).
Figure 9. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of Carlile Shale. Contour interval is 25 ft (7.6 m).
Figure 10. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of Niobrara Formation. Contour interval is 50 ft (15.2 m).
Figure 11. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of upper limestone of Niobrara Formation. Unit is absent in ruled area. Contour interval is 20 ft (6.1 m). After Weimer, 1980.
Figure 12. (see animation of Figures 2, 5-12, 17-20, and 25) Paleostructure indicated by isopach map from top of Niobrara Formation to top of J Sandstone. Contour interval is 50 ft (15.2 m).
Figure 13. Mechanical log patterns for a typical well in the Wattenberg field. H.M. is Horsetooth Member and F.C.M. is Fort Collins Member of the J Sandstone. Refer to Figure 16 for core descriptions.
Figure 14. [Color] Thin-section photomicrograph of J Sandstone showing clay rims and quartz overgrowths, argillaceous lithic fragments (AL), and pseudomatrix (Pm) resulting from diagenetic pore filling (from Fort Collins Member).
Figure 15. [Grey Scale] SEM photomicrograph of J Sandstone. Quartz overgrowths (Q) are abundant; authigenic smectite (S) lines pores.
Figure 16. Electric log section C-D with core descriptions of J Sandstone in the Wattenberg area. Refer to Figures 17 and 18 for location of section.
Figure 17. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of Fort Collins Member of J Sandstone. Contour interval is 20 ft (6.1 m).
Figure 18. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of Horsetooth Member of J Sandstone. Contour interval is 20 ft (6.1 m).
Figure 19. (see animation of Figures 2, 5-12, 17-20, and 25) Contour map of cumulative gas production, Wattenberg field. Contour interval is 250 mmcf.
Figure 20. (see animation of Figures 2, 5-12, 17-20, and 25) Contour map of cumulative oil production, Wattenberg field. Contour interval is 5,000 bbl.
Figure 21. East-west electric log section E-F. Refer to Figure 23 for location. (1) Amoco Hergenreder 1, NW SW Sec. 28, T3N, R68W; (2) Crystal State 13-4, NW SW Sec. 4, T3N, R62W; (3) Davis Foley 1, SE NW Sec. 1, T3N, R60W; (4) Menzel Brand 1, NE NE Sec. 17, T3N, R46W.
Figure 22. Mechanical log patterns for a typical well productive from the Codell Sandstone.
Figure 23. (see animation of Figures 23 and 24) Isopach map of Codell Sandstone. Isopach interval is 20 ft (6.1 m).
Figure 24. (see animation of Figures 23 and 24) Isopach map of lower Carlile Shale. Isopach interval is 50 ft (15.2 m).
Figure 25. (see animation of Figures 2, 5-12, 17-20, and 25) Isopach map of Fort Hays Limestone Member of Niobrara Formation. Isopach interval is 5 ft (1.5 m).
Figure 26. (see animation of Figures 26, 27 and 29) Block diagram showing deposition of Fort Collins Member of J Sandstone during high stand of sea. Shoreline regressed from position at time 1 (T1) to position at time 2 (T2). The Wattenberg fault block related to inferred basement movement is shown.
Figure 27. (see animation of Figures 26, 27 and 29) Block diagram of area during time 3 (T3). A drop in sea level caused a regional erosional surface and an incised drainage.
Figure 28. Regional isopach map of J Sandstone showing distribution of incised drainages for time 3 (before deposition of lowermost J). Contour interval is 50 ft (15.2 m).
Figure 29. (see animation of Figures 26, 27 and 29) Block diagram showing deposits in areas of incised drainage as valleys filled during a rising sea. Subsequent deposits of this transgressive event are also depicted.
Figure 30. Diagrams illustrating depositional topography in Cretaceous basin during times of Carlile and Greenhorn deposition (A, B, C). Codell Sandstone was deposited on erosional surface in the general Wattenberg area as a result of tectonic movement and a drop and subsequent rise in sea level (D).
Figure 31. Annual production graph of gas and condensate, Wattenberg field. Figures for J Sandstone production only.
Figure 32. Annual and cumulative production figures for wells on production.
Figure 33. Decline curve for J Sandstone production, Amoco Rocky Mtn Fuel well, NW SW Sec. 8, T1N, R67W.
Figure 34. Decline curve for Codell Sandstone production, Energy Oil Areas 1 well, sec. 22, T4N, R65W.
Figure 35. Decline curve for Codell Sandstone production, Machii-Ross Barclay 1, sec. 20, T3N, R66W, J Sandstone well that was recompleted in Codell.