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Zhang, Z. F.

Publications and source records attributed to Zhang, Z. F..

11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

CONCEPTUAL MODEL FOR HYDROLOGY-BASED GEOMORPHIC EVAPOTRANSPIRATION COVERS FOR RECLAMATION OF MINE LAND

Currently there are about half a million abandoned mine sites in the U.S. and New Mexico has an estimated 15,000. Surface mining imposes severe ecological effects on the land because it not only alters the vegetation, soils, bedrock, and landforms, but also changes the surface hydrology, groundwater, and flow paths that ultimately result in degraded ecology and water quality. Two relatively new methodologies, fluvial geomorphic landform design and evapotranspiration (ET) waste covers, offer solutions to reclaim these sites for long term. GeoFluvTM is a specific geomorphic grading design method that uses natural analogues for post-mining landscapes and uses design input values taken from stable natural landscapes to make a reclamation design that provides hydrological function, supports ecosystem integrity, and is cost-effective, sustainable, and more visually attractive. It has documented the ability to produce surface runoff water quality equal to or better than adjacent undisturbed lands and has been used for disturbed lands, including active and abandoned mine sites. To manage the subsurface hydrology, surface ET covers have been used above landfills, waste sites, and mine lands. ET covers protect the underlying materials against erosion, provide a medium for vegetation growth, store precipitation within the cover, and release the stored water into atmosphere so that the infiltration of precipitation is minimized. A conceptual design study is carried out based on an actual, typical abandoned mine site near Raton, New Mexico, to which common problem conditions at abandoned mine sites are assumed. The purpose of this study is to demonstrate that superior covers can be designed by integrating these two remediation technologies (geomorphic grading and ET cover) as a geomorphic ET (GET) cover. The overall shape of the GET cover can mimic the natural topography of the surrounding area, while the thickness and layering of the cover can be optimized for best vegetation growth and infiltration control. The application of GET cover technology on mine land is expected to substantially improve the reclamation effects by coupling the benefits of the geomorphic cover (drainage reduction, runoff management, vegetation diversity) with the benefits of ET covers (vegetation growth and sustainability, percolation reduction, protection of surface and groundwater).

Tailings, Geotechnical, Water Management, Vegetati↗
DOE OSTI2017

A novel ultrafine-grained Fe−22Mn−0.6C TWIP steel with superior strength and ductility

A fully recrystallized ultrafine-grained (UFG) Fe−22wt.%Mn−0.6wt.%C twinning-induced plasticity (TWIP) steel with mean grain size of 576 nm was fabricated by cold rolling and annealing process. Tensile test showed that this UFG steel possessed high yield strength of 785 MPa, and unprecedented uniform elongation of 48%. The Hall-Petch relationship was verified from the coarse-grained (CG) regime to the ultrafine-grained (UFG) regime. The microstructures at specified tensile strains were characterized by electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The microstructures and strain hardening behavior of the UFG TWIP steel were compared with the CG counterpart. The strong strain hardening capability of the UFG steel is supposed to be responsible for the high strength and good ductility. - Highlights: • A fully recrystallized Fe−22Mn−0.6C TWIP steel with mean grain size of 576 nm was fabricated. • The ultrafine-grained (UFG) steel exhibits strong strain-hardening capability, excellent strength and ductility. • The Hall-Petch relationship is fitted well from the CG regime to the UFG regime.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Simulation of carbon dioxide injection at the FutureGen2.0 site: Class VI permit model and local sensitivity analysis

Numerical simulation was conducted to evaluate supercritical CO 2 (scCO 2 ) storage in the Mt. Simon sandstone at the FutureGen 2.0 site in Morgan County, Illinois. The simulations illustrate the recent modeling effort conducted to successfully obtain a Class VI permit under the Underground Injection Control Program of the U.S. Environmental Protection Agency. The scCO2 was injected into a highly stratified reservoir, distributed among four lateral wells. Results show that each of the multiple reservoir layers with low permeability traps a fraction of the scCO 2 beneath it so that the injected scCO 2 does not reach the top of the reservoir by the end of the simulation period. Hence, all of the injected scCO 2 is considered to be safely trapped by the stratified structure within the reservoir. A local sensitivity analysis (LSA) was conducted for injectivity and plume size at the end of the 20 year injection period. The LSA indicates that the imposed initial conditions and the hydraulic properties of the injection layer contribute the most to the sensitivity. Overall, the simulation outputs are very sensitive to only a small fraction of the inputs. However, the parameters that are important for controlling CO 2 injectivity are not the same as those controlling the plume area. The three most sensitive inputs for injectivity are the horizontal permeability and the residual aqueous saturation of the injection layer, and the initial fracture-pressure gradient. For the plume area, the most sensitive inputs are the horizontal permeability of the injection layer and the residual aqueous saturation of the two adjacent layers above the injection layer. Furthermore, the advantages of requiring just a single set of simulation results, scalability to the proper parameter errors, and straightforward calculation of the composite sensitivities make the proposed analysis attractive for guiding site characterization, injection well design, estimating AoR uncertainty and, and monitoring network design.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Performance of a Surface Barrier for Waste Isolation and Flux Reduction at the Hanford Site

Based on the knowledge gained from a decade of laboratory, field, and numerical studies, the Prototype Hanford Barrier (PHB) was designed and constructed between late 1993 and late 1994 over the 216-B-57 Crib in the 200-BP-1 Operable Unit at the Hanford Site. The PHB has been monitored since 1994 to evaluate the physical, hydrologic, and ecological performance. Two stress tests were carried out in the past: (1) an enhanced (about 3 times the multi-year average of 160 mm/year) precipitation test from water year (WY) 1995 to WY1997, which included a man-made 1000-year return 24-hour rainstorms in March each year, and (2) a controlled fire test in 2008. The purpose of this article is to present the main findings of the PHB demonstration since 1994. From 1994 to present, the PHB has limited drainage of less than 0.2 mm yr-1, which is below the 0.5 mm yr-1 design goal, and minimized erosion. The observations suggest the PHB is robust enough to endure the hydrological stress of three times average precipitation and 1000-year return 24-hour rainstorms. After the controlled fire, far less vegetation grows and grasses are the dominant vegetation (compared to shrubs on the unburned section). Even so, the grasses can remove nearly all the stored water in the burned section, although during a longer period of time than in the unburned section. The findings at the PHB are useful for the design and monitoring of future surface barriers at Hanford and elsewhere.

ET Cover↗
DOE OSTI2016

Scale-Dependent Solute Dispersion in Variably Saturated Porous Media

This work was performed to support performance assessment (PA) calculations for the Integrated Disposal Facility (IDF) at the Hanford Site. PA calculations require defensible estimates of physical, hydraulic, and transport parameters to simulate subsurface water flow and contaminant transport in both the near- and far-field environments. Dispersivity is one of the required transport parameters.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Field Soil Water Retention of the Prototype Hanford Barrier and Its Variability with Space and Time

Engineered surface barriers (or covers) are used to isolate underlying contaminants from water, plants, animals, and humans. To understand the flow processes within a barrier and the barrier's ability to store and release water, the field hydraulic properties of the barrier need to be known. A multiyear test of the evapotranspiration (ET) barrier at the US Department of Energy's Hanford Site in the southeast of the state of Washington has yielded in situ soil water content and pressure data from multiple locations for a 9‐yr period, offering the opportunity to estimate soil water retention properties at different locations and times. The upper 2‐m layer of the ET barrier is a silt loam, and the top 1 m also contains 15% (w/w) pea gravel. Within this layer, valid monitoring data from 1995 to 2003 for four depths at 12 monitoring stations were used to determine the field water retention of the silt loam, with and without gravel. The data covered a wide range of wetness, from near saturation to the permanent wilting point, and each retention curve contained 51 to 96 data points. The data were described well with the commonly used van Genuchten water retention model. It was found that the spatial variation of the saturated and residual water content and the pore size distribution parameter was relatively small, while that of the van Genuchten α was relatively large. The effects of spatial variability of the retention properties appeared to be larger than the combined effects of added pea gravel and plant roots on the properties. Neither the primary wetting process in the winter season nor the drying process in the summer season nor time had a detectable effect on the water retention of the silt loam barrier.

Zhang, Z. Fred↗
DOE OSTI2015

Physical, Hydraulic, and Transport Properties of Sediments and Engineered Materials Associated with Hanford Immobilized Low-Activity Waste

Current plans for treatment and disposal of immobilized low-activity waste (ILAW) from Hanford’s underground waste storage tanks include vitrification and storage of the glass waste form in a nearsurface disposal facility. This Integrated Disposal Facility (IDF) is located in the 200 East Area of the Hanford Central Plateau. Performance assessment (PA) of the IDF requires numerical modeling of subsurface flow and reactive transport processes over very long periods (thousands of years). The models used to predict facility performance require parameters describing various physical, hydraulic, and transport properties. This report provides updated estimates of physical, hydraulic, and transport properties and parameters for both near- and far-field materials, intended for use in future IDF PA modeling efforts. Previous work on physical and hydraulic property characterization for earlier IDF PA analyses is reviewed and summarized. For near-field materials, portions of this document and parameter estimates are taken from an earlier data package. For far-field materials, a critical review is provided of methodologies used in previous data packages. Alternative methods are described and associated parameters are provided.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Fully Coupled Well Models for Fluid Injection and Production

Wells are the primary engineered component of geologic sequestration systems with deep subsurface reservoirs. Wells provide a conduit for injecting greenhouse gases and producing reservoirs fluids, such as brines, natural gas, and crude oil, depending on the target reservoir. Well trajectories, well pressures, and fluid flow rates are parameters over which well engineers and operators have control during the geologic sequestration process. Current drilling practices provided well engineers flexibility in designing well trajectories and controlling screened intervals. Injection pressures and fluids can be used to purposely fracture the reservoir formation or to purposely prevent fracturing. Numerical simulation of geologic sequestration processes involves the solution of multifluid transport equations within heterogeneous geologic media. These equations that mathematically describe the flow of fluid through the reservoir formation are nonlinear in form, requiring linearization techniques to resolve. In actual geologic settings fluid exchange between a well and reservoir is a function of local pressure gradients, fluid saturations, and formation characteristics. In numerical simulators fluid exchange between a well and reservoir can be specified using a spectrum of approaches that vary from totally ignoring the reservoir conditions to fully considering reservoir conditions and well processes. Well models are a numerical simulation approach that account for local conditions and gradients in the exchange of fluids between the well and reservoir. As with the mathematical equations that describe fluid flow in the reservoir, variation in fluid properties with temperature and pressure yield nonlinearities in the mathematical equations that describe fluid flow within the well. To numerically simulate the fluid exchange between a well and reservoir the two systems of nonlinear multifluid flow equations must be resolved. The spectrum of numerical approaches for resolving these equations varies from zero coupling to full coupling. In this paper we describe a fully coupled solution approach for well model that allows for a flexible well trajectory and screened interval within a structured hexahedral computational grid. In this scheme the nonlinear well equations have been fully integrated into the Jacobian matrix for the reservoir conservation equations, minimizing the matrix bandwidth.

coupled well model↗
DOE OSTI2013

Evaluating the Suitability for CO 2 Storage at the FutureGen 2.0 Site, Morgan County, Illinois, USA

FutureGen 2.0 site will be the first near-zero emission power plant with fully integrated long-term storage in a deep, non-potable saline aquifer in the United States. The proposed FutureGen 2.0 CO 2 storage site is located in northeast Morgan County, Illinois, U.S.A., forty-eight kilometres from the Meredosia Energy Center where a large-scale oxy-combustion demonstration will be conducted. The demonstration will involve > 90% carbon capture, which will produce more than one million metric tons (MMT) of CO 2 per year. The CO 2 will be compressed at the power plant and transported via pipeline to the storage site. To examine CO 2 storage potential of the site, a 1,467m characterization well (FGA#1) was completed in December 2011. The target reservoir for CO 2 storage is the Mt. Simon Sandstone and Elmhurst Sandstone Member of the lower Eau Claire Formation for a combined thickness of 176 m. Confining beds of the overlying Lombard and Proviso Members (upper Eau Claire Formation) reach a thickness of 126 m. Characterization of the target injection zone and the overlying confining zone was based on wellbore data, cores, and geophysical logs, along with surface geophysical (2-D seismic profiles, magnetic and gravity), and structural data collected during the initial stage of the project . Based on this geological model, 3D simulations of CO 2 injection and redistribution were conducted using STOMP-CO 2 , a multiphase flow and transport simulator. After this characterization stage, it appears that the injection site is a suitable geologic system for CO 2 sequestration and that the injection zone is sufficient to receive up to 33 MMT of CO 2 at a rate of 1.1 MMT/yr. GHGT-11 conference

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

STOMP Subsurface Transport Over Multiple Phases: STOMP-CO2 and STOMP-CO2e Guide: Version 1.0

This STOMP (Subsurface Transport Over Multiple Phases) guide document describes the theory, use, and application of the STOMP-CO2 and STOMP-CO2e operational modes. These operational modes of the STOMP simulator are configured to solve problems involving the sequestration of CO2 in geologic saline reservoirs. STOMP-CO2 is the isothermal version and STOMP-CO2e is the nonisothermal version. These core operational modes solve the governing conservation equations for component flow and transport through geologic media; where, the STOMP-CO2 components are water, CO2 and salt and the STOMP-CO2e operational mode also includes an energy conservation equation. Geochemistry can be included in the problem solution via the ECKEChem (Equilibrium-Conservation-Kinetic-Equation Chemistry) module, and geomechanics via the EPRMech (Elastic-Plastic-Rock Mechanics) module. This addendum is designed to provide the new user with a full guide for the core capabilities of the STOMP-CO2 and -CO2e simulators, and to provide the experienced user with a quick reference on implementing features. Several benchmark problems are provided in this addendum, which serve as starting points for developing inputs for more complex problems and as demonstrations of the simulator’s capabilities.

Carbon Dioxide↗