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Jung, Hun Bok

Publications and source records attributed to Jung, Hun Bok.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Long-term sorption and desorption of uranium in saprolite subsoil with nanoporous goethite

Long-term (2–3 months) batch U(VI) sorption-desorption experiments were conducted to understand the long-term sorption-desorption behavior of U(VI) in saprolite subsoils from Oak Ridge Field Research Center (ORFRC), Tennessee, which contained naturally occurring nanoporous goethite. Three subsoil samples containing a range of dithionite-citrate-bicarbonate (DCB) extractable Fe oxide content (7138, 11,161, and 22,582 mg Fe/kg) were used for the experiments. Sorption of 50 μM U(VI) to the subsoils in the presence of Ca 2+ and HCO 3 - at circumneutral pH occurred rapidly during the first 2 days, after which slow U(VI) sorption continued over 3 months. U(VI) desorption from the soils by 10 mM NaHCO 3 solution exhibited an initial fast desorption step during the first 24 h, followed by slower desorption over a week. Sorption of 50 μM U(VI) for 1 day to 3 months in the presence or absence of Ca 2+ consistently resulted in higher U(VI) sorption to saprolite soil with higher amount of nanoporous goethite, while desorption of U(VI) for 1 week to 2 months was consistently lower in saprolite soil with higher amount of nanoporous goethite. Saprolite subsoils containing higher amounts of nanoporous goethite exhibited more resistant U(VI) desorption, and the proportions of irreversible U(VI) sorption increased with longer residence time with soils. These results indicates that more U(VI) became bound to the internal surfaces of nanoporous iron oxides during long-term sorption. This study suggests that naturally occurring nanoporous goethite may exert a significant role in controlling the mobility and transport of U(VI) in historically contaminated sites that have existed over decades.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Corrigendum to "Environmentally friendly, rheoreversible, hydraulic fracturing fluids for enhanced geothermal systems" [Geothermics 58 (2015) 22–31]

Cost-effective creation of high-permeability reservoirs inside deep crystalline bedrock is the primary challenge for the feasibility of enhanced geothermal systems (EGS). Current reservoir stimulation entails adverse environmental impacts and substantial economic costs due to the utilization of large volumes of water “doped” with chemicals including rheology modifiers, scale and corrosion inhibitors, biocides, friction reducers among others where, typically, little or no information of composition and toxicity is disclosed. An environmentally benign, CO2-activated, rheoreversible fracturing fluid has recently been developed that significantly enhances rock permeability at effective stress significantly lower than current technology. We evaluate the potential of this novel fracturing fluid for application on geothermal sites under different chemical and geomechanical conditions, by performing laboratory-scale fracturing experiments with different rock sources under different confining pressures, temperatures, and pH environments. The results demonstrate that CO2-reactive aqueous solutions of environmentally amenable Polyallylamine (PAA) represent a highly versatile fracturing fluid technology. This fracturing fluid creates/propagates fracture networks through highly impermeable crystalline rock at significantly lower effective stress as compared to control experiments where no PAA was present, and permeability enhancement was significantly increased for PAA compared to conventional hydraulic fracturing controls. This was evident in all experiments, including variable rock source/type, operation pressure and temperature (over the entire range for EGS applications), as well as over a wide range of formation-water pH values. This versatile novel fracturing fluid technology represents a great alternative to industrially available fracturing fluids for cost-effective and competitive geothermal energy production.

Shao, Hongbo↗
DOE OSTI2018

Electrophilic acid gas-reactive fluid, proppant, and process for enhanced fracturing and recovery of energy producing materials

An electrophilic acid gas-reactive fracturing fluid, proppant, and process are detailed. The fluid expands in volume to provide rapid and controlled increases in pressure that enhances fracturing in subterranean bedrock for recovery of energy-producing materials. The proppant stabilizes fracture openings in the bedrock to enhance recovery of energy-producing materials.

15 GEOTHERMAL ENERGY↗
DOE OSTI2016

Electrophilic acid gas-reactive fluid, proppant, and process for enhanced fracturing and recovery of energy producing materials

An electrophilic acid gas-reactive fracturing and recovery fluid, proppant, and process are detailed. The fluid expands in volume to provide rapid and controlled increases in pressure that enhances fracturing in subterranean bedrock for recovery of energy-producing materials. Proppants stabilize openings in fractures and fissures following fracturing.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

Numerical Simulation of Permeability Change in Wellbore Cement Fractures after Geomechanical Stress and Geochemical Reactions Using X-ray Computed Tomography Imaging

X-ray microtomography (XMT) imaging combined with a three-dimensional (3D) computational fluid dynamics (CFD) modeling technique was used to study the effect of geochemical and geomechanical processes on fracture properties in composite Portland cement–basalt caprock core samples. The effect of fluid properties and flow conditions on fracture permeability was numerically studied by using fluids with varying physical properties and simulating different pressure conditions. CFD revealed that the application of geomechanical stress led to increased fluid flow, which resulted in increased fracture permeability. After CO2-reaction, XMT images displayed preferential precipitation of calcium carbonate within the fractures in the cement matrix and less precipitation in fractures located at the cement–basalt interface. CFD predicted changes in flow characteristics and differences in absolute values of flow properties due to different pressure gradients. CFD was able to highlight the profound effect of fluid properties on flow characteristics and hydraulic properties of fractures. This study demonstrates the applicability of XMT imaging and CFD as powerful tools for characterizing the hydraulic properties of fractures in a number of applications like geologic carbon sequestration and storage, hydraulic fracturing for shale gas production, and enhanced geothermal systems.

CO2 storage↗
DOE OSTI2015

Bench-scale electrokinetic remediation for cesium-contaminated sediment at the Hanford Site, USA

Electrokinetic (EK) remediation has been applied to extract various contaminants such as radionuclides, heavy metals, and organic compounds from contaminated sediment and soil using electric currents. We conducted a laboratory experiment to investigate the efficiency of EK remediation method for Hanford sediment (76% sand and 24% silt-clay) after artificial contamination with nonradioactive 133Cs (0.01 M CsNO3) as a surrogate for radioactive 137Cs. The initial 133Cs concentration in the bulk sediment was 668 mg kg-1, with a higher 133Cs concentration for the silt-clay fraction (867 mg kg-1) than for the sand fraction (83 mg kg-1). A significant removal of cationic 133Cs from the sediment occurred from the cathode side (-), whereas the removal was negligible from the anode side (+) during the EK remediation process for 68 days. Based on microwave-assisted total digestion, 312 mg kg-1 of 133Cs was removed from the bulk sediment, which corresponds to the removal efficiency of 47%. The EK method was significantly more efficient for the silt-clay fraction than for the sand fraction. X-ray diffraction (XRD) and scanning electron microscopy-electron dispersive spectroscopy (SEM-EDS) analyses indicate that change in major crystalline mineral phases was insignificant during the EK remediation and the removal of 133Cs from the Hanford sediment by the EK method is attributed mainly to cation exchange with K in clay minerals. The experimental results suggest that the EK method can effectively remove radioactive Cs from the surface or subsurface sediment contaminated by radioactive materials in the Hanford Site, Washington, USA.

Cation exchange↗
DOE OSTI2015

Stimuli-Responsive/Rheoreversible Hydraulic Fracturing Fluids as a Greener Alternative to Support Geothermal and Fossil Energy Production

Cost-effective yet safe creation of high-permeability reservoirs within deep bedrock is the primary challenge for the viability of enhanced geothermal systems (EGS) and unconventional oil/gas recovery. Although fracturing fluids are commonly used for oil/gas, standard fracturing methods are not developed or proven for EGS temperatures and pressures. Furthermore, the environmental impacts of currently used fracturing methods are only recently being determined. Widespread concerns about the environmental contamination have resulted in a number of regulations for fracturing fluids advocating for greener fracturing processes. To enable EGS feasibility and lessen environmental impact of reservoir stimulation, an environmentally benign, CO2-activated, rheoreversible fracturing fluid that enhances permeability through fracturing (at significantly lower effective stress than standard fracturing fluids) due to in situ volume expansion and gel formation is investigated herein. The chemical mechanism, stability, phase-change behavior, and rheology for a novel polyallylamine (PAA)-CO2 fracturing fluid was characterized at EGS temperatures and pressures. Hydrogel is formed upon reaction with CO2 and this process is reversible (via CO2 depressurization or solubilizing with a mild acid) allowing removal from the formation and recycling, decreasing environmental impact. Rock obtained from the Coso geothermal field was fractured in laboratory experiments under various EGS temperatures and pressures with comparison to standard fracturing fluids, and the fractures were characterized with imaging, permeability measurement, and flow modeling. This novel fracturing fluid and process may vastly reduce water usage and the environmental impact of fracturing practices and effectively make EGS production and unconventional oil/gas exploitation cost-effective and cleaner.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2014

Geochemical and Geomechanical Effects on Wellbore Cement Fractures

Experimental studies were conducted using batch reactors, X-ray microtomograpy (XMT), and computational fluid dynamics (CFD) simulation to determine changes in cement fracture surfaces, fluid flow pathways, and permeability with geochemical and geomechanical processes. Composite Portland cement-basalt caprock core with artificial fractures was prepared and reacted with CO2-saturated groundwater at 50°C and 10 MPa for 3 to 3.5 months under static conditions to understand the geochemical and geomechanical effects on the integrity of wellbores containing defects. Cement-basalt interface samples were subjected to mechanical stress at 2.7 MPa before the CO2 reaction. XMT provided three-dimensional (3-D) visualization of the opening and interconnection of cement fractures due to mechanical stress. After the CO2 reaction, XMT images revealed that calcium carbonate precipitation occurred extensively within the fractures in the cement matrix, but only partially along fractures located at the cement-basalt interface. The permeability calculated based on CFD simulation was in agreement with the experimentally measured permeability. The experimental results imply that the wellbore cement with fractures is likely to be healed during exposure to CO2-saturated groundwater under static conditions, whereas fractures along the cement-caprock interface are still likely to remain vulnerable to the leakage of CO2. CFD simulation for the flow of different fluids (CO2-saturated brine and supercritical CO2) using a pressure difference of 20 kPa and 200 kPa along ~2 cm-long cement fractures showed that a pressure gradient increase resulted in an increase of CO2 fluids flux by a factor of only ~3-9 because the friction of CO2 fluids on cement fracture surfaces increased with higher flow rate as well. At the same pressure gradient, the simulated flow rate was higher for supercritical CO2 than CO2-saturated brine by a factor of only ~2-3, because the viscosity of supercritical CO2 is much lower than that of CO2-saturated brine. The study suggests that in deep geological reservoirs the geochemical and geomechanical processes have coupled effects on the wellbore cement fracture evolution and fluid flow along the fracture surfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Stimuli Responsive/Rheoreversible Hydraulic Fracturing Fluids for Enhanced Geothermal Energy Production (Part II)

We have used an environmentally friendly and recyclable hydraulic fracturing fluid - diluted aqueous solutions of polyallylamine or PAA – for reservoir stimulation in Enhanced Geothermal System (EGS). This fluid undergoes a controlled and large volume expansion with a simultaneous increase in viscosity triggered by CO2 at EGS temperatures. We are presenting here the results of laboratory-scale hydraulic fracturing experiment using the fluid on small cylindrical rock cores (1.59 cm in diameter and 5.08 cm in length) from the Coso geothermal field in California. Rock samples consisted of Mesozoic diorite metamorphosed to greenschist facies. The experiments were conducted on 5 samples for realistic ranges of pressures (up to 275 bar) and temperatures (up to 210 °C) for both the rock samples and the injected fluid. After fracturing, cores were subjected to a CO2 leakage test, injection of KI solution, and X-ray microtomography (XMT) scanning to examine the formation and distribution of fractures. The design and conduct of these experiments will be presented and discussed in details. Based on the obtained XMT images, Computational Fluid Dynamics (CFD) simulations were then performed to visualize hydraulic fractures and compute the bulk permeability. OpenFOAM (OpenCFD Ltd., Reading, UK), was used to solve the steady state simulation. The flow predictions, based upon the laminar, 3-D, incompressible Navier-Stokes equations for fluid mass and momentum, show the remarkable stimulation of the permeability in the core samples and demonstrate the efficiency of such a CO2 triggered fluid in EGS.

CO2-activated↗
DOE OSTI2014

Wellbore cement fracture evolution at the cement–basalt caprock interface during geologic carbon sequestration

Composite Portland cement-basalt caprock cores with fractures, as well as neat Portland cement columns, were prepared to understand the geochemical and geomechanical effects on the integrity of wellbores with defects during geologic carbon sequestration. The samples were reacted with CO2-saturated groundwater at 50 ºC and 10 MPa for 3 months under static conditions, while one cement-basalt core was subjected to mechanical stress at 2.7 MPa before the CO2 reaction. Micro-XRD and SEM-EDS data collected along the cement-basalt interface after 3-month reaction with CO2-saturated groundwater indicate that carbonation of cement matrix was extensive with the precipitation of calcite, aragonite, and vaterite, whereas the alteration of basalt caprock was minor. X-ray microtomography (XMT) provided three-dimensional (3-D) visualization of the opening and interconnection of cement fractures due to mechanical stress. Computational fluid dynamics (CFD) modeling further revealed that this stress led to the increase in fluid flow and hence permeability. After the CO2-reaction, XMT images displayed that calcium carbonate precipitation occurred extensively within the fractures in the cement matrix, but only partially along the fracture located at the cement-basalt interface. The 3-D visualization and CFD modeling also showed that the precipitation of calcium carbonate within the cement fractures after the CO2-reaction resulted in the disconnection of cement fractures and permeability decrease. The permeability calculated based on CFD modeling was in agreement with the experimentally determined permeability. This study demonstrates that XMT imaging coupled with CFD modeling represent a powerful tool to visualize and quantify fracture evolution and permeability change in geologic materials and to predict their behavior during geologic carbon sequestration or hydraulic fracturing for shale gas production and enhanced geothermal systems.

basalt↗
DOE OSTI2014

Geochemical and Geomechanical Effects on Wellbore Cement Fractures: Data Information for Wellbore Reduced Order Model

The primary objective of the National Risk Assessment Partnership (NRAP) program is to develop a defensible, generalized, and science-based methodology and platform for quantifying risk profiles at CO 2 injection and storage sites. The methodology must incorporate and define the scientific basis for assessing residual risks associated with long-term stewardship and help guide site operational decision-making and risk management. Development of an integrated and risk-based protocol will help minimize uncertainty in the predicted long-term behavior of the CO 2 storage site and thereby increase confidence in storage integrity. The risk profile concept has proven useful in conveying the qualitative evolution of risks for CO 2 injection and storage site. However, qualitative risk profiles are not sufficient for specifying long-term liability for CO 2 storage sites. Because there has been no science-based defensible and robust methodology developed for quantification of risk profiles for CO 2 injection and storage, NRAP has been focused on developing a science-based methodology for quantifying risk profiles for various risk proxies.

58 GEOSCIENCES↗
DOE OSTI2013

Technetium Removal Using Tc-Goethite Coprecipitation

This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory for the U.S. Department of Energy (DOE) EM-31 Support Program (EMSP) subtask, “Low temperature waste forms coupled with technetium removal using an alternative immobilization process such as Fe(II) treated-goethite precipitation” to increase our understanding of 99Tc long-term stability in goethite mineral form and the process that controls the 99Tc(VII) reduction and removal by the final Fe (oxy)hydroxide forms. The overall objectives of this task were to 1) evaluate the transformation process of Fe (oxy)hydroxide solids to the more crystalline goethite (α-FeOOH) mineral for 99 Tc removal and 2) determine the mechanism that limits 99 Tc(IV) reoxidation in Fe(II)-treated 99 Tc-goethite mineral and 3) evaluate whether there is a long-term 99 Tcoxidation state change for Tc sequestered in the iron solids.

Goethite↗
DOE OSTI2013

Characterization of Technetium Speciation in Cast Stone

This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) EM-31 Support Program (EMSP) subtask, “Production and Long-Term Performance of Low Temperature Waste Forms” to provide additional information on technetium (Tc) speciation characterization in the Cast Stone waste form. To support the use of Cast Stone as an alternative to vitrification for solidifying low-activity waste (LAW) and as the current baseline waste form for secondary waste streams at the Hanford Site, additional understanding of Tc speciation in Cast Stone is needed to predict the long-term Tc leachability from Cast Stone and to meet the regulatory disposal-facility performance requirements for the Integrated Disposal Facility (IDF). Characterizations of the Tc speciation within the Cast Stone after leaching under various conditions provide insights into how the Tc is retained and released. The data generated by the laboratory tests described in this report provide both empirical and more scientific information to increase our understanding of Tc speciation in Cast Stone and its release mechanism under relevant leaching processes for the purpose of filling data gaps and to support the long-term risk and performance assessments of Cast Stone in the IDF at the Hanford Site.

Cast Stone↗
DOE OSTI2013

Effect of oxygen co-injected with carbon dioxide on Gothic shale caprock–CO 2 –brine interaction during geologic carbon sequestration

Co-injection of oxygen, a significant component in CO 2 streams produced by the oxyfuel combustion process, can cause a significant alteration of the redox state in deep geologic formations during geologic carbon sequestration. The potential impact of co-injected oxygen on the interaction between synthetic CO 2 –brine (0.1 M NaCl) and shale caprock (Gothic shale from the Aneth Unit in Utah) and mobilization of trace metals was investigated at ~ 10 MPa and ~ 75 °C. A range of relative volume percentages of O 2 to CO 2 (0, 1, 4 and 8%) were used in these experiments to address the effect of oxygen on shale–CO 2 –brine interaction under various conditions. Major mineral phases in Gothic shale are quartz, calcite, dolomite, montmorillonite, and pyrite. During Gothic shale–CO 2 –brine interaction in the presence of oxygen, pyrite oxidation occurred extensively and caused enhanced dissolution of calcite and dolomite. Pyrite oxidation and calcite dissolution subsequently resulted in the precipitation of Fe(III) oxides and gypsum (CaSO 4 ·2H 2 O). In the presence of oxygen, dissolved Mn and Ni were elevated because of oxidative dissolution of pyrite. The mobility of dissolved Ba was controlled by barite (BaSO 4 ) precipitation in the presence of oxygen. Dissolved U in the experimental brines increased to ~ 8–14 μg/L, with concentrations being slightly higher in the absence of oxygen than in the presence of oxygen. Experimental and modeling results indicate the interaction between shale caprock and oxygen co-injected with CO 2 during geologic carbon sequestration can exert significant impacts on brine pH, solubility of carbonate minerals, stability of sulfide minerals, and mobility of trace metals. The major impact of oxygen is most likely to occur in the zone near CO 2 injection wells where impurity gases can accumulate. Finally, oxygen in CO 2 –brine migrating away from the injection well will be continually consumed through the reactions with sulfide minerals in deep geologic formations.

Carbon sequestration↗
DOE OSTI2013

Experimental study of potential wellbore cement carbonation by various phases of carbon dioxide during geologic carbon sequestration

Hydrated Portland cement was reacted with carbon dioxide (CO2) in supercritical, gaseous, and aqueous phases to understand the potential cement alteration processes along the length of a wellbore, extending from deep CO2 storage reservoir to the shallow subsurface during geologic carbon sequestration. The 3-D X-ray microtomography (XMT) images displayed that the cement alteration was significantly more extensive by CO2-saturated synthetic groundwater than dry or wet supercritical CO2 at high P (10 MPa)-T (50°C) conditions. Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) analysis also exhibited a systematic Ca depletion and C enrichment in cement matrix exposed to CO2-saturated groundwater. Integrated XMT, XRD, and SEM-EDS analyses identified the formation of extensive carbonated zone filled with CaCO3(s), as well as the porous degradation front and the outermost silica-rich zone in cement after exposure to CO2-saturated groundwater. The cement alteration by CO2-saturated groundwater for 2-8 months overall decreased the porosity from 31% to 22% and the permeability by an order of magnitude. Cement alteration by dry or wet supercritical CO2 was slow and minor compared to CO2-saturated groundwater. A thin single carbonation zone was formed in cement after exposure to wet supercritical CO2 for 8 months or dry supercritical CO2 for 15 months. Extensive calcite coating was formed on the outside surface of a cement sample after exposure to wet gaseous CO2 for 1-3 months. The chemical-physical characterization of hydrated Portland cement after exposure to various phases of carbon dioxide indicates that the extent of cement carbonation can be significantly heterogeneous depending on CO2 phase present in the wellbore environment. Both experimental and geochemical modeling results suggest that wellbore cement exposure to supercritical, gaseous, and aqueous phases of CO2 during geologic carbon sequestration is unlikely to damage the wellbore integrity because cement alteration by all phases of CO2 is dominated by carbonation reaction. This is consistent with previous field studies of wellbore cement with extensive carbonation after exposure to CO2 for 3 decades. However, XMT imaging indicates that preferential cement alteration by supercritical CO2 or CO2-saturated groundwater can occur along the cement-steel or cement-rock interfaces. This highlights the importance of further investigation of cement degradation along the interfaces of wellbore materials to ensure permanent geologic carbon storage.

Calcite↗
DOE OSTI2013

Imaging Wellbore Cement Degradation by Carbon Dioxide under Geologic Sequestration Conditions Using X-ray Computed Microtomography

ABSTRACT: X-ray microtomography (XMT), a nondestructive three-dimensional imaging technique, was applied to demonstrate its capability to visualize the mineralogical alteration and microstructure changes in hydrated Portland cement exposed to carbon dioxide under geologic sequestration conditions. Steel coupons and basalt fragments were added to the cement paste in order to simulate cement-steel and cement-rock interfaces. XMT image analysis showed the changes of material density and porosity in the degradation front (density: 1.98 g/cm3, porosity: 40%) and the carbonated zone (density: 2.27 g/cm3, porosity: 23%) after reaction with CO2- saturated water for 5 months compared to unaltered cement (density: 2.15 g/cm3, porosity: 30%). Three-dimensional XMT imaging was capable of displaying spatially heterogeneous alteration in cement pores, calcium carbonate precipitation in cement cracks, and preferential cement alteration along the cement-steel and cement-rock interfaces. This result also indicates that the interface between cement and host rock or steel casing is likely more vulnerable to a CO2 attack than the cement matrix in a wellbore environment. It is shown here that XMT imaging can potentially provide a new insight into the physical and chemical degradation of wellbore cement by CO2 leakage.

Imaging Wellbore Cement Degradation by Carbon Diox↗