Showing papers on "Permeability (earth sciences) published in 2020"
TL;DR: Nuclear magnetic resonance (NMR) has been applied widely and successfully in conventional and unconventional reservoirs, and can be used to investigate petrophysical properties and fluid flow characteristics.
131 citations
TL;DR: In this article, the authors reviewed the permeability of natural gas hydrate-bearing sediments with respect to its relevant factors and development in characterization, and highlighted multi-scale analysis on the hydrate permeability with appropriate parameters as well as developing models for safe and economically feasible gas production from HBS eventually.
90 citations
TL;DR: In this article, a 3D X-ray micro-computed tomography (μ-CT) image of bituminous coal at pore scale was used to investigate the effect of liquid nitrogen N2 fracturing on coal.
90 citations
TL;DR: In this article, an analytical apparent porosity and permeability model was proposed to model gas storage and gas permeability in shale gas reservoirs with noncircular nanopores, where the SSA and aspect ratio of height to the width of non-circular nano-nodes were both used in the model.
76 citations
TL;DR: In this paper, a coupled compositional flow model by integrating the methane-air mixture flow in fracture, methane flow within the matrix, mass transfer between fractures and matrixes, and permeability evolution induced by gas depletion is presented.
73 citations
TL;DR: In this article, the largest contact area of asperity is defined as the area of contact with elastic critical contact area (ECCCA) of a sample cross-sectional area.
Abstract: List of Symbols a Contact area aec Elastic critical contact area aepc Elastoplastic critical contact area al The largest contact area of asperity A Sample cross-sectional area Ar The total real contact area K Permeability C Water compressibility Cf Fracture compressibility E Young’s moduli F Contact load Fec Elastic critical contact load Fmax Maximum contact load before unloading Fne Contact load for elastic deformation Fnep Contact load for elastoplastic deformation H Hardness of the asperity K Hardness coefficient L Sample length R Radius of asperity Sd Maximum depth of valleys Sh Maximum absolute height Sm Arithmetical mean height Sp Maximum peak height Vu Volume of the upstream chamber Vd Volume of the downstream chamber Y The yield strength of material α The fitting parameter of the pressure decay curve δ Normal displacement μ Fluid viscosity ν Poisson’s ratio ω Deformation of the asperity ωc Critical deformation at the inception of plastic deformation ωmax Maximum contact interference before unloading ωres Residual contact interference after complete unloading
67 citations
TL;DR: In this paper, a fractal geometry model was proposed to explain the effects of axial stress and creeping microstructure on the permeability for natural gas hydrate reservoir, and the model provided good match with experimental data when the axial stresses is larger, while poor agreement with experimental results at low pressure.
67 citations
TL;DR: In this article, a fully coupled thermo-hydro-mechanical model was developed and validated with analytical solutions and experimental result, and a series of parameter sensitivity analyses were implemented to investigate the effect of parameters on gas recovery.
66 citations
TL;DR: In this article, the authors analyzed the effects of compaction on gas permeability in soil at different degrees and different biochar amendment contents (i.e., 65, 80% and 95%), and identified relative significance of parameters (soil suction, water content, biochar content and compaction).
Abstract: Soil compaction has contrasting effect on soil strength (i.e., positive) and vegetation growth (i.e., negative), respectively. Biochar has been utilized mostly in combination with soils in both agricultural fields (i.e., loose soils) and geo-structures (i.e., dense soil slopes, landfill cover) for improving water retention due to its microporous structure. Biochar is also found to be useful to reduce gas permeability in compacted soil recently. However, the efficiency of biochar in reducing gas permeability in loose and dense soils is rarely understood. The objective of this study is to analyze effects of compaction on gas permeability in soil at different degrees of compaction (i.e., 65%, 80% and 95%) and also different biochar amendment contents (0%, 5% and 10%). Another aim is to identify relative significance of parameters (soil suction, water content, biochar content and compaction) in affecting gas permeability. Experiments were conducted before applying k-nearest neighbor (KNN) modeling technique for identifying relative significance of parameters. Biochar was synthesized from a coastal invasive species (water hyacinth), which has relatively no influence on food chain (as unlike in biochar produced from biomass such as rice husk, straw, peanut shell). Based on measurements and KNN modeling, it was found that gas permeability of biochar-amended soil is relatively lower than that of soil without amendment. It was found from KNN model that for denser soils, higher amount of soil suction is mobilized for a significant increase in gas permeability as compared to loose soils. Among all parameters, soil suction is found to be most influential in affecting gas permeability followed by water content and compaction.
63 citations
TL;DR: In this paper, the impact of nonlinearity of low velocity flows on the drainage design of grouted subsea tunnels was investigated by considering non-Darcy effects in the design of tunnel drainage system.
60 citations
TL;DR: In this article, the authors used CT scanning of krypton hydrate formation in silica sand using the excess gas method, together with a pore network model, to investigate variations in hydrate morphology and associated permeation.
TL;DR: In this paper, a dual-damage thermal-mechanical model accommodating the interaction of thermal conductivity, thermally-induced deformation, rock mechanical deformation and damage is defined to define the evolution of the thermal and mechanical properties of rock during thermal treatment.
TL;DR: In this article, a 3D X-ray micro-analyzer and Dragonfly software were used to analyze the 3D fractal features, spatial size distribution, and connectivity of pore-fractures.
TL;DR: Impact of reservoir confinement (stress) on porosity and permeability of shales was investigated using two digital rock 3D models, which represented nanoporous organic/mineral microstructure of the Marcellus Shale.
Abstract: Porosity and permeability are the key factors in assessing the hydrocarbon productivity of unconventional (shale) reservoirs, which are complex in nature due to their heterogeneous mineralogy and poorly connected nano- and micro-pore systems. Experimental efforts to measure these petrophysical properties posse many limitations, because they often take weeks to complete and are difficult to reproduce. Alternatively, numerical simulations can be conducted in digital rock 3D models reconstructed from image datasets acquired via e.g., nanoscale-resolution focused ion beam–scanning electron microscopy (FIB-SEM) nano-tomography. In this study, impact of reservoir confinement (stress) on porosity and permeability of shales was investigated using two digital rock 3D models, which represented nanoporous organic/mineral microstructure of the Marcellus Shale. Five stress scenarios were simulated for different depths (2,000–6,000 feet) within the production interval of a typical oil/gas reservoir within the Marcellus Shale play. Porosity and permeability of the pre- and post-compression digital rock 3D models were calculated and compared. A minimal effect of stress on porosity and permeability was observed in both 3D models. These results have direct implications in determining the oil-/gas-in-place and assessing the production potential of a shale reservoir under various stress conditions.
TL;DR: In this article, a series of seepage experiments was performed on methane hydrate-bearing clayey sediments, and the results showed that water flow in clayy sediments with different hydrate saturations exhibits both Non-Darcy and Darcy flow behaviors.
TL;DR: In this paper, the porosity and permeability of the main lithologies forming the reservoir, and the impacts of different thermal and mechanical stimulation practices to improve fluid flow, were investigated in Krafla Volcano, North-East Iceland.
TL;DR: In this paper, porosity was calculated by a downhole resistivity log of a nearby borehole close to Munich for comparison and the attempt of transferability of the data set to other locations within the Central Molasse Basin.
Abstract: For the successful realization and productivity prediction of new hydrothermal projects in the South German Molasse Basin, the hydraulic matrix properties of the Upper Jurassic Malm reservoir have to be determined as accurately as possible. To obtain specific information on the distribution of the petrophysical parameters (e.g., rock density, porosity, and permeability) 363 samples of rare drilling cores from the reservoir northeast of Munich (wells Moosburg SC4 and Dingolfing FB) were investigated using different experimental methods. Additionally, porosity was calculated by a downhole resistivity log of a nearby borehole close to Munich for comparison and the attempt of transferability of the data set to other locations within the Central Molasse Basin. Core data were divided into groups of different stratigraphic and petrographic units to cover the heterogeneity of the carbonate aquifer and provide data ranges to improve reservoir and prediction models. Data for effective porosity show a high variance from 0.3 to 19.2% throughout this heterogeneous aquifer. Permeability measured on core samples is scattered over several orders of magnitude (10−4–102 mD). Permeability models based on the porosity–permeability relationship were used to estimate permeability for the whole aquifer section and identify possible flow zones. A newly developed empirical model based on distinct lithofacies types allows a permeability estimation with a deviation < 10 mD. However, fractured, karstified, and vuggy zones occurring in this typically karstified, fractured, and porous reservoir cannot yet be taken into account by the model and result in an underestimation of permeability on reservoir scale. Overall, the dominant permeability trends can be mapped well using this model. For the regional transfer and the correlation of the results, a core-related porosity/permeability log for the reservoir was compiled for a well close to Munich showing similarities to the core investigations. The validation of the regional transferability of the parameter set to other locations in the Molasse Basin was carried out by correlation with the interpreted log data of a well near Munich.
TL;DR: In this paper, the authors show that prefracturing can dramatically decrease the IPLRi, stress sensitivity coefficient and PALR of coal seams, which may be the potential and effective measure to enhence the injectivity of CO2 in coal seams.
TL;DR: In this paper, the effect of subcritical (SubCO2) and supercritical CO2 saturation and its action time on the permeability evolution of fractured shale sample was examined, and five saturation times (4, 10, 12, 18, 24) were introduced to the shale sample.
TL;DR: The SG scaffold type was determined to be the most permeable one while the SD was the least permeable, and the Forchheimer's law proved to be a good mathematical tool as a Darcy's law expansion for the calculation of the structure's permeability.
Abstract: This study presents an experimental evaluation of permeability of triply periodic minimal surfaces (TPMS). Permeability is widely used to characterize scaffolds for Tissue Engineering (TE) applications as it gives information about the structure porosity, pore size, tortuosity and pore interconnectivity which have an important impact in cell seeding and proliferation. Three different TPMS structures were used: Schwartz Diamond (SD), Gyroid (SG) and Schwartz Primitive (SP), in four different porosity levels (50, 60, 70 and 80%). Overall, the SG scaffold type was determined to be the most permeable one while the SD was the least permeable. Furthermore, the presence of microscopic inertial pressure losses was verified and the Forchheimer's law proved to be a good mathematical tool as a Darcy's law expansion for the calculation of the structure's permeability while the weak-inertia regime was hard to detect or quantify.
TL;DR: In this article, the horizontal stress and permeability of coalbed methane (CBM) reservoir were continuously monitored during different gases depletion, and a stability factor was proposed to evaluate the reservoir stability during depletion.
TL;DR: In this article, the authors used electrical image logs in the carbonate Asmari Formation reservoir in Zagros Basin, SW Iran, to evaluate natural fractures, porosity system, permeability profile and heterogeneity index and accordingly compare the results with core and well data.
TL;DR: In this article, the authors determined the dominant CaCO3 distributions in pore space and investigated the effects of these distributions on the small-strain stiffness (measured by S-and P-wave velocities) and permeability of MICP-treated sands.
TL;DR: In this article, the authors established an analytical model to study the influence mechanism of hydraulic fracturing around vertical wellbores under the unsteady seepage in hydrocarbon reservoirs, deduced the analytical solution of water pressure and hydraulic gradient of the model, and compared the law of hydraulic pressure and gradient changing with time with the results of numerical simulation.
TL;DR: In this article, a high pressure triaxial automated system for rock (HPTAS) is employed to test red sandstone under different seepage pressures, and the variation laws of strength, deformation, axial strain stiffness and permeability during rock failure are analyzed.
TL;DR: Wang et al. as mentioned in this paper used a rough capillary bundle to characterize the coal structure and combined with fractal theory, a model including the tortuosity fractal dimension and the specific surface area of the pores was established based on the traditional Kozeny-Carman equation.
TL;DR: The model demonstrated that back-filling the excavated areas and drainage tunnel with low permeability materials could reduce the flux of Zn in AMD by up to 61%.
TL;DR: In this article, a new permeability model of shale matrix is derived based on rock and fluid properties, and its reliability is proved by using four methods, and the characteristics of matrix permeability are successfully analyzed by using this model and a simplified method of model application is given.
TL;DR: In this paper, a coupled hydromechanical numerical approach is developed and their complex interactions are analyzed using the energy method to study the influence of outburst factors during underground coal seam excavation.
Abstract: The mining of underground coal seam often induces the dynamic disasters of coal seam, such as rock burst and gas outburst. The determination of evolution characteristics of mechanical parameters and seepage parameters of coal mass after excavation is the basis for analyzing the formation mechanism of dynamic disasters. In this study, a coupled hydromechanical numerical approach is developed and their complex interactions are analyzed using the energy method to study the influence of outburst factors during underground excavation. A finite element model of porous media, which represents the gas flow field, the coal deformation field, the coal damage field and the cross-couplings between them, is established and the reliability of the model is ensured by numerical and experimental validation. Subsequently, during underground excavation, the coal deformation and gas flow properties around the borehole associated with different factors, including gas sorption, the matrix-fracture characteristics of coal and the seepage characteristics, are analyzed quantitatively using numerical simulations. Furthermore, an energy index is developed based on the energy method to analyze the comprehensive influence of in situ stress and gas pressure on coal mass. The results revealed that in the damage zone, coal permeability increases greatly by one to two orders of magnitude and the gas pressure remains low. Gas adsorption not only affects the stress and deformation of coal, but also affects the extent of the damage zone. High in situ stress, high gas pressure and low coal strength cause the failure range to increase.
TL;DR: In this article, a fully coupled thermo-hydro-mechanical cellular development model is established to simulate the heat production in the artificial fractured geothermal reservoir, and the results show that the production capacity can be overestimated by 13.06% when without considering the variation of permeability and porosity of the rock matrix over a 40-year of operation.