Showing papers on "Permeability (earth sciences) published in 2018"
TL;DR: In this article, the authors investigated the effect of reservoir depth, temperature, and sample heterogeneity during hydraulic fracturing and the influences of rock micro-structure on fracture propagation in deep geothermal reservoirs.
170 citations
TL;DR: In this article, a review of porosity-permeability relations in simulation models on the REV scale is presented, with a focus on the porosity at which the porous medium becomes impermeable.
Abstract: Reactive transport processes in a porous medium will often both cause changes to the pore structure, via precipitation and dissolution of biomass or minerals, and be affected by these changes, via changes to the material’s porosity and permeability. An understanding of the pore structure morphology and the changes to flow parameters during these processes is critical when modeling reactive transport. Commonly applied porosity–permeability relations in simulation models on the REV scale use a power-law relation, often with slight modifications, to describe such features; they are often used for modeling the effects of mineral precipitation and/or dissolution on permeability. To predict the reduction in permeability due to biomass growth, many different and often rather complex relations have been developed and published by a variety of authors. Some authors use exponential or simplified Kozeny–Carman relations. However, many of these relations do not lead to fundamentally different predictions of permeability alteration when compared to a simple power-law relation with a suitable exponent. Exceptions to this general trend are only few of the porosity–permeability relations developed for biomass clogging; these consider a residual permeability even when the pore space is completely filled with biomass. Other exceptions are relations that consider a critical porosity at which the porous medium becomes impermeable; this is often used when modeling the effect of mineral precipitation. This review first defines the scale on which porosity–permeability relations are typically used and aims at explaining why these relations are not unique. It shows the variety of existing approaches and concludes with their essential features.
167 citations
TL;DR: In this paper, the authors explored the coal seams of Chinese coal seams with high gas content and low permeability and proposed to improve coal seams' permeability to achieve maximum extraction of coalbed methane.
Abstract: Chinese coal seams are characterized by high gas content and low permeability. The permeability of coal seams should be improved to achieve maximum extraction of coalbed methane. This study explore...
147 citations
TL;DR: In this paper, a composite model was proposed to investigate the pressure behavior and production performance of a multi-wing hydraulically fractured multiple fractured vertical well (MFVW) in a coalbed gas reservoir with a stimulated reservoir volume (SRV).
141 citations
TL;DR: In this article, the effect of the porous layer on increasing the convective heat transfer coefficient is larger than the Reynolds number, since, at a given volume fraction, the porous medium plays a greater role in increasing the heat transfer compared to the increasing Reynolds number.
118 citations
TL;DR: In this article, a model for gas transport in shale is proposed by accounting for three major fluid flow mechanisms in shale stratum, which is modeled as a 3D fractal media.
114 citations
TL;DR: In this article, the effects of varying pore/throat radii, non-even distribution of hydrates and fluid flow directions on the absolute and relative permeability are discussed.
109 citations
TL;DR: In this article, the Cembureau method and ASTM C1202 test were used to measure the gas permeability coefficient and effective chloride diffusion coefficient of concrete, and the pore structure of concrete was determined by mercury intrusion porosimetry and nuclear magnetic resonance (NMR).
108 citations
105 citations
TL;DR: In this paper, the authors used profilometry to measure the roughness and complexity of the resulting fracture surfaces and measure the permeability of the fractures, and found that the topography of Sc-CO2 fracture surfaces is more rough and complex compared to that of H2O fractured surfaces.
101 citations
TL;DR: A series of static soaking experiments, combined with the bulk-rock X-ray diffraction and scanning electron microscopy analyses, was conducted to investigate the influences of supercritical CO2 fracturing on the physical-chemical properties of shales as mentioned in this paper.
TL;DR: In this paper, industrial experiments of pulsating hydraulic fracturing (PHF) were carried out, and physical properties including the reasonable fracture radius, gas extraction concentration, water content, permeability, pore and mineral composition of a coal seam, were investigated.
TL;DR: In this article, the quenching effect on mechanical and flow behavior of Australian Strathbogie granite was investigated by conducting a series of micro and macro-experiments, profiling the micro-structure of rock with CT scanning, microscopic imaging and quantifying the thermally induced damage due to quenched treatment.
TL;DR: In this paper, a topology optimization methodology for optimizing cooling channels using an approximate but low-cost flow and heat transfer model is presented, where the fluid flow is modeled using the Darcy model, which is a linear problem that can be solved very efficiently compared to the Navier-Stokes equations.
TL;DR: In this article, the fluid flow and heat transfer of a nanofluid is numerically examined in a two dimensional microchannel filled by a porous media, and the slip velocity and temperature jump boundary conditions are assumed on the microchannel horizontal sides.
Abstract: The fluid flow and heat transfer of a nanofluid is numerically examined in a two dimensional microchannel filled by a porous media. Present nanofluid consists of the functionalized multi-walled carbon nanotubes suspended in water which are enough stable through the base fluid. The homogenous mixture is in the thermal equilibrium which means provide a single phase substance. The porous media is considered as a Darcy- Forchheimer model. Moreover the slip velocity and temperature jump boundary conditions are assumed on the microchannel horizontal sides which mean the influences of permeability and porosity values on theses boundary conditions are presented for the first time at present work. To do this, the wide range of thermo physical parameters are examined as like Da = 0.1 to 0.001, Re = 10,100, dimensionless slip coefficient from 0.001 to 0.1 at different mass fraction of nanoparticles. It is observed that less Darcy number leads to more local Nusselt number and also applying the porous medium corresponds to higher slip velocity.
TL;DR: In this article, the same authors compared the MICP data collected from 46 Montney wells in Alberta and British Columbia with the results obtained using other measurements, such as pressure fall-off and pressure pulse-decay measurements.
Abstract: Permeability is a critical parameter for evaluating unconventional shale or tight gas and oil reservoirs such as the Montney Formation in the Western Canada Sedimentary Basin. Permeability is also one of the most difficult parameters to be accurately and consistently determined in the laboratory and field as it is a second-order tensor and is dependent on many factors (e.g. test methods, sampling or testing scales, heterogeneities in fabrics, pore networks and pore-throat size distribution, transport mechanisms, pore pressure and confining stress). Although laboratory permeability measurement is limited to samples on the scale of centimeters or less, it provides valuable insights on hydrocarbon transmissibility of the reservoir matrix rock. Several methods have been developed for permeability measurements of unconventional reservoirs but each method has limitations and specific applications and often yields different permeability values even for the same sample. In this study, various permeability measurements on samples from 46 Montney wells in Alberta and British Columbia are examined. The permeability data set has primarily been obtained using transient pressure fall-off and pressure pulse-decay methods due to the relatively low permeability seen throughout the Montney Formation. A unique data set of permeability determined from canister desorption tests is also analyzed and compared to other permeability measurements. Direct permeability measurements obtained using different techniques are further compared with permeability values predicted using models based on mercury intrusion capillary pressure (MICP) data. The results show that the pressure fall-off (kpf) or GRI (kgri) permeability to helium correlates strongly with porosity. The kpf of crushed samples (20/35 meshes) ranges from 1e-3 md with porosity increasing from 3% to 13%. The pressure fall-off permeability (kpf) of plug samples is about two orders of magnitude higher than kpf of crushed samples. Pressure pulse-decay permeability (kpdp) under initial in-situ effective confining stress conditions is generally higher than the pressure fall-off permeability of crushed samples but lower than that of core plugs. Pressure pulse-decay permeability (kpdp) of visually intact samples varies over two orders of magnitude for a given porosity, which is likely a result of variable sample characteristics (e.g. with or without micro fractures, net confining stresses applied due to different sample depths and regional locations, mineralogy, amount and type of organic matter, and pore-throat size). The pulse-decay permeability of fractured samples varies widely over three orders of magnitude and is up to three orders of magnitude higher than kpdp of intact samples, indicating favorable enhancement of permeability by unpropped fractures in the Montney Formation. Out of eight MICP-based permeability models tested in this study, the Winland model (Kolodzie, 1980) and the modified Winland model by Di and Jensen (2015) predict the most comparable permeability to the pulse-decay permeability measured on intact samples, and the rest models also predict acceptable values if proper conformance and compaction corrections are done to MICP data. The permeability from these models has stronger correlations with pressure fall-off permeability measured on both intact and fractured core plugs than the other models. For the Montney Formation, the strong dependence of gas permeability on pore pressure and confining stress is also highlighted. The pore pressure and stress dependence of permeability is characterized by a modified Klinkenberg effects correction equation. Liquid permeability to decane or oil is about one order of magnitude lower than gas permeability under similar confining stresses. Variable permeability from different methods, even on the same Montney samples, underlines the limitations and specific applications of each method, and implies the strong heterogeneities in mineralogical fabrics, organic matter distribution and pore size distributions of the Montney samples. The implications of different laboratory methods for formation evaluation are further discussed, and a practical fit-for purpose approach is recommended for the measurement of permeability, which allows for a more rigorous evaluation of in-situ matrix permeability of the Montney Formation and other unconventional shale and tight reservoirs.
TL;DR: In this article, the authors proposed a new simplified method for measuring the permeability of highly porous media with a permeability threshold of 10−8−10−4m2, using a Venturi tube to gauge the gas flowing rate through the sample.
TL;DR: In this article, the authors developed and applied an alternative approach to resolve this dilemma, which comprises flow within a nanotube capillary embedded within the shale matrix (discrete approach) and allows the evolution of shale permeability to be followed during the processes of shale gas flow.
TL;DR: In this article, the gas phase permeability changes due to hydrate decomposition of natural gas hydrates in marine sediments and permafrost areas, which have attracted global attentions as potential energy resources.
TL;DR: In this paper, the authors presented a mathematical model of the gas extraction from a reservoir initially saturated with methane and its hydrate, under conditions of negative (below 0°C) initial temperature of the reservoir.
TL;DR: In this paper, an experimental study was performed to investigate the impact of low salinity water on wettability alteration in carbonate core samples from southern Iranian reservoirs by spontaneous imbibition.
TL;DR: In this paper, a geologically constrained, two-layer global map of shallower and deeper permeability of the Earth's surface is presented, which is consistent with the dominance of the coarse-grained sediments.
Abstract: The spatial distribution of subsurface parameters such as permeability are increasingly relevant for regional to global climate, land surface, and hydrologic models that are integrating groundwater dynamics and interactions. Despite the large fraction of unconsolidated sediments on Earth’s surface with a wide range of permeability values, current global, high-resolution permeability maps distinguish solely fine-grained and coarse-grained unconsolidated sediments. Representative permeability values are derived for a wide variety of unconsolidated sediments and applied to a new global map of unconsolidated sediments to produce the first geologically constrained, two-layer global map of shallower and deeper permeability. The newmean logarithmic permeability of the Earth’s surface is 12.7 ± 1.7 m being 1 order of magnitude higher than that derived from previous maps, which is consistent with the dominance of the coarser sediments. The new data set will benefit a variety of scientific applications including the next generation of climate, land surface, and hydrology models at regional to global scales.
TL;DR: A novel Hybrid High-Order method for the simulation of Darcy flows in fractured porous media that is fully robust with respect to the heterogeneity of the permeability coefficients, and it exhibits only a mild dependence on the square root of the local anisotropy of the bulk permeability.
Abstract: We develop a novel Hybrid High-Order method for the simulation of Darcy flows in fractured porous media. The discretization hinges on a mixed formulation in the bulk region and a primal formulation inside the fracture. Salient features of the method include a seamless treatment of nonconforming discretizations of the fracture, as well as the support of arbitrary approximation orders on fairly general meshes. For the version of the method corresponding to a polynomial degree $k\ge 0$, we prove convergence in $h^{k+1}$ of the discretization error measured in an energy-like norm. In the error estimate, we explicitly track the dependence of the constants on the problem data, showing that the method is fully robust with respect to the heterogeneity of the permeability coefficients, and it exhibits only a mild dependence on the square root of the local anisotropy of the bulk permeability. The numerical validation on a comprehensive set of test cases confirms the theoretical results.
TL;DR: In this paper, a coupled seepage-erosion water inrush model is presented to investigate the characteristics of seepageseepage and erosion properties. But the model is based on classical theories of solute transport and fluid dynamics in porous media.
Abstract: During tunnel construction, groundwater inrush from completely weathered granite strata is a significant challenge to geotechnical engineers. Up to the present, prevention of water inrushing hazards is almost exclusively based on the experience of engineers. This paper presents a coupled seepage–erosion water inrush model to investigate the characteristics of seepage–erosion properties. The proposed model is based on classical theories of solute transport and fluid dynamics in porous media. In the model, changes of porosity link permeability with the accumulation of particle loss in the seepage–erosion process. The coupled seepage–erosion model was applied to examine the influence of curtain grouting thickness on the seepage–erosion process. The results showed that the seepage–erosion process was attenuated as thickness increased. The results also showed that the porosity and permeability visibly changed and the water inflow clearly exceeded the acceptable engineering criterion when the thickness was less than 6 m. However, with a further increase in thickness, the seepage–erosion process was suppressed and little changes of the relative parameters were showed. The numerical results demonstrated that a curtain grouting thickness of 6 m was suitable for curtain grouting in completely weathered granite. Field investigation of Cenxi tunnel verified the effectiveness of the thickness determined by the proposed model.
TL;DR: An artificial neural network model can be used to predict the permeability of heterogeneous reservoir based on three logs only, namely resistivity, bulk density, and neutron porosity, and a new term, mobility index, which is derived from the mobile oil saturation that occurred due to the drilling fluid filtrate invasion is introduced.
Abstract: Permeability is an important parameter for oil and gas reservoir characterization. Permeability can be traditionally determined by well testing and core analysis. These conventional methods are very expensive and time-consuming. Permeability estimation in heterogeneous carbonate reservoirs is a challenge task to be handled accurately. Many researches tried to relate permeability and reservoir properties using complex mathematical equations which resulted in inaccurate estimation of the formation permeability values. Permeability prediction based on well logs using artificial intelligent techniques was presented by many authors. They used several wire-line logs such as gamma ray, neutron porosity, bulk density, resistivity, sonic, spontaneous potential, hole size, depths, and other logs. The objective of this paper is to develop an artificial neural network (ANN) model that can be used to predict the permeability of heterogeneous reservoir based on three logs only, namely resistivity, bulk density, and neutron porosity. In addition to the ANN model, in this paper and for the first time a mathematical equation from the ANN model will be extracted that can be used for permeability prediction for any data set without the need for the ANN model. Also, in this study and for the first time we introduced a new term which is the mobility index that can be used effectively in the permeability prediction. Mobility index term is derived from the mobile oil saturation that occurred due to the drilling fluid filtrate invasion. The obtained results showed that ANN model gave a comparable results with support vector machine and adaptive neuro-fuzzy inference system model. The developed mathematical equation from ANN model can be used to estimate the permeability for heterogamous carbonate reservoir based only on three parameters: bulk density, neutron porosity, and mobility index. Actual core data points (1223 points) with the three logs were used to train (857 data points, 70% of the data) and test the model for unseen data (366 data points, 30% of the data). The correlation coefficient for training and testing was 0.95, and the root-mean-square error was 0.28. The developed mathematical equation will help the engineers to save time and predict the permeability with a high accuracy using inexpensive technique. Introducing the new parameter, mobility index, in the prediction process greatly improved the permeability prediction from the log data compared to the actual measured data.
TL;DR: In this paper, the properties of porous concrete modified with fine aggregate and fly ash were investigated comparing with those of several ordinary road base materials, and the results indicated that fine aggregate can improve compressive strength and durability of porouscrete as road base material.
TL;DR: Wang et al. as mentioned in this paper investigated the effect of the layer number and type of proppant on fracture permeability and compressibility in a cubic shale sample from the Niutitang Formation at Sangzhi, Hunan Province, China.
TL;DR: In this article, the authors collected 4 types of cubic coal samples (samples cut parallel to face and butt cleats and perpendicular to the bedding plane) from the Fukang mining area in China to investigate the anisotropic characteristics of P-wave velocity, fractures and permeability under varying effective stresses from 3.5 to 8.5
TL;DR: In this paper, the authors employed MIP and ultrasound waveform analysis to evaluate concrete porosity, pore size distribution and the fractal dimension of pores, and found that the porosity and mean pore diameter of concrete decrease slightly when up to 30 wt% limestone powder is added, though further increase in the limestone content reverses the trend.
TL;DR: In this article, the authors proposed an overlapping dual permeability approach to derive coal permeability maps under the influence of multiple coupled processes, where the coal is characterized by a well-defined macroscopic model consisting of four overlapping/interpenetrating continua comprising: (1) coal matrix system, (2) coal fracture system; (3) gas flow in the matrix system; and (4) gas flows in the fracture system.