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Hangseok Choi - One of the best experts on this subject based on the ideXlab platform.
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slug Test Analysis in vertical cutoff walls with consideration of filter cake
Journal of Geotechnical and Geoenvironmental Engineering, 2011Co-Authors: The-bao Nguyen, Hangseok ChoiAbstract:In constructing a vertical cutoff wall, bentonite-water slurry is frequently used to maintain the stability of sidewalls during excavation before backfilling the trench with less permeable materials to complete the cutoff wall construction. This procedure leads to a thin but relatively impermeable layer, called a filter cake, on the excavation surface. The aim of this paper is to examine the effect of a filter cake on evaluating hydraulic conductivity of the cutoff wall backfill through a slug Test Analysis with the aid of the verified numerical program, Slug_3D. As an upper bound solution for evaluation of the hydraulic conductivity of the cutoff wall backfill, no-flux boundary conditions for the boundaries of cutoff walls are imposed to consider the effect of filter cakes. The type-curve method and modified line-fitting method are employed to reanalyze the case of EMCON/OWT, Inc., as an example. The previous Analysis, without consideration of a filter cake, is compared with the current results that cons...
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Hydraulic Conductivity Evaluation of Vertical Cutoff Walls Bearing Filter Cake From Slug Test Analysis
Advances in Environmental Geotechnics, 2010Co-Authors: The-bao Nguyen, Chul-ho Lee, Yonghoon Ahn, Hangseok ChoiAbstract:The hydraulic conductivity of a vertical cutoff wall can be estimated through a slug Test Analysis. A filter cake is a thin and impervious layer formed on the interface between the vertical cutoff wall and the natural soil formation. The conventional line-fitting methods for a slug Test Analysis have never considered the presence of the filter cake. Therefore, results of a slug Test Analysis using the line-fitting methods for the vertical cutoff wall is believed to be inaccurate due to the effect of the filter cake. In this study, the hydraulic conductivity of the filter cake was evaluated using a modified fluid loss Test. The result of the Test indicated that a very low hydraulic conductivity is an important characteristic of the filter cake. The slug Test Analysis with the consideration of the filter cake in the line-fitting method was then employed to estimate the hydraulic conductivity of the cutoff wall in a case study. Result of the case study proves the significance of the filter cake in the estimation of the hydraulic conductivity of a vertical cutoff wall through a slug Test.
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Slug Test Analysis in vertical cutoff walls. I: Analysis methods
Journal of Geotechnical and Geoenvironmental Engineering, 2006Co-Authors: Hangseok Choi, David E. DanielAbstract:Analysis of a slug Test to estimate hydraulic conductivity of a vertical cutoff wall is complicated by the high compressibility of the backfill materials and by the proximity of the well intake section to the edge of the cutoff wall. The writers developed two methods to evaluate hydraulic conductivity of the vertical cutoff wall with the aid of a numerical program, Slug_3D. The first method, named the type curve method, expands the general type curve concept frequently used by hydrogeologists to take into account the complex boundary conditions of the vertical cutoff wall. The other method, named the modified linear curve fitting method and modified from the Hvorslev and the Bouwer and Rice methods, provides an easy and practical way of evaluating hydraulic conductivity of the vertical cutoff wall. To illustrate the use of the type curve and the modified linear curve fitting methods in practice, a case study involving two slug Tests at a landfill site is presented. The methods are shown to be useful and p...
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Slug Test Analysis in Vertical Cutoff Walls. II: Applications
Journal of Geotechnical and Geoenvironmental Engineering, 2006Co-Authors: Hangseok Choi, David E. DanielAbstract:This paper addresses practical applications of the type curve method and modified linear curve fitting method described in a companion paper for evaluating the hydraulic conductivity of a vertical cutoff wall. Sensitivity analyses were performed for factors that might influence results from a slug Test in a vertical cutoff wall. The factors considered are (1) width of the vertical cutoff wall, (2) eccentricity of a well location, (3) well aspect ratio, and (4) distance from the upper and lower boundaries of the wall to a well intake and discharge section. In addition, the effects of variable hydraulic properties—hydraulic conductivity (k) and specific storage ( Ss ) —on the results of a slug Test are evaluated. Also, the effect of initial slug size and difference between a rising and falling head slug Test are investigated in connection with the variability of the hydraulic properties. Analyses show that the compressibility of the porous medium has a dominant effect. Various errors can arise from the simp...
Nelson Del Castillo - One of the best experts on this subject based on the ideXlab platform.
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Well Test Analysis of Naturally Fractured Vuggy Reservoirs with an Analytical Triple Porosity – Double Permeability Model and a Global Optimization Method
Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles, 2014Co-Authors: Susana Gómez, Gustavo Ramos, Alejandro Mesejo, Rodolfo Camacho, Mario Vásquez, Nelson Del CastilloAbstract:The aim of this work is to study the automatic characterization of Naturally Fractured Vuggy Reservoirs via well Test Analysis, using a triple porosity-dual permeability model. The inter-porosity flow parameters, the storativity ratios, as well as the permeability ratio, the wellbore storage effect, the skin and the total permeability will be identified as parameters of the model. In this work, we will perform the well Test interpretation in Laplace space, using numerical algorithms to transfer the discrete real data given in fully dimensional time to Laplace space. The well Test interpretation problem in Laplace space has been posed as a nonlinear least squares optimization problem with box constraints and a linear inequality constraint, which is usually solved using local Newton type methods with a trust region. However, local methods as the one used in our work called TRON or the well-known Levenberg-Marquardt method, are often not able to find an optimal solution with a good fit of the data. Also well Test Analysis with the triple porosity-double permeability model, like most inverse problems, can yield multiple solutions with good match to the data. To deal with these specific characteristics, we will use a global optimization algorithm called the Tunneling Method (TM). In the design of the algorithm, we take into account issues of the problem like the fact that the parameter estimation has to be done with high precision, the presence of noise in the measurements and the need to solve the problem computationally fast. We demonstrate that the use of the TM in this study, showed to be an efficient and robust alternative to solve the well Test characterization, as several optimal solutions, with very good match to the data were obtained.
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well Test Analysis of naturally fractured vuggy reservoirs with an analytical triple porosity double permeability model and a global optimization method
Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 2014Co-Authors: Susana Gómez, Gustavo Ramos, Alejandro Mesejo, Rodolfo Camacho, Mario Vásquez, Nelson Del CastilloAbstract:The aim of this work is to study the automatic characterization of Naturally Fractured Vuggy Reservoirs via well Test Analysis, using a triple porosity-dual permeability model. The inter-porosity flow parameters, the storativity ratios, as well as the permeability ratio, the wellbore storage effect, the skin and the total permeability will be identified as parameters of the model. In this work, we will perform the well Test interpretation in Laplace space, using numerical algorithms to transfer the discrete real data given in fully dimensional time to Laplace space. The well Test interpretation problem in Laplace space has been posed as a nonlinear least squares optimization problem with box constraints and a linear inequality constraint, which is usually solved using local Newton type methods with a trust region. However, local methods as the one used in our work called TRON or the well-known Levenberg-Marquardt method, are often not able to find an optimal solution with a good fit of the data. Also well Test Analysis with the triple porosity-double permeability model, like most inverse problems, can yield multiple solutions with good match to the data. To deal with these specific characteristics, we will use a global optimization algorithm called the Tunneling Method (TM). In the design of the algorithm, we take into account issues of the problem like the fact that the parameter estimation has to be done with high precision, the presence of noise in the measurements and the need to solve the problem computationally fast. We demonstrate that the use of the TM in this study, showed to be an efficient and robust alternative to solve the well Test characterization, as several optimal solutions, with very good match to the data were obtained.
Aydogan Ozcan - One of the best experts on this subject based on the ideXlab platform.
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google glass based immunochromatographic diagnostic Test Analysis
Proceedings of SPIE, 2015Co-Authors: Steve Feng, Romain Caire, Bingen Cortazar, Mehmet Turan, Andrew L Wong, Aydogan OzcanAbstract:Integration of optical imagers and sensors into recently emerging wearable computational devices allows for simpler and more intuitive methods of integrating biomedical imaging and medical diagnostics tasks into existing infrastructures. Here we demonstrate the ability of one such device, the Google Glass, to perform qualitative and quantitative Analysis of immunochromatographic rapid diagnostic Tests (RDTs) using a voice-commandable hands-free software-only interface, as an alternative to larger and more bulky desktop or handheld units. Using the built-in camera of Glass to image one or more RDTs (labeled with Quick Response (QR) codes), our Glass software application uploads the captured image and related information (e.g., user name, GPS, etc.) to our servers for remote Analysis and storage. After digital Analysis of the RDT images, the results are transmitted back to the originating Glass device, and made available through a website in geospatial and tabular representations. We Tested this system on qualitative human immunodeficiency virus (HIV) and quantitative prostate-specific antigen (PSA) RDTs. For qualitative HIV Tests, we demonstrate successful detection and labeling (i.e., yes/no decisions) for up to 6-fold dilution of HIV samples. For quantitative measurements, we activated and imaged PSA concentrations ranging from 0 to 200 ng/mL and generated calibration curves relating the RDT line intensity values to PSA concentration. By providing automated digitization of both qualitative and quantitative Test results, this wearable colorimetric diagnostic Test reader platform on Google Glass can reduce operator errors caused by poor training, provide real-time spatiotemporal mapping of Test results, and assist with remote monitoring of various biomedical conditions.
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immunochromatographic diagnostic Test Analysis using google glass
ACS Nano, 2014Co-Authors: Steve Feng, Romain Caire, Bingen Cortazar, Mehmet Turan, Andrew L Wong, Aydogan OzcanAbstract:We demonstrate a Google Glass-based rapid diagnostic Test (RDT) reader platform capable of qualitative and quantitative measurements of various lateral flow immunochromatographic assays and similar biomedical diagnostics Tests. Using a custom-written Glass application and without any external hardware attachments, one or more RDTs labeled with Quick Response (QR) code identifiers are simultaneously imaged using the built-in camera of the Google Glass that is based on a hands-free and voice-controlled interface and digitally transmitted to a server for digital processing. The acquired JPEG images are automatically processed to locate all the RDTs and, for each RDT, to produce a quantitative diagnostic result, which is returned to the Google Glass (i.e., the user) and also stored on a central server along with the RDT image, QR code, and other related information (e.g., demographic data). The same server also provides a dynamic spatiotemporal map and real-time statistics for uploaded RDT results accessible through Internet browsers. We Tested this Google Glass-based diagnostic platform using qualitative (i.e., yes/no) human immunodeficiency virus (HIV) and quantitative prostate-specific antigen (PSA) Tests. For the quantitative RDTs, we measured activated Tests at various concentrations ranging from 0 to 200 ng/mL for free and total PSA. This wearable RDT reader platform running on Google Glass combines a hands-free sensing and image capture interface with powerful servers running our custom image processing codes, and it can be quite useful for real-time spatiotemporal tracking of various diseases and personal medical conditions, providing a valuable tool for epidemiology and mobile health.
Sanni, Moshood Olajide - One of the best experts on this subject based on the ideXlab platform.
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Well Test Analysis in volatile oil reservoirs
2008Co-Authors: Sanni, Moshood OlajideAbstract:This thesis discusses characterization of volatile oil reservoirs using well Test Analysis. For this purpose, typical well Test behaviours were simulated with a one-dimensional single well compositional reservoir model, for different production rates; fluid composition and relative permeability curves, with bottomhole pressures above and below the bubble point pressure. It was found that, when the bottomhole pressure falls below the bubble point pressure during a drawdown, a high gas saturation zone is created around the wellbore with two-phase (oil and gas) flow, whereas single phase (oil) with the initial gas saturation remains away from the wellbore. During the subsequent build up, the gas created around the wellbore during the preceding drawdown condenses into the oil and the saturation in the near-wellbore region returns to the initial gas saturation. The log-log pressure-derivative behaviours below the bubble point correspond to a twozone radial composite model, with decreasing mobility during drawdowns and increasing mobilities during build ups. The log-log pressure derivative plot of the build up reflects oil mobility distribution of the reservoir at the end of the preceding drawdown. Knowledge obtained from the study was applied to the Analysis of a well Test in an actual volatile oil reservoir. Analysis results were validated with compositional reservoir simulation that included the effect of capillary number and non-Darcy flow. Finally, factors affecting well deliverability in volatile oil reservoirs producing at flowing bottomhole pressure below bubble point pressure were studied. The result shows that end point relative permeability of oil phase and oil fluid composition are the most important factors affecting productivity of volatile oil reservoirs producing below bubble point pressure. This study suggests in volatile oil reservoirs, both vertical hydraulic fractures and horizontal wells are best implemented early in the wells life to delay the time when the flowing bottomhole pressure drops below the bubble point pressure, hence improving ultimate recovery.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
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Well Test Analysis in Volatile Oil Reservoirs
2008Co-Authors: Sanni, Moshood OlajideAbstract:This thesis discusses characterization of volatile oil reservoirs using well Test Analysis. For this purpose, typical well Test behaviours were simulated with a one-dimensional single well compositional reservoir model, for different production rates; fluid composition and relative permeability curves, with bottomhole pressures above and below the bubble point pressure. It was found that, when the bottomhole pressure falls below the bubble point pressure during a drawdown, a high gas saturation zone is created around the wellbore with two-phase (oil and gas) flow, whereas single phase (oil) with the initial gas saturation remains away from the wellbore. During the subsequent build up, the gas created around the wellbore during the preceding drawdown condenses into the oil and the saturation in the near-wellbore region returns to the initial gas saturation. The log-log pressure-derivative behaviours below the bubble point correspond to a twozone radial composite model, with decreasing mobility during drawdowns and increasing mobilities during build ups. The log-log pressure derivative plot of the build up reflects oil mobility distribution of the reservoir at the end of the preceding drawdown. Knowledge obtained from the study was applied to the Analysis of a well Test in an actual volatile oil reservoir. Analysis results were validated with compositional reservoir simulation that included the effect of capillary number and non-Darcy flow. Finally, factors affecting well deliverability in volatile oil reservoirs producing at flowing bottomhole pressure below bubble point pressure were studied. The result shows that end point relative permeability of oil phase and oil fluid composition are the most important factors affecting productivity of volatile oil reservoirs producing below bubble point pressure. This study suggests in volatile oil reservoirs, both vertical hydraulic fractures and horizontal wells are best implemented early in the wells life to delay the time when the flowing bottomhole pressure drops below the bubble point pressure, hence improving ultimate recovery.Imperial Users onl
Susana Gómez - One of the best experts on this subject based on the ideXlab platform.
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Well Test Analysis of Naturally Fractured Vuggy Reservoirs with an Analytical Triple Porosity – Double Permeability Model and a Global Optimization Method
Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles, 2014Co-Authors: Susana Gómez, Gustavo Ramos, Alejandro Mesejo, Rodolfo Camacho, Mario Vásquez, Nelson Del CastilloAbstract:The aim of this work is to study the automatic characterization of Naturally Fractured Vuggy Reservoirs via well Test Analysis, using a triple porosity-dual permeability model. The inter-porosity flow parameters, the storativity ratios, as well as the permeability ratio, the wellbore storage effect, the skin and the total permeability will be identified as parameters of the model. In this work, we will perform the well Test interpretation in Laplace space, using numerical algorithms to transfer the discrete real data given in fully dimensional time to Laplace space. The well Test interpretation problem in Laplace space has been posed as a nonlinear least squares optimization problem with box constraints and a linear inequality constraint, which is usually solved using local Newton type methods with a trust region. However, local methods as the one used in our work called TRON or the well-known Levenberg-Marquardt method, are often not able to find an optimal solution with a good fit of the data. Also well Test Analysis with the triple porosity-double permeability model, like most inverse problems, can yield multiple solutions with good match to the data. To deal with these specific characteristics, we will use a global optimization algorithm called the Tunneling Method (TM). In the design of the algorithm, we take into account issues of the problem like the fact that the parameter estimation has to be done with high precision, the presence of noise in the measurements and the need to solve the problem computationally fast. We demonstrate that the use of the TM in this study, showed to be an efficient and robust alternative to solve the well Test characterization, as several optimal solutions, with very good match to the data were obtained.
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well Test Analysis of naturally fractured vuggy reservoirs with an analytical triple porosity double permeability model and a global optimization method
Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 2014Co-Authors: Susana Gómez, Gustavo Ramos, Alejandro Mesejo, Rodolfo Camacho, Mario Vásquez, Nelson Del CastilloAbstract:The aim of this work is to study the automatic characterization of Naturally Fractured Vuggy Reservoirs via well Test Analysis, using a triple porosity-dual permeability model. The inter-porosity flow parameters, the storativity ratios, as well as the permeability ratio, the wellbore storage effect, the skin and the total permeability will be identified as parameters of the model. In this work, we will perform the well Test interpretation in Laplace space, using numerical algorithms to transfer the discrete real data given in fully dimensional time to Laplace space. The well Test interpretation problem in Laplace space has been posed as a nonlinear least squares optimization problem with box constraints and a linear inequality constraint, which is usually solved using local Newton type methods with a trust region. However, local methods as the one used in our work called TRON or the well-known Levenberg-Marquardt method, are often not able to find an optimal solution with a good fit of the data. Also well Test Analysis with the triple porosity-double permeability model, like most inverse problems, can yield multiple solutions with good match to the data. To deal with these specific characteristics, we will use a global optimization algorithm called the Tunneling Method (TM). In the design of the algorithm, we take into account issues of the problem like the fact that the parameter estimation has to be done with high precision, the presence of noise in the measurements and the need to solve the problem computationally fast. We demonstrate that the use of the TM in this study, showed to be an efficient and robust alternative to solve the well Test characterization, as several optimal solutions, with very good match to the data were obtained.
