Download or read book Quarried block experiment numerical simulations of flow and transport experiments in a natural fracture written by D. J. Brush and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two D Simulations of Flow and Transport on a Meter Sized Unsaturated Fractured Tuff Block written by and published by . This book was released on 2002 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-D numerical flow and transport experiments were performed with a meter-sized unsaturated fractured block in an attempt to validate the active fracture model (AFM) by estimating [gamma], a positive constant relating the fraction of active fractures to the effective water saturation for the block. Two different models developed for the study include a discrete fracture network model (DFNM) and a dual continuum model (DCM). The DFNM served to synthetically generate experimental measurements for water flow rates and tracer breakthroughs, against which numerical simulation data with DCM was calibrated to estimate [gamma] values for the fracture network. Water flow rates were monitored at both top and bottom to find balanced (''pseudo-steady'') states, when a pulse of tracer injection was initiated from the top of the block. During the transient state, water flow rates in DCM did not closely predict the measurements from DFNM, which show step-wise increments with time. Based on goodness-of-fit values, the water flow rates in the range of 7.12 x 10−8 and 7.12 x 10−7 kg/s (0.2-2.0 % of the saturated flow rate) provide better estimates of [gamma]. The DCM may be not suitable to estimate [gamma] when the injection rates are too high or low. Water flows predominantly through a few major fractures as preferential fast flow when the injection rate is high (> 10% of saturated flow rate), and capillary pressure solely governs water flow when the injection rate is low (

Download or read book An Evaluation of the Active Fracture Concept with Modelingunsaturated Flow and Transport in a Fractured Meter sized Block Ofrock written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical simulation is an effective and economical tool for optimally designing laboratory experiments and deriving practical experimental conditions. We executed a detailed numerical simulation study to examine the active fracture concept (AFC, Liu et al., 1998) using a cubic meter-sized block model. The numerical simulations for this study were performed by applying various experimental conditions, including different bottom flow boundaries, varying injection rates, and different fracture-matrix interaction (by increasing absolute matrix permeability at the fracture matrix boundary) for a larger fracture interaction under transient or balanced-state flow regimes. Two conceptual block models were developed based on different numerical approaches: a two-dimensional discrete-fracture-network model (DFNM) and a one-dimensional dual continuum model (DCM). The DFNM was used as a surrogate for a natural block to produce synthetic breakthrough curves of water and tracer concentration under transient or balanced-state conditions. The DCM is the approach typically used for the Yucca Mountain Project because of its computational efficiency. The AFC was incorporated into the DCM to capture heterogeneous flow patterns that occur in unsaturated fractured rocks. The simulation results from the DCM were compared with the results from the DFNM to determine whether the DCM could predict the water flow and tracer transport observed in the DFNM at the scale of the experiment. It was found that implementing the AFC in the DCM improved the prediction of unsaturated flow and that the flow and transport experiments with low injection rates in the DFNM were compared better with the AFC implemented DCM at the meter scale. However, the estimated AFC parameter varied from 0.38 to 1.0 with different flow conditions, suggesting that the AFC parameter was not a sufficient to fully capture the complexity of the flow processes in a one meter sized discrete fracture network.

Download or read book Numerical Simulation of Air and Water flow Experiments in a Block of Variably Saturated Fractured Tuff from Yucca Mountain Nevada written by and published by . This book was released on 1998 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow and Transport in Porous Media and Fractured Rock written by Muhammad Sahimi and published by John Wiley & Sons. This book was released on 2011-05-09 with total page 635 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this standard reference of the field, theoretical and experimental approaches to flow, hydrodynamic dispersion, and miscible displacements in porous media and fractured rock are considered. Two different approaches are discussed and contrasted with each other. The first approach is based on the classical equations of flow and transport, called 'continuum models'. The second approach is based on modern methods of statistical physics of disordered media; that is, on 'discrete models', which have become increasingly popular over the past 15 years. The book is unique in its scope, since (1) there is currently no book that compares the two approaches, and covers all important aspects of porous media problems; and (2) includes discussion of fractured rocks, which so far has been treated as a separate subject. Portions of the book would be suitable for an advanced undergraduate course. The book will be ideal for graduate courses on the subject, and can be used by chemical, petroleum, civil, environmental engineers, and geologists, as well as physicists, applied physicist and allied scientists that deal with various porous media problems.

Download or read book Fluid Flow in Fractured Rocks written by Robert W. Zimmerman and published by John Wiley & Sons. This book was released on 2023-12-19 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: FLUID FLOW IN FRACTURED ROCKS "The definitive treatise on the subject for many years to come" (Prof. Ruben Juanes, MIT) Authoritative textbook that provides a comprehensive and up-to-date introduction to fluid flow in fractured rocks Fluid Flow in Fractured Rocks provides an authoritative introduction to the topic of fluid flow through single rock fractures and fractured rock masses. This book is intended for readers with interests in hydrogeology, hydrology, water resources, structural geology, reservoir engineering, underground waste disposal, or other fields that involve the flow of fluids through fractured rock masses. Classical and established models and data are presented and carefully explained, and recent computational methodologies and results are also covered. Each chapter includes numerous graphs, schematic diagrams and field photographs, an extensive reference list, and a set of problems, thus providing a comprehensive learning experience that is both mathematically rigorous and accessible. Written by two internationally recognized leaders in the field, Fluid Flow in Fractured Rocks includes information on: Nucleation and growth of fractures in rock, with a multiscale characterization of their geometric traits Effect of normal and shear stresses on the transmissivity of a rock fracture and mathematics of fluid flow through a single rock fracture Solute transport in rocks, with quantitative descriptions of advection, molecular diffusion, and dispersion Fluid Flow in Fractured Rocks is an essential resource for researchers and postgraduate students who are interested in the field of fluid flow through fractured rocks. The text is also highly suitable for professionals working in civil, environmental, and petroleum engineering.

Download or read book Numerical Simulation of Air and Water flow Experiments in a Block of Variably Saturated Fractured Tuff from Yucca Mountain Nevada written by and published by . This book was released on 1998 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical models of water movement through variably saturated, fractured tuff have undergone little testing against experimental data collected from relatively well-controlled and characterized experiments. This report used the results of a multistage experiment on a block of variably saturated, fractured, welded tuff and associated core samples to investigate if those results could be explained using models and concepts currently used to simulate water movement in variably saturated, fractured tuff at Yucca Mountain, Nevada, the potential location of a high-level nuclear-waste repository. Aspects of the experiment were modeled with varying degrees of success. Imbibition experiments performed on cores of various lengths and diameters were adequately described by models using independently measured permeabilities and moisture-characteristic curves, provided that permeability reductions resulting from the presence of entrapped air were considered. Entrapped gas limited maximum water saturations during imbibition to approximately 0.70 to 0,80 of the fillable porosity values determined by vacuum saturation. A numerical simulator developed for application to fluid flow problems in fracture networks was used to analyze the results of air-injection tests conducted within the tuff block through 1.25-cm-diameter boreholes. These analyses produced estimates of transmissivity for selected fractures within the block. Transmissivities of other fractures were assigned on the basis of visual similarity to one of the tested fractures. The calibrated model explained 53% of the observed pressure variance at the monitoring boreholes (with the results for six outliers omitted) and 97% of the overall pressure variance (including monitoring and injection boreholes) in the subset of air-injection tests examined.

Download or read book Flow and Contaminant Transport in Fractured Rock written by Jacob Bear and published by Academic Press. This book was released on 1993-04-20 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling flow and contaminant transport in fractured rocks / J. Bear -- Solute transport in fractured rock--applications to radionuclide waste repositories / I. Neretnieks -- Solute transport through fracture networks / L. Smith, F.W. Schwartz -- Stochastic models of fracture systems and their use in flow and transport modeling / J.-P. Chilès, G. de Marsily -- Tracer transport in fracture systems / C.-F. Tsang --Multiphase flow in fractured petroleum reservoirs / H. Kazemi, J.R. Gilman -- Unsaturated flow in fractured porous media / J.S.Y. Wang, T.N. Narasimhan -- Simulation of flow and transport in fractured porous media / G.F. Pinder, P.S. Huyakorn, E.A. Sudicky -- A summary of field test methods in fractured rocks / P. Jouanna -- Index.

Download or read book Experimental and Theoretical Investigation of Multiphase Flow in Fractured Porous Media SUPRI TR 116 Topical Report written by and published by . This book was released on 1999 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fluid transfer parameters between rock matrix and fracture are not well known. Consequently, simulation of fractured reservoirs uses, in general, very crude and unproven hypotheses such as zero capillary pressure in the fracture and/or relative permeability linear with saturation. In order to improve the understanding of flow in fractured media, an experimental study was conducted and numerical simulations of the experiments were made. A laboratory flow apparatus was built to obtain data on water- air imbibition and oil-water drainage displacements in horizontal single-fractured block systems. For this purpose, two configurations have been used: a two-block system with a 1 mm spacer between the blocks, and a two-block system with no spacer. During the experiments, porosity and saturation measurements along the cores have been made utilizing an X-ray Computerized Tomography (CT) scanner. Saturation images were reconstructed in 3-D to observe matrix-fracture interactions. Differences in fluid saturations and relative permeabilities caused by changes in fracture width have also been analyzed.

Download or read book Modeling Fluid Flow Through Single Fracture Using Experimental Stochastic and Simulation Approaches written by Dicman Alfred and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research presents an approach to accurately simulate flow experiments through a fractured core using experimental, stochastic, and simulation techniques. Very often, a fracture is assumed as a set of smooth parallel plates separated by a constant width. However, the flow characteristics of an actual fracture surface are quite different, affected by tortuosity and the impact of surface roughness. Though several researchers have discussed the effect of friction on flow reduction, their efforts lack corroboration from experimental data and have not converged to form a unified methodology for studying flow on a rough fracture surface. In this study, an integrated methodology involving experimental, stochastic, and numerical simulations that incorporate the fracture roughness and the friction factor is shown to describe flow through single fractures more efficiently. Laboratory experiments were performed to support the study in quantifying the flow contributions from the matrix and the fracture. The results were used to modify the cubic law through reservoir simulations. Observations suggest that the fracture apertures need to be distributed to accurately model the experimental results. The methodology successfully modeled fractured core experiments, which were earlier not possible using the parallel plate approach. A gravity drainage experiment using an X-ray CT scan of a fractured core has also validated the methodology.

Download or read book Numerical Simulation of Flow and Transport in Partially Saturated Fractured Tuff written by and published by . This book was released on 1983 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The unsaturated, fractured tuff of Yucca Mountain in the Nevada Test Site is one of the target sites for geologic storage of high-level radioactive waste. A modeling study of flow and transport in this geologically complex site is presented. Numerical models of mass and heat flow in conjunction with analytical solutions are being used for sensitivity and pathway analysis studies and to aid in design and interpretation of laboratory and field flow and transport tests in tuff. 11 references, 9 figures, 1 table.

Download or read book Fracture flow and transport experiments in laboratory scale testing experimental and modelling techniques using a small block written by Pirkko Holtta and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow and Transport Through and Deformation of Rough Fractures written by Lichun Wang and published by . This book was released on 2015 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding physical, chemical, and mechanical processes and properties of a single fracture is fundamental to many processes on Earth, particularly hydrogeological phenomena across many scales. However, classical and widely used theories governing flow and transport processes are founded on the parallel plates model; this ignores the complex morphology of natural fracture. To fill this gap, I have investigated the role of fracture morphology on flow (permeability), transport (dispersion coefficients and other surrogate parameters), and mechanical (stiffness) properties through complementary theoretical analysis and computational experiments. The collection of single fractures used in this dissertation included natural fractures mapped through high-resolution x-ray computed tomography and synthetic ones generated through a model which produces fractures with fractal properties. I developed a modified Local Cubic Law (MLCL) allowing for fracture roughness, tortuosity, and weak inertial force to improve the prediction of fluid flow process. The validation of the MLCL was tested by comparing volumetric flux from solving the Navier-Stokes equations to that from the MLCL. Secondly, the effect of fracture roughness on the non-Fickian or anomalous transport was studied through an ensemble of 2D direct transport simulations. Moreover, I was able to show, analyze, and predict the transition from non-Fickian to Fickian transport by developing a quasi-3D particle tracking algorithm. Finally, I developed a fracture deformation model. The co-evolving permeability and stiffness were then determined through the MLCL and strain-stress relationship based on the deformation model. Through my dissertation research, I confirm that the classical LCL fails to predict bulk permeability or volumetric flux (errors up to 41%). The MLCL performs better in characterizing local and effective fluid flow processes, with only 4% error. Moreover, I find out that fracture roughness leads to non-Fickian transport, and that the degree of non-Fickian behavior depends directly on the fracture roughness. Additionally, I theoretically derive asymptotic time and lengths scales for distinguishing non-Fickian from Fickian transport for the simplified Poiseuille and Hagan-Poiseuille flow fields. The increasing scales drives non-Fickian transitioning into Fickian transport even though the presence of persistent intermittent velocity structure. Lastly, I show that scaling between fracture permeability and normal stiffness depends on both fracture roughness and aperture correlation length, indicating a potentially universal model that can describe this behavior.

Download or read book Laboratory Studies of Flow and Transport in Single Fractures Artificial Fracture and Granite Block Experiments written by M. C. Braney and published by . This book was released on 1991 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental and Numerical Investigations of Fluid Flow for Natural Single Rock Fractures written by and published by . This book was released on 2005 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: To quantify the roughness of natural rock fracture surfaces, a two dimensional version of the modified divider method was adopted. The parameter Dr2d9Cx was found to be suitable to quantify the roughness of natural rock fractures. In addition to the mean aperture, a modified 3D box counting method was used to quantify aperture distributions of the same fractures. The modified 3D box counting method produced fractal dimensions in the range 2.3104 to 2.5661. The following new functional relations were developed for aperture parameters: (a) power-functionally decreasing mean aperture with increasing normal stress, (b) power-functionally decreasing 3D box fractal dimension with increasing normal stress, (c) linearly increasing mean aperture with increasing 3D box fractal dimension, (d) linearly decreasing mean aperture with increasing fracture closure, and (e) linearly decreasing 3D box fractal dimension with increasing fracture closure. Fluid flow through nine natural single rock fractures was measured at different normal stresses. The flow calculated for three out of the nine fractures according to sample scale cubic law using mean apertures overestimated the experimental flow by 2.2 ̃235.0 times within a normal stress range of 0 ̃8 MPa. The elementally applied cubic law (EACL) through a finite element model (FEM) also overestimated the experimental flow by 1.9 ̃111.7 times within the same normal stress range. As the normal stress applied on a natural rock fracture increases, the overestimation increases due to increasing contact areas and increasing tortuous behavior of flow. These findings clearly show the inapplicability of the cubic law to estimate flow through natural rock fractures especially under high normal stresses. New hyperbolic functions were developed to relate mean aperture to the power n to applied normal stress at both the sample and finite element scales. The following new functional relations were developed between fluid flow rate and the aperture parameters: (a) power-functionally increasing flow rate per unit head with increasing mean aperture, (b) exponentially decreasing flow rate per unit head with increasing fracture closure, and (c) power-functionally increasing flow rate per unit head with increasing 3D box fractal dimension.

Download or read book Numerical Simulation of Fluid Flow Proppant Transport and Fracture Propagation in Hydraulic Fractures for Unconventional Reservoirs written by Yatin Suri and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Modeling of Nonlinear Problems in Hydraulic Fracturing written by Endrina Rivas and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic fracturing is a stimulation technique in which fluid is injected at high pressure into low-permeability reservoirs to create a fracture network for enhanced production of oil and gas. It is the primary purpose of hydraulic fracturing to enhance well production. The three main mechanisms during hydraulic fracturing for oil and gas production which largely impact the reservoir production are: (1) fracture propagation during initial pad fluid injection, which defines the extent of the fracture; (2) fracture propagation during injection of proppant slurry (fluid mixed with granular material), creating a propped reservoir zone; and (3) shear dilation of natural fractures surrounding the hydraulically fractured zone, creating a broader stimulated zone. The thesis has three objectives that support the simulation of mechanisms that lead to enhanced production of a hydraulically-fractured reservoir. The first objective is to develop a numerical model for the simulation of the mechanical deformation and shear dilation of naturally fractured rock masses. In this work, a two-dimensional model for the simulation of discrete fracture networks (DFN) is developed using the extended finite element method (XFEM), in which the mesh does not conform to the natural fracture network. The model incorporates contact, cohesion, and friction between blocks of rock. Shear dilation is an important mechanism impacting the overall nonlinear response of naturally fractured rock masses and is also included in the model--physics previously not simulated within an XFEM context. Here, shear dilation is modeled through a linear dilation model, capped by a dilation limiting displacement. Highly nonlinear problems involving multiple joint sets are investigated within a quasi-static context. An explicit scheme is used in conjunction with the dynamic relaxation technique to obtain equilibrium solutions in the face of the nonlinear constitutive models from contact, cohesion, friction, and dilation. The numerical implementation is verified and its convergence illustrated using a shear test and a biaxial test. The model is then applied to the practical problem of the stability of a slope of fractured rock. The second objective is to develop a numerical model for the simulation of proppant transport through planar fractures. This work presents the numerical methodology for simulation of proppant transport through a hydraulic fracture using the finite volume method. Proppant models commonly used in the hydraulic fracturing literature solve the linearized advection equation; this work presents solution methods for the nonlinear form of the proppant flux equation. The complexities of solving the nonlinear and heterogeneous hyperbolic advection equation that governs proppant transport are tackled, particularly handling shock waves that are generated due to the nonlinear flux function and the spatially-varying width and pressure gradient along the fracture. A critical time step is derived for the proppant transport problem solved using an explicit solution strategy. Additionally, a predictor-corrector algorithm is developed to constrain the proppant from exceeding the physically admissible range. The model can capture the mechanisms of proppant bridging occurring in sections of narrow fracture width, tip screen-out occurring when fractures become saturated with proppant, and flushing of proppant into new fracture segments. The results are verified by comparison with characteristic solutions and the model is used to simulate proppant transport through a KGD fracture. The final objective is to develop a numerical model for the simulation of proppant transport through propagating non-planar fractures. This work presents the first monolithic coupled numerical model for simulating proppant transport through a propagating hydraulic fracture. A fracture is propagated through a two-dimensional domain, driven by the flow of a proppant-laden slurry. Modeling of the slurry flow includes the effects of proppant bridging and the subsequent flow of fracturing fluid through the packed proppant pack. This allows for the simulation of a tip screen-out, a phenomenon in which there is a high degree of physical interaction between the rock deformation, fluid flow, and proppant transport. Tip screen-out also leads to shock wave formation in the solution. Numerical implementation of the model is verified and the model is then used to simulate a tip screen-out in both planar and non-planar fractures. An analysis of the fracture aperture, fluid pressure, and proppant concentration profiles throughout the simulation is performed for three different coupling schemes: monolithic, sequential, and loose coupling. It is demonstrated that even with time step refinement, the loosely-coupled scheme fails to converge to the same results as the monolithic and sequential schemes. The monolithic and sequential algorithms yield the same solution up to the onset of a tip screen-out, after which the sequential scheme fails to converge. The monolithic scheme is shown to be more efficient than the sequential algorithm (requiring fewer iterations) and has comparable computational cost to the loose coupling algorithm. Thus, the monolithic scheme is shown to be optimal in terms of computational efficiency, robustness, and accuracy. In addition to this finding, a robust and more efficient algorithm for injection-rate controlled hydraulic fracturing simulation based on global mass conservation is presented in the thesis.