Graduate Thesis Or Dissertation

 

Sequence-Stratigraphic Controls on Reservoir-Scale Architecture of the Middle Mesaverde Group, Douglas Creek Arch, Colorado Public Deposited

https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/gh93gz87x
Abstract
  • The middle Mesaverde Group of the Douglas Creek Arch, northwestern Colorado, is represented by a complex succession of fluvial to marine strata that serve as outcrop analogs to laterally equivalent natural gas reservoirs in the Piceance and Uinta basins. The interval includes ~380 ft (~115.9 m) of mudrock, coal, and sandstone within the lower (Kmvl) to main coal-bearing (Kmvc) intervals of the Mesaverde Group (equivalent to the upper Iles and lower Williams Fork formations). Based on 2,488 ft (758.5 m) of measured section, facies associations include: (1) coastal plain; (2) estuarine; (3) lagoon; and (4) shallow marine. Nine architectural elements are identified and include: (1) channel bodies; (2) crevasse splays; (3) discrete flood bodies; (4) a bayhead delta; (5) an estuarine assemblage; (6) foreshores; (7) tidal barforms; (8) middle shorefaces; and (9) washover fans. The study interval records an overall transgression from coastal-plain to shallow-marine facies associations to regression from shallow-marine to coastal-plain facies associations. Based on 38 sandstone-body measurements, channel bodies have an apparent width (W) of 287.7 ft (87.7 m), and thickness (T) of 4.9 ft (1.5 m) and are larger than crevasse splays (W=90.5 ft [28.0 m]; T=1.8 ft [0.5 m]) and discrete flood bodies (W=61.5 ft [18.8 m]; T=1.6 ft [0.5 m]). Net-to-gross ratios (N:G) create packages in the study interval and show direct ties to the sequence-stratigraphic framework. High N:G packages lie above sequence boundaries and fine upward into low N:G packages. Moderate N:G packages occur in late transgressive to early regressive strata.
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  • 2011
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  • 2019-11-17
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