Pore Network Connectivity Research Articles

Effects of correlated morphological and topological heterogeneity of pore network on effective transport and reaction parameters

The effective diffusivity and the effective Thiele modulus of reactive porous matrices are determined by using a hybrid discrete and continuum model. The model describes static heterogeneity with weak noise on both morphology and topology of the matrix. Variations in diffusivity with respect to pore size (radius and length) and network connectivity up to second order are analyzed to assess the effect of stochastic media on catalytic reaction and transition of a single species. The porous medium is simulated by several building blocks (BB) which are regular in topology and morphology. A methodology is presented to construct a BB such that it fits the true matrix. Permutation of several regular pore networks in series constructs the porous media. Local mass balances over each BB yields model equations for reaction and transport in the matrix. Correlated random walk theory is used in each BB in order to relate the diffusivity to the coordination number.The Gaussian correlation function is assumed to model the autocorrelation of independent variables which are used to characterize the correlated porous media. The contribution of the fluctuating parameters in the mass conservation of the matrix yields a new closure equation in which ensemble average concentration of the reactant depends on different cross-correlations. The model is stable as long as the Thiele modulus at the correlation length scale is small. It predicts that geometrical heterogeneities lead to correction in effective diffusivity while the reaction rate is unaffected due to small Thiele modulus at correlation length scale. The model is verified by assessing the Thiele modulus of a pore network under Knudsen regime during a first order catalytic reaction; a good agreement was found especially for moderate Thiele modulus of correlated network. However, it fails to simulate random networks. Our systematic study revealed that the pore radius statistics impact significantly the diffusivity and the Thiele modulus while the topological parameters are important in weakly connected networks. The model predictions show that the diffusion constant decreases sharply as pore radius variance increases but increases smoothly with Thiele modulus.

Numerical study on mechanical and hydraulic behaviour of blast-induced fractured rock

In this research paper, smoothed particle hydrodynamics (SPH) with Johnson Holmquist damage model is adopted for modelling of the blast-induced fractures in Barre granite rock. The permeability of the blast-induced rock is then obtained using the implemented finite volume method code in OpenFOAM. It is found that the calculated permeability depends on the direction of fluid flow and with higher value in radial direction than the axial one. This is mainly due to the higher and larger connected pore network in the radial direction. This research work shows that the adopted SPH method along with finite volume method code can be effectively combined to qualitatively and quantitatively predict the fractured network, to analyse geometry of the fractured network, and to calculate the permeability of blast-induced rock.

Transport under confinement: Hindrance factors for diffusion in core-shell and fully porous particles with different mesopore space morphologies

Abstract We quantify confinement effects on hindered transport in mesoporous silica particles through using physical reconstructions of their mesopore space morphology obtained by electron tomography as geometric models in direct diffusion simulations for passive, finite-size tracers. Studied are fully porous particles with mean mesopore sizes of dmeso = 16.0 and 23.9 nm, prepared by classical sol–gel processing, and solid core–porous shell particles (dmeso = 9.4 and 16.8 nm) originating from a layer-by-layer assembly of sol particles around a solid, impermeable core followed by thermal consolidation of the porous shell. Because shell thickness and core size are independently adjustable, core–shell particles allow to decouple the intraparticle diffusion distance in a fixed-bed reactor or chromatographic column from the external surface area of the particles and the hydraulic permeability of the bed, impossible with fully porous particles. Effective diffusivity, accessible porosity, and pore network connectivity recorded in the four reconstructions as a function of λ, the ratio of tracer to mean mesopore size, demonstrate an unfavorable shell morphology for the core–shell particles that opposes their design advantage over fully porous particles. The reconstructions reveal that core–shell particles contain an increased number of narrow and constricted as well as closed pores. These structural features reflect compacted and sintered packings and are most likely formed during shell consolidation. The presented expressions for hindered diffusion and accessible porosity can be used to optimize mesopore space morphologies in sensitive applications, e.g., catalysis under confinement and controlled drug release.

MicroCT-based bulk density measurement method for soils

High-resolution micro-computed tomography (microCT) is a method growing rapidly in popularity and has been applied to various soil studies with great success, especially for 3D characterisation of pore spaces or mineral distributions. However, microCT is not typically used for soil bulk density measurements, probably due to relatively simple and fast alternatives. Besides the complex process of image analysis from microCT scans, the method is also limited in resolution, which can result in incorrect total porosity estimation. This is especially true for granular materials, such as soils with small pore spaces between particles. In this work we demonstrate a different, yet very simple methodology for microCT adapted to overcome these limitations by using only volumetric measurements of the samples, and not segmentation of pore spaces or density calibrations. This method allows accurate bulk density determination for soil clods and cores. The method is faster than tradition methods, and it allows for additional analyses, such as surface area, macro-porosity, connected pore network and macro-particle shape analysis. The method is tested and directly compared for the same samples to the traditional waxing Archimedes method, with good correlation. The microCT scans of waxed samples also indicate sources of possible error in the waxing Archimedes method by visualising trapped air and wax penetration into open pore spaces. The method is then applied to cores and local bulk density measurements, and their variability down the cores is demonstrated, which can be very useful in complex soil profiles. The method is robust in varying resolution and image blur as it makes use only of volumetric measurements of the entire sample, not image grey-value calibration or segmentation of pore spaces.

Tracer‐Guided Characterization of Dominant Pore Networks and Implications for Permeability and Wettability in Shale

AbstractPore network characterization is an important aspect in unconventional reservoir evaluation. While application of the technique of scanning electron microscope (SEM) brings substantial advances in pore characterization in shale, understanding the connected pore network that dominates flow in shale samples is limited by using SEM alone because of small fields of view and lack of views of connectivity in 3D. In this research, a technique integrating tracer imbibition, micro‐computed tomography (CT) imaging, and SEM imaging was developed to provide a solution for multiscale imaging in shale. Tracer imbibition indicates pore connectivity; micro‐CT imaging after tracer imbibition thus provides an overview of the connected pore network at the millimeter scale. With guidance from micro‐CT images after tracer imbibition, a more accurate and detailed characterization of pore systems and related mineralogy can be conducted using higher‐resolution SEM. The method was applied to five samples from Wolfcamp and Eagle Ford Formations. Results reveal the effectiveness of the integrated method by showing different patterns of distribution of the dominant pore network and different controlling mineralogy. Dominant porosity, estimated from grayscale analyses, displays a good correlation with permeability. This result indicates that dominant porosity is more relevant to permeability than is total porosity. Results from imbibition tests are also compared with that from contact angle measurement, and important implications on wettability can be obtained. The integrated method thus has the capacity to link the dominant pore network and wettability with microscale to submicroscale mineralogy, which can help better understand the pore systems and fluid flow in shale.

Quantitative Analysis of Micro-structural Changes in a Bituminous Coal After Exposure to Supercritical CO2 and Water

High-volatile bituminous coal samples were reacted in deionized water with supercritical CO2 (ScCO2–water) under simulated in situ pressure and temperature conditions (8 MPa and 40 °C) in unconfined stress state for 14 days, in order to characterize potential CO2–water–coal reactions. Micro-structural changes were identified pre- and post-experiment using X-ray powder diffraction (XRD) analysis for powdered coal (mineralogical changes), optical microscopy and scanning electron microscopy (SEM) for polished thin sections (surface feature changes) and micro-CT scanning for a small core (porosity and permeability changes). XRD analysis revealed that carbonic acid leaches out mineral matters in coal, including carbonates (calcite) and silicate minerals (albite, illite and kaolinite). Optical microscopy, SEM and CT images confirmed that the interaction of coal with ScCO2–water causes an abundance of micro-cracks to open or propagate in unconfined coal samples. Most micro-cracks preferably propagated along maceral–mineral and maceral–maceral interfaces, which demonstrates that the micro-cracking was caused by differential swelling of different coal lithotypes. Wormhole formation was observed in coal caused by mineral dissolution and hydrocarbon mobilization, which significantly increases coal porosity compared with swelling-induced cracking. 3-D pore network models extracted from CT images show that ScCO2–water treatment enlarges the pore and throat size, increases the numbers of pores and throats and improves pore network connectivity. Overall, CO2–water–coal interactions under unconfined conditions enhance coal porosity, connectivity and permeability, which can be attributed to the combined effect of micro-cracking, mineral dissolution and hydrocarbon mobilization.

Effect of long-term irrigation and tillage practices on X-ray CT and gas transport derived pore-network characteristics

The gas transport parameters, diffusivity and air-filled porosity are crucial for soil aeration, microbial activity and greenhouse gas emission, and directly depend on soil structure. In this study, we analysed the effect of long-term tillage and irrigation practices on the surface structure of an arable soil in New Zealand. Our hypothesis was that topsoil structure would change under intensification of arable production, affecting gas exchange. Intact soil cores were collected from plots under intensive tillage (IT) and direct drill (DD), irrigated or rainfed. In total, 32 cores were scanned by X-ray computed tomography (CT) to derive the pore network >30µm. The cores were then used to measure soil-gas diffusivity, air-permeability and air-filled porosity of pores close to the resolution of the X-ray CT scans, namely ≥30µm. The gas measurements allow the calculation of pore-network connectivity and tortuosity parameters, which were compared with the CT-derived structural characteristics. Long-term irrigation had little effect on any of the parameters analysed. Total porosity tended to be lower under IT than DD, whereas the CT-derived porosity was comparable. Both the CT-derived mean pore diameter (MPD) and other morphological parameters, as well as gas measurement-derived parameters, highlighted a less developed structure under IT. The differences in the functional pore-network structure were attributed to SOC depletion and the mechanical disturbance through IT. Significant correlations between CT-derived parameters and functional gas transport parameters such as tortuosity and MPD were found, which suggest that X-ray CT could be useful in the prediction of gas transport.

Mesoscale structure, mechanics, and transport properties of source rocks’ organic pore networks

Organic matter is responsible for the generation of hydrocarbons during the thermal maturation of source rock formation. This geochemical process engenders a network of organic hosted pores that governs the flow of hydrocarbons from the organic matter to fractures created during the stimulation of production wells. Therefore, it can be reasonably assumed that predictions of potentially recoverable confined hydrocarbons depend on the geometry of this pore network. Here, we analyze mesoscale structures of three organic porous networks at different thermal maturities. We use electron tomography with subnanometric resolution to characterize their morphology and topology. Our 3D reconstructions confirm the formation of nanopores and reveal increasingly tortuous and connected pore networks in the process of thermal maturation. We then turn the binarized reconstructions into lattice models including information from atomistic simulations to derive mechanical and confined fluid transport properties. Specifically, we highlight the influence of adsorbed fluids on the elastic response. The resulting elastic energy concentrations are localized at the vicinity of macropores at low maturity whereas these concentrations present more homogeneous distributions at higher thermal maturities, due to pores' topology. The lattice models finally allow us to capture the effect of sorption on diffusion mechanisms with a sole input of network geometry. Eventually, we corroborate the dominant impact of diffusion occurring within the connected nanopores, which constitute the limiting factor of confined hydrocarbon transport in source rocks.

In situ synthesis of mesoporous Co3O4 nanorods anchored on reduced graphene oxide nanosheets as supercapacitor electrodes

In situ synthesis of mesoporous Co3O4 nanoparticles embedded in reduced graphene oxide nanosheets (GNSs) was implemented through coprecipitation method and pyrolytic process. In the charge-discharge process, electrolyte ions can fill with three-dimensional GNS matrix with connected pore network structures and mesoporous Co3O4 nanoparticles with uniform nanoscale structures as double ion buffer reservoirs. The capacitance value of Co3O4/GNS nanocomposites is 1085.6 F g−1 at the current density of 2 A g−1 in 2 M KOH solution. The composite has good cyclic stability, and the maximum capacitance loss is only 17.3% in 10,000 successive cycles.

Comparing organic-hosted and intergranular pore networks: topography and topology in grains, gaps and bubbles

Abstract The relationship between pore structures was examined using a combination of normalized topographical and topological measurements in two qualitatively different pore systems: organic-hosted porosity, common in unconventional shale reservoirs; and intergranular porosity, common in conventional siliciclastic reservoirs. The organic-hosted pore network was found to be less well connected than the intergranular pore network, with volume-weighted coordination numbers of 1.16 and 8.14 for organic-hosted and intergranular pore systems, respectively. This disparity in coordination number was explained by differences in the pore shapes that are caused by variations in the geological processes associated with the generation of the pore network. Measurements of pore shape showed that the pores in the organic-hosted network were both significantly more spherical and had a more positive curvature distribution than the pores present within the intergranular network. The impact of such changes in pore shape on pore-network connectivity was examined by creating a suite of synthetic pore geometries using both erosion/dilation of the existing network and image-guided object-based methods. Coordination number, Euler characteristic and aggregate porosity analyses performed on these synthetic networks showed that organic-type pore networks become connected at much higher aggregate porosities (35–50%) than intergranular-type pore networks (5–10%).

Can the Volume Ratio of Coarse to Fine Particles Explain the Hydraulic Properties of Sandy Soil?

Core Ideas The volume ratio of large to small particles controls intact sand hydraulic properties. Simple model explained sand saturated hydraulic conductivity within a factor of two. The new concept was also related to effective porosity and water retention points. Soil mineral particles larger than 0.1 mm and organic matter need to be considered. The volume ratio concepts seem promising for developing pedotransfer functions. Hydraulic conductivity (Ks) and effective porosity (ϕeff) for saturated water flow are essential hydraulic properties for describing fluid and chemical transport in soil and groundwater systems. Typically, Ks is predicted by pedotransfer functions of soil texture and total porosity or ϕeff. This study shows that a more conceptual approach that uses a volume‐weighted ratio of coarser (part of the sand fraction) to finer (clay and organic matter) particles alongside total porosity could explain variations in both Ks and φeff in intact 100‐cm3 samples of 20 sandy surface and subsurface soils with <10% fines (clay + organic matter). The Ks function used was a simple power‐law function of the volume‐weighted coarse/fine particle ratio with two calibration parameters [A and pore network connectivity (PNC)]. The value of the power‐law exponent (PNC) in the calibrated function was 1.8, similar to power‐law exponents for gas diffusivity and air permeability in unsaturated soil (1.5–2). The second calibration parameter (A) probably depends on the soil classes under consideration, the Ks measurement method, and the sample scale. A sensitivity analyses showed that both Ks and ϕeff (taken as the volume content of pores larger than 30 μm, that is, drained at –10 kPa of soil water matric potential) are especially sensitive to organic matter content. Besides the water transport parameters, water retention under dry conditions was also closely correlated with the volume‐weighted fines content. Therefore, the volume ratio concept seems to be a promising platform for the development of simple, accurate functions for the hydraulic properties of coarse‐textured soils.

Inferring pore connectivity from sorption hysteresis in multiscale porous media

HypothesisVapor adsorption experiments are widely used to assess pore size distributions, but the large hysteresis sometimes observed between sorption and desorption isotherms remains difficult to interpret. Such hysteresis is influenced pore network connectivity, which has previously been modeled by percolation on infinite lattices. Our hypothesis is that percolation occurs instead through finite networks of micropores connecting accessible macropores, always exposed to the outside environment. TheoryWe derive a general formula for sorption/desorption isotherms that introduces a simple measure of hierarchical pore connectivity - the fraction of always exposed pores. The model thus accounts for “small world” connections in finite-size percolation, while also incorporating other hysteresis mechanisms, in single-pore filling, liquid insertion into the solid matrix, and cavitation. FindingsOur formula is able to fit and interpret both primary and scanning sorption/desorption isotherms for a variety of adsorbates (noble gases, water, and organics) and porous materials (cement pastes, dental enamels, porous glasses, carbon black and nanotubes), including cases with broad pore-size distributions and large hysteresis. It allows quantification of the prevalence of percolating macropores in the material, even though these pores are never filled during the sorption experiments. A distinct bump in sorption isotherms is explained as a lowering of the barrier to nucleation of the vapor phase with a universal temperature scaling.

Determining porosity and pore network connectivity of cement-based materials by a modified non-contact electrical resistivity measurement: Experiment and theory

A modified non-contact electrical resistivity measurement is proposed to determine porosity and pore network connectivity of cement-based materials. The porosity of mortar with different water-to-cement ratios was tested by mercury intrusion porosimetry (MIP) and the tortuosity was calculated from pore entrapment volume fraction. The relationship between pore structure and resistivity was studied using the three most commonly used theories. It was observed that the multi-phase phenomenological model can indicate the effect of porosity and pore connectivity on the resistivity of cement-based materials. The parameter m in Archie's Law as an index of pore connectivity can be expressed as a variable that varies with the tortuosity. The parameters in the GEM model are closely related to the nature of the material: the parameter M should be related to the composition of the material and the degree of hydration of the cement, and the parameter t is a variable that varies with the pore connectivity. Based on these theories, equations are derived to correlate the porosity and pore network connectivity to the formation factor of cement based materials. The developed approach thus has a potential to be used as a simple and effective tool for pore structure investigation of cement based materials.

Morphological analysis of pore size and connectivity in a thick mixed-culture biofilm.

Morphological parameters are commonly used to predict transport and metabolic kinetics in biofilms. Yet, quantification of biofilm morphology remains challenging because of imaging technology limitations and lack of robust analytical approaches. We present a novel set of imaging and image analysis techniques to estimate internal porosity, pore size distributions, and pore network connectivity to a depth of 1 mm at a resolution of 10 µm in a biofilm exhibiting both heterotrophic and nitrifying activities. Optical coherence tomography (OCT) scans revealed an extensive pore network with diameters as large as 110 µm directly connected to the biofilm surface and surrounding fluid. Thin-section fluorescence in situ hybridization microscopy revealed that ammonia-oxidizing bacteria (AOB) distributed through the entire thickness of the biofilm. AOB were particularly concentrated in the biofilm around internal pores. Areal porosity values estimated from OCT scans were consistently lower than those estimated from multiphoton laser scanning microscopy, though the two imaging modalities showed a statistically significant correlation (r = 0.49, p < 0.0001). Estimates of areal porosity were moderately sensitive to gray-level threshold selection, though several automated thresholding algorithms yielded similar values to those obtained by manually thresholding performed by a panel of environmental engineering researchers (±25% relative error). These findings advance our ability to quantitatively describe the geometry of biofilm internal pore networks at length scales relevant to engineered biofilm reactors and suggest that internal pore structures provide crucial habitat for nitrifier growth.

A pore structure based real gas transport model to determine gas permeability in nanoporous shale

Gas flows in the forms of multiple transport mechanisms in shale nanoporous media with complex pore structure and different pore types. Laboratory pressure pulse decay technique is often applied to measure gas permeability but the current gas permeability interpretation model is mostly based on the homogeneous macro scale model while the influence of pore structure on real gas transport is neglected. In this study, a novel pore structure based real gas transport model is proposed to determine gas permeability in nanoporous shale combining laboratory pressure pulse decay technique with pore network simulation. The laboratory pressure pulse decay process is simulated in a virtual system based on the similarity principle which contains upstream vessel, downstream vessel, and core sample. The core sample is constructed by a series of connected pore networks and the sizes of pores and throats in each location of the pore network are randomly assigned according to laboratory measured pore size distribution. Gas transport mechanisms inside the core sample consider viscous flow, Knudsen diffusion, surface diffusion and real gas effect. At each time step, the upstream vessel pressure decreases and the downstream vessel pressure increases until the upstream vessel pressure and downstream vessel pressure become equal. The simulated pressure drop versus time curve is obtained and is applied to fit the laboratory measured pressure drop data by repeating core sample construction and pressure pulse decay process. The proposed model is applied to measure gas permeability of Sichuan basin, Longmaxi formation shale core sample. The results indicate that the predicted value based on the proposed model matches well with the experimental measured pressure drop data. The proposed model is used to study the influences of test gas type and pore size on gas permeability. When the average organic pore radius is less than 20 nm, helium tested permeability overestimates at least 40% of the methane permeability.

Solvents Molecular Mobility in Coked Catalyst ZSM-5 Studied by NMR Relaxation and Pulsed Field Gradient Techniques

Through gasification and methanol synthesis, biomass can produce methanol and then produce light olefins through the methanol-to-hydrocarbon (MTH) process. To make this new biomass based production route profitable, the efficiency of the MTH process is important. Catalyst deactivation is the main reason for the decline of conversion and selectivity. NMR was applied to detect the relaxation and diffusion of liquid molecules in a series of coked ZSM-5, investigating the effect of coke on molecular transport properties. n-Heptane was chosen as a probe molecule in describing pore network connectivity, whereas methanol was used for relaxation measurements. Though there were only minor differences of pore connectivity among the samples, the longitudinal relaxation time showed an almost linear relationship with coke contents, suggesting that the interaction between reactants and catalyst surface influences the catalyst performance within low coke contents. PFG-NMR and NMR relaxation, as fast and straightforward ...

Mechanisms of reservoir pore/throat characteristics evolution during long-term waterflooding

Formation pore structure and reservoir parameters change continually during waterflooding due to sand production, clay erosion, and pressure/temperature variation, which causes great challenge in geological modeling and simulation. In this work, the XA Oilfield, a block with more than 20 years’ waterflooding history, is used as an example to better understand the fundamental evolution mechanisms of reservoir pore network characteristics over long time waterflooding. We performed a large number of core analyses and experiments to obtain formation parameters (e.g., permeability, porosity, relative permeability, and etc.) at different development stages. The comparison illustrates that reservoir permeability can not only decrease with clay plugging, but also increase by the detachment of fine particles and even the destruction of microscopic structure. We also observed that the point/line contacts among grains decreases, the pore network connectivity increases, the clay content reduces and the rock trends to be more hydrophilic with increasing water injection. Moreover, we developed a pore network model to simulate the variation of formation parameter. The model parameters are also compared and analyzed to get a qualitative understanding of the evolvement laws, which will provide a useful guidance for reservoir accurate modeling. Cited as : Wang, S., Han, X., Dong, Y., et al. Mechanisms of reservoir pore/throat characteristics evolution during long-term waterflooding. Advances in Geo-Energy Research, 2017, 1(3): 148-157, doi: 10.26804/ager.2017.03.02

Numerical study on seepage flow in pervious concrete based on 3D CT imaging

Pervious concrete specimens are prepared for CT (Computed Tomography) imaging and numerical simulation to observe pore characteristics and study law of seepage flow. 3D reconstruction based on CT imaging is utilized to generate virtual 3D pervious concrete structures, extract the connected pore network models, and analyze the target porosity, actual porosity, 3D porosity etc. Pore characteristics analysis shows the 3D porosity, and average planar porosity can generally represent the actual porosity, and 3D connected porosity is close to the effective porosity. The connected pore network models are used to simulate the water seepage flow using CFD (Computed Fluid Dynamics) method. The seepage flow simulation shows the permeable capacity increases clearly with increasing porosity under the same inlet pressure. The relationship between seepage velocity and pressure gradient is obtained and fitted by the nonlinear Forchheimer formula. The acquired hydraulic conductivity can be used to assess the seepage flow capacity.

Characterization of micro-nano pore networks in shale oil reservoirs of Paleogene Shahejie Formation in Dongying Sag of Bohai Bay Basin, East China

Abstract For typical blocky, laminated and bedded mudrock samples from the Paleogene Shahejie Formation in the Dongying Sag of Bohai Bay Basin, this work systematically focuses on their structure characterization of multiple micro-nano pore networks. A use of mercury injection capillary pressure (MICP) documented the presence of multiple μm-nm pore networks, and obtained their respective porosity, permeability and tortuosity. Different sample sizes (500-841 μm GRI fractions, 1 cm-sized cubes, and 2.54 cm in diameter and 2-3 cm in height core plugs) and approaches (low-pressure N 2 gas physisorption, GRI matrix permeability, MICP, helium pycnometry, and pulse decay permeameter) were used to measure pore size distribution, porosity and permeability. The average porosity and matrix permeability determined from MICP are (6.31±1.64)% and (27.4±31.1)×10 -9 μm 2 , the pore throat diameter of pores is mainly around 5 nm, and the median pore throat diameter based on 50% of final cumulative volume is (8.20±3.01) nm in shale. The pore-throat ratios decrease with a decrease of pore size diameter. Moreover, the permeability of shale samples with lamination is nearly 20 times larger than matrix permeability. The geometrical tortuosity of the nano-scale 2.8−10.0 nm pore networks is 8.44 in these shales, which indicates a poor connectivity of matrix pore network and low flow capability. Overall, the variable and limited pore connectivity of shale samples will affect hydrocarbon preservation and recovery.

Relative permeability estimates for Wolfcamp and Eagle Ford shale samples from oil, gas and condensate windows using adsorption-desorption measurements

Relative permeability in shales is an important petrophysical parameter for purposes of accurate estimation of production rate and recovery factor, efficient secondary recovery, and effective water management. We present a method to estimate relative permeability of aqueous and hydrocarbon phase in shales by processing the low-pressure nitrogen adsorption-desorption isotherm measurements. The interpretation method is applied to 35 samples from various maturity windows of Eagle Ford and Wolfcamp shale formations. The method assumes that effective medium theory, percolation theory, and critical path analysis can quantify the biphasic fluid transport in shales.The relative permeability curves were estimated for samples collected from 100ft interval in Eagle Ford gas window, 30ft interval in Eagle Ford oil window, and 60ft interval in Wolfcamp condensate window. Although the samples exhibit large variations in organic content, pore connectivity, range of connected pore network, and pore complexity, the relative permeability curves estimated for these samples exhibit relatively similar trends. Samples from gas and oil windows were low temperature plasma ashed to study the effects of removal of organic matter on relative permeability and pore network characteristics. The relative permeability of aqueous phase decreases sharply with decrease in water saturation, whereas the relative permeability of hydrocarbon phase decreases at a relatively slow and constant rate with increase in water saturation. Relative permeability estimates for the shale samples explain the low water-cut during hydrocarbon production, absence of correlation between hydrocarbon production decline and the increase in water production, and the existence of permeability jail in shale reservoirs.