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Collaborating Authors
Reservoir Fluid Dynamics
ABSTRACT: Flow in fractured porous media is investigated by a direct, exact and complete numerical solution of the flow equations for arbitrary distributions of permeabilities in the porous matrix and in the fracture network. For single phase flow, the macroscopic permeability of the network has been systematically computed; the main parameters are the fracture density, the ratio between the characteristic fracture and porous medium permeabilifies. Some results are presented and discussed; they show the importance of the percolafion threshold of the fracture network and possibly of the porous matrix. The same work is underway for twophase flow. The unsteady non-linear equations are solved in the same general setting. The method of solution is presented, together with illustrative simulation results. INTRODUCTION Consider a set of permeable fractures embodied in a permeable porous solid matrix. When a fluid is flowing through such a medium, the fractures and the porous matrix interact. Historically, this complex situation was first addressed by Barenblatt & Zheltoy 0960) and Barenblatt et al. 0960); though these papers motivated many further works, progress in this area has been slow and so far no complete solution of this problem for any fracture network and for any permeability distribution in the porous matrix has been described to the best of our knowledge in the literature. Warren & Root (1963) modeled a fractured porous rock as an idealized system made up of identical rectangular porous parallelepipeds separated by an orthogonal network of fractures. Flow is assumed to take place in the fracture network which is fed by the porous blocks. This sort of model was further developed by Odeh (1965). All these equations have been thoroughly studied in the literature with many different boundary conditions (van Golf-Racht 1982, Chen 1989, Chen 1990 and Pinder 1993). Other possible approaches have also been presented by Adler & Thovert 0999). The most important is probably the multiscale analysis of flow through fractured porous media, initiated by Aifantis (1980) and extended by Arbogast (1990), Levy 0988, 1990) and Panfilov (1990,1994). The purpose of this paper is to briefly present the methodology and the first results obtained in the determination of the single-phase permeability of fractured porous media. It is a significant extension of our previous paper on the permeability of fractured media Koudina et al. (1998). In addition, a further extension to two-phase flow is presented, with a set of illustrative results.
ABSTRACT: We consider the use of a modified diffusion-limited aggregation.(DLA) process to model immiscible viscous displacements in rough-walled fractures. We include the effects of local aperture field variability to channelize flow within a fluid phase and capillarity to smooth the displacement front. Model behavior is illustrated over a limited set of simulations in both a Hele-Shaw cell, and a variable aperture field that is correlated well below the simulation scale. INTRODUCTION The issue of immisicble displacement of one fluid by another rises in the context of enhanced oil recovery, remediation of nonaqueous phase liquids, CO2 sequestration, and other applied geologic problems. In discrete fractures, accessibility will combine with competition between capillary, gravity, and viscous forces to control the displacement process. Here we focus on behavior in a single horizontal fracture at the sub-meter scale for conditions where viscous forces cannot be ignored. Immiscible displacement processes can (and have been) modeled using a number of different approaches that may be broadly categorized as continuum or discrete. In continuum approaches, one either: 1) solves the Navier-Stokes equations for each fluid within complex geometry, and separated by a moving boundary where kinetic and dynamic boundary conditions must be met; or, 2) describes the system as a two-phase continuum with relative permeability and pressure-saturation relations defined for both fluids at every point. In the discrete approaches, a set of local 'rules' are applied to model pore-scale behavior; broad categories of rules include: 1) Particle interaction models (PIM) such as cellular automata, lattice-Boltzman, or lattice-gas where large quantities of particles simultaneously move and interact according to a list of rules; 2) Invasion percolation (IP) where individual apertures along the fluid-fluid interface are filled according to local accessibility and capillary criteria; and, 3) Diffusion-limited aggregation (DLA) in which random particles moving through the displaced fluid are used to identify locations on the interface for advancement. Both the Navier-Stokes and PIM approaches are currently limited by the difficulty of defining the fluid-fluid interface, and computational requirements at our scale of interest. Two-phase continuum approaches are computationally tractable, but do not correctly include the physics of displacement processes; i.e. the fluid phases intermingle where they should be separate. IP and DLA have potential at the scale of interest, both are growth models that encapsulate the critical unit process (aperture filling), and iterate that process to yield large scale behavior. The basic IP process models capillary dominated horizontal displacements on a random aperture field. However, IP has recently been modified to include gravity and the dynamic calculation of interfacial curvature at the fluid-fluid interface within a fracture (e.g. Glass, 1993, Glass et al., 1998). The latter, termed MIP, yields simulated behavior that matches experimental measurements quite well. In addition, there have also been recent attempts to further include viscous forces in IP or MIP (Xu et al., 1998, Ewing & Berkowitz, 1998) with excellent correspondence to experiments in heterogeneous porous media where capillary, gravity, and viscous forces all played a role (Glass et al., in press). Here we focus on a DLA based approach for simulating fluid-fluid displacement. The DLA process begins with a cluster that consists of a single occupied grid block at the center of a large regular lattice (Witten & Sander, 1981). A particle introduced at a random location far from the cluster walks randomly on the lattice u
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
ABSTRACT: The study of hydromechanics has identified that surface roughness has an impact on the flow characteristics of single and two-phase fitfids. Technical developments in the field of two-phase flow are of great importance for improving the understanding of underground inundation and gas outbursts, in order to reduce the risks to personnel. The paper describes recent advances in the understanding of two-phase (airwater) stratified flow. A new constitutive model is presented, based upon an extension of Darcy's Law and using the concept of relative permeability. The proposed model is verified by experimental results using 'state of the art' Two Phase High Pressure Triaxial Apparatus (TPHPTA). This study presents the results of laboratory testing that will enable the development of a relationship between roughness (Joint Roughness Coefficient, JRC) and the flow rate for steady state conditions. INTRODUCTION Fracture roughness in the form of the Joint Roughness Coefficient (JRC) is acknowledged to have a fundamental impact on the hydromechanical properties of discontinuous media. Previous studies (Barton et al, 1985) have used a series of standard roughness profiles that enable the estimation of fracture hydraulic conductivity. This relationship has also been examined in terms of gas flow (Schrauf & Evans, 1986). With the onset of research into twophase flow, several different approaches have been adopted. A number of studies have considered applied numerical techniques, typically using fractures generated with various mathematical models (Rasmussen, 1991). Laboratory studies have also been carried out using artificial fi'actures (Fourar et al, 1993). The nature of two-phase flow is of practical interest to civil and mining engineering projects especially with regard to the storage of waste in fraetured rock mass and minerals extraction in the mining and petroleum industries. The aim of the current research program is to study the effect of roughness on fracture aperture and two-phase flow behaviour for both natural and induced fractures, extending over a range of JRC values. A further objective is to evaluate the effect of capillary pressure, phase interference and fracture roughness on the relative permeability and twophase flow behaviour. In underground rock mass, excavation of multiple openings causestress redistribution and associated fitfid flow through existing and newly created discontintfities. In the Australian coal industry, the risks from gas outburst and groundwater inundation are still only partially understood, and damage to underground eqtfipment and fatalities occur too frequently. The study of two-phase flow characteristics provides a more thorough understanding of nearfield pore pressure variations associated with the redistribution of stresses. Phase interference and the 'blocking-off' of pockets of gas can lead to 1ocalised pressure concentrations that can result in outburst. It is hoped that from the better understanding of fracture characteristics obtained in the laboratory, the field behaviour can be more accurately predicted so that the risks from outburst and inundation can be controlled more effectively.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (0.74)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Multiphase flow (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (1.00)
ABSTRACT: The Invasion Percolation in a Gradient (IPG) model is capable of incorporating all forces -viscous (in both the wetting and nonwetting fluids), buoyancy, and capillary forces -relevant to geologic problems of two-phase flow in a porous medium. Calibration of the IPG model to a pre-existing data set of two-phase flow experiments on glass bead packs shows that the characteristic throat radius Rt is about 10% of the site radius Rs, assuming Rs-P?, the grain size. Two-dimensional model results of the fractal dimension D and the invasion probability of a throat on the interface are in excellent agreement with predictions for limiting cases of Capillary number Ca and Bond number Bo. In moving from twoto three-dimensional media, trapped wetting clusters do not scale with the extent of the invading cluster, remaining under 5 to 8 pores in size. INTRODUCTION Two-phase flow in a porous medium has been an active area of research for more than five decades. Representative Elementary Volume (REV) assumptions, coupled with continuum concepts (Bear 1972), have provided the fundamental basis for most largescale models of two-phase flow. Recent experimental and theoretical work (Lenormand 1989, Baveye & Sposito 1984), however, show that such models fail to represent accurately both very slow and buoyancy dominated processes. This results in their inability to incorporate appropriately the influence of pore-scale mechanics on the geometry of the nonwetting fluid cluster at a macroscopic scale. Percolation theory has received increasing attention for providing both a quantitative and conceptual framework for describing all types of two-phase flow phenomena (Yortsos et al. 1997, Xu et al. 1998, Hirsch & Thompson 1995). Although Ordinary Percolation (OP) theory was initially used to describe the final fluid configuration observed following (slow) immiscible displacement processes, it was the introduction of the Invasion Percolation (IP) model by Wilkinson & Willemsen, 1983 that allowed for a more complete investigation of the entire displacement process. Numerous experimental studies validate the use of IP to describe very slow immiscible displacement, yet it is not an appropriate model when spatial gradients in the capillary pressure Pc are present. Such gradients include not only viscous and buoyancy related gradients in the nonwetting fluid, but also gradients associated with viscous forces in the wetting fluid and with spatial variations in the permeability k (Chaouche et al. 1994, Meakin et al. 1992). The Invasion Percolation in a Gradient (IPG) model is capable of including all of these factors.
- Research Report > New Finding (0.34)
- Research Report > Experimental Study (0.34)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Multiphase flow (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
ABSTRACT: We describe coupled reservoir-geomechanical modeling of production at the Lost Hills oil field. We first review a database that was developed to discern the depth distribution of casing damage and to motivate model development. We then describe the development of constitutive models for the overburden formations, reservoir formations, and underlying strata. 3D reservoir fluid flow and geomechanical models that cover portions of Sections 4, 5, 32, and 33 were developed. Black oil reservoir simulations were performed that included 229 wells and modeled 17 years of primary production and waterflooding. The timedependent reservoir pressures were then used as input to non-linear finite element geomechanical simulations. The simulations predict surface subsidence and shearing displacements in the subsurface that can result in well casing damage. Multiple simulations were performed to assessensitivity to the initial stress state and to the friction coefficient at the contact surfaces that are used to model the behavior of thin claystones. INTRODUCTION The shallow diatomaceous oil reservoirs located in Kern County, California are susceptible to depletion-induced compaction because of the high porosity (45-60%) and large vertical extent of the producing formation. More than a thousand wells at the Belridge and Lost Hills fields have experienced severe casing damage as the reservoir pressures have been drawn down. The purpose of this study is to improve understanding of the geomechanical behavior by integrated analyses of field data, experimental measurement of rock mechanical behavior, and numerical simulation of the reservoir and overburden behavior during primary and secondary recovery. In our work, time-dependent reservoir pressures derived from three-dimensional (3d) black oil reservoir simulations are coupled unidirectionally and applied as loads in 3d nonlinear finite element geomechanical simulations. Central to the numerical modeling is the use of sophisticated material models that accurately capture the nonlinear deformation behavior of the reservoir rock, including inelastic compaction (yield) at stress states below the shear failure surface. Fredrich et al. (2000) described development of 3d geomechanical models for the Belridge field and historical simulations that were performed of sections 33 and 29 using the quasi-static largedeformation structural mechanics finite element code JAS3D. The historical simulations served to validate both the conceptual model that was formulated for casing damage and the modeling approaches. That work also showed that geomechanical simulation could be applied as a reservoir management tool to optimize production and injection policies, and to identify the most economical density and spacing of production and injection wells during infill drilling. Following the successful application at Belddge, attention shifted to Lost Hills. The Lost Hills field is at an earlier stage of development, and therefore, development and application of geomechanical models were expected to be particularly useful in regard to future infill drilling and expansion of the waterflood.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.34)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.46)
- North America > United States > California > San Joaquin Basin > San Joaquin Valley > Tulare Formation (0.99)
- North America > United States > California > San Joaquin Basin > Lost Hills Field (0.99)
- North America > United States > California > San Joaquin Basin > Belridge Field (0.99)
- (3 more...)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Integration of geomechanics in models (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- (2 more...)
ABSTRACT: Discrete particle models, which simulate inter-particle mechanics explicitly and can be coupled with fluid flow mechanics, often provide a more realistic simulation of granular deformation and fracture than continuum models. We apply such models to investigate fracture processes in weakly cemented media,. providing insights on material parameters which influence a change from discrete brittle fracturing (as occurs in stiff and strong geomaterial) to general dilation and parting (as occurs in very soft and weak geomaterials). The primary influence on parting behavior is shear bonding at the granular scale. We also investigate slurry injection processes in granular media by coupling fluid flow simulators with particle models for several near wellbore assemblies. Although there are clear challenges remaining with scaling issues and practical model size, we conclude that coupled particle and fluid flow codes can simulate slurry injection processes well, reproducing dilation and parting patterns consistent with laboratory observations and pressure response consistent with field observations. INTRODUCTION There are several important petroleum, mining, and environmental engineering applications that involve large-scale deformation, failure, and fluid flow processes in weakly consolidated media. These include gravel injection and "frae-pack" operations to both stimulate a well and provide sanding control, grout injection to create barriers for contaminant flow in porous media, and slurry waste injection in deep wells. Unfortunately, the geomechanical aspects and controls on such operations remain poorly understood. Continuum models have difficulty capturing the basic physical processes of microcracking, disaggregation, and grain movement that occur during fracture and slurry injection in weakly consolidated media. These are inherently "discontinuous" failure processes. Traditional fracture mechanics approaches are particularly ill suited for modeling such phenomena because they are fundamentally based on stress singularities and strain energy dissipation processes at an advancing fracture tip. Fracture or "parting" of weakly consolidated media with near zero shear strength, however, is dominated by energy dissipatedeforming, shearing, and dilating material over a large area; fracture toughness and traditional tip mechanics are relatively inconsequential. The objective of our research, funded in part by the U.S. Department of Energy and the Alberta Department of Energy, has been to develop an improved understanding of such processes by developing alternative modeling techniques. One component of our effort has involved coupled particle and fluid flow modeling. In this paper we first present an overview of traditional linear elastic fracture mechanics, starting from first energy principles and extending to the stress intensity factor approach common to most hydraulic fracture models. We describe the limitations of such models when considering distributed damage proc-esses involved in fracture and parting of weakly consolidated media, and suggest an alternative approach using discrete particle modeling techniques. We investigate and conclude that particle models can capture observed physical processes in weakly cemented media, providing insights on material parameters which influence a change from discrete brittle fracturing (as occurs in stiff and strong geomaterial) to general dilation and parting (as occurs in very soft and weak geomaterials). The primary influence on parting behavior is shear bonding at the granular scale. Tensile bond properties have much less influence. Next we investigate slurry injection processes in granular media by coupling fluid flow simulators with part
- North America > United States (1.00)
- North America > Canada > Alberta (0.24)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.68)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
ABSTRACT: A numerical scheme to couple pore fluid flow in a 2-dimensional discrete particle model is developed based on the commercial code PFC (Particle Flow Code). The fluid-coupled particle model is used to study the permeability change of a simulated granular material while subjected to stress change. The particle model simulates granular material like sandstones with an aggregate of cemented particles (balls or disks). The pore fluid flow network is simulated with pores connected by pipes. It is solved in an explicit scheme. The pores and pipes are associated with the particle model. They are updated with the deformation and damage development of the solid part. The fluid pressure around a particle is integrated and applied to the particle. The fundaments of the coupling scheme and some modeling results are presented in this paper. INTRODUCTION Hydrocarbons are often produced with pore pressure depletion. This changes the in-situ effective stresses in the reservoir. The stress changes may induce damage and shear-enhanced compaction, which may affect the permeability of the reservoir materials. Reliable estimates of permeability and its stress de-pendence are crucial to successful planning and management of petroleum reservoirs. Many researchers have investigated the relatioaship between permeability changes and stress changes. When porous materials deform elastically the permeability reduction is quite small and can often he predicted by, for example, the semi-empirical Kozeny-Carman equation (Holt, 2000). Network models can also make good evaluation of the permeability (Bryant, 1993). When the materials yield, however, significant permeability alteration may occur (Holt, 1990; Bruno, 1994; Ruistuen, 1997; Ferfera et al., 1997; Bout?ca et al., 2000). The permeability change of the reservoir materials depends on the constitutive mechanical behavior of the rock (dilatancy or non-dilatancy) and on the stress path. A rigid relationship is not yet established. Particle models have been applied to study mechanical properties of weakly cemented sandstones with success (Ruistuen, 1997; Holt et al., 2000). Compared to laboratory experiments, numerical modeling is economic and efficient. The parameters in numerical models are easy to change, and hence can he thoroughly studied. Numerical modeling is a good tool to improve the design of experiments and the data interpretation, even though it is not a substitution. Combining it with a flow network model, Bruno (1994) applied a discrete particle model to study stress-induced permeability anisotropy. Considering the mutual effects between the fluid and solid part, fluid coupled particle models have been developed (Cundall, 1999) and applied to study stress dependent permeability (Li et al., 2000). This paper presents a numerical scheme of the fluid coupled particle model (2D) and results by applying the model to study stress dependent permeability. A commercial code, PFC2D is used as the basis of the developments.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.83)
Extensional wave attenuation and velocity in partially-saturated sand in the sonic frequency range
Liu, Z. (University of California) | Rector, J.W. (University of California) | Nihei, K.T. (Lawrence Berkeley National Laboratory) | Tomutsa, L. (Lawrence Berkeley National Laboratory) | Myer, L.R. (Lawrence Berkeley National Laboratory) | Nakagawa, S. (Lawrence Berkeley National Laboratory)
ABSTRACT: Extensional wave attenuation and velocity measurements on a high permeability Monterey sand were performed over a range of gas saturations for imbibition and degassing conditions. These measurements were conducted using extensional wave pulse propagation and resonance over a 1 9 kHz frequency range for a hydrostatic confining pressure of 8.3 MPa. Analysis of the extensional wave data and the corresponding Xray CT images of the gas saturation show strong attenuation resulting from the presence of the gas (QE dropped from 300 for the dry sand to 30 for the partially-saturated sand), with larger attenuation at a given saturation resulting from heterogeneous gas distributions. The extensional wave velocities are in agreement with Gassmann theory for the test with near-homogeneous gas saturation and with a patcry saturation model for the test with heterogeneous gas saturation. These results show that partially-saturated sands under moderate confining pressure can produce strong intrinsic attenuation for extensional waves. INTRODUCTION The acoustic properties of poorly-consolidated sands is a topic of importance in a number of fields, including geotechnical investigation of soil properties for stability (Stoll, 1989; Ishihara, 1996), environmental monitoring of contaminants in the shallow subsurface (Geller and Myer, 1995; Seifert et al., 1998), and geophysical characterization of sand reservoirs and aquifers for petroleum production (Gardner et al., 1964) and CO2 sequestration (Eiken et al., 2000). Poorly-consolidated sands can be viewed as an end-member of the spectrum of naturally-occurring granular materials, with tight sandstones as the other end-member. From a macroscopic scale, poorly consolidated sand might appear as a deceptively simple porous granular material. However, the strong stress sensitivity of sand packings, along with the added complexities resulting from the presence of clay, and multiple fluid and gas phases, conspire to make the present understanding of this class of materials incomplete. Systematic studies of these effects over a broad frequency-range are required for a comprehensive understanding of the acoustic properties of poorly consolidated sands. The overall objective of our research program on sands is to investigate the role of partial gas saturation on the attenuation and velocity of acoustic waves in the seismic to sonic frequency range (1 Hz to 20 kHz) over a range of confining pressures. As a first step towards this goal, we have developed a sonic frequency apparatus that utilizes resonance and pulse propagation to measure the velocities and attenuation of poorly consolidated sands under hydrostatic confinement. The confining vessel is fabricated of aluminum, allowing the gas and fluid phases to be imaged with an X-ray CT scanner. In this paper, we report our recent efforts to measure the extensional wave velocities and attenuation of a Monterey sand with homogeneous and heterogeneous distributions of gas.
- Research Report > New Finding (0.67)
- Research Report > Experimental Study (0.49)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.55)
- Geology > Geological Subdiscipline > Geomechanics (0.47)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.89)
ABSTRACT : Laboratory experiments and numerical simulations, using Particle Flow Code (PFC3D), were performed to study the behavior of jointed blocks of model material under uniaxial loading. The fracture tensor component in a given direction is used to quantify the combined directional effect of joint geometry parameters including joint density, orientation and size distributions, and the number of joint sets. Both the laboratory experiments and the numerical simulations showed that the uniaxial block strength decreases in a nonlinear manner with increasing values of the fracture tensor component. Joint geometry configuration was also observed to control the mode of failure of the jointed blocks and three modes of failure were identified, namely (a) tensile splitting through the intact material, (b) either only shear failure along the joint planes or both shear and tensile failure with respect to the joint planes and, (c) mixed mode failure involving both the failure mechanisms in (a) and (b). It has also been shown that with very careful parameter calibration procedures, PFC3D could be used to model the strength behavior of jointed blocks of rock under uniaxial loading. 1 INTRODUCTION Rock encountered in most engineering applications is, in its most general form, an anisotropic, discontinuous mass containing blocks of intact rock interspaced with cracks, joints, fissures, faults and bedding planes, all with their own unique mechanical behavior characteristics. Thus, in attempting to construct a peak strength criterion for rock masses, one should take into account the effect of various discontinuity geometry parameters and their mechanical properties, in addition to the mechanical properties of the intact rock material and the stress field.
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Well Drilling > Wellbore Design > Wellbore integrity (0.55)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (0.40)
Numerical Derivation of the Equivalent Hydro-Mechanical Properties of Fractured Rock Masses Using Distinct Element Method
Min, K.-B. (Civil & Environmental Engineering, Royal Institute of Technology (KTH)) | Ivars, D.M. (Civil & Environmental Engineering, Royal Institute of Technology (KTH)) | Jing, L. (Civil & Environmental Engineering, Royal Institute of Technology (KTH))
ABSTRACT : This paper presents a numerical method for deriving the equivalent mechanical and hydraulic properties of fractured rock masses using the Distinct Element Method (DEM). Based on 2D fracture system realizations, numerical experiments were performed on a series of square DEM models of increasing side lengths with constant velocity or constant hydraulic pressure gradient boundary conditions. Representative Elementary Volumes (REVs) were established as the minimum model area after which the average mechanical and hydraulic properties maintain constant values. The results of numerical simulations show that DEM can be an effective numerical tool for the homogenization of the hydro-mechanical properties of fractured rock masses. 1 INTRODUCTION The fact that the properties of rock samples measured in the laboratory-scale cannot represent the field-scale properties of rock masses has always been the weak point for the solutions of many rock engineering problems, especially for the numerical method applications (Pariseau 1999). Because the confidence of the numerical simulation is highly dependent on the properties of rock masses, the development of the proper method to determine the hydro-mechanical properties of rock masses is very important. The attempts to determine the “equivalent ” properties of rock masses using numerical methods from the given characteristics of intact rock and fractures can be justified because it is very difficult to measure the field-scale properties of rock masses directly.
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- (2 more...)