scholarly journals Estimation of the mass transport parameters of aquifers according to data from field tests with a pulse or a continuous source and an arbitrary location of the observation well

2021 ◽  
Vol 35 (1) ◽  
pp. 71-82
Author(s):  
Nikolay Stoyanov
Keyword(s):  
Mass Transport ◽  
Tracer Tests ◽  
Field Tests ◽  
Tracer Transport ◽  
Transport Parameters ◽  
Observation Well ◽  
Detection And Identification ◽  
Marquardt Algorithm ◽  
Longitudinal Dispersivity ◽  
Continuous Source

An identification method for determining the aquifer’s mass transport parameters is proposed, based on data from field tracer tests with a pulse or a continuous source and an arbitrary position of the observation well in respect to the tracer entry point. The method is also applicable in the presence of a representative set of data on changes in the concentration of pollutants at different points in the aquifer around a short-term (instantaneous) or a continuous surface or underground source. The identification procedure is based on the automated comparison of the observations data with a series of theoretical curves by varying the required parameters in order to achieve maximum compliance. The tracer transport is represented by analytical solutions of the partial differential equation for mass transfer in a homogeneous and isotropic two-dimensional porous media. The developed computer programs include numerical optimization using the Levenberg-Marquardt algorithm. Results from tests performed in order to assess reliability and errors of detection and identification are presented. Using the programs, the mass transport parameters: active porosity n0, effective (sorption) porosity nS, longitudinal dispersivity αL, transverse dispersivity αT and rate constant γ can be determined.

Study on the Estimation Error Caused by Using One-Dimensional Model for the Evaluation of Dipole Tracer Test

2010 ◽  
Author(s):  
Yuji Ijiri ◽  
Yumi Naemura ◽  
Kenji Amano ◽  
Keisuke Maekawa ◽  
Atsushi Sawada ◽  
...  
Keyword(s):  
Estimation Error ◽  
Tracer Tests ◽  
Fracture Plane ◽  
Nuclear Waste Repository ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Transport Parameters ◽  
Experimental Conditions ◽  
One Dimensional ◽  
Longitudinal Dispersivity

In-situ tracer tests are a valuable approach to obtain parameters for a performance assessment of nuclear waste repository. A one-dimensional model is simple and is commonly used to identify radionuclide transport parameters by fitting breakthrough curves simulated using the model to those obtained from tracer tests. However, this method can increase uncertainty and introduce errors in the estimated parameters. In particular, such uncertainties and errors will be significant when evaluating parameters for tests conducted in a dipole (two-dimensional) flow field between injection and withdrawal wells. This paper describes a numerical analysis investigation into the effects of various experimental conditions on parameters estimated using a one-dimensional model for cases involving tracer tests in a two-dimensional fracture plane. Results show that longitudinal dispersivity tends to be overestimated by the one-dimensional model analysis. This overestimation is the result of several factors: smaller pumping rate, larger dipole ratio, stronger heterogeneity of the fracture hydraulic conductivity, and greater orthogonally-oriented background groundwater flow. Such information will help us to better plan and design tracer tests at underground research laboratories located in both Mizunami in central Japan and Horonobe in northern Japan. Understanding appropriate experimental conditions will help decrease the uncertainty in the results of tracer tests.

Solute transport in dual conduit structure: experiment and modelling

2020 ◽  
Author(s):  
Chaoqi Wang ◽  
Xiaoguang Wang ◽  
Samer Majdalani ◽  
Vincent Guinot ◽  
Hervé Jourde
Keyword(s):  
Solute Transport ◽  
Peak Concentration ◽  
Dispersion Model ◽  
Tracer Tests ◽  
Breakthrough Curves ◽  
Physical Models ◽  
Length Ratio ◽  
Tracer Transport ◽  
Transport Parameters ◽  
Total Length

<p>An important phenomenon often encountered when interpreting tracer tests in karst aquifers is the occurrence of dual-peaked breakthrough curves (BTCs). The dual-peaked BTCs are usually attributed to tracer transport through a conduit system consisting of a dual-conduit structure: an auxiliary conduit that deviates from the main conduit at the upstream and converges back at the downstream. In order to understand how the geometric configuration of the dual-conduit structure influences the BTCs, laboratory experiments utilizing plastic tubes were conducted. The physical models were constructed by varying: 1) the total length of the conduits, while fixing the length ratio; 2) length ratio between the two conduits, while fixing the length of the main conduit; and 3) conduits connection angle. The tracer experiments are then fitted by a Multi-Region Advection Dispersion model and a Transfer Function model to derive effective transport parameters. This allows us to quantitatively compare the experimental results, and thus to analyse the conduit geometry effects on solute transport and to compare the performance of the two models.</p><p>Results show that the dual-conduit structure causes the double peaks of BTCs. Keeping the length ratio of the two conduits and increasing their total length leads to a larger separation of the two peaks of the BTCs. Keeping the length of main conduit while increasing the length of the secondary conduit causes similar effects. As (θ<sub>1</sub>-θ<sub>2</sub>) increases, the first peak concentration value decreases, the second peak concentration value increases.</p><p><strong>Keywords</strong>: karst, lab experiment, dual-peaked BTCs, modelling</p>

scholarly journals Truncation Effect on Estimation of Transport Parameters for Slug-injection Tracer Tests

2021 ◽  
Author(s):  
Tomoki Kurasawa ◽  
Yoshitaro Takahashi ◽  
Mariko Suzuki ◽  
Kazuya Inoue
Keyword(s):  
Detection Limit ◽  
Estimation Error ◽  
Finite Size ◽  
Tracer Tests ◽  
Travel Distance ◽  
Hydrodynamic Dispersion ◽  
Transport Parameters ◽  
Spatial Moment ◽  
Longitudinal Dispersivity ◽  
Measured Mass

Abstract For slug-injection tracer tests, tracer concentrations below the detection limit of the measurement instrument can cause truncation of the observed data. This study investigated the truncation effect on the estimation error of parameters based on analytical solutions and the results of a laboratory-scale experiment. Spatial moment analysis was performed to estimate the measured total mass and transport parameters, including the pore velocity and the longitudinal and transverse dispersivities. Increasing the travel distance and detection limit caused the measured mass and dispersivities to be underestimated regardless of the dimensionality because hydrodynamic dispersion occurs with increasing travel distance, which smoothens the concentration front. The one- and two-dimensional cases showed that the truncation effect on the measured mass and longitudinal dispersivity depended on dimensionality. In contrast, the pore velocity showed no such dependence; the center of mass did not change as the unmeasured portion due to truncation was increased because the plume, which exhibited a Gaussian distribution, was truncated symmetrically. In the experiment, the measured mass and dispersivities likewise depended on the travel distance and detection limit, but there were large differences in the detection limit at which the dimensionless parameter reached a value of zero between the experimental results and analytical solution. This is because the initial plume in the experiment was of a finite size. Thus, experimental design factors such as the scale, device, and dimensionality should be considered to minimize the estimation error of transport parameters, excluding the pore velocity.

Comparison of Water and Gas Tracers Field Breakthrough

2021 ◽  
Author(s):  
Hsieh Chen ◽  
Sehoon Chang ◽  
Gawain Thomas ◽  
Wei Wang ◽  
Afnan Mashat ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Detection Method ◽  
Tracer Tests ◽  
Field Tests ◽  
Field Trials ◽  
Breakthrough Curves ◽  
Detection Methods ◽  
Reservoir Conditions ◽  
Gas Tracer

Abstract We are developing new classes of barcoded advanced tracers, which, compared to present commercial offerings, can be optically detected in an automated fashion. The eventual goal for the advanced tracers is to deploy cost-effective, ubiquitous, long-term, and full-field tracer tests in supporting large-scale waterflooding optimization for improved oil recovery. In this paper, we compare model predictions to breakthrough data from two field tests of advanced tracers in a pilot during water alternating gas (WAG) cycles, where gas tracer tests have recently been performed as well. Two advanced tracer injections were performed at the test site. For the first injection, only a dipicolinic acid based advanced tracer (DPA) was injected. For the second injection, DPA and a phenanthroline- based advanced tracer, 4,7-bis(sulfonatophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BSPPDA), was injected in conjunction with a commercially available fluorobenzoic acid-based tracer (FBA) to benchmark their performance. Produced water samples were collected weekly for tracer analysis. Both newly developed 2D-high performance liquid chromatography/time-resolved fluorescence optical detection method (2D-HPLC/TRF) and liquid chromatography-mass spectrometry (LC-MS) were used to construct the breakthrough curves for the advanced tracers. In parallel, gas chromatography-mass spectrometry (GC-MS) was used to detect FBA tracer. Gas tracer tests have been performed on the same field. Since DPA, BSPPDA and FBA tracers were water tracers as designed, they were expected to appear in between gas tracer breakthroughs, and we observed exactly that for BSPPDA and FBA. Unexpectedly, the DPA predominantly appeared along with gas tracer breakthroughs, suggesting its favorable compatibility with the gas phase. We suspect the presence of some gas components rendered the medium more acidic, which likely protonates DPA molecules, thereby alters its hydrophilicity. A wealth of information could be gathered from the field tests. First, all tracers survived not only the harsh reservoir conditions but also the irregular WAG injections. Their successful detection from the producers suggested robustness of these materials for reservoir applications. Second, the breakthrough curves of the BSPPDA tracers using optical detection method were very similar to those of FBA tracers detected by GC-MS, substantiating the competency of our in-house materials and detection methods to the present commercial offerings. Finally, even though DPA has passed prior lab tests as a good water tracer, its high solubility to gas phase warrants further investigation. This paper summarizes key results from two field trials of the novel barcoded advanced tracers, of which both the tracer materials and detection methods are new to the industry. Importantly, the two co- injected advanced tracers showed opposite correlations to the gas tracers, highlighting the complex physicochemical interactions in reservoir conditions. Nevertheless, the information collected from the field trials is invaluable in enabling further design and utilization of the advanced tracers in fulfilling their wonderful promises.

scholarly journals Non-equilibrium model for solute transport in differently designed biofilters targeting agricultural drainage water

2017 ◽  
Vol 76 (6) ◽  
pp. 1324-1331 ◽  
Author(s):  
Lorenzo Pugliese ◽  
Jacob Bruun ◽  
Charlotte Kjaergaard ◽  
Carl Christian Hoffmann ◽  
Guenter Langergraber
Keyword(s):  
Flow Direction ◽  
Tracer Tests ◽  
Drainage Water ◽  
Degree Of Saturation ◽  
Model Parameters ◽  
Liquid Phase Mass Transfer ◽  
Flow Rates ◽  
Hydraulic Design ◽  
Longitudinal Dispersivity ◽  
Transport Behaviour

Biogeochemical processes in subsurface flow constructed wetlands are influenced by flow direction, degree of saturation and influent loading position. This study presents a simulation tool, which aims to predict the performance of the unit and improve the design. The model was developed using the HYDRUS program, calibrated and verified on previously measured bromide (Br−) pulse tracer tests. Three different hydraulic designs (Horizontal (HF), Vertical upward (VF-up), Vertical downward (VF-down) and two different flow rates: Low (L), and High (H)) were investigated. The model simulated well the Br− transport behaviour and the results underline the importance of the hydraulic design. Calibrated model parameters (longitudinal dispersivity, immobile liquid phase, mass transfer coefficient) showed a common trend for all the designs, for increasing flow rates within the investigated range. The VF-down performed best, i.e. had the highest hydraulic retention time.

scholarly journals Quantifying solute spreading and mixing in reservoir rocks using 3-D PET imaging

2016 ◽  
Vol 796 ◽  
pp. 558-587 ◽  
Author(s):  
Ronny Pini ◽  
Nicholas T. Vandehey ◽  
Jennifer Druhan ◽  
James P. O’Neil ◽  
Sally M. Benson
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Tracer Tests ◽  
Spatial Arrangement ◽  
Small Scale ◽  
Local Dispersion ◽  
Advection Dispersion ◽  
Driving Mechanisms ◽  
Positron Emission ◽  
Longitudinal Dispersivity

We report results of an experimental investigation into the effects of small-scale (mm–cm) heterogeneities on solute spreading and mixing in a Berea sandstone core. Pulse-tracer tests have been carried out in the Péclet number regime $Pe=6{-}40$ and are supplemented by a unique combination of two imaging techniques. X-ray computed tomography (CT) is used to quantify subcore-scale heterogeneities in terms of permeability contrasts at a spatial resolution of approximately $10~\text{mm}^{3}$, while [11C] positron emission tomography (PET) is applied to image the spatial and temporal evolution of the full tracer plume non-invasively. To account for both advective spreading and local (Fickian) mixing as driving mechanisms for solute transport, a streamtube model is applied that is based on the one-dimensional advection–dispersion equation. We refer to our modelling approach as semideterministic, because the spatial arrangement of the streamtubes and the corresponding solute travel times are known from the measured rock’s permeability map, which required only small adjustments to match the measured tracer breakthrough curve. The model reproduces the three-dimensional PET measurements accurately by capturing the larger-scale tracer plume deformation as well as subcore-scale mixing, while confirming negligible transverse dispersion over the scale of the experiment. We suggest that the obtained longitudinal dispersivity ($0.10\pm 0.02$  cm) is rock rather than sample specific, because of the ability of the model to decouple subcore-scale permeability heterogeneity effects from those of local dispersion. As such, the approach presented here proves to be very valuable, if not necessary, in the context of reservoir core analyses, because rock samples can rarely be regarded as ‘uniformly heterogeneous’.

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