GeoDigital Information's Denver Basin Paleozoic Study is designed to enhance both exploration and development efforts that are directed at Paleozoic reservoirs in the Denver Basin. GDI's stratigraphic study in the northern Denver Basin focuses on the relationship between structure and depositional systems in Desmoinesian through Wolfcampian strata. The study area covers more than 51,000 square miles in 1415 townships. Included in the study database are analyses of logs from 373 wells, 27 cores 160 thinsections, and paleontological analyses from seven wells.

     GDI correlated eleven regional stratigraphic markers throughout the study area. Interval isopachs, lithofacies, and paleogeographic maps were used to develop depositional models and to document the complex depositional history of the area. During the late Paleozoic, cyclic marine incursions resulted from changes in eustatic sea level and variations in local subsidence rates. The major structural feature affecting depositional rates and patterns was the Transcontinental Arch, which bisected the study area. This positive feature separated two subbasins, each with distinct depositional environments and stratigraphic relationships. Along its crest, a mosaic of carbonate facies was deposited in a variety of shallow-marine environments within a barrier/shoal complex. To the north, restricted conditions in the Alliance Basin resulted in resulted in thick evaporites, organic-rich source-potential shales, and dolomites. To the south, more normal marine conditions prevailed in the Sterling Basin, where progradational reservoir-potential carbonate ramp facies interfingered with dolomitic siltstones.

     A major feature of the GDI study is an internally consistent stratigraphic database. Laterally extensive carbonate and anhydrite beds were correlated over much of the area. These GDI correlations were compared to micropaleontological zonations showing that they have chronostratigraphic significance. The resultant stratigraphic units delineated by the correlations represent time-stratigraphic intervals. This permitted the construction of a variety of genetically significant maps. Core descriptions and petrographic analyses were integrated with wireline log data to determine facies and structural relationships. These relationships are presented in a series of subregional depositional models and documented by cross sections, lithofacies maps, and isopach maps.

     Petrographic analyses, focusing upon diagenetic alterations and their effects on porosity development, are integrated with the stratigraphy, tectonic framework, and depositional models to predict the distribution of potential reservoir facies. Detailed studies of Amazon and Bird fields further illustrate factors controlling hydrocarbon distribution

     The study components include an extensive summary text and figures, maps and cross sections, core and thinsection descriptions, and stratigraphic data appendices. These components provide the client with a presentation format that is concise and readily useable.