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1
Mallants, Dirk. "Field-scale solute transport parameters derived from tracer tests in large undisturbed soil columns." Soil Research 52, no. 1 (2014): 13. http://dx.doi.org/10.1071/sr13143.
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Transport parameters obtained from laboratory tracer experiments were used to evaluate the stochastic form of the equilibrium convection–dispersion equation (CDE) in describing the transition of scale, i.e. from the column or local scale to a larger field scale. Local-scale solute breakthrough curves (BTCs) were measured in 1-m-long and 0.3-m-diameter undisturbed soil columns by means of time-domain reflectometry at six depths for a 79-h input pulse of chloride. The local-scale data were analysed in terms of the equilibrium CDE and the mobile–immobile non-equilibrium transport model (MIM). At the local scale, the MIM transport model better described the observed early breakthrough and the tailing of the BTC than did the CDE. A linear regression analysis indicated that the relationship between the hydrodynamic dispersion D and pore-water velocity v was of the form D = 31vl.92 (correlation ρv,D = 0.74). Averaging of the local-scale BTCs across the field produced a large-scale or field-scale mean BTC; at the greatest observation depth (0.8 m) the field-scale dispersivity <D>/<v> = λ equals 0.656 m. The results further showed that for large values of the mean dispersion coefficient, <D>, local-scale dispersion is an important mechanism for field-scale solute spreading, whereas the standard deviation, σD, and the correlation between v and D, ρvD, have negligible effects on field-scale transport. Stochastic stream tube models supplemented with statistical properties of local-scale transport parameters provide a practical and computationally efficient tool to describe heterogeneous solute transport at large spatial scales.
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Illiassov, Pavel A., and Akhil Datta-Gupta. "Field-Scale Characterization of Permeability and Saturation Distribution Using Partitioning Tracer Tests: The Ranger Field, Texas." SPE Journal 7, no. 04 (December 1, 2002): 409–22. http://dx.doi.org/10.2118/81198-pa.
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Kim, Byung-Woo, and Hangbok Lee. "Modified Convergent Flow Tracing Method for Evaluating Advective Velocity and Effective Porosity in Fractured Rock Aquifers." Water 12, no. 12 (December 18, 2020): 3565. http://dx.doi.org/10.3390/w12123565.
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This study presented the analysis of the modified convergent flow tracing method, which is a modified virtual solute transport approach to retrieve tracer masses from a pulse image (virtual) well to an extraction well. In the convergent flow tracer test, approximate analytical solutions were extended for the pulse image well using a single-well tracing method. This method transformed the drift-and-pumpback conditions of the single-well tracing method. The method requires a prior information of the effective porosity. Using sodium chloride as a tracer mass, the tracer data sampled through field-scale tests were used to obtain breakthrough curves. This modified method was different from the pre-existing single method because it considers both the ambient groundwater movement (the two classes of drifts) and the constant volumetric flow rate during the pumping phase. The method was applied to the tracer test at underground research tunnel for verifying the theory inductively derived from the single tracing method. Through field tests, the values of velocity and porosity were compared to the results of the drift-and-pumpback equations of the single-well test, and the several different equations related to breakthrough curves of the two-well tests conducted on a field scale.
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Champ, D. R., and J. Schroeter. "Bacterial Transport in Fractured Rock – A Field-Scale Tracer Test at the Chalk River Nuclear Laboratories." Water Science and Technology 20, no. 11-12 (November 1, 1988): 81–87. http://dx.doi.org/10.2166/wst.1988.0269.
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The potential for transport of bacteria by groundwater in fractured crystalline rock was assessed in a series of field-scale tracer tests. The breakthrough curves for injected Escherichla coll and “non-reactive” particle tracers were compared with those for conservative inorganic and radioactive tracers. Rapid transport, relative to the conservative tracers, of both bacteria and non-reactive particles was observed. The first appearance of both was with, or slightly before, the conservative tracers for water movement. Removal of the bacteria and particles by filtration processes occurred and was quantified through the calculation of filter factors. The filtration process in this fracture system is similar to that found in a gravel aquifer. From the results we can conclude that particulate contaminants can be very rapidly transported in fracture systems and that continuing sources of contamination could lead to relatively high local concentrations of particulate contaminants compared with the average at any given distance from the source. It was also concluded that the use of traditional conservative tracers, for water movement, to assess the potential for movement of particulate contaminants could lead to significant underestimates of exposure to particulate contaminants due to consumption of water from water recovery wells located in fractured media.
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Deleu, Romain, Sandra Soarez Frazao, Amaël Poulain, Gaëtan Rochez, and Vincent Hallet. "Tracer Dispersion through Karst Conduit: Assessment of Small-Scale Heterogeneity by Multi-Point Tracer Test and CFD Modeling." Hydrology 8, no. 4 (November 10, 2021): 168. http://dx.doi.org/10.3390/hydrology8040168.
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Tracer tests are widely used for characterizing hydrodynamics, from stream-scale to basin-wide scale. In karstic environments, the positioning of field fluorometers (or sampling) is mostly determined by the on-site configuration and setup difficulties. Most users are probably aware of the importance of this positioning for the relevance of data, and single-point tests are considered reliable. However, this importance is subjective to the user and the impact of positioning is not well quantified. This study aimed to quantify the spatial heterogeneity of tracer concentration through time in a karstic environment, and its impact on tracer test results and derived information on local hydrodynamics. Two approaches were considered: on-site tracing experiments in a karstic river, and Computational Fluid Dynamics (CFD) modeling of tracer dispersion through a discretized karst river channel. A comparison between on-site tracer breakthrough curves and CFD results was allowed by a thorough assessment of the river geometry. The results of on-site tracer tests showed significant heterogeneities of the breakthrough curve shape from fluorometers placed along a cross-section. CFD modeling of the tracer test through the associated discretized site geometry showed similar heterogeneity and was consistent with the positioning of on-site fluorometers, thus showing that geometry is a major contributor of the spatial heterogeneity of tracer concentration through time in karstic rivers.
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Huseby, Olaf, Randi Valestrand, Geir Nœvdal, and Jan Sagen. "Natural and Conventional Tracers for Improving Reservoir Models Using the EnKF Approach." SPE Journal 15, no. 04 (July 8, 2010): 1047–61. http://dx.doi.org/10.2118/121190-pa.
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Summary Natural tracers (geochemical and isotopic variations in injected and formation waters) are a mostly unused source of information in reservoir modeling. On the other hand, conventional interwell tracer tests are an established method to identify flow patterns. However, they are typically underexploited, and tracer-test evaluations are often performed in a qualitative manner and are rarely compared systematically to simulation results. To integrate naturaland conventional-tracer data in a reservoir-modeling workflow, we use the ensemble Kalman filter (EnKF), which has recently gained popularity as a method for history matching. The EnKF includes online update of parameters and the dynamical states. An ensemble of model representations is used to represent the model uncertainty. In this paper, we include conventional water tracers as well as natural tracers (i.e., geochemical variations) in the EnKF approach. The methodology is demonstrated by estimating permeability and porosity fields in a synthetic field case based on a real North Sea field example. The results show that conventional tracers and geochemical variations yield additional improvement in the estimates and that the EnKF approach is well suited as a tool to include in this process. The principal benefit from the methodology is improved models and forecasts from reservoir simulations, through optimal use of conventional and natural tracers. Some of the natural-tracer data (e.g., scale-forming ions and toxic compounds) are monitored for other purposes, and exploiting such data can yield significant reservoir-model improvement at a small cost.
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Keller, Jason M., and Mark L. Brusseau. "In-Situ Characterization of Soil−Water Content Using Gas-Phase Partitioning Tracer Tests: Field-Scale Evaluation." Environmental Science & Technology 37, no. 14 (July 2003): 3141–44. http://dx.doi.org/10.1021/es0340329.
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Cheng, Hao, G. Michael Shook, Malik Taimur, Varadarajan Dwarakanath, and Bruce R. Smith. "Interwell Tracer Tests To Optimize Operating Conditions for a Surfactant Field Trial: Design, Evaluation, and Implications." SPE Reservoir Evaluation & Engineering 15, no. 02 (March 30, 2012): 229–42. http://dx.doi.org/10.2118/144899-pa.
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Summary Enhanced oil recovery (EOR) by surfactant flooding is the key to unlocking the next billion barrels of oil for Minas, one of the world's largest waterflood fields. An interwell tracer test (ITT-1) was performed before a surfactant field trial (SFT) to ensure well injectivity, demonstrate pattern confinement, quantitatively describe interwell connectivity and sweep efficiency, and provide sufficient data for reservoir evaluation. The tracer test was designed by numerical simulation. The test started in November 2009 and was terminated in February 2010. Analytical interpretation based on moment analysis and numerical reservoir simulations was conducted to evaluate ITT-1 results. Interpretation of the test results indicated various operational and reservoir properties that would have likely led to failure of the surfactant pilot. Hydraulic control of the SFT pattern was not achieved; in fact, less than 20% of one tracer was recovered. Many small-scale heterogeneities were identified that led to a lower-than-expected reservoir volume contacted. Unexpected communication between the target sand and the underlying sands outside the pattern also contributed to low tracer recovery and low swept volume. The tracer test was history matched, and additional features were incorporated in the reservoir model, and a new tracer design (ITT-2) was optimized to correct low sweep efficiency and poor hydraulic control. New information from ITT-2 will be used to further optimize operating conditions for SFTs. Failure to conduct the tracer tests would have likely revealed these unfavorable reservoir and operational conditions during the SFT. Had oil recovery been poor (because of low swept volume), it would have erroneously been attributed to a poor SFT rather than to the true causes. ITT-1 is considered successful because it allowed us to redesign injection/hydraulic control during the relatively inexpensive tracer test and thus evaluate the surfactant trial without bias.
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Li, Yuan Yao, Rong Lin Sun, and Ren Quan Chen. "Hydraulic Conductivity and Scale Effects Investigation in Basalt in the Dam Area of Xiluodu Hydroelectric Station, Jinshajiang River, China." Applied Mechanics and Materials 405-408 (September 2013): 2123–29. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2123.
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Hydraulic conductivity (K) and scale effects in basalt in the dam area of Xiluodu hydroelectric station were investigated by three kinds of field hydraulic tests with different test scale, 2608 water pressure tests in single borehole, 54 water seepage tests in adit and groundwater tracer test. Statistical results show the high heterogeneity of fractured rock and K difference between two neighboring test intervals are often more than two orders of magnitude. However, there is a strong decreasing trend of hydraulic conductivity with the increase of vertical depth. Moreover, these three kinds of hydraulic test results demonstrate that hydraulic conductivity increases with the increase of test scale in heterogeneous basalt and the heterogeneous degree of K decreases with the increase of test scale. K from water seepage test in adit, with the test scale of 1-2 m, is dispersed from 0.00024 m/d to 3.46 m/d. K from water pressure test in single borehole, with the test scale of 4-7 m, is 0.0002-1.04 m/d. K from groundwater tracer test, with the test scale of 70-145 m, is concentrated between 0.46 m/d and 2.1 m/d. High heterogeneity of fractured rock and multi-level of fractures are thought as the major reason resulted in scale effects of hydraulic conductivity.
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Yang, H., D. C. Florence, E. L. McCoy, W. A. Dick, and P. S. Grewal. "Design and hydraulic characteristics of a field-scale bi-phasic bioretention rain garden system for storm water management." Water Science and Technology 59, no. 9 (May 1, 2009): 1863–72. http://dx.doi.org/10.2166/wst.2009.186.
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A field-scale bioretention rain garden system was constructed using a novel bi-phasic (i.e. sequence of anaerobic to aerobic) concept for improving retention and removal of storm water runoff pollutants. Hydraulic tests with bromide tracer and simulated runoff pollutants (nitrate-N, phosphate-P, Cu, Pb, and Zn) were performed in the system under a simulated continuous rainfall. The objectives of the tests were (1) to determine hydraulic characteristics of the system, and (2) to evaluate the movement of runoff pollutants through the system. For the 180 mm/24 h rainfall, the bi-phasic bioretention system effectively reduced both peak flow (∼70%) and runoff volume (∼42%). The breakthrough curves (BTCs) of bromide tracer suggest that the transport pattern of the system is similar to dispersed plug flow under this large runoff event. The BTCs of bromide showed mean 10% and 90% breakthrough times of 5.7 h and 12.5 h, respectively. Under the continuous rainfall, a significantly different transport pattern was found between each runoff pollutant. Nitrate-N was easily transported through the system with potential leaching risk from the initial soil medium, whereas phosphate-P and metals were significantly retained indicating sorption-mediated transport. These findings support the importance of hydraulics, in combination with the soil medium, when creating bioretention systems for bioremediation that are effective for various rainfall sizes and intervals.
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Moltyaner, G. L. "Mixing cup and through-the-wall measurements in field-scale tracer tests and their related scales of averaging." Journal of Hydrology 89, no. 3-4 (January 1987): 281–302. http://dx.doi.org/10.1016/0022-1694(87)90183-1.
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Gimenez, J. R., S. C. Nassr, R. D. Maestri, and L. O. Monteggia. "Physical modelling of an upflow anaerobic sludge blanket reactor: near-field study." Water Science and Technology 45, no. 10 (May 1, 2002): 157–62. http://dx.doi.org/10.2166/wst.2002.0317.
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This paper presents a physical evaluation of an upflow anaerobic sludge blanket reactor. Specifically, the study contemplates the region influenced by the wastewater inlet jets at the bottom of the reactor, here termed the near-field area. A three-dimensional physical model of a UASB reactor in reduced scale, geometrically and dynamically correlated to a full-scale prototype was used in the evaluation. From the analysis of the major forces acting and of the physical properties investigated in the prototype, it was possible to establish non-dimensional relations that were applied to the reduced scale model, allowing the investigation of the phenomenon of interest. Tests were developed on the model to visualise the inlet flows under the buoyant effect at the bottom of the reactor, through the injection of a tracer fluid in the area with higher density, simulating the effects of the sludge bed. Based on the experimental results, it was possible to provide dimensioning criteria for the jet distribution system in UASB reactors.
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Prigiobbe, V., and M. Giulianelli. "Quantification of sewer leakage by a continuous tracer method." Water Science and Technology 64, no. 1 (July 1, 2011): 132–38. http://dx.doi.org/10.2166/wst.2011.639.
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Water authorities interested in the evaluation of the structural state of a sewer must quantify leakage to plan strategic intervention. However, the quantification of the exfiltration and the localisation of structural damage are challenging tasks that usually require expensive and time-consuming inspections. Herein, we report one of the first applications of the QUEST-C method to quantify the exfiltration in a continuously operating sewer by dosing two chemical tracers, sodium bromide (NaBr) and lithium chloride (LiCl). The method was applied at the catchment scale in a 14-year-old sewer in Rome, Italy. Preliminary laboratory tests, field measurements, and numerical simulations showed that reliable results require the QUEST-C method to be applied to sewers without lateral inflows, during periods of quasi-steady flow, and that the travel time of the NaBr tracer is minimised. Three sewer reaches were tested and the estimated exfiltration, as a fraction of the dry weather flow (DWF), increased from 0.128 in the agricultural area to 0.208 in the urban area. Although our estimates are at the lower end of the range given in the literature (0.01–0.56 DWF), the exfiltration was not negligible, and interventions should focus on the sewers in urban areas. This illustrates the capability of the QUEST-C method to guide strategic intervention at low cost and without an interruption of sewer operation. However, careful interpretation of the results is recommended for sewers with many lateral inflows, where leakage may be overestimated.
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Wicke, D., P. Rouault, B. Krause Camilo, C. Pagotto, M. Dechesne, and E. Soyeux. "Nitrate reduction in reactive swales at low temperatures: full-size field system vs. technical scale." Water Supply 15, no. 3 (February 6, 2015): 642–48. http://dx.doi.org/10.2166/ws.2015.008.
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Diffuse nitrate (NO3) contamination from intense agriculture adversely impacts freshwater ecosystems, and can also result in nitrate concentrations exceeding limits set in drinking water regulation, when receiving surface waters are used for drinking water production. Implementation of near-natural mitigation zones such as reactive swales or wetlands have been proven to be promising measures to reduce nitrate loads in agricultural drainage waters. However, the behavior of these systems at low temperatures and its dependence on system design has not been well known until now. In this study, the behavior of a full-scale (length: 45 m) reactive swale treating drainage water from an agricultural watershed in Brittany (France), with high nitrate concentrations in the receiving river, was monitored for one season (6 months). As flow in this full-size field system is usually restricted to winter and spring months (December–May), it usually operates at low water temperatures of 5–10 °C. Tracer tests revealed shorter than designed retention times due to high inflows and preferential flow in the swale. Results show a correlation between residence time and nitrate reduction with low removal (<10%) for short residence times (<0.1 day), increasing to >25% at residence times >10 h (0.4 day). Performance was compared to results of two technical-scale reactive swales (length: 8 m) operated for 1.5 years with two different residence times (0.4 and 2.5 days), situated at a test site of the German Federal Environmental Agency in Berlin (Germany). Similar nitrate reduction was observed for comparable temperature and residence time, showing that up-scaling is a suitable approach to transferring knowledge gathered from technical-scale experiments to field conditions. For the design of new mitigation systems, one recommendation is to investigate carefully the expected inflow volumes in advance to ensure a sufficient residence time for effective nitrate reduction at low temperatures.
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Hu, Qinhong, Wen Zhou, Paul Huggins, and Wenling Chen. "Pore Structure and Fluid Uptake of the Springer/Goddard Shale Formation in Southeastern Oklahoma, USA." Geofluids 2018 (July 11, 2018): 1–16. http://dx.doi.org/10.1155/2018/5381735.
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Hosting an emerging play of the Springer/Goddard shale, the South Central Oklahoma Oil Province (SCOOP), is also the main production field for the underlying Woodford Formation. Understanding the reservoir quality of the Chesterian-age Goddard shale, currently little has been achieved, is vital to sustainable hydrocarbon production and exploration. Using polar (DI water and/or API brine) and nonpolar (n-decane) fluids to probe hydrophilic and hydrophobic pore networks, the purpose of this study is to examine wettability, pore connectivity, fluid imbibition, and tracer migration of the Springer shale. To achieve this, we collected core samples from two wells located at the heart of the play and performed mercury injection capillary pressure, wettability, fluid imbibition, and vapor absorption tests. Results from these studies show that the Springer shale has a stronger affinity to oil (n-decane in this study), compared to DI water and API brine. With porosity values averaging at 6.32 ± 0.75% and permeability of 20.0 ± 6.52 nD, the majority of pore-throat sizes for the Springer shale are 5–50 nm. The utility of wettability tracers of different molecular sizes helps tease out the intertwined relationship of pore-throat sizes, connectivity, and associated wettability of shale. The imbibition results suggest a molecular entanglement effect at the scale of 0.5 nm, even for the tracer penetration of a wetting fluid of n-decane. A petrophysical analysis of the Springer shale presented in this work is beneficial to further understand the pore structure and fluid movement within the shale to facilitate increased production and accurate economic evaluations.
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Barreto, A. B., G. R. Vasconcellos, M. von Sperling, P. Kuschk, U. Kappelmeyer, and J. L. Vasel. "Field application of a planted fixed bed reactor (PFR) for support media and rhizosphere investigation using undisturbed samples from full-scale constructed wetlands." Water Science and Technology 72, no. 4 (May 20, 2015): 553–60. http://dx.doi.org/10.2166/wst.2015.238.
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This study presents a novel method for investigations on undisturbed samples from full-scale horizontal subsurface-flow constructed wetlands (HSSFCW). The planted fixed bed reactor (PFR), developed at the Helmholtz Center for Environmental Research (UFZ), is a universal test unit for planted soil filters that reproduces the operational conditions of a constructed wetland (CW) system in laboratory scale. The present research proposes modifications on the PFR original configuration in order to allow its operation in field conditions. A mobile device to obtain undisturbed samples from real-scale HSSFCW was also developed. The experimental setting is presented with two possible operational configurations. The first allows the removal and replacement of undisturbed samples in the CW bed for laboratory investigations, guaranteeing sample integrity with a mobile device. The second allows the continuous operation of the PFR and undisturbed samples as a fraction of the support media, reproducing the same environmental conditions outside the real-scale system. Investigations on the hydrodynamics of the adapted PFR were carried out with saline tracer tests, validating the proposed adaptation. Six adapted PFR units were installed next to full-scale HSSFCW beds and fed with interstitial liquid pumped from two regions of planted and unplanted support media. Fourteen points were monitored along the system, covering carbon fractions, nitrogen and sulfate. The results indicate the method as a promising tool for investigations on CW support media, rhizosphere and open space for studies on CW modeling, respirometry, kinetic parameters, microbial communities, redox potential and plant influence on HSSFCW.
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Steventon, James, and Mike Bowman. "An assessment of the Upper Succession and the related secondary reservoirs in the Welton Field, onshore UK." Geological Society, London, Petroleum Geology Conference series 8, no. 1 (December 15, 2016): 595–609. http://dx.doi.org/10.1144/pgc8.22.
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AbstractThe Welton oil field has produced nearly 20 MMBO (million barrels of oil) since discovery in 1981. Now in post-plateau decline, there is increasing reliance on a series of secondary reservoirs. Production has been from a suite of stacked reservoirs deposited by large-scale prograding delta-plain systems of early Westphalian age. Whilst the bulk of production has been from the Basal Succession, a considerable upside is considered to exist in the less well-studied Upper Succession that comprises predominantly distributary channel and crevasse splay deposits which have produced in excess of 3 MMBO. These accumulations occur within the Deep Soft Rock, Deep Hard Rock and Tupton reservoirs.This paper focuses on a sedimentological analysis of cored intervals, integrated with petrophysical logs and detailed production data to enable further recommendations to identify areas of undrained pay, along with identifying additional reservoir management activities that could optimize future offtake from the field. These reservoirs consist predominantly of very fine-grained sandstone, with permeability values rarely attaining 100 mD and average porosity values of 10–12%.Recommendations include executing tracer communication tests and building a detailed field model, as well as a pilot water-injection scheme to increase production from some of Welton's secondary reservoirs.Supplementary material: A full set of detailed sedimentological logs for each of the cored wells in this study is available at https://doi.org/10.6084/m9.figshare.c.3593984
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Tu, Ran, Junqing Gu, Yi Zeng, Xuejin Zhou, Kai Yang, Jiaojiao Jing, Zhihong Miao, and Jianhong Yang. "Development and Validation of a Tunable Diode Laser Absorption Spectroscopy System for Hot Gas Flow and Small-Scale Flame Measurement." Sensors 22, no. 17 (September 5, 2022): 6707. http://dx.doi.org/10.3390/s22176707.
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TDLAS (tunable diode laser absorption spectroscopy) is an important gas analysis method that can be employed to obtain characteristic parameters non-invasively by the infrared absorption spectra of tracer molecules such as CH4, H2O and O2. In this study, a portable H2O-based TDLAS system with a dual optical path was developed with the aim of assessing the combustion characteristics of flammable gases. Firstly, a calculation method of gas characteristics including temperature and velocity combining absorption spectra and a HITRAN database was provided. Secondly, to calibrate and validate this TDLAS system precisely, a pressure vessel and a shock tube were introduced innovatively to generate static or steady flow fields with preset constant temperatures, pressures, or velocities. Static tests within environment pressures up to 2 MPa and steady flow field tests with temperatures up to 1600 K and flow velocities up to 950 m/s were performed for verification. It was proved that this system can provide an accurate values for high temperature and velocity gas flows. Finally, an experimental investigation of CH4/air flames was conducted to test the effectiveness of the system when applied to small diffusion flames. This TDLAS system gave satisfactory flame temperature and velocity data owing to the dual optical path design and high frequency scanning, which compensated for scale effects and pulsation of the flame. This work demonstrates a valuable new approach to thermal hazard analysis in specific environments.
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Tronicke, Jens, and Klaus Holliger. "Quantitative integration of hydrogeophysical data: Conditional geostatistical simulation for characterizing heterogeneous alluvial aquifers." GEOPHYSICS 70, no. 3 (May 2005): H1—H10. http://dx.doi.org/10.1190/1.1925744.
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High-resolution geophysical parameter information, as it can be provided, for example, by crosshole georadar and seismic tomography, has proven to provide useful spatial information to complement traditional hydrological methods such as core analyses, logging techniques, and tracer or pumping tests. Quantitative integration of these diverse database components is one of the major challenges in the field of high-resolution hydrogeophysics because of their different scales of measurement and the usually weak petrophysical relations among the measurements. In this study, we systematically explore the usefulness of a conditional stochastic simulation approach based on simulated annealing for this purpose. First, we generate a realistic model of an alluvial aquifer consisting of a 2D scale-invariant porosity field. On the basis of this model, we generate synthetic neutron porosity logs and crosshole georadar tomographic surveys. We then use the proposed geostatistical simulation approach to integrate this hydrogeophysical database. The effectiveness of this approach to characterize the detailed porosity distribution in heterogeneous alluvial aquifers is assessed by comparing the results for a variety of simulated porosity fields that differ fundamentally in terms of their conditioning information. Our results indicate this approach has the potential to allow for a realistic hydrogeophysical characterization in the submeter range of the porosity distribution in heterogeneous alluvial aquifers.
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Defratyka, Sara M., Jean-Daniel Paris, Camille Yver-Kwok, Daniel Loeb, James France, Jon Helmore, Nigel Yarrow, Valérie Gros, and Philippe Bousquet. "Ethane measurement by Picarro CRDS G2201-i in laboratory and field conditions: potential and limitations." Atmospheric Measurement Techniques 14, no. 7 (July 27, 2021): 5049–69. http://dx.doi.org/10.5194/amt-14-5049-2021.
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Abstract. Atmospheric ethane can be used as a tracer to distinguish methane sources, both at the local and global scale. Currently, ethane can be measured in the field using flasks or in situ analyzers. In our study, we characterized the CRDS Picarro G2201-i instrument, originally designed to measure isotopic CH4 and CO2, for measurements of ethane-to-methane ratio in mobile-measurement scenarios, near sources and under field conditions. We evaluated the limitations and potential of using the CRDS G2201-i to measure the ethane-to-methane ratio, thus extending the instrument application to simultaneously measure two methane source proxies in the field: carbon isotopic ratio and the ethane-to-methane ratio. First, laboratory tests were run to characterize the instrument in stationary conditions. Subsequently, the instrument performance was tested in field conditions as part of a controlled release experiment. Finally, the instrument was tested during mobile measurements focused on gas compressor stations. The results from the field were afterwards compared with the results obtained from instruments specifically designed for ethane measurements. Our study shows the potential of using the CRDS G2201-i instrument in a mobile configuration to determine the ethane-to-methane ratio in methane plumes under measurement conditions with an ethane uncertainty of 50 ppb. Assuming typical ethane-to-methane ratios ranging between 0 and 0.1 ppb ppb−1, we conclude that the instrument can accurately estimate the “true” ethane-to-methane ratio within 1σ uncertainty when CH4 enhancements are at least 1 ppm, as can be found in the vicinity of strongly emitting sites such as natural gas compressor stations and roadside gas pipeline leaks.
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Guyonnet, Dominique, Jean-Christophe Gourry, Lucien Bertrand, and Nadia Amraoui. "Heterogeneity detection in an experimental clay liner." Canadian Geotechnical Journal 40, no. 1 (February 1, 2003): 149–60. http://dx.doi.org/10.1139/t02-092.
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In situ hydraulic tests to characterize the field hydraulic conductivity of clay liners used in landfill applications are often positioned randomly. Yet it is well known that the field performance of low permeability clay liners is generally controlled by heterogeneities that may provide preferential pathways for flow. In this paper, an experimental clay liner is investigated in which heterogeneities were incorporated in a controlled fashion. Heterogeneities were embedded within a compacted clay liner at different locations in the plane and at different depths. Heterogeneities of composition were installed by excavating compacted clay at specific locations and replacing it with a more permeable material. Heterogeneities of compaction were introduced by loosely backfilling the clay into the excavations. Two geophysical methods, ground penetrating radar (GPR) and the EM-38 electromagnetic method, were used to examine whether anomalies detected by geophysics were or were not correlated with the precise locations of the heterogeneities. Hydraulic tests were used to characterize the permeability of the intact clay on the one hand and of the heterogeneities on the other hand. Three different in situ hydraulic test methods were used: a pulse test performed in a hand-augered borehole, a sealed single ring infiltrometer test, and a large scale infiltration test (4 m2) that uses a color tracer to detect possible preferential flowpaths. The GPR showed no significant correlation with heterogeneity locations, nor did the EM-38 method when used in the vertical dipole mode. The EM-38 method used in the horizontal dipole mode, showed significant correlation with heterogeneities when they were apparent at the surface. On the other hand, the method did not clearly detect heterogeneities located at depth. There was consistency between the values of hydraulic conductivity obtained from the different hydraulic field and laboratory tests. "Intact" clay hydraulic conductivities were found to lie between 1010 and 4 × 109 m/s, while the hydraulic conductivity of the heterogeneities of composition was approximately 107 m/s. The results of this experiment suggest that the EM-38 method may be useful to optimize hydraulic test locations when characterizing clay liners for landfill applications.Key words: clay liner, hydraulic conductivity, heterogeneity.
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Zech, Alraune, Peter Dietrich, Sabine Attinger, and Georg Teutsch. "A field evidence model: how to predict transport in heterogeneous aquifers at low investigation level." Hydrology and Earth System Sciences 25, no. 1 (January 4, 2021): 1–15. http://dx.doi.org/10.5194/hess-25-1-2021.
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Abstract. Aquifer heterogeneity in combination with data scarcity is a major challenge for reliable solute transport prediction. Velocity fluctuations cause non-regular plume shapes with potentially long-tailing and/or fast-travelling mass fractions. High monitoring cost and a shortage of simple concepts have limited the incorporation of heterogeneity into many field transport models up to now. We present an easily applicable hierarchical conceptualization strategy for hydraulic conductivity to integrate aquifer heterogeneity into quantitative flow and transport modelling. The modular approach combines large-scale deterministic structures with random substructures. Depending on the modelling aim, the required structural complexity can be adapted. The same holds for the amount of monitoring data. The conductivity model is constructed step-wise following field evidence from observations, seeking a balance between model complexity and available field data. The starting point is a structure of deterministic blocks, derived from head profiles and pumping tests. Then, subscale heterogeneity in the form of random binary inclusions is introduced to each block. Structural parameters can be determined, for example, from flowmeter measurements or hydraulic profiling. As proof of concept, we implemented a predictive transport model for the heterogeneous MADE site. The proposed hierarchical aquifer structure reproduces the plume development of the MADE-1 transport experiment without calibration. Thus, classical advection–dispersion equation (ADE) models are able to describe highly skewed tracer plumes by incorporating deterministic contrasts and effects of connectivity in a stochastic way without using uni-modal heterogeneity models with high variances. The reliance of the conceptual model on few observations makes it appealing for a goal-oriented site-specific transport analysis of less well investigated heterogeneous sites.
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Bhanja, Soumendra N., Abhijit Mukherjee, R. Rangarajan, Bridget R. Scanlon, Pragnaditya Malakar, and Shubha Verma. "Long-term groundwater recharge rates across India by in situ measurements." Hydrology and Earth System Sciences 23, no. 2 (February 7, 2019): 711–22. http://dx.doi.org/10.5194/hess-23-711-2019.
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Abstract. Groundwater recharge sustains groundwater discharge, including natural discharge through springs and the base flow to surface water as well as anthropogenic discharge through pumping wells. Here, for the first time, we compute long-term (1996–2015) groundwater recharge rates using data retrieved from several groundwater-level monitoring locations across India (3.3 million km2 area), the most groundwater-stressed region globally. Spatial variations in groundwater recharge rates (basin-wide mean: 17 to 960 mm yr−1) were estimated in the 22 major river basins across India. The extensive plains of the Indus–Ganges–Brahmaputra (IGB) river basins are subjected to prevalence of comparatively higher recharge. This is mainly attributed to occurrence of coarse sediments, higher rainfall, and intensive irrigation-linked groundwater-abstraction inducing recharge by increasing available groundwater storage and return flows. Lower recharge rates (<200 mm yr−1) in most of the central and southern study areas occur in cratonic, crystalline fractured aquifers. Estimated recharge rates have been compared favorably with field-scale recharge estimates (n=52) based on tracer (tritium) injection tests. Results show that precipitation rates do not significantly influence groundwater recharge in most of the river basins across India, indicating human influence in prevailing recharge rates. The spatial variability in recharge rates could provide critical input for policymakers to develop more sustainable groundwater management in India.
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Yuan, Hemin, Majken C. Looms, and Lars Nielsen. "On the usage of diffractions in ground-penetrating radar reflection data: Implications for time-lapse gas migration monitoring." GEOPHYSICS 85, no. 5 (July 28, 2020): H83—H95. http://dx.doi.org/10.1190/geo2019-0343.1.
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Time-lapse ground-penetrating radar (GPR) measurements are used to image/monitor, for example, water infiltration, water table changes, and fluid/gas flow patterns. Although crosshole GPR is often preferred over surface-reflection GPR in such studies, its application is limited by the selected borehole geometry, which may be difficult to define in an optimal way, especially in experiments in which flow pathways are difficult to predict. Surface-reflection GPR data sets are generally faster to collect over relatively large areas and are therefore more efficient for covering the volume when a fast-moving tracer (e.g., gas) may infiltrate a heterogeneous subsurface medium. We have used a diffraction imaging approach on time-lapse surface-reflection GPR data to detect changes in radar wave velocity associated with gas (CO2) injected into a heterogeneous chalk succession. We initially test and evaluate the diffraction imaging approach on synthetic GPR data. Afterward, we apply the methodology to time-lapse GPR field data, and we evaluate the robustness of using information from diffractions in light of the obtained data quality. The synthetic tests indicate that diffractions provide essential information for delimiting the area affected by gas in the heterogeneous chalk section studied. Our field experiment shows that using the diffraction information alone allows for detection of gas-affected zones and, therefore, potential flow characteristics of gas movement. We infer that the CO2 flow patterns in our study most likely are determined by small-scale fractures rather than the porosity/permeability of the rock matrix. Moreover, the approach used may serve as an initial study for future more targeted experiments or for further detail-retrieving full-waveform inversion.
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Oehlmann, S., T. Geyer, T. Licha, and M. Sauter. "Reducing the ambiguity of karst aquifer models by pattern matching of flow and transport on catchment scale." Hydrology and Earth System Sciences 19, no. 2 (February 12, 2015): 893–912. http://dx.doi.org/10.5194/hess-19-893-2015.
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Abstract. Assessing the hydraulic parameters of karst aquifers is a challenge due to their high degree of heterogeneity. The unknown parameter field generally leads to a high ambiguity for flow and transport calibration in numerical models of karst aquifers. In this study, a distributed numerical model was built for the simulation of groundwater flow and solute transport in a highly heterogeneous karst aquifer in south-western Germany. Therefore, an interface for the simulation of solute transport in one-dimensional pipes was implemented into the software COMSOL Multiphysics® and coupled to the three-dimensional solute transport interface for continuum domains. For reducing model ambiguity, the simulation was matched for steady-state conditions to the hydraulic head distribution in the model area, the spring discharge of several springs and the transport velocities of two tracer tests. Furthermore, other measured parameters such as the hydraulic conductivity of the fissured matrix and the maximal karst conduit volume were available for model calibration. Parameter studies were performed for several karst conduit geometries to analyse the influence of the respective geometric and hydraulic parameters and develop a calibration approach in a large-scale heterogeneous karst system. Results show that it is possible not only to derive a consistent flow and transport model for a 150 km2 karst area but also to combine the use of groundwater flow and transport parameters thereby greatly reducing model ambiguity. The approach provides basic information about the conduit network not accessible for direct geometric measurements. The conduit network volume for the main karst spring in the study area could be narrowed down to approximately 100 000 m3.
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Oehlmann, S., T. Geyer, T. Licha, and M. Sauter. "Reducing the ambiguity of karst aquifer models by pattern matching of flow and transport on catchment scale." Hydrology and Earth System Sciences Discussions 11, no. 8 (August 4, 2014): 9281–326. http://dx.doi.org/10.5194/hessd-11-9281-2014.
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Abstract. Assessing the hydraulic parameters of karst aquifers is a challenge due to their high degree of heterogeneity. The unknown parameter field generally leads to a high ambiguity for flow and transport calibration in numerical models of karst aquifers. In this study, a distributive numerical model was built for the simulation of groundwater flow and solute transport in a highly heterogeneous karst aquifer in south western Germany. Therefore, an interface for the simulation of solute transport in one-dimensional pipes was implemented into the software Comsol Multiphysics® and coupled to the three-dimensional solute transport interface for continuum domains. For reducing model ambiguity, the simulation was matched for steady-state conditions to the hydraulic head distribution in the model area, the spring discharge of several springs and the transport velocities of two tracer tests. Furthermore, other measured parameters such as the hydraulic conductivity of the fissured matrix and the maximal karst conduit volume were available for model calibration. Parameter studies were performed for several karst conduit geometries to analyse the influence of the respective geometric and hydraulic parameters and develop a calibration approach in a large-scale heterogeneous karst system. Results show that it is not only possible to derive a consistent flow and transport model for a 150 km2 karst area, but that the combined use of groundwater flow and transport parameters greatly reduces model ambiguity. The approach provides basic information about the conduit network not accessible for direct geometric measurements. The conduit network volume for the main karst spring in the study area could be narrowed down to approximately 100 000 m3.
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Cockin, A. P., L. T. Malcolm, P. L. McGuire, R. M. Giordano, and C. D. Sitz. "Analysis of a Single-Well Chemical Tracer Test To Measure the Residual Oil Saturation to a Hydrocarbon Miscible Gas Flood at Prudhoe Bay." SPE Reservoir Evaluation & Engineering 3, no. 06 (December 1, 2000): 544–51. http://dx.doi.org/10.2118/68051-pa.
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Summary In 1990, a single-well chemical tracer (SWCT) test was performed in Prudhoe Bay to measure the effective waterflood and miscible gasflood residuals over a 12 ft reservoir interval. This is believed to be the first such use of this technology for a hydrocarbon miscible gas. This paper describes how the usual SWCT design was modified to accommodate the miscible gas, the results of the SWCT, which indicate significantly higher residual oil saturation for miscible gasflood than expected from coreflood experiments, and the subsequent simulation of the test which has provided good agreement with the observed results. The paper shows, with compositional simulation support, that the high apparent residual oil saturation was a consequence of incomplete volumetric sweep by the miscible gas and draws on the experiences of this test to make recommendations for the design of future SWCT tests measuring residuals to gasflooding. Introduction The Prudhoe Bay Miscible Gas Project (PBMGP) is the world's largest miscible flood. Prior to startup in 1987, numerous slim tube, coreflood, and phase behavior experiments were carried out to confirm the recovery potential of the process. Since the startup of the PBMGP a fibreglass observation well has been used to observe the flood progress and a sidetrack cored to observe the extent of the gas sweep. In 1990, a single-well chemical tracer (SWCT) test was carried out on a producing well which first measured the effective residual to waterflood and then to miscible gasflood. The attraction of the SWCT was that it investigated a much larger volume of rock than a coreflood and native wettability, away from the wellbore, should be assured. However, it should be recognized that this still only represents a small sample which may not represent the average performance on a broader scale. The tests were successfully carried out although production problems resulted in four tests, instead of the originally planned two, finally being performed. The subsequent analysis suggested an effective residual oil saturation to the miscible flood (Sorm) of 8%±2%. This was somewhat higher than the coreflood observed values of around 2%. Compositional simulation work has since been carried out to model the full suite of tests, including the aborted ones, to ascertain whether this higher value really conflicted with the coreflood results. Throughout the paper the remaining oil saturation following a water- or gasflood is referred to as the effective residual oil saturation since the paper demonstrates that the apparent high residual oil saturation after a miscible gasflood was a consequence of incomplete volumetric sweep. Hence, the measured remaining, or effective, residual saturation could have been lowered further if complete sweep had occurred. The theory behind a SWCT test is described in detail in Ref. 1 and recovery methods in Ref. 2. Background The Prudhoe Bay oil field on the north coast of Alaska is the largest oil field in the USA. The major producing sand is the Sadlerochit, which can be over 400-ft thick in some locations. It is mostly comprised of high-permeability fluvial sands with interbedded shales. Some of these shales are continuous over large areas while the majority are discontinuous over interwell distances. The structural and hydrocarbon histories are documented in Ref. 3, while Ref. 4 covers the reservoir description. Prudhoe Bay is overlain by a large gas cap. All produced gas components not used for fuel or spiked into the export oil line are reinjected either as a lean gas back into the gas cap or as a rich gas into the PBMGP or other projects. Lean gas injection into the gas cap recovers additional relict oil by vaporization. The expansion of the gas cap downwards recovers oil by gravity drainage. Around the periphery of the field there are approximately 200 inverted nine-spot patterns undergoing waterflood or water-alternating miscible gasflood. The general history of the development of Prudhoe Bay is described in more detail in Ref. 5. The PBMGP was preceded by a pilot at Drill Site 13 in 1982 prior to the startup of the central gas facility (CGF) in 1987. The CGF has since been expanded several times and now produces up to 550 mmscf/d of miscible gas. To date, 1.6 trillion scf of miscible gas have been injected. The development of the PBMGP is documented by Refs. 6 and 7. The optimization of the flood is achieved by directing the miscible gas to the most efficient patterns, as described in Ref. 8, and the use of predictive tools described in Refs. 9 and 10. During 1993, the need to sidetrack Injector DS 13-18 provided an opportunity to acquire additional information on the vertical sweep of the injected gas and the extent to which the miscible gas was reducing the oil saturations in this immature pattern (see Ref. 11). Prior to the start of the PBMGP, continuous and water-alternating miscible gas (WAG) floods were carried out on 16 plugs taken from a total of 4 preserved cores. These cores were injected with different miscible gas compositions and varying quantities of between 0.88 and 3.74 stock tank pore volumes. They exhibited residual to miscible gas saturation values between 1.0% and 4.5% (see Ref. 12), with an average of S orm. In 1990, the magnitude of the reserves being booked to the PBMGP warranted the investment in a SWCT test to provide additional confidence that miscible flooding in the field could achieve the low residuals suggested by the preserved state corefloods.
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Klaus, J., and E. Zehe. "A novel explicit approach to model bromide and pesticide transport in connected soil structures." Hydrology and Earth System Sciences 15, no. 7 (July 12, 2011): 2127–44. http://dx.doi.org/10.5194/hess-15-2127-2011.
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Abstract. The present study tests whether an explicit treatment of worm burrows and tile drains as connected structures is feasible for simulating water flow, bromide and pesticide transport in structured heterogeneous soils at hillslope scale. The essence is to represent worm burrows as morphologically connected paths of low flow resistance in a hillslope model. A recent Monte Carlo study (Klaus and Zehe, 2010, Hydrological Processes, 24, p. 1595–1609) revealed that this approach allowed successful reproduction of tile drain event discharge recorded during an irrigation experiment at a tile drained field site. However, several "hillslope architectures" that were all consistent with the available extensive data base allowed a good reproduction of tile drain flow response. Our second objective was thus to find out whether this "equifinality" in spatial model setups may be reduced when including bromide tracer data in the model falsification process. We thus simulated transport of bromide for the 13 spatial model setups that performed best with respect to reproduce tile drain event discharge, without any further calibration. All model setups allowed a very good prediction of the temporal dynamics of cumulated bromide leaching into the tile drain, while only four of them matched the accumulated water balance and accumulated bromide loss into the tile drain. The number of behavioural model architectures could thus be reduced to four. One of those setups was used for simulating transport of Isoproturon, using different parameter combinations to characterise adsorption according to the Footprint data base. Simulations could, however, only reproduce the observed leaching behaviour, when we allowed for retardation coefficients that were very close to one.
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Ranjan, Rakesh, Rajeev Sinha, Lav R. Khot, Gwen-Alyn Hoheisel, Matthew J. Grieshop, and Mark Ledebuhr. "Effect of Emitter Modifications on Spray Performance of a Solid Set Canopy Delivery System in a High-Density Apple Orchard." Sustainability 13, no. 23 (November 30, 2021): 13248. http://dx.doi.org/10.3390/su132313248.
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Optimally configured solid set canopy delivery systems (SSCDS) can provide adequate spray performance in high-density apple orchards with a minimized risk of off-target pesticide drift. SSCDS configured in a shower-down emitter arrangement have been reported to be the simplest and most economical system. However, existing off-the-shelf emitters used in shower-down configurations have resulted in minimal deposition in lower canopy zones. Therefore, this study was focused on the modifications of off-the-shelf emitters to obtain a desirable spray pattern for adequate spray deposition in all the canopy zones. The modifications include redesigning the impact plate of two existing micro-emitters. Field tests were conducted to evaluate the spray performance of SSCDS with the non-modified emitters (treatment: SD1 and SD3) and contrast the results with modified emitters (treatment: SD2 and SD4). While the treatments SD1 and SD3 had off-the-shelf emitters with swivel plate and static spreader, respectively, the treatment SD2 and SD4 had similar emitters with modified impactor plates. In each treatment block, the apple canopy was divided into six zones and sprayed with a 500 ppm fluorescent tracer solution. Mylar cards and water-sensitive paper samplers were placed on the adaxial and abaxial leaf surfaces in each canopy zone to quantify spray deposition and coverage, respectively. The SSCDS treatments retrofitted with modified emitters, i.e., SD2 and SD4, were observed to have uniform and numerically higher deposition and coverage compared to SD1 and SD3. The SSCDS treatment with modified static spreader (i.e., SD4) resulted in the highest overall spray deposition (1405.7 ± 156.4 ng cm−2 [mean ± standard error]) with improved mid (1121.6 ± 186.9 ng cm−2) and bottom (895.6 ± 149.3 ng cm−2) canopy deposition. Overall, the proposed emitter modification assisted in improved SSCDS spray performances and may be a way forward toward large-scale emplacements of such systems.
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Salama, Imane, and Christophe Dano. "Direct interface shear tests on Dunkirk sand." E3S Web of Conferences 92 (2019): 13003. http://dx.doi.org/10.1051/e3sconf/20199213003.
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After a field test campaign conducted in Dunkirk (north of France) on open-ended steel piles aiming to study the ageing phenomenon, laboratory scale shear tests were designed to study the behaviour of the sand-steel interface. In order to carry out this laboratory investigation, the direct interface shear apparatus was used for characterizing Dunkirk sand (in dry or unsaturated conditions with about 6% water content as in the field) consolidated on initially smooth mild steel plates at different consolidation time intervals (0, 1 and 7 days) and different consolidation stresses (50, 100, 200 and 300 kPa). The test program also included two normal boundary conditions (Constant normal load CNL and constant volume CV) so that they can be compared to the field results and determine the most approaching configuration. More, the unsaturated condition induced a corrosion of the mild steel plates, causing a layer of sand remaining glued to the plate after removing the shear box. Traces of corrosion were also observed on the lower part of the sand samples (in contact with the plate). These observations lead to the interpretation of an increase of the mechanical properties (local cohesion and increase of the friction angle). In order to follow the evolution of the corrosion for each plate, thickness measurements of the sand layer stuck on the plates were carried out.
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Cherubini, C., C. I. Giasi, and N. Pastore. "Evidence of non-Darcy flow and non-Fickian transport in fractured media at laboratory scale." Hydrology and Earth System Sciences 17, no. 7 (July 9, 2013): 2599–611. http://dx.doi.org/10.5194/hess-17-2599-2013.
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Abstract. During a risk assessment procedure as well as when dealing with cleanup and monitoring strategies, accurate predictions of solute propagation in fractured rocks are of particular importance when assessing exposure pathways through which contaminants reach receptors. Experimental data obtained under controlled conditions such as in a laboratory allow to increase the understanding of the fundamental physics of fluid flow and solute transport in fractures. In this study, laboratory hydraulic and tracer tests have been carried out on an artificially created fractured rock sample. The tests regard the analysis of the hydraulic loss and the measurement of breakthrough curves for saline tracer pulse inside a rock sample of parallelepiped shape (0.60 × 0.40 × 0.08 m). The convolution theory has been applied in order to remove the effect of the acquisition apparatus on tracer experiments. The experimental results have shown evidence of a non-Darcy relationship between flow rate and hydraulic loss that is best described by Forchheimer's law. Furthermore, in the flow experiments both inertial and viscous flow terms are not negligible. The observed experimental breakthrough curves of solute transport have been modeled by the classical one-dimensional analytical solution for the advection–dispersion equation (ADE) and the single rate mobile–immobile model (MIM). The former model does not properly fit the first arrival and the tail while the latter, which recognizes the existence of mobile and immobile domains for transport, provides a very decent fit. The carried out experiments show that there exists a pronounced mobile–immobile zone interaction that cannot be neglected and that leads to a non-equilibrium behavior of solute transport. The existence of a non-Darcian flow regime has showed to influence the velocity field in that it gives rise to a delay in solute migration with respect to the predicted value assuming linear flow. Furthermore, the presence of inertial effects enhance non-equilibrium behavior. Instead, the presence of a transitional flow regime seems not to exert influence on the behavior of dispersion. The linear-type relationship found between velocity and dispersion demonstrates that for the range of imposed flow rates and for the selected path the geometrical dispersion dominates the mixing processes along the fracture network.
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Westerhoff, Paul, Michelle De Haan, Alan Martindale, and Mohammad Badruzzaman. "Arsenic Adsorptive Media Technology Selection Strategies." Water Quality Research Journal 41, no. 2 (May 1, 2006): 171–84. http://dx.doi.org/10.2166/wqrj.2006.020.
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Abstract More stringent arsenic regulations are requiring water utilities of all sizes to install treatment systems on wells which historically only had chlorination. A case study is presented for evaluating arsenic adsorption media at a well site in Mesa, Arizona, but the approach and methodological conclusions are transferable to any arsenic treatment system. The goal of this project is to develop a comprehensive, cost-effective and rapid approach for selecting arsenic adsorptive media. Batch laboratory tests, labscale continuous flow column tests and pilot-scale tests were conducted to evaluate removal efficiency, robustness, operational benefits and cost effectiveness of eight different commercially available adsorbents. Batch tests conducted at multiple pH levels provided limited benefit when compared against continuous flow rapid small-scale column tests (RSSCTs) to evaluate arsenic removal capability by different media. Breakthrough curves of arsenic, vanadium, silica and other trace metals corresponded well between lab-scale RSSCT and field-based pilot scale, suggesting that RSSCTs offer a timesaving approach for adsorptive media selection. Leaching tests on spent media verified that media could be safely disposed and high-resolution microscopic analysis indicated that calcium and silica accumulate on media surfaces and affect the longevity of arsenic removal systems.
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Guerra, Peter, Akemi Bauer, Rebecca A. Reiss, and Jim McCord. "In Situ Bioremediation of a Chlorinated Hydrocarbon Plume: A Superfund Site Field Pilot Test." Applied Sciences 11, no. 21 (October 26, 2021): 10005. http://dx.doi.org/10.3390/app112110005.
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The North Railroad Avenue Plume, discovered in 1989, contained chlorinated solvent groundwater plumes extending over 23.5 hectares (58 acres) and three hydrostratigraphic units. The source contaminant, tetrachloroethene, stemmed from release at a dry cleaner/laundromat business. The anaerobic biodegradation byproducts trichloroethene, isomers of dichloroethene (DCE), and vinyl chloride were detected in groundwater samples collected prior to remedial action. The impacted aquifers are the sole source drinking water aquifers for the communities near the site. Following the remedial investigation and feasibility study, the selected alternative for full-scale remedial action at the site was enhanced reductive dichlorination (ERD) focused on four treatment areas: the shallow source zone, the shallow hotspot area, the shallow downgradient area, and the deep zone. Pilot testing, which was conducted in the source zone and hotspot areas, is the subject of this paper. The primary objectives of the pilot test were to obtain the necessary information to select an ERD treatment formulation, dose, and frequency of dosing for use during full-scale remedial action, as well as to refine the site’s hydrogeologic conceptual site model and design parameters. Four (4) test cells, each of which contained well pairs of injection and downgradient extraction wells, were used to test ERD bio-amendment formulations: ethyl lactate, dairy whey, emulsified vegetable oil (EVO), and a combination of EVO and a hydrogen gas infusion. A conservative tracer, bromide, was added to the recirculation flow to record tracer breakthrough, peak, and dissipation at extraction wells. The results of these dipole tracer tests were used to reassess the hydraulic conductivity and hydrodynamic dispersity used in the remedial design. In addition to water quality analyses of contaminants and substrates, groundwater samples were also analyzed for biological analyses before, during, and after the addition of bioamendment. Analyses of phospholipid fatty acids and deoxyribonucleic acid (DNA) extracts from fresh groundwater samples informed decisions on the capacity for complete ERD without DCE stalling and tracked the shifts in the bacterial and archaeal taxonomy and phylogeny stemming from the addition of bioamendments. The pilot test concluded that EVO was the most suitable, considering (1) support of the native microbial consortia for ERD, (2) mechanics and hydraulics of the remediation system, and (3) sustainability/retention of the substrate in the subsurface. Along with EVO, the addition of a nutrient broth derived from brewery waste accelerated and sustained the desired conditions and microbial diversity and population levels. The pilot test results were also used to assess the utilization kinetics of the injected substrates based on total organic carbon (TOC) concentrations measured in the groundwater. After determining that substrate utilization followed Monod kinetics, a TOC threshold at 300 milligrams per liter, equivalent to approximately twice its half-saturation constant was established. Full scale treatment dosing and dose frequency were designed around this threshold, assuming the maximum substrate utilization would yield optimum ERD.
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Yuan, Sanyi, Xinqi Jiao, Yaneng Luo, Wenjing Sang, and Shangxu Wang. "Double-scale supervised inversion with a data-driven forward model for low-frequency impedance recovery." GEOPHYSICS 87, no. 2 (December 27, 2021): R165—R181. http://dx.doi.org/10.1190/geo2020-0421.1.
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Low-frequency information is important in reducing the nonuniqueness of absolute impedance inversion and for quantitative seismic interpretation. In traditional model-driven impedance inversion methods, the low-frequency impedance background is from an initial model and is almost unchanged during the inversion process. Moreover, the inversion results are limited by the quality of the modeled seismic data and the extracted wavelet. To alleviate these issues, we have investigated a double-scale supervised impedance inversion method based on the gated recurrent encoder-decoder network (GREDN). We first train the decoder network of GREDN called the forward operator, which can map impedance to seismic data. We then implement the well-trained decoder as a constraint to train the encoder network of GREDN called the inverse operator. Besides matching the output of the encoder with broadband pseudowell impedance labels, data generated by inputting the encoder output into the known decoder match the observed narrowband seismic data. The broadband impedance information and the already-trained decoder largely limit the solution space of the encoder. Finally, after training, only the derived optimal encoder is applied to unseen seismic traces to yield broadband impedance volumes. Our approach is fully data driven and does not involve the initial model, seismic wavelet, and model-driven operator. Tests on the Marmousi model illustrate that our double-scale supervised impedance inversion method can effectively recover low-frequency components of the impedance model, and we determine that low frequencies of the predicted impedance originate from well logs. Furthermore, we apply the strategy of combining the double-scale supervised impedance inversion method with a model-driven impedance inversion method to process field seismic data. Tests on a field data set indicate that the predicted impedance results not only reveal a classic tectonic sedimentation history but also match the corresponding results measured at the locations of two wells.
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Gamal, Hany, Khaled Abdelgawad, and Salaheldin Elkatatny. "New Environmentally Friendly Acid System for Iron Sulfide Scale Removal." Sustainability 11, no. 23 (November 27, 2019): 6727. http://dx.doi.org/10.3390/su11236727.
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Iron sulfide scale is a common problem in the oil and gas industry. The precipitation of the iron sulfide scale on the well completion tools or inside surface flow lines restricts the flow of the produced fluids and might affect the integrity of the pipelines or the surface and subsurface tools. Failure of the downhole completions tools will not only reduce the production rates but it might require workover and remedial operations that will add extra cost. The main objective of this paper is to evaluate a new environmentally friendly acid system (NEFAS) for iron sulfide scale removal using an actual field sample. The scale sample collected from a natural gas well is dominated by pyrrhotite (55%) in addition to calcite (21%), pyrite (8%), and torilite (6%) with minor traces of hibbingite, siderite, geothite, akaganeite, and mackinawite. High-temperature solubility tests were performed by soaking 2 g of the scale field sample with 20 cm3 of the NEFAS under static condition at 125 °C for different time periods (2, 6, 12, 18, and 24 h). The solubility results were compared with commercial solutions for iron sulfide scale removal such as hydrochloric acid (15 wt.%), glutamic acid diacetic acid (GLDA, 20 wt.%), and high density converters (HDC-3) under the same conditions. The corrosion test was performed at 125 °C for the developed solution after mixing with 2 wt.% corrosion inhibitor (CI) and 2 wt.% corrosion intensifier (CIN). The results were compared with HCl (15 wt.%) under the same conditions. NEFAS consists of 75 wt.% biodegradable acid at pH of 0.04. NEFAS achieved 83 g/L solubility of iron sulfide scale after 6 h at 125 °C under static conditions. The solubility efficiency was very close to 15 wt.% HCl after 24 h where the solubility was 82 and 83 g/L for NEFAS and HCl, respectability. HDC-3 and GLDA (20 wt.%) achieved a lower scale solubility; 18 g/L and 65 g/L respectively, after 24 h. NEFAS achieved a corrosion rate of 0.211 kg/m2 after adding the CI and and CIN compared to 0.808 kg/m2 for HCl. The new environmentally friendly biodegradable acid system provides efficient performance for the scale removal without harming the environment and causing any side effects to the operation.
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Behm, Michael, and Bharath Shekar. "Blind deconvolution of multichannel recordings by linearized inversion in the spectral domain." GEOPHYSICS 79, no. 2 (March 1, 2014): V33—V45. http://dx.doi.org/10.1190/geo2013-0170.1.
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In seismology, blind deconvolution aims to recover the source wavelet and the Green’s function, or parts of it (e.g., reflectivity series), from a recorded seismic trace. A multitude of algorithms exist that tackle this ill-posed problem by different approaches. Making assumptions on the phase spectra of the source wavelet and/or the statistical distribution of the reflectivity series is useful for single trace. The nature of closely spaced multichannel recordings enables a better estimation of a common source wavelet and thus increases the confidence of the results. This approach has been exploited in the past, although different types of assumptions are used for a variety of algorithms. We introduced a new method for simultaneous reconstruction of arbitrary source wavelets and local vertical reflectivity series from teleseismic earthquakes. Closely spaced receivers record vertically incident earthquake body waves and their surface-related multiples, which comprise the unknown reflectivity series. By assuming a common source wavelet for all receivers, the observation of several events resulted in a set of convolution equations relating the unknown source wavelets and unknown reflectivity series to the observed seismic trace. The overdetermined system of equations was linearized and solved by conventional inversion algorithms in the spectral domain. Synthetic tests indicated a better performance of the introduced method than conventional deconvolution in the presence of white noise, which is attributed to the constraint of a common model for all observations. Application to field data from a local deployment allowed imaging a basement reflector from teleseismic body waves, although the data were contaminated with strong coherent noise. From a practical point of view, the presented method is potentially well suited for local and regional large-scale imaging from multichannel passive seismic data.
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Dahlberg, Anders, and Jan Stenlid. "Spatiotemporal patterns in ectomycorrhizal populations." Canadian Journal of Botany 73, S1 (December 31, 1995): 1222–30. http://dx.doi.org/10.1139/b95-382.
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To understand the functioning and ecological roles of ectomycorrhizal fungi in natural ecosystems, it is necessary to have adequate knowledge of the spatial distribution of individual mycelial systems in populations and communities and how this distribution may persist or vary with time. However, this issue has attracted relatively little attention until recently. Moreover, the limited information available is mostly based on the distribution of sporocarps, which is at best an unreliable indicator of the location and activity of mycelia. More useful information can be obtained using somatic and sexual incompatibility tests, as well as molecular markers to trace the distribution of individual genets over a range of spatial and temporal scales. For example, it has been possible using this approach to demonstrate that while young populations tend to consist of numerous small mycelia, individuals in older populations tend to be fewer and larger but heterogeneous in scale. It has also been possible to verify the persistence over several years of mycorrhizal mycelial individuals. Such findings represent only the first step in the study of the spatiotemporal dynamics of ectomycorrhizal fungi, which promises to be a rich and important field for future research. Concepts concerning the process and mechanisms likely to affect distribution patterns are discussed. Key words: ectomycorrhiza, population structure, population dynamics, spatiotemporal patterns.
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Karp, Daniel S., Sasha Gennet, Christopher Kilonzo, Melissa Partyka, Nicolas Chaumont, Edward R. Atwill, and Claire Kremen. "Comanaging fresh produce for nature conservation and food safety." Proceedings of the National Academy of Sciences 112, no. 35 (August 10, 2015): 11126–31. http://dx.doi.org/10.1073/pnas.1508435112.
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In 2006, a deadly Escherichia coli O157:H7 outbreak in bagged spinach was traced to California’s Central Coast region, where >70% of the salad vegetables sold in the United States are produced. Although no definitive cause for the outbreak could be determined, wildlife was implicated as a disease vector. Growers were subsequently pressured to minimize the intrusion of wildlife onto their farm fields by removing surrounding noncrop vegetation. How vegetation removal actually affects foodborne pathogens remains unknown, however. We combined a fine-scale land use map with three datasets comprising ∼250,000 enterohemorrhagic E. coli (EHEC), generic E. coli, and Salmonella tests in produce, irrigation water, and rodents to quantify whether seminatural vegetation surrounding farmland is associated with foodborne pathogen prevalence in California’s Central Coast region. We found that EHEC in fresh produce increased by more than an order of magnitude from 2007 to 2013, despite extensive vegetation clearing at farm field margins. Furthermore, although EHEC prevalence in produce was highest on farms near areas suitable for livestock grazing, we found no evidence of increased EHEC, generic E. coli, or Salmonella near nongrazed, seminatural areas. Rather, pathogen prevalence increased the most on farms where noncrop vegetation was removed, calling into question reforms that promote vegetation removal to improve food safety. These results suggest a path forward for comanaging fresh produce farms for food safety and environmental quality, as federal food safety reforms spread across ∼4.5 M acres of US farmland.
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Wang, Dongmei, Huanzhong Dong, Changsen Lv, Xiaofei Fu, and Jun Nie. "Review of Practical Experience by Polymer Flooding at Daqing." SPE Reservoir Evaluation & Engineering 12, no. 03 (May 31, 2009): 470–76. http://dx.doi.org/10.2118/114342-pa.
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Summary This paper describes successful practices applied during polymer flooding at Daqing that will be of considerable value to future chemical floods, both in China and elsewhere. On the basis of laboratory findings, new concepts have been developed that expand conventional ideas concerning favorable conditions for mobility improvement by polymer flooding. Particular advances integrate reservoir-engineering approaches and technology that is basic for successful application of polymer flooding. These include the following:Proper consideration must be given to the permeability contrast among the oil zones and to interwell continuity, involving the optimum combination of oil strata during flooding and well-pattern design, respectively;Higher polymer molecular weights, a broader range of polymer molecular weights, and higher polymer concentrations are desirable in the injected slugs;The entire polymer-flooding process should be characterized in five stages--with its dynamic behavior distinguished by water-cut changes; -Additional techniques should be considered, such as dynamic monitoring using well logging, well testing, and tracers; effective techniques are also needed for surface mixing, injection facilities, oil production, and produced-water treatment; andContinuous innovation must be a priority during polymer flooding. Introduction China's Daqing oil field entered its ultrahigh-water-cut period after 30 years of exploitation. Just before large-scale polymer-flooding application, the average water-cut was more than 90%. The Daqing oil-field is a large river-delta/lacustrine facies, multilayered with complex geologic conditions and heterogeneous sandstone in an inland basin. After 30 years of waterflooding, many channels and high-permeability streaks were identified in this oil field (Wang and Qian 2002). Laboratory research began in the 1960s, investigating the potential of enhanced-oil-recovery (EOR) processes in the Daqing oil field. After a single-injector polymer flood with a small well spacing of 75 m in 1972, polymer flooding was set on pilot test. During the late 1980s, a pilot project in central Daqing was expanded to a multiwell pattern with larger well spacing. Favorable results from these tests--along with extensive research and engineering from the mid-1980s through the 1990s--confirmed that polymer flooding was the preferred method to improve areal- and vertical-sweep efficiency at Daqing and to provide mobility control (Wang et al. 2002, Wang and Liu 2004). Consequently, the world's largest polymer flood was implemented at Daqing, beginning in 1996. By 2007, 22.3% of total production from the Daqing oil field was attributed to polymer flooding. Polymer flooding boosted the ultimate recovery for the field to more than 50% of original oil in place (OOIP)--10 to 12% OOIP more than from waterflooding. At the end of 2007, oil production from polymer flooding at the Daqing oil field was more than 10 million tons (73 million bbl) per year (sustained for 6 years). The focus of this paper is on polymer flooding, in which sweep efficiency is improved by reducing the water/oil mobility ratio in the reservoir. This paper is not concerned with the use of chemical gel treatments, which attempt to block water flow through fractures and high-permeability strata. Applications of chemical gel treatments in China have been covered elsewhere (Liu et al. 2006).
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Yadav, Sushma, Anupama Asthana, Ajaya Kumar Singh, Rupa Chakraborty, S. Vidya, Ambrish Singh, and Sónia A. C. Carabineiro. "Methionine-Functionalized Graphene Oxide/Sodium Alginate Bio-Polymer Nanocomposite Hydrogel Beads: Synthesis, Isotherm and Kinetic Studies for an Adsorptive Removal of Fluoroquinolone Antibiotics." Nanomaterials 11, no. 3 (February 25, 2021): 568. http://dx.doi.org/10.3390/nano11030568.
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In spite of the growing demand for new antibiotics, in the recent years, the occurrence of fluoroquinolone antibiotics (as a curative agent for urinary tract disorders and respiratory problems) in wastewater have drawn immense attention. Traces of antibiotic left-overs are present in the water system, causing noxious impact on human health and ecological environments, being a global concern. Our present work aims at tackling the major challenge of toxicity caused by antibiotics. This study deals with the efficient adsorption of two commonly used fluoroquinolone (FQ) antibiotics, i.e., Ofloxacin (OFX) and Moxifloxacin (MOX) on spherical hydrogel beads generated from methionine‒functionalized graphene oxide/ sodium alginate polymer (abbreviated Met-GO/SA) from aqueous solutions. The composition, morphology and crystal phase of prepared adsorbents were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HR-TEM) and thermogravimetric analysis/differential thermogravimetry (TGA/DTG). Batch adsorption tests are followed to optimize the conditions required for adsorption process. Both functionalized and non-functionalized adsorbents were compared to understand the influence of several experimental parameters, such as, the solution pH, contact time, adsorbent dosage, temperature and initial concentration of OFX and MOX on adsorption. The obtained results indicated that the functionalized adsorbent (Met-GO/SA) showed a better adsorption efficiency when compared to non-functionalized (GO/SA) adsorbent. Further, the Langmuir isotherm was validated as the best fitting model to describe adsorption equilibrium and pseudo second-order-kinetic model fitted well for both types of adsorbate. The maximum adsorption capacities of Met-GO/SA were 4.11 mg/g for MOX and 3.43 mg/g for OFX. Thermodynamic parameters, i.e., ∆G°, ∆H° and ∆S° were also calculated. It was shown that the overall adsorption process was thermodynamically favorable, spontaneous and exothermic in nature. The adsorbents were successfully regenerated up to four cycles with 0.005 M NaCl solutions. Overall, our work showed that the novel Met-GO/SA nanocomposite could better contribute to the removal of MOX and OFX from the liquid media. The gel beads prepared have adequate features, such as simple handling, eco-friendliness and easy recovery. Hence, polymer gel beads are promising candidates as adsorbents for large-scale water remediation.
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Bailey, Adam, Rosalind King, and Guillaume Backé. "Integration of structural, stress, and seismic data to define secondary permeability networks through deep-cemented sediments in the Northern Perth Basin." APPEA Journal 52, no. 1 (2012): 455. http://dx.doi.org/10.1071/aj11036.
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Understanding natural fracture networks has increasingly been recognised as an important factor for the prospectivity of a geothermal play, as they commonly exert a prime control over permeability at depth. The onshore Northern Perth Basin provides a good example of how fracture stimulation, and subsequent enhancement of the structural permeability, during hydrocarbon production can enhance flow rate from original tight gas reservoirs. Low primary porosity and permeability values have been initially recorded in the Northern Perth Basin due to silica-rich groundwater infiltration and consequent quartz cementation. Geothermal energy prospectivity in the region will therefore depend heavily on similar engineering techniques or on the presence of secondary permeability due to interconnected natural fractures. The existence and extent of these natural fractures are verified in this study through an integrated analysis of geophysical logs (including wellbore image logs), wells tests, and 3D seismic data. Wellbore image logs from 11 petroleum wells in the Northern Perth Basin are used to identify borehole failure (such as borehole breakout and drilling-induced tensile fractures) to give a present-day maximum horizontal stress orientation of N076°E (with an s.d. of 13°). Density logs and leak off tests from 13 petroleum wells are used to constrain the present-day stress magnitudes, giving a transitional strike-slip fault to reverse-fault stress regime in the Northern Perth Basin. 870 fractures are identified in image logs from 13 petroleum wells in the Northern Perth Basin, striking roughly north to south and northwest to northeast. Fractures aligned in the present-day stress field are optimally oriented for reactivation, and are hence likely to be open to fluid flow. Electrically resistive and conductive natural fractures are identified on the wellbore image logs. Resistive fractures are considered to be cemented with electrically resistive cement (such as quartz or calcite) and thus closed to fluid-flow. Conductive fractures are considered to be uncemented and open to fluid-flow, and are thus important to geothermal exploration. Fracture susceptibility diagrams constructed for the identified fractures illustrate that the conductive fractures are optimally oriented for reactivation in the present-day strike-slip fault to reverse-fault stress regime, and so are likely to be open to fluid flow. This is reinforced by the correlation of drilling fluid loss and conductive natural fractures in three wells in the Northern Perth Basin. To gain an understanding of the extent and interconnectedness of these fractures, it is necessary to look at more regional data, such as 3D seismic surveys. It is, however, well-documented that fault and fracture networks like those generally observed in image logs lie well below seismic amplitude resolution, making them difficult to observe directly on amplitude data. Seismic attributes can be calculated to provide some information on sub-seismic scale structural and stratigraphic features. Using a 3D seismic cube acquired over the Dongara North gas field, attribute maps of complex multi-trace dip-steered coherency and most positive curvature were used to document the presence of natural fractures and to best constrain the likely extent of the fracture network. The resulting fracture network model displays relatively good connectivity, which is likely to extend across much of the basin. These optimally oriented fractures are therefore likely to form a secondary permeability network throughout the cemented sediments of the Northern Perth Basin, offering potential deep fluid flow conduits, which may be exploited for the production of geothermal energy.
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Tazioli, Alberto, and Stefano Palpacelli. "Best tracer selection for hydrogeological investigations: preliminary results from laboratory test." Acque Sotterranee - Italian Journal of Groundwater 2, no. 2 (June 30, 2013). http://dx.doi.org/10.7343/as-026-13-0051.
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Tracers techniques are a good tool to investigate groundwater dynamics; they are essential to perform measurement of hydrogeological parameters of aquifers. This study was aimed at characterizing adsorption, effective porosity and pore water velocity in soil samples collected in a hydrographic basin of Marche Region (Italy). This basin has the typical geologic and hydrogeological features of many basins in Central Italy. Therefore. the principal aim is to evaluate the best tracer to be used for hydrogeological purpose (i.e. groundwater tracer test and aquifer parameter estimation). Adsorption has been investigated by means of laboratory batch tests using different tracers and involving different soils. In literature some application of tracers both to laboratory scale and to field scale can be found. Column tests have been performed also to test the effectiveness of different test equipment and to investigate the influence of some test parameters on the calculation of effective porosity and pore water velocity. These considerations and test results are very useful to advise the choice of the best tracer to be used in tracer field tests.
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Hölttä, Pirkko, A. Poteri, M. Hakanen, and A. Hautojärvi. "Fracture flow and radionuclide transport in block-scale laboratory experiments." Radiochimica Acta 92, no. 9-11 (January 1, 2004). http://dx.doi.org/10.1524/ract.92.9.775.55005.
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SummaryBlock-scale migration experiments were introduced to evaluate the simplified radionuclide transport concept used in assessing the safety of underground spent nuclear fuel repositories. The experiments were aimed to demonstrate visually the fracture flow, and to determine the hydraulic characteristics of a natural planar fracture and the transport behaviour of non-sorbing and sorbing radionuclides. For drill holes orthogonal to the fracture and equipped with injection or sealing packers flow rates in this study were measured as a function of hydraulic head. The outflow positions of water at each four side of the block were determined using uranine dye tracer. Tracer tests were performed using uranine,Transport of a non-sorbing tracer through one of the flow channels was interpreted using an advection-dispersion model that on the generalised Taylor dispersion.Characterisation of the hydraulic properties of the fracture indicated that some drill holes were located in the region where the fracture was open and water conductive. No water conductivity was observed in two drill holes indicating closure of the fracture. Reasonably low flow rates obtained from three drill holes indicated their suitability for further radionuclide transport experiments. Elution times of technetium and uranine were fairly similar. Sodium was slightly retarded and was spread over a wider area than uranine and technetium. High water flow rates suggest that advective flow field dominated tracer transport. Experimental and calculated elution curves substantiate the suitability of our experimental set-up for further radionuclide transport experiments.
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Chen, Jingyi, Tianfu Xu, Xu Liang, and Zhenjiao Jiang. "Stochastic inversion of tracer test data with seismicity constraint for permeability imaging in the enhanced geothermal reservoir." GEOPHYSICS, September 4, 2022, 1–51. http://dx.doi.org/10.1190/geo2022-0130.1.
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Inference of permeability distribution in an enhanced geothermal reservoir is crucial for the sustainable management of geothermal energy. However, interpreting the uneven permeability distribution in deep geothermal reservoir remains a challenging task, because in practice there are often merely one to two wells available for hydro-geophysical tests. Considering that the induced seismicity data are widely captured during reservoir stimulation in enhanced geothermal systems, a framework of tracer test data inversion with the constraint of induced seismic data is proposed for permeability imaging. Hydraulic diffusivity, representing the prior estimation of permeability, is inferred from the occurrence time of seismic event. This is followed by the determination of petrophysical model, which relates hydraulic diffusivity to permeability, by tracer test data inversion based on the Monte Carlo Markov Chain algorithm. Implementation of seismicity-constraint tracer data inversion algorithm in the Habanero enhanced geothermal system, Australia, demonstrates that the proposed inversion model allows uneven permeability estimation at field scale in shorter burn-in period and lower uncertainty, than the traditional inversion model without seismicity constraint. Using the estimated permeability in the hydrothermal model enables accurate prediction of thermal performance in a 150-day trial-production test. Results indicates that the proposed algorithm can reliably characterize the spatial distribution of permeability in deep enhanced reservoirs, based on tracer test via doublet wells.
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Smith, Katherine A., Alexander Vandenbohed, Ann Maes, Willy Verstraet, and Luc Lebbe. "Hydrogeological investigations in preparation of an in situ bioremediation strategy based on a novel bacterial desulfitobacterium dichloroeliminans strain DCAl." Linnaeus Eco-Tech, January 30, 2020, 413–24. http://dx.doi.org/10.15626/eco-tech.2005.042.
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Understanding the wide variety of aquifer physical, chemical and microbiological processes is necessary for the effective implementation of in situ bioaugmentation strategies. Therefore, a numerical density dependent 3D solute transport model MOCDENS3D was developed in combination with field experiments to characterise the subsurface control parameters. This also allowed for the study of the effect of aquifer heterogeneity upon the fate and transport of the reactive solutes and the injected bacterial strain.
These investigations were conducted during the evaluation of an in situ bioremediation strategy intended for the cleanup of a test site. The site lies within a historically 1,2- dichloroethane (l ,2-DCA) contaminated sandy phreatic aquifer in Tessenderlo (Belgium). The halogenated compound has a putative carcinogenic effect and a high recalcitrance towards reductive dechlorination. The isolation of the novel anaerobic Desulfitobacterium dichloroeliminans strain DCAI from the soil matrix of the Tessenderlo site at LabMET (Ghent University, Belgium) offered perspectives for the execution of a bioaugmentation strategy at this site, since this strain selectively degrades 1,2-DCA to ethene under anaerobic conditions without the production of toxic vinyl chloride.
First, a step-drawdown pumping test followed by a forced gradient multiple-well tracer test was conducted to obtain values for the hydrogeological parameters such as hydraulic conductivity, longitudinal and transverse dispersivity and effective porosity. The solute transport model was used as a predictive field-scale modelling tool in aid of designing the preliminary field tests as well as the bacterial injection. The aim of the latter was the assessment of the transport of the augmented strain DCAI. Prior modelling of these experiments provides an insight in the possible design strategies and hence, it can be concluded that profound preliminary field investigation aided by a solute transport model such as MOCDENS3D, results in a more time- and cost-effective execution of large scale cleanup processes of contaminated sites.
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Leishear, Robert A., Si Y. Lee, Mark D. Fowley, Michael R. Poirier, and Timothy J. Steeper. "Comparison of Experiments to Computational Fluid Dynamics Models for Mixing Using Dual Opposing Jets in Tanks With and Without Internal Obstructions." Journal of Fluids Engineering 134, no. 11 (October 24, 2012). http://dx.doi.org/10.1115/1.4007536.
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This paper documents testing methods, statistical data analysis, and a comparison of experimental results to computational fluid dynamics (CFD) models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an 8-foot-diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors, such as turbulence, pump fluctuations, and eddies, required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations—or scatter—occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times was shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy and determined statistical correction factors that can be applied to CFD models and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending using a pump with dual opposing jets, which recirculate fluids in the tank to promote blending when fluids are added to the tank. In all, 85 tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full-scale, liquid radioactive waste storage tank. Also, different jet diameters and different horizontal orientations of the jets were investigated with respect to blending. Two types of blending tests were performed. The first set of 81 tests blended small quantities of tracer fluids into solution. Data from these tests were statistically evaluated to determine blending times for the addition of tracer solution to tanks, and blending times were successfully compared to computational fluid dynamics (CFD) models. The second set of four tests blended bulk quantities of solutions of different density and viscosity. For example, in one test, a quarter tank of water was added to three quarters of a tank of a more viscous salt solution. In this case, the blending process was noted to significantly change due to stratification of fluids and blending times increased substantially. However, CFD models for stratification and the variability of blending times for different density fluids were not pursued, and further research is recommended in the area of blending bulk quantities of fluids. All in all, testing showed that CFD models can be effectively applied if statistically validated through experimental testing, but, in the absence of experimental validation, CFD models can be extremely misleading as a basis for design and operation decisions.
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Molecke, Martin A., N. Rob Sorensen, and James L. Krumhansl. "Results From Simulated Contact-Handled Transuranic Waste Experiments at the Waste Isolation Pilot Plant." MRS Proceedings 333 (1993). http://dx.doi.org/10.1557/proc-333-681.
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ABSTRACTWe conducted in situ experiments with simulated, i.e., nonradioactive, contact-handled trans-uranic (CH TRU) waste drums at the Waste Isolation Pilot Plant (WIPP) facility for a period of about four years. We performed these tests in two rooms in rock salt, at WIPP, with drums surrounded by crushed salt or 70 wt. % salt/30 wt. % bentonite clay backfills, or partially submerged in a NaCl brine pool. Air and brine temperatures were maintained at ~40°C. These full-scale (210-L drum) experiments provided in situ data on: backfill material moisture-sorption and physical properties in the presence of brine; waste container corrosion adequacy; and, migration of chemical tracers (nonradioactive actinide and fission product simulants) in the near-field vicinity, all as a function of time. Individual drums, backfill, and brine samples were removed periodically for laboratory evaluations. Waste container testing in the presence of brine and brine-moistened backfill materials served as a severe overtest of long-term conditions that could be anticipated in an actual salt waste repository. We also obtained relevant operational-test emplacement and retrieval experience. All test results are intended to support both the acceptance of actual TRU wastes at the WIPP and performance assessment data needs. We provide an overview and technical data summary focusing on the WIPP CH TRU environmental overtests involving ] 74 waste drums in the presence of backfill materials and the brine pool, with posttest laboratory materials analyses of backfill sorbed-moisture content, CH TRU drum corrosion, tracer migration, and associated test observations.
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Vettorello, Luca, and Andrea Sottani. "Using water level and temperature time series to improve hydrogeological parameterization in a complex alluvial system." Acque Sotterranee - Italian Journal of Groundwater, December 20, 2019. http://dx.doi.org/10.7343/as-2019-413.
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A new pumping station was designed in the northern high plain of the province of Padua (Veneto region, north-eastern Italy), aiming to reach an overall abstraction rate of about 2 m3/s, in order to relevantly contribute to the regional drinking water supply. Local unconfined aquifer is a highly permeable alluvial system, hydraulically connected to the Brenta river, one of the most important groundwater recharging sources of the entire hydrogeological basin, and the Camazzole lake, a former open-pit mine. This lake deepens below the water table and is directly connected to the surrounding phreatic aquifer and indirectly to the river, forming a 3-element hydraulic equilibrium. In order to evaluate the sustainability of the groundwater exploitation, this case study required an in-depth analysis of the hydrogeological resource, focusing on the estimation of hydraulic conductivity values and distribution. A numerical simulation was needed since the first step of the study, to plan the following field activities and provide a rough representation of the expectable drawdown in the pumped aquifer, even if the initial model had a very high level of uncertainty. Before the pumping tests no experimental data were available, so a homogeneous distribution of hydraulic conductivity was preliminarily assigned to the entire mesh, referring to a single bibliographic value available for the aquifer. After the analytical interpretation of pumping tests, different punctual values of hydraulic conductivity were estimated, but the parameter field was still very difficult to define, due to the complexity of the hydrogeological context and the non-uniqueness of the possible spatial interpolations. The availability of groundwater level observations at a larger scale allowed to calculate a set of hydraulic conductivity fields through the pilot points method, integrating the pumping tests results and extending aquifer characterization to a wider domain. The numerical model was finally calibrated with groundwater temperature monitored trends, reproducing the interaction between the lake and the phreatic aquifer through a heat transport simulation. The resulting hydraulic conductivity distribution has been considerably refined, especially at the interface between the lake and the aquifer, and the parameterization has been further validated using heat as a groundwater tracer.
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Chesnut, Dwayne A. "Groundwater Flux, Travel Time, and Radionuclide Transport." MRS Proceedings 353 (1994). http://dx.doi.org/10.1557/proc-353-463.
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AbstractInflow measurements at Stripa and in other underground openings in Sweden, as well as observations elsewhere in mines and tunnels, reveal that there is generally an extremely broad distribution of groundwater flux in fractured rock. Non-sorbing and sorbing tracer tests typically show similar variability in groundwater travel time (GWTT) and tracer transport.In the U.S. Nuclear Waste Program, Nuclear Regulatory Commission regulations require the GWTT from the disturbed zone to the accessible environment to exceed 1000 years. The regulations seem to envision a rather uniform and narrow distribution of travel time, with perhaps a few identifiable “fast pathways” contained within the rock mass surrounding a potential repository. The premise is that most of these features could be mapped during site characterization, and that regions of the potential repository host rock containing such features could be avoided during waste emplacement.However, both field experience and theoretical studies in recent years provide strong evidence that groundwater flux, GWTT, and aqueous transport of dissolved substances exhibit extremely heterogeneous behavior, even in intact porous media and in fractured rock regions between major features. These phenomena are all dominated by the spatial distribution of permeability within the rock mass of interest. The permeability distribution is often approximately log-normal, with a natural log standard deviation, σ. For unfractured porous rock, σ typically ranges from about 0.6 to about 1.2 for field-scale investigations, and for fractured permeable media, it frequently exceeds 2. Values of σ smaller than 0.6 may be observed in small field-scale projects when the macroscopic flow regime is essentially linear within very uniform sediments and in laboratory displacement experitments.With some additional assumptions, a log-normal permeability distribution implies that groundwater flux, GWTT, and the transport of radionuclides from a potential repository are also log-normal. To first order, the appropriate value of σ describing these distributions is the same as the value for the permeability distribution. This allows σ to be estimated from a large number of hydraulic or pneumatic packer tests within the fractured rock mass of interest.We define a groundwater transport function (GWTF) for the rate of radioactivity release to the accessible environment (AE) at time t resulting from the release of a pulse of unit activity at time 0. The GWTF depends on the mean groundwater travel time, tw, and σ, as well as the retardation factor and decay constant. As σ increases from 0 (a hypothetical completely homogeneous system), the radioactivity breakthrough at early time increases from 0 to 100%. This behavior is consistent with our intuitive notions of “fast transport pathways” in heterogeneous systems, and σ is thus seen to be a parameter for quantifying the effects of heterogeneity.Convolution of the GWTF with a time-dependent release function for the Engineered Barrier System (EBS) is easily performed numerically, resulting in the rate of release to the AE as a function of time, which can then be integrated numerically to calculate the cumulative release as a function of time. The convolution approach clearly separates the effects of uncertainty and heterogeneity on repository performance and is extremely useful for sensitivity analyses. An example calculation shows the combinations of σ and tw required for compliance with total system release standards.Since the effect of heterogeneity is captured by a single parameter in a deterministic calculation, uncertainty can be investigated separately by Monte Carlo sampling from distributions of such parameters as σ, tw and source term strength, allowing (in the future) specific and scientifically meaningful goals to be defined for both site characterization and design.Finally, we emphasize that this approach, in its present form, does not include thermal effects. These effects may dominate both the EBS failure rate and hydrogeochemical behavior, including radionuclide transport, for most of the compliance period and beyond. It cannot be used directly to support any particular thermal loading strategy.
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Zouch, Afef, Yannick Mamindy-Pajany, Nor-Edine Abriak, and Mohamed Ksibi. "Storage facilities reclamation using dredged sediments from waterways: Growing media formulation for plants according to the EU Ecolabel requirements." Waste Management & Research: The Journal for a Sustainable Circular Economy, June 18, 2021, 0734242X2110252. http://dx.doi.org/10.1177/0734242x211025201.
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Dredged sediments display a great potential for growing media applications; however, there are few studies about their beneficial reuse for the waste storage reclamation. This research study aims at checking the agronomic values and environmental impacts of three growing media based on waterways sediments (WSs) and green waste (GW) according ecolabel requirements. For this purpose, three growing media named GW0, GW25, and GW50 were prepared at field pilot scale by co-composting WS and GWs during 12 months. Samples were submitted to ecolabel analyses package. Following to the ecolabel requirements, the growing media comply with criteria like pH, electrical conductivity, trace elements and polycyclic aromatic hydrocarbon contents, chlorides, and pathogens, whereas they are not in compliance with the EU Ecolabel guidelines for propagules, organic matter, and zinc contents. Results of laboratory leaching tests performed according to NF EN 12457-2 for GW0, GW25, and GW50 have shown that sulfates, soluble fraction exceed limit for inert waste storage. Lysimeter tests at pilot scale were performed during 6 months to check the leaching potential of pollutants from growing media under real field conditions, including a European ecolabel product. Results demonstrate that Ba, Mo, Sb, Zn, Se, and Sb are higher in GW0, GW25, and GW50 than in the European ecolabel. As, Cd, Cr, Ni, and F− are more soluble in the commercial product compared to other growing media. This study allowed to demonstrate that main characteristics are fulfilling for reusing these growing media in the specific field of waste storage reclamation.