Theses and Dissertations at Montana State University (MSU)
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Item Sequence stratigraphic framework of the late Devonian (Frasnian) Duperow Formation in western and central Montana(Montana State University - Bozeman, College of Letters & Science, 2019) Steuer, Christopher Johann; Chairperson, Graduate Committee: David W. BowenThe Late Devonian Duperow Formation in western and central Montana and it's equivalent lower Jefferson Formation, is comprised of shallow marine carbonate strata deposited on the western margin of North America. It has produced significant volumes of oil and natural gas in the Alberta and Williston basins where the sequence stratigraphic framework of the formation is well-documented. However, in western and central Montana, the Duperow remains largely understudied. Additionally, at Kevin Dome, in northwest Montana, the Duperow hosts a large naturally occurring carbon-dioxide (CO^2) accumulation which is a potential economic resource and an analog for CO^2 sequestration over geologic time scales. The goal of this study is to determine the facies relationships and sequence stratigraphic architecture of the Late Devonian Duperow Formation in western and central Montana. This interpretation could help in exploration for oil and natural gas and provide useful information to aid in future carbon sequestration efforts. Multiple data sets are used in this study to best constrain depositional environments on the platform during Duperow deposition. Seven measured sections, three drill cores with associated well-logs, and forty-one thin sections are used to characterize facies, facies associations, parasequences, parasequence sets and sequences of the Duperow Formation and to construct the sequence stratigraphic framework within which these strata occur. Ten lithofacies comprising six lithofacies associations allow the interpretation of six depositional environments responsible for deposition of the Duperow Formation. The Duperow thins from the west and north onto the Central Montana Uplift, a paleohigh at the time, and thickens into the Central Montana Trough, a sub-basin on the platform. Two 2nd order and seven 3rd order sequences are interpreted from measured sections. Sequences are comprised of a transgressive systems tract and a highstand systems tract with no evidence for lowstand strata on the shelf. Transgression across the Central Montana Uplift did not occur until after the basal sequence boundary of the upper 2nd order sequence. Prior to this transgression, sequences lapped out before reaching the Central Montana Uplift. Overall, the Duperow in central and western Montana exhibits retrogradational stacking and thus is part of the transgressive systems tract of a lower-order megasequence.Item Design and experimental testing of a high pressure, high temperature flow-through rock core reactor using supercritical carbon dioxide(Montana State University - Bozeman, College of Letters & Science, 2009) Hansen, Logan Carl; Chairperson, Graduate Committee: Mark L. SkidmoreAnthropogenic CO 2 emission is of concern due to its likely contribution to global climate change. Geologic storage of CO 2 in deep brine-bearing aquifers is currently viewed as an alternative to its release to the atmosphere. The effects of injecting CO 2 into these aquifers are poorly understood. An experimental apparatus was developed to reproduce subsurface conditions relevant to geologic sequestration to simulate CO 2 injection and assess CO 2-brine-rock interactions. Technology available for this type of experimental apparatus was advanced by enhancing monitoring capabilities to include in situ pH, EC, pressure, and temperature measurement and continuous logging of these variables. This thesis describes the experimental apparatus and its novel capabilities, demonstrates its accuracy and precision, and presents and discusses a suite of CO 2-brine and CO 2-brine-rock interaction studies relevant to geologic sequestration. Experiments were conducted by flowing brine and/or supercritical CO 2 through the apparatus, with and without rock cores in line. Rock samples were limestones/dolostones from the Madison Formation in the western Black Hills, South Dakota, which was selected based on its applicability as a primary large-scale geological CO 2 storage target. Outcrop blocks were machined to produce cores with minimal evidence of weathering to best simulate subsurface Madison Formation rock. Brines were prepared in the laboratory of a similar composition to reported literature values for in situ Madison formation fluids. Results from the experimental system show good agreement with bench pH and EC measurements when utilizing standardized fluids. Experimental data indicate that adding CO 2 to brine under all tested conditions significantly reduces brine pH, an important control on subsurface geochemistry. This effect is partially buffered by flowing the fluids through Madison rock cores, due to dissolution of carbonate minerals, predominantly dolomite. The experiments indicate that samples of the Madison Formation with in situ brines can be partially dissolved via exposure to supercritical CO 2. Similar processes would likely occur in the subsurface Madison Formation in response to addition of supercritical CO 2. The novel experimental system provided new data that could be utilized in refining geochemical models; however, further improvements can be made to the system to improve its capabilities in this regard.