121 research outputs found

    Simulation of complex fluid processes in the subsurface: Numerical models of undergrounds CO2 sequestration, heavy oil, oil shale, and oil sands

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    Concern over global warming has made the sequestration of CO2 national news. Subsurface storage of CO2, often in depleted oil reservoirs, is being actively studied for this purpose. United States energy security policies have provided motivation for many energy companies to investigate strategies for in-situ extraction of liquid fuels from oil shale and oil sands. Simulation plays a critical role in evaluating the feasibility of both of these processes. While each of these applications has different goals, they are governed by similar physics and chemistry: multi-phase heat and mass transfer, a compositional formulation for the mixed hydrocarbon phase, and supercritical fluid behavior. For each of these problems, I will describe typical geologic settings, goals, and environmental concerns. Current state-of-the-art simulation techniques, including numerical formulation and nonlinear iteration techniques will be presented. Some example simulations will be shown that highlight current capability. Challenges to the accurate simulation of these large scale problems will be summarized and future directions presented

    Impacts of and Alternatives to Solitary Confinement in Adult Correctional Facilities

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    The use of solitary confinement in adult correctional facilities has recently been scrutinized due to concerns surrounding offenders’ mental health and what impacts come from its use. The purpose of this research was to examine the impacts of and alternatives to solitary confinement in adult correctional facilities through the lens of professionals with direct experience working with offenders. A qualitative research design was executed, contacting a total of twenty-two professionals, completing four semi-structured interviews. All participants had professional experience working with offenders in an adult correctional facility in Minnesota. Three major themes emerged within the data: working definitions of solitary confinement, impact on mental health, and alternatives to the use of solitary confinement. Findings were consistent with the literature, emphasizing the importance of the current reform surrounding solitary confinement practices and recognizing the continued need for future research

    Great SCO2T! Rapid tool for carbon sequestration science, engineering, and economics

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    CO2 capture and storage (CCS) technology is likely to be widely deployed in coming decades in response to major climate and economics drivers: CCS is part of every clean energy pathway that limits global warming to 2C or less and receives significant CO2 tax credits in the United States. These drivers are likely to stimulate capture, transport, and storage of hundreds of millions or billions of tonnes of CO2 annually. A key part of the CCS puzzle will be identifying and characterizing suitable storage sites for vast amounts of CO2. We introduce a new software tool called SCO2T (Sequestration of CO2 Tool, pronounced "Scott") to rapidly characterizing saline storage reservoirs. The tool is designed to rapidly screen hundreds of thousands of reservoirs, perform sensitivity and uncertainty analyses, and link sequestration engineering (injection rates, reservoir capacities, plume dimensions) to sequestration economics (costs constructed from around 70 separate economic inputs). We describe the novel science developments supporting SCO2T including a new approach to estimating CO2 injection rates and CO2 plume dimensions as well as key advances linking sequestration engineering with economics. Next, we perform a sensitivity and uncertainty analysis of geology combinations (including formation depth, thickness, permeability, porosity, and temperature) to understand the impact on carbon sequestration. Through the sensitivity analysis we show that increasing depth and permeability both can lead to increased CO2 injection rates, increased storage potential, and reduced costs, while increasing porosity reduces costs without impacting the injection rate (CO2 is injected at a constant pressure in all cases) by increasing the reservoir capacity.Comment: CO2 capture and storage; carbon sequestration; reduced-order modeling; climate change; economic

    Mathematical Formulation Requirements and Specifications for the Process Models

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    The Advanced Simulation Capability for Environmental Management (ASCEM) is intended to be a state-of-the-art scientific tool and approach for understanding and predicting contaminant fate and transport in natural and engineered systems. The ASCEM program is aimed at addressing critical EM program needs to better understand and quantify flow and contaminant transport behavior in complex geological systems. It will also address the long-term performance of engineered components including cementitious materials in nuclear waste disposal facilities, in order to reduce uncertainties and risks associated with DOE EM's environmental cleanup and closure activities. Building upon national capabilities developed from decades of Research and Development in subsurface geosciences, computational and computer science, modeling and applied mathematics, and environmental remediation, the ASCEM initiative will develop an integrated, open-source, high-performance computer modeling system for multiphase, multicomponent, multiscale subsurface flow and contaminant transport. This integrated modeling system will incorporate capabilities for predicting releases from various waste forms, identifying exposure pathways and performing dose calculations, and conducting systematic uncertainty quantification. The ASCEM approach will be demonstrated on selected sites, and then applied to support the next generation of performance assessments of nuclear waste disposal and facility decommissioning across the EM complex. The Multi-Process High Performance Computing (HPC) Simulator is one of three thrust areas in ASCEM. The other two are the Platform and Integrated Toolsets (dubbed the Platform) and Site Applications. The primary objective of the HPC Simulator is to provide a flexible and extensible computational engine to simulate the coupled processes and flow scenarios described by the conceptual models developed using the ASCEM Platform. The graded and iterative approach to assessments naturally generates a suite of conceptual models that span a range of process complexity, potentially coupling hydrological, biogeochemical, geomechanical, and thermal processes. The Platform will use ensembles of these simulations to quantify the associated uncertainty, sensitivity, and risk. The Process Models task within the HPC Simulator focuses on the mathematical descriptions of the relevant physical processes
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