Showing papers on "Permeability (earth sciences) published in 2002"
TL;DR: In this article, two computer codes, TOUGH2 and FLAC3D, are linked and jointly executed for coupled thermal-hydrologic-mechanical (THM) analysis of multiphase fluid flow, heat transfer, and deformation in fractured and porous rock.
771 citations
TL;DR: In this paper, a process-based method for reconstructing the full three-dimensional microstructure of sandstones is presented, which utilizes petrographical information obtained from two-dimensional thin sections to stochastically model the results of the main sandstone forming processes such as sedimentation, compaction, and diagenesis.
Abstract: We present a process based method for reconstructing the full three-dimensional microstructure of sandstones. The method utilizes petrographical information obtained from two-dimensional thin sections to stochastically model the results of the main sandstone forming processes – sedimentation, compaction, and diagenesis. We apply the method to generate Fontainebleau sandstone and compare quantitatively the reconstructed microstructure with microtomographic images of the actual sandstone. The comparison shows that the process based reconstruction reproduces adequately important intrinsic properties of the actual sandstone, such as the degree of connectivity, the specific internal surface, and the two-point correlation function. A statistical reconstruction of Fontainebleau sandstone that matches the porosity and two-point correlation function of the microtomography data differs strongly from the actual sandstone in its connectivity properties. Transport properties of the samples are determined by solving numerically the local equations governing the transport. Computed permeabilities and formation factors of process based reconstructions of Fontainebleau sandstone compare well with experimental measurements over a wide range of porosity.
554 citations
TL;DR: In this paper, the authors focus on quantification and predictability of three major causes of anomalous high porosity: (1) grain coats and grain rims, (2) early emplacement of hydrocarbons, and (3) shallow development of fluid overpressure.
Abstract: Porosity and permeability generally decrease with increasing depth (thermal exposure and effective pressure); however, a significant number of deep (>4 km [approximately 13,000 ft]) sandstone reservoirs worldwide are characterized by anomalously high porosity and permeability. Anomalous porosity and permeability can be defined as being statistically higher than the porosity and permeability values occurring in typical sandstone reservoirs of a given lithology (composition and texture), age, and burial/temperature history. In sandstones containing anomalously high porosities, such porosities exceed the maximum porosity of the typical sandstone subpopulation. Major causes of anomalous porosity and permeability were identified decades ago; however, quantification of the effect of processes responsible for anomalous porosity and permeability and the assessment of the predictability of anomalous porosity and permeability occurrence in subsurface sandstones have rarely been addressed in published literature. The focus of this article is on quantification and predictability of three major causes of anomalously high porosity: (1) grain coats and grain rims, (2) early emplacement of hydrocarbons, and (3) shallow development of fluid overpressure. Grain coats and grain rims retard quartz cementation and concomitant porosity and permeability reduction by inhibiting precipitation of quartz overgrowths on detrital-quartz grains. Currently, prediction of anomalous porosity associated with grain coats and grain rims is dependent on the availability of empirical data sets. In the absence of adequate empirical data, sedimentologic and diagenetic models can be helpful in assessing risk due to reservoir quality. Such models provide a means to evaluate the effect of geologic constraints on coating occurrence and coating completeness required to preserve economically viable porosity and permeability (Begin page 302) in a given play or prospect. These constraints include thermal history and sandstone grain size and composition. The overall effect of hydrocarbon emplacement on reservoir quality is controversial. It appears that at least some cements (quartz and illite) may continue to precipitate following emplacement of hydrocarbons into the reservoir. Our work indicates that integration of basin modeling with reservoir quality modeling can be used to quantify, prior to drilling, the potential impact of hydrocarbon emplacement on porosity and permeability. The best-case scenario for significant reservoir quality preservation due to fluid overpressure development is in rapidly deposited Tertiary or Quaternary sandstones. Our models suggest that significant porosity can be preserved in sandstones that have experienced continuous high fluid overpressures from shallow burial depths. The models also indicate that the potential for porosity preservation is greatest in ductile-grain-rich sandstones because compaction tends to be the dominant control on reservoir quality in such rocks. The case for significant porosity preservation associated with fluid overpressures in pre-Tertiary basins, however, is more problematic because of the complexities in the history of fluid overpressure and the greater significance of quartz cementation as a potential mechanism of porosity loss.
481 citations
TL;DR: A flow-stress-damage coupling model for heterogeneous rocks that takes into account the growth of existing fractures and the formation of new fractures is proposed in this article, which is used to investigate the behaviour of fluid flow and damage evolution, and their coupling action, in samples that are subjected to both hydraulic and biaxial compressive loadings.
358 citations
TL;DR: A method is proposed to measure the water permeability of membrane channels by means of molecular dynamics simulations by applying a constant force to the bulk water molecules and a counter force on the complementary system, producing a net directional water flow.
305 citations
TL;DR: In this paper, the capillary sealing efficiency of fine-grained sedimentary rocks has been investigated by gas breakthrough experiments on fully water saturated claystones and siltstones (Boom Clay from Belgium, Opalinus Clay from Switzerland and Tertiary mudstone from offshore Norway) of different lithological compositions.
Abstract: The capillary sealing efficiency of fine-grained sedimentary rocks has been investigated by gas breakthrough experiments on fully water saturated claystones and siltstones (Boom Clay from Belgium, Opalinus Clay from Switzerland and Tertiary mudstone from offshore Norway) of different lithological compositions. Sand contents of the samples were consistently below 12%, major clay minerals were illite and smectite. Porosities determined by mercury injection lay between 10 and 30% while specific surface areas determined by nitrogen adsorption (BET method) ranged from 20 to 48 m2 g − 1. Total organic carbon contents were below 2%.
Prior to the gas breakthrough experiments the absolute (single phase) permeability (kabs) of the samples was determined by steady state flow tests with water or NaCl brine. The kabs values ranged between 3 and 550 nDarcy (3 × 10−21 and 5.5 × 10−19 m2). The maximum effective permeability to the gas-phase (keff) measured after gas breakthrough on initially water-saturated samples extended from 0.01 nDarcy (1 × 10−23 m2) up to 1100 nDarcy (1.1 × 10−18 m2). The residual differential pressures after re-imbibition of the water phase, referred to as the ‘minimum capillary displacement pressures’ (Pd), ranged from 0.06 to 6.7 MPa. During the re-imbibition process the effective permeability to the gas phase decreases with decreasing differential pressure. The recorded permeability/pressure data were used to derive the pore size distribution (mostly between 8 and 60 nm) and the transport porosity of the conducting pore system (10-5–10-2%).
Correlations could be established between (i) absolute permeability coefficients and the maximum effective permeability coefficients and (ii) effective or absolute permeability coefficients and capillary sealing efficiency. No correlation was found between the capillary displacement pressures determined from gas breakthrough experiments and those derived theoretically by mercury injection.
296 citations
TL;DR: In this paper, an approach to estimate the large-scale permeability of reservoirs using seismic emission (microseismicity) induced by fluid injection is presented. But this approach is based on the hypothesis that the triggering front of hydraulically-induced microseismic propagates like a diffusive process (pore pressure relaxation) in an effective homogeneous anisotropic poroelastic fluid-saturated medium.
Abstract: We systematically describe an approach to estimate the large-scale permeability of reservoirs using seismic emission (microseismicity) induced by fluid injection. We call this approach seismicity-based reservoir characterization (SBRC). A simple variant of the approach is based on the hypothesis that the triggering front of hydraulically-induced microseismicity propagates like a diffusive process (pore pressure relaxation) in an effective homogeneous anisotropic poroelastic fluid-saturated medium. The permeability tensor of this effective medium is the permeability tensor upscaled to the characteristic size of the seismically active heterogeneous rock volume. We show that in a homogeneous medium the surface of the seismicity triggering front has the same form as the group-velocity surface of the low-frequency anisotropic, second-type Biots wave (i.e., slow wave). Further, we generalize SBRC for 3-D mapping of the permeability tensor of heterogeneous reservoirs and aquifers. For this we apply an approach similar to the geometric optics approximation. We derive an equation describing kinematic aspects of triggering-front propagation in a way similar to the eikonal equation for seismic wavefronts. In the case of isotropic heterogeneous media, the inversion for the hydraulic properties of rocks follows from a direct application of this equation. In the case of an anisotropic heterogeneous medium, only the magnitude of a global effective permeability tensor can be mapped in a 3-D spatial domain. We demonstrate the method on several field examples and also test the eikonal equation-based inversion.
293 citations
TL;DR: In this article, a hydraulic testing system was built to investigate the hydraulic behavior of rough tension fracture, which is capable of measuring both the flow rates and the normal and shear displacement of a rock fracture.
Abstract: A hydro-mechanical testing system, which is capable of measuring both the flow rates and the normal and shear displacement of a rock fracture, was built to investigate the hydraulic behaviour of rough tension fractures. Laboratory hydraulic tests in linear flow were conducted on rough rock fractures, artificially created using a splitter under various normal and shear loading. Prior to the tests, aperture distributions were determined by measuring the topography of upper and lower fracture surfaces using a laser profilometer. Experimental variograms of the initial aperture distributions were classified into four groups of geostatistical model, though the overall experimental variograms could be well fitted to the exponential model. The permeability of the rough rock fractures decayed exponentially with respect to the normal stress increase up to 5 MPa. Hydraulic behaviours during monotonic shear loading were significantly affected by the dilation occurring until the shear stress reached the peak strength. With the further dilation, the permeability of the rough fracture specimens increased more. However, beyond shear displacement of about 7 to 8 mm, permeability gradually reached a maximum threshold value. The combined effects of both asperity degradation and gouge production, which prohibited the subsequent enlargement of mean fracture aperture, mainly caused this phenomenon. Permeability changes during cyclic shear loading showed somewhat irregular variations, especially after the first shear loading cycle, due to the complex interaction from asperity degradations and production of gouge materials. The relation between hydraulic and mechanical apertures was analyzed to investigate the valid range of mechanical apertures to be applied to the cubic law.
223 citations
TL;DR: In this article, a brief and simple account of continuum models for transport in porous media, and the role of length scales in passing from pore-scale phenomena to “Darcy” continuum scale representations using averaged variables.
Abstract: This article first provides a brief and simple account of continuum models for transport in porous media, and of the role of length scales in passing from pore-scale phenomena to “Darcy” continuum scale representations using averaged variables. It then examines the influence of non-Newtonian rheology on the single- and multi-phase transport parameters, i.e. Darcy viscosity, dispersion lengths and relative permeabilities. The aim is to deduce functional forms and values for these parameters given the rheological properties of the fluid or fluids in question, and the porosity, permeability, dispersion lengths and relative permeabilities (based on Newtonian fluids and equivalent capillary pressures) of the porous medium. It is concluded that micro-models, typically composed of capillary networks, applied at a sub-Darcy-scale, parameterised using data for flows of a well-characterised set of non-Newtonian fluids, are likely to provide the most reliable means.
213 citations
TL;DR: In this article, eight samples cored from the same mortar were used to investigate their respective gas, ethanol and water permeability, and two gas and liquid permeability cells, using special devices for measuring the injected flow under steady conditions, were designed and presented in this paper.
190 citations
TL;DR: In this article, in situ measurements of fluid flow and pressure in floor strata were carried out in a double longwall mining face in the Yangzhuang colliery, and 3D numerical modeling was carried out to better understand this change in hydraulic behavior around the mining faces.
TL;DR: In this paper, a fractal in-plane permeability model for various fabrics is developed based on the fractal characteristics of pores in fiber preforms, which can be expressed as a function of the pore area fractal dimension and architectural parameters of the fiber preform.
Abstract: In this paper, a fractal in-plane permeability model for various fabrics is developed. The model is based on the fractal characteristics of pores in fiber preforms. Four different glass fabrics are considered in the modeling: plain woven, 4-harness, bidirectional stitched, and continuous strand random mats. The fractal in-plane permeability model can be expressed as a function of the pore area fractal dimension and architectural parameters of the fiber preform. This model also relates the permeability to porosity changes of fiber preforms under compression, which usually occurs in the molding processes. To verify the applicability of the model, the results from the present fractal model are compared with those from the one-dimensional analysis model and with a set of permeability measurements. Good agreement is found between the two models and the permeability measurements in the general porosity ranges of interest.
TL;DR: In this paper, the authors present an equation for estimating fault zone thickness from fault throw based on outcrop data from Sinai and Northumberland, showing that the throw/thickness relationship is dependent on lithology, and can be related to the clay content of the fault zone.
Abstract: Faults in clastic sequences are often significant barriers to single-phase fluid flow and can act as absolute barriers to the flow of non-wetting phases over geological time. Knowledge of the fault rock flow properties, as well as the width of the fault zone is required in order to conduct fluid flow simulations in faulted reservoirs. In this paper we present an equation for estimating fault zone thickness from fault throw based on outcrop data from Sinai and Northumberland. These data show that the throw/thickness relationship is dependent on lithology, and can be related to the clay content of the fault zone. The permeability and threshold pressures of fault rocks are dependent on factors such as the mineralogical composition of the faulted rock, the effective stress conditions and the time-temperature history of the reservoir prior to, during and following deformation. A strong power law relationship is established between threshold pressure and permeability, which is insensitive to the faulting mechanisms. The permeability and the threshold pressures of both the host rocks and the fault rocks can be represented by functions which are dependent on the clay content and the maximum burial depth (i.e. time-temperature history), whereas for the fault rocks the depth (i.e. effective stress conditions) at the time of deformation also needs to be taken into account. The database from which these empirical relationships were derived contains core measurements from faults and their associated host rocks in siliciclastic sequences from the North Sea. Many types of fault rock are contained within the database (disaggregation zones, cataclastic faults, phyllosilicate-framework faults and clay smears) and these have experienced a wide range in their maximum burial depths (2000–4500 m). In reservoir simulation the sealing effect of the faults can be represented as transmissibility modifiers for each grid cell, calculated from knowledge of fault rock permeability, the width of the fault zone, the grid block permeabilities and the geometry of the simulation grid. We have applied the technique to a number of North Sea reservoirs, using the new equation for calcu- lating fault rock permeability. However, even if the new equation produced lower permeabilities than previously published relationships, in all cases the transmissibility modifiers generated by this technique proved consistently too high (1–2 orders of magnitude) in order to produce good history matches. In order to further improve the model, and to get better history match, we think that it is important to include capillary effects, relative transmissibility multipliers, the new equation for calculating fault zone width and to better constrain the clay content of the fault zone. However, better methods are still required for capturing complex fault geometries in the reservoir model.
TL;DR: In this article, the large-scale equivalent permeabilities of strike-slip faults in porous sandstone are computed from detailed field measurements, which can be used for any type of fault for which detailed structural and permeability data are available.
Abstract: The large-scale equivalent permeabilities of strike-slip faults in porous sandstone are computed from detailed field measurements. The faults, which occur in the Valley of Fire State Park, Nevada, were previously characterized, and the flow properties of their individual features were estimated. The faults formed from the shearing of joint zones and are composed of a core of fine-grain fault rock (gouge) and deformation bands and a peripheral damage zone of joints and sheared joints. High-resolution fault-zone maps and permeability data, estimated using image analysis calibrated to actual measurements, are incorporated into detailed finite difference numerical calculations to determine the permeability of regions of the fault zone. Faults with slips of magnitude 6, 14, and 150 m are considered. The computed fault-zone permeabilities are strongly anisotropic in all cases. Permeability enhancement of nearly 1 order of magnitude (relative to the host rock) is observed for the fault-parallel component in some regions. Fault-normal permeability, by contrast, may be 2 orders of magnitude less than the host rock permeability. The fault-normal permeability is a minimum for the fault with the highest slip. For a representative fault region, the fault-parallel component of permeability is highly sensitive to the fracture aperture, although the fault-normal permeability is insensitive. The procedures developed and applied in this article can be used for any type of fault for which detailed structural and permeability data are available or can be estimated.
01 Jan 2002
TL;DR: In this paper, a method based on interrelationships between petrophysical properties is used to calculate maximum residual gas saturation (Sgrm) as a function of porosity, permeability, capillary pressure, and initial water saturation.
Abstract: Residual gas saturation controls the volume of gas trapped in that portion of the reservoir that has experienced water encroachment. As water moves into a rock volume filled with gas, the water displacement of the gas is incomplete. The water fills pores and pore throats, causing capillary pressure and relative permeability effects to stop the flow of gas and allow only water to pass through the rock volume. This stoppage results in gas being trapped behind the encroaching waterfront as residual gas. The volume and location of the residual gas are controlled by the distribution of the petrophysical properties. A method based on interrelationships between petrophysical properties is used to create a model for calculating maximum residual gas saturation (Sgrm). The model is developed as a function of porosity, permeability, capillary pressure, and initial water saturation. The input to the model and its results compare favorably with actual field data where aquifer encroachment is verified from well production history.
TL;DR: In this article, a coupling between crack growth and permeability change was determined to fully understand the hydro-mechanical response of rocks subjected to non-hydrostatic stress, particularly when we deal with highly damaged granite.
TL;DR: In this article, the authors used power law fracture length and fracture permeability distributions to model the equivalent permeability of two-dimensional (2D) discrete fracture networks by using numerical simulations and theoretical arguments.
Abstract: [1] Field observations have revealed that the diffusion properties of fractured materials are strongly influenced by the presence of fractures. Using power law fracture length and fracture permeability distributions currently observed on natural fractured networks, we model the equivalent permeability of two-dimensional (2D) discrete fracture networks by using numerical simulations and theoretical arguments. We first give the dependence of the network equivalent permeability, obtained at the scale of the network, on the characteristic power law exponents of the fracture length and fracture permeability distributions. We especially show that the equivalent permeability depends simply on the geometrical mean of the local fracture permeability distribution. Such networks are characterized by an increase of permeability with scale without limitations, provided that the fracture length and fracture permeability distributions are broad enough. Although a correlation length cannot be systematically defined, the flow structure is still characterized by simple properties. The flow is either extremely channeled in one dominant path or distributed in several separated structures. We show finally that the observed scale effects and flow structure are very different from the one obtained in the lognormal fracture permeability distribution case.
TL;DR: In this paper, the authors analyze the correction to be considered when non-negligible mass exchanges between the constituents are present, both on a thermodynamical basis and using a symmetry and frame indifferent argument.
Abstract: The flow of a Newtonian fluid in porous media can be described using Darcy's law when inertial effects and deformations in the solid can be neglected and no mass interchange occur between the solid and the fluid components. Having in mind bio-medical applications, we analyze the correction to be considered when non-negligible mass exchanges between the constituents are present. This is done both on a thermodynamical basis and using a symmetry and frame indifferent argument.
TL;DR: In this article, the role of shear dilation as a mechanism of enhancing fluid flow permeability in naturally fractured reservoirs was mainly recognized in the context of hot dry rock (HDR) geothermal reservoir stimulation.
Abstract: The role of shear dilation as a mechanism of enhancing fluid flow permeability in naturally fractured reservoirs was mainly recognized in the context of hot dry rock (HDR) geothermal reservoir stimulation. Simplified models based on shear slippage only were developed and their applications to evaluate HDR geothermal reservoir stimulation were reported. Research attention is recently focused to adjust this stimulation mechanism for naturally fractured oil and gas reservoirs which reserve vast resources worldwide. This paper develops the overall framework and basic formulations of this stimulation model for oil and gas reservoirs. Major computational modules include: natural fracture simulation, response analysis of stimulated fractures, average permeability estimation for the stimulated reservoir and prediction of an average flow direction. Natural fractures are simulated stochastically by implementing ‘fractal dimension’ concept. Natural fracture propagation and shear displacements are formulated by following computationally efficient approximate approaches interrelating in situ stresses, natural fracture parameters and stimulation pressure developed by fluid injection inside fractures. The average permeability of the stimulated reservoir is formulated as a function of discretized gridblock permeabilities by applying cubic law of fluid flow. The average reservoir elongation, or the flow direction, is expressed as a function of reservoir aspect ratio induced by directional permeability contributions. The natural fracture simulation module is verified by comparing its results with observed microseismic clouds in actual naturally fractured reservoirs. Permeability enhancement and reservoir growth are characterized with respect to stimulation pressure, in situ stresses and natural fracture density applying the model to two example reservoirs. Copyright © 2002 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors present experiments conducted in sand-packed columns with initially steady unsaturated flow conditions that show significant biomass-induced changes in pressure heads and water contents and permeability reduction during growth of a Pseudomonas fluorescens bacterium, and discuss characteristics of unsaturated or variably saturated porous media that may be important to consider when modeling such phenomena in these systems.
01 Jan 2002
TL;DR: In this paper, the authors evaluated the relationship between in-place air voids, lift thickness, and permeability, 23 hot mix asphalt (HMA) construction projects were visited and field permeability tests conducted.
Abstract: In order to evaluate the relationships between in-place air voids, lift thickness, and permeability, 23 on-going hot mix asphalt (HMA) construction projects were visited and field permeability tests conducted. Field permeability tests were conducted at 15 randomly determined sites for each project. Cores were taken at each of the 15 locations to determine pavement density using AASHTO T166. In addition, for some of the projects, the cores were tested with the Corelok device and a laboratory permeameter. As agencies begin to include permeability specifications, mix designers need tools they can use during the mix design process to evaluate the permeability characteristics of a given aggregate structure. Two techniques were evaluated: laboratory permeability measurements on samples compacted using the Superpave gyratory compactor and water absorption determined with AASHTO T166 or the Corelok device. Results of testing within this study indicated a good relationship between permeability (measured in the field and laboratory) and pavement density. Both the gradation nominal maximum aggregate size (NMAS) and the lift thickness placed in the field were shown to affect the permeability-density relationship. Increasing the NMAS requires higher densities to ensure an impermeable pavement. Also, as the lift thickness of a given pavement (and mixture) increases, permeability decreases at a given density level. Some reasonable relationships were found between the permeability of samples compacted using the gyratory compactor and field samples. Reasonable relationships were found between permeability and water absorption regardless of NMAS.
TL;DR: In this article, double-porosity materials were introduced as models for oil and gas reservoirs having both storage and transport porosities, and were at first usually treated as static mechanical systems in order to study the flow patterns of fluids during reservoir pump-down.
Abstract: Double-porosity materials were introduced as models for oil and gas reservoirs having both storage and transport porosities, and were at first usually treated as static mechanical systems in order to study the flow patterns of fluids during reservoir pump-down. Because fluid withdrawal normally increases the effective stress acting on the reservoir, it also turns out to be important to study the geomechanics of the reservoir and how changing fluid pressure affects the solid compaction and fluid permeability of these systems. At the microscale, the mechanical properties of the solid constituents and their distribution in space determine the overall macromechanics of the reservoir system. For systems containing two porosities and two types of solid constituents, exact results for all but one (which may be taken as the overall drained bulk modulus of the system) of the mechanical constants can be derived when the constituents’ properties are known using methods developed in this paper. For multi-porosity systems, closure of the system of equations remains an open question, although it is clear that the system can always be closed by the addition of further macroscale measurements.
TL;DR: It is suggested that the nonuniqueness of capillary pressure-relative permeability-saturation relationships is due to the presence of microheterogeneities within a laboratory sample, and a large number of "numerical experiments" are carried out.
TL;DR: In this article, the performance of a new type of simple and inexpensive field permeameter (PD) is compared with two established alternatives, the laboratory constant head permeameters (LP) and the field Guelph permeammeter (GP).
Abstract: One of the most sensitive parameters in hydrological models, the saturated hydraulic conductivity (K s ), is also one of the most problematic measurements at field scale in regard to variability and uncertainty. The performance of a new type of simple and inexpensive field permeameter, the Philip-Dunne permeameter (PD), is compared with two established alternatives, the laboratory constant head permeameter (LP) and the field Guelph permeameter (GP). A PD prototype, a protocol of usage, and a numerical routine to find K s were developed and tested on a 70-point array laid out on an 850-m 2 volcanic soil plot. A power transformation was applied to the raw data using the three methods, and the transformed data were shown to be normally distributed. The LP and GP data were better described by a log-normal distribution, whereas the PD data could also be approximated with a power-normal distribution. A factor of 3 was found to relate PD, LP, and GP hydraulic conductivity estimates, E[Ks], such that E[K s -PD] ≅ 3 E[K s -LP]; E[K s -LP] ≅ 3 E[K s -GP]. Such differences may be explained by the different water infiltration geometries and sample wetted volume for the three methods. The PD has advantages over the other two methods in terms of personnel involved, preparation time, and ease of operation. Additionally, the PD methodology required a smaller number of samples (41% less than GP and 69% less than LP) to estimate the population mean K s . Both PD and GP also give the suction at the wetting front, an important parameter that characterizes the unsaturated flow properties of the soil.
TL;DR: An approach for using flow information from a system of wells to characterize hydrologic properties of an aquifer is given, using Markov chain Monte Carlo for exploring the high-dimensional posterior distribution and an intrinsically stationary Markov random field is used.
Abstract: We give an approach for using flow information from a system of wells to characterize hydrologic properties of an aquifer. In particular, we consider experiments where an impulse of tracer fluid is injected along with the water at the input wells and its concentration is recorded over time at the uptake wells. We focus on characterizing the spatially varying permeability field, which is a key attribute of the aquifer for determining flow paths and rates for a given flow experiment. As is standard for estimation from such flow data, we use complicated subsurface flow code that simulates the fluid flow through the aquifer for a particular well configuration and aquifer specification, in particular the permeability field over a grid. The solution to this ill-posed problem requires that some regularity conditions be imposed on the permeability field. Typically, this regularity is accomplished by specifying a stationary Gaussian process model for the permeability field. Here we use an intrinsically stationary ...
01 Jul 2002
TL;DR: In this article, the authors evaluated the relationship between in-place air voids, lift thickness, and permeability in hot mix asphalt (HMA) construction projects and field permeability tests conducted.
Abstract: In order to evaluate the relationships between in-place air voids, lift thickness, and permeability, 23 on-going hot mix asphalt (HMA) construction projects were visited and field permeability tests conducted. Field permeability tests were conducted at 15 randomly determined locations for each project. Cores were taken at each of the 15 locations to determine pavement density using AASHTO T166. In addition, for some of the projects, cores taken from roadway were tested with the Corelok device and a laboratory permeameter. As agencies begin to include permeability specifications, mix designers need tools they can use during the mix design process to evaluate the permeability characteristics of a given aggregate structure. Two techniques were evaluated: laboratory permeability measurements on samples compacted using the Superpave gyratory compactor and water absorption determined with AASHTO T 166 or the Corelok device. Results of testing within this study indicated a good relationship between permeability (measured in the field and lab) and pavement density. Both the gradation's nominal maximum aggregate size (NMAS) and the lift thickness placed in the field were shown to affect the permeability-density relationship. Increasing the NMAS requires higher densities to ensure an impermeable pavement. Also, as the lift thickness of a given pavement (and mixture) increases, permeability decreases at a given density level. Some reasonable relationships were found between the permeability of samples compacted using the gyratory compactor and field samples. Reasonable relationships were also found between permeability and water absorption regardless of nominal maximum aggregate size.
TL;DR: In this article, the transverse permeability of new multiaxial stitched materials, referred to as NC2, is investigated in the framework of Darcy's flows, and the results from a simplified FE study carried out at the blanket scale are shown to correlate quite well the experimental measurements and evidences established in the first part.
TL;DR: The Permian Salado Formation in the Delaware Basin of New Mexico is an extensively studied evaporite deposit because it is the host formation for the Waste Isolation Pilot Plant, a repository for transuranic wastes as mentioned in this paper.
01 Jan 2002
TL;DR: In this article, a summary of a number of laboratory measurements performed on North Sea material, which can serve as a database for initial evaluation, is provided, with particular consideration given to residual saturation and end-point relative permeability.
Abstract: In an early stage of field evaluation there is a need to predict SCAL properties of the reservoir. Particular consideration should be given to residual saturation and end-point relative permeability. However, very limited amounts of experimental data are available at the initial stage. Hence, the objective of this work was to provide a summary of a number of laboratory measurements performed on North Sea material, which can serve as a database for initial evaluation. General trends with respect to variation of SCAL properties have been investigated with for instance, depositional environment, permeability, or wettability. We have summarised waterflooding, gas injection and trapped gas measurements and tried to find relations to reservoir characteristics. Examples of such relations are; End-point relative permeability as a function of permeability, rock type, depositional environment and wettability. Residual oil saturation was studied as function of; initial water saturation, permeability, and wettability. Finally, trapped gas as a function of; initial gas saturation, permeability, rock type, and depositional environment, have also been investigated. Gas trapping is found to be lower in three-phase flow than two-phase flow. The results from waterflooding, and wettability indices (USBM and Amott-Harvey) have identified three different types of intermediate wetting state.
TL;DR: In this paper, a numerical model is presented to evaluate the interactions between mechanisms that determine the shape of a reactive front, which includes the effects of grain dissolution and the alteration of porosity and permeability due to mineral-fluid reactions.