Permeability Of Porous Rocks Research Articles

Permeability prediction for porous sandstone using digital twin modeling technology and Lattice Boltzmann method

The permeability of porous rock is a crucial indicator evaluating its ability to allow liquids to pass through it. However, challenges are always encountered in measurement and prediction of permeability, including the complicated process of laboratory experiments and the refined 3D numerical reconstruction. In order to improve the efficiency and accuracy of permeability prediction, the digital twin modeling technology is proposed to generate homologous and heterogeneous digital sandstone models based on a single two-dimensional image in this paper. Comparison of the CT reconstruction with the digital twin of sandstone indicates that they are very similar in complementary solid-phase morphology of porous media, global parameters (total porosity, fractal dimension, tortuosity), and local parameters (porosity of sequence layer, pore and throat characteristics, coordination number). In addition, the permeability of CT reconstruction and ten digital twins are analyzed by using the Lattice Boltzmann Method. The results show that the permeability of digital twins is very stable and close to the CT reconstruction at three orthogonal directions. The findings in this study may provide an accurate, stable, rapid and economic method for predicting the permeability of porous media.

Accurate permeability prediction in tight gas rocks via lattice Boltzmann simulations with an improved boundary condition

Accurately predicting gas transport in rocks is required for enhancing the accuracy of field production models. The mesoscale lattice Boltzmann (LB) method can be implemented to predict gas permeability in porous rocks. However, the published LB results for the Klinkenberg effect are often inconsistent with the widely used Beskok-Karniadakis-Civan's (BKC's) correlation. The culprit of the unphysical effect has been identified in the typically implemented boundary conditions (BCs). An improved BC is proposed herein to reliably predict gas permeability. Non-equilibrium molecular dynamics simulations are conducted to benchmark the proposed approach. The results show that the presented LB predictions for the Klinkenberg effect are quantitatively consistent with experimental data and the BKC's correlation, indicating that the unphysical effects have been minimized. More importantly, a numerical consistency is achieved for describing the Klinkenberg effect at molecular through macroscopic scales. These observations are relevant for improving our ability to predict gas production from tight formations.

Stress-Dependent Porosity and Permeability of Porous Rocks Represented by a Mechanistic Elastic Cylindrical Pore-Shell Model

The stress dependency of the porosity and permeability of porous rocks is described theoretically by representing the preferential flow paths in heterogeneous porous rocks by a bundle of tortuous cylindrical elastic tubes. A Lame-type equation is applied to relate the radial displacement of the internal wall of the cylindrical elastic tubes and the porosity to the variation of the pore fluid pressure. The variation of the permeability of porous rocks by effective stress is determined by incorporating the radial displacement of the internal wall of the cylindrical elastic tubes into the Kozeny–Carman relationship. The fully analytical solutions of the mechanistic elastic pore-shell model developed by combining the Lame and Kozeny–Carman equations are shown to lead to very accurate correlations of the stress dependency of both the porosity and the permeability of porous rocks.

Fluid flow simulation and permeability computation in deformed porous carbonate grainstones

Abstract In deformed porous carbonates, the architecture of the pore network may be modified by deformation or diagenetic processes altering the permeability with respect to the pristine rock. The effects of the pore texture and morphology on permeability in porous rocks have been widely investigated due to the importance during the evaluation of geofluid reservoirs. In this study, these effects are assessed by combining synchrotron X-ray computed microtomography (SR micro-CT) and computational fluid dynamics. The studied samples pertain to deformed porous carbonate grainstones highly affected by deformation bands (DBs) exposed in Northwestern Sicily and Abruzzo regions, Italy. The high-resolution SR micro-CT images of the samples, acquired at the SYRMEP beamline of the Elettra - Sincrotrone Trieste laboratory (Italy), were used for simulating a pressure-driven flow by using the lattice-Boltzmann method (LBM). For the experiments, a multiple relaxation time (MRT) model with the D3Q19 scheme was used to avoid viscosity-dependent results of permeability. The permeability was calculated using Darcy's law once steady conditions were reached. After the simulations, the pore-network properties (effective porosity, specific surface area, and geometrical tortuosity) were calculated using 3D images of the velocity fields. These images were segmented considering a velocity threshold value higher than zero. The study showed that DBs may generate significant heterogeneity and anisotropy of the permeability of the evaluated rock samples. Cataclasis and cementation process taking place within the DBs reduce the effective porosity and therefore the permeability. Contrary to this, pressure dissolution and faulting may generate connected channels which contribute to the permeability only parallel to the DB.

Quantifying tight-gas sandstone permeability via critical path analysis

Rock permeability has been actively investigated over the past several decades by the geosciences community. However, its accurate estimation still presents significant technical challenges, particularly in spatially complex rocks. In this short communication, we apply critical path analysis (CPA) to estimate permeability in porous rocks from measured mercury intrusion porosimetry and electrical conductivity data. Theoretical estimations of various CPA-based models are then compared to experimental measurements using eighteen tight-gas sandstones. Except for two of the samples, we find permeability estimations performed with the Skaggs model (assuming pore diameter independent of its length) more accurate than other models, within a factor of two of the measured permeabilities. We discuss some plausible sources of the uncertainties.

A New Device for Measuring the Supercritical CO2 Permeability in Porous Rocks Under Reservoir Conditions

Abstract This paper describes a newly developed device for measuring the CO2 permeability coefficient in porous rocks under reservoir conditions, in which the pressure and temperature of injected CO2 are usually beyond the critical point of 7.38 MPa and 31.8°C. The device consists of a pressure cell, a syringe pump for CO2, a pressure amplifier, a heating unit, and a measurement system. Two buffer tanks are set at the inlet and outlet of the seepage chamber to maintain stable CO2 injection and back pressures during testing. The supercritical CO2 flowing through the rock sample is depressurized to the gaseous phase to measure its flow rate at low pressure. An average flow rate over time is used to calculate the permeability coefficient of CO2 in the rock sample. A performance test was conducted to demonstrate the detailed characteristics of the device. A sample application using silt rock for testing proved that the device can effectively measure the permeability coefficient of supercritical CO2 in porous rock.

Acoustics simulation and analysis of three phase fluid patchy saturations porous rock

Fluid saturation distribution is patchy due to variation of lithology, porosity and permeability of porous rock. Traditional porous medium theory based on homogeneous saturation does not apply to acoustical signatures calculation of patchy saturation porous medium. Employing three phase fluid Brooks-Corey model, Gassmann theory and bound theory, acoustical signatures calculation method of mesoscopic-scale inhomogeneous porous rock with three phase fluid patchy saturation is proposed, in order to research the effect of fluid saturation distribution on acoustical signatures of rock. Under conditions of capillary equilibrium, the quantitative relationship between porous medium acoustical signatures and global water saturation is established, then rules of compressional wave velocity ( V p) and shear wave velocity ( V s) of different fluid saturated rock vary with different global water saturation are revealed. Numerical results demonstrate that V p of porous rock with three phase fluid patchy saturations more continuous variation across the entire global water saturation range. It will be more suitable for quantitative interpretation of hydrocarbon saturations than the case of three phase fluid homogeneous saturations. V s of porous rock doesn’t depend on saturations distribution. However, the relationship between V s and global water saturation in three phase fluid saturations porous rock is more complex than that in two phase fluid saturations porous rock.

Effects of pressure on pore characteristics and permeability of porous rocks as estimated from seismic wave velocities in cores from TCDP Hole-A

SUMMARY Changes in Vp/Vs (Poisson's ratio) around a fault are related to changes in the fluid transport properties of rocks, which play a significant role in seismogenic processes. Here we report a notable relationship between Vp/Vs and the permeability of porous fault-related rocks (Chelungpu fault, Taiwan) by direct and simultaneous measurement of elastic wave velocities (Vp and Vs) and permeability under increasing effective confining pressure (Peff) up to 25 MPa. Vp and Vs for all samples increased with Peff in the range up to 20 MPa, then were nearly constant as Peff increased to 25 MPa. Most silty sandstones with large proportions of fine-grained material showed positive correlations between Vp/Vs and permeability with rising pressure. On the other hand, well-sorted sandstones showed only slight changes in permeability with respect to Vp/Vs with rising pressure. We infer that grain size distributions, in particular the amount of silt- and clay-size grains, are responsible for the change in permeability with pressure as small particles clog pore networks with increasing Peff, causing the decrease in permeability. These findings may be useful to explain changes in permeability and pore pressure in the deep crust.

A probabilistic damage model of stress‐induced permeability anisotropy during cataclastic flow

A fundamental understanding of the effect of stress on permeability evolution is important for many fault mechanics and reservoir engineering problems. Recent laboratory measurements demonstrate that in the cataclastic flow regime, the stress‐induced anisotropic reduction of permeability in porous rocks can be separated into 3 different stages. In the elastic regime (stage I), permeability and porosity reduction are solely controlled by the effective mean stress, with negligible permeability anisotropy. Stage II starts at the onset of shear‐enhanced compaction, when a critical yield stress is attained. In stage II, the deviatoric stress exerts primary control over permeability and porosity evolution. The increase in deviatoric stress results in drastic permeability and porosity reduction and considerable permeability anisotropy. The transition from stage II to stage III takes place progressively during the development of pervasive cataclastic flow. In stage III, permeability and porosity reduction becomes gradual again, and permeability anisotropy diminishes. Microstructural observations on deformed samples using laser confocal microscopy reveal that stress‐induced microcracking and pore collapse are the primary forms of damage during cataclastic flow. A probabilistic damage model is formulated to characterize the effects of stress on permeability and its anisotropy. In our model, the effects of both effective mean stress and differential stress on permeability evolution are calculated. By introducing stress sensitivity coefficients, we propose a first‐order description of the dependence of permeability evolution on different loading paths. Built upon the micromechanisms of deformation in porous rocks, this unified model provides new insight into the coupling of stress and permeability.

Neutron radiography imaging, porosity and permeability in porous rocks

Research Article| December 01, 2006 Neutron radiography imaging, porosity and permeability in porous rocks F.C. de Beer; F.C. de Beer Building 1500, NECSA, Pelindaba, PO Box 582, Pretoria, 0001, e-mail: fdebeer@necsa.co.za Search for other works by this author on: GSW Google Scholar M.F. Middleton M.F. Middleton Geological Survey of Western Australia (GSWA), Australia; e-mail: mfmiddleton@iinet.net.au Search for other works by this author on: GSW Google Scholar South African Journal of Geology (2006) 109 (4): 541–550. https://doi.org/10.2113/gssajg.109.4.541 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation F.C. de Beer, M.F. Middleton; Neutron radiography imaging, porosity and permeability in porous rocks. South African Journal of Geology 2006;; 109 (4): 541–550. doi: https://doi.org/10.2113/gssajg.109.4.541 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search Abstract The visualization of fluid flow and characterization of porous media, by means of Neutron Radiography (NRad), has been tested using the Safari-1 nuclear reactor in South Africa – the only neutron imaging facility available in South Africa for R & D purposes and yet not fully explored by scientists, engineers and researchers. This has been enhanced by the capabilities of neutron imaging equipment and the subsequent improvement of imaging software features that support this type of characterization and analysis.A low light level CCD Camera that was converted into a neutron detection system was used to study the porosity and permeability features of laboratory scale porous sandstone and concrete samples and to compare the results obtained from conventional detection methods.The study develops the theory of mensuration of water saturation fluid of porous media of various types, but specifically concrete and sandstone, using Nrad techniques. Examples of these are fully developed.The study also investigated a number of often poorly understood situations of liquid with full and partial saturations of porous media, including concrete, sandstone aquifers and petroleum reservoir rocks. Never previously studied using NRad is the situation of two-phase fluid flow through oil-bearing rock inside a Hassler high-pressurized apparatus. The Hassler cell is used to reproduce deep reservoir pressure conditions, and is a standard petroleum petrophysical apparatus. For the present experiments, the Hassler cell was constructed of stainless steel (which is not optimum for neutron attenuation), and “heavy water” (D2O) was used instead of water in order to enhance the neutron attenuation contrast between petroleum and the resident liquid (normally water, but in this case deuterium). The heavy water and petroleum combination permitted sufficient contrast in neutron attenuation to enable resolution of D2O versus petroleum concentration within the pore volume to about 10% of the total concentration. Results were obtained of significant quality to suggest that NRad may supply valuable information on multi-phase fluid behaviour in such experimental apparatus.This study shows the capability and ability of neutron radiation imaging to obtain information about porous media and to validate existing data obtained through conventional methods. Although this study concentrate only on 2D neutron imaging and its advantages, exciting new 3D tomography imaging equipment are envisaged at SAFARI-1 that will enhance these R & D capabilities through future studies. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Zirconium speciation in lactate solutions and polyacrylate gels.

Controlling gelation kinetics is an important objective for several applications (ceramic and thin film syntheses, reduction in permeability of porous rock, etc). There is a growing interest in studying the gelation of polymers by zirconium, a crosslinker of lower toxicity than the chromium which is still commonly used. XAS at the Zr K-edge was performed at the European Synchrotron Radiation Facility (ESRF) on the BM32 beamline. The fluorescence detection was used to carry out successful in situ speciation at concentrations as low as 36 ppm. The Zr speciation was determined both in ZrLa (where La stands for lactate) aqueous solutions and in gels of a terpolymer of acrylamide having 2% of zirconium reactive acrylate side groups and 2% of sulfonate groups introduced to prevent syneresis. XANES results show that Zr is always in a dodecahedral geometry. In ZrLa solutions. EXAFS results indicate that Zr species grow from a dimer Zr2(La)6 to a tetramer (Zr4(La)x) and then to larger polymers resulting from tetramer associations, as the Zr concentration decreases from 51840 ppm to 36ppm. In polymer gels, Zr species appear to be dimers at pH 6 while tetramers are found when gelation occurred at pH 7. Calculations taking into account multiple scattering effects as well as dynamic molecular calculation confirmed conclusions derived from conventional EXAFS analysis.

The Permeability of Porous Rocks under High-Pressure

Characters of deep reservoir rocks have been studied recently. In this paper the relationship between pressure and permeability, which varies with the kind of gases, was investigated from the experimental and theoretical studies of the permeability of gases through porous rocks under pressure.In this experiment, high-pressure gases such as He, Ar, N2, CH4, C2H6 and C3H8, were forced to flow through rocks, and permeabilities of each gas have been decided.In the discussion of the experimental result, it was confirmed that Klinkenberg's result was obtained under higher pressure if the gas flow was laminar. It was also, confirmed that there was a linear relation between Klinkenberg's Constant and the mean free path of gases.It may well be said that, in the future, permeability of gases can be computed using the permeability data of a certain gas.