AN INTEGRATED PETROLEUM EVALUATION OF NORTHEASTERN NEVADA |
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GEOCHEMISTRY DISCUSSION The objectives of the geochemical portion of this evaluation are fourfold. First, to characterize the source potential of various Paleozoic through Cenozoic sediments through the analysis of 287 outcrop samples collected from 12 formations across the evaluation area. Secondly, to characterize and type the known Nevada oils through whole rock and extract gas chromatograph analysis of crude oil from the Grant Canyon, Blackburn, Trap Spring and Eagle Springs oil fields, as well as outcrop samples of probable source rocks. Third, to assess the modern thermal gradient(s) present across the region through the compilation of bottomhole temperature data from wells drilled to date within the evaluation area. Fourth, to assess the ancient thermal gradients and timing of hydrocarbon generation events through the collection and analysis of 12 surface and subsurface samples using microcline paleothermometry. This volume contains the geochemical data collected and analyzed as well as the conclusions drawn from the data set. The volume is divided into three major sections. In the first section, the results of the surface geochemistry are discussed by formation, youngest to oldest. For each formation, the total organic carbon and kerogen type, vitrinite reflectance, and thermal alteration index, and pyrolysis results are discussed. Much of this discussion refers to contoured geochemical overlays V through XII. This discussion is followed by the results of the whole rock and saturate extract analysis performed on the Nevada oils and outcrop samples. The second section of this volume discusses the subsurface geochemistry and geothermal data. The results of the bottomhole thermal analysis and the microcline paleothermometry are described by area, and in terms of generation history. The third portion of the volume is a set of appendices I through VIII which detail the entire geochemical data set by list or display. These appendices include sample descriptions for all surface geochemical and microcline samples, discussions of the various analytical procedures, and the analytical results including TOC, kerogen type, TAI, Ro, pyrolysis, reflectance histograms, hydrogen/oxygen index plots, gas chromatographic analyses, bottomhole temperature data and histograms, and microcline age spectrum plots. These appendices should be carefully reviewed since they contain the actual raw data and also include discussions not found in the first two portions of this volume. |
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