scholarly journals Impact of Low- or High-Permeability Inclusion on Free Convection in a Porous Medium

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Min Yan ◽  
Chunhui Lu ◽  
Jie Yang ◽  
Yifan Xie ◽  
Jian Luo
Keyword(s):  
Porous Media ◽  
Free Convection ◽  
Solute Transport ◽  
Large Scale ◽  
Effective Area ◽  
Source Zone ◽  
Sensitivity Analyses ◽  
Low Permeability ◽  
High Permeability ◽  
The Impact

Density-driven free convection in porous media is highly affected by large-scale heterogeneity, typical of which are low- or high-permeability inclusions imbedded in homogeneous porous media. In this research, we applied the modified Elder problem to investigate the impact of low- or high-permeability inclusions on the migration of a dense, unstable salt plume. Sensitivity analyses were conducted in terms of the permeability contrast, the effective area (the area of the inclusion beneath the source zone), and the distance of the inclusion from the source zone, all of which were found to play a significant role in controlling the total mass flux released from the source into the media. Results show that (1) a high-permeability inclusion has stronger effects than low-permeability inclusion, due to significantly unbalanced solute distributions caused by accelerated solute transport, (2) the inclusion with a larger effective area has more potential to influence free convection, (3) free convection is more sensitive to the low-/high-permeability inclusion vertically closer to the source zone, and (4) free convection is more susceptible to the low-permeability inclusion horizontally closer to the source zone. For high-permeability inclusions, the inclusion horizontally closer to the source zone influences the transport process more significantly at the early stage, and conversely, the inclusion far from the source zone has a later impact. The results obtained could offer significant implications for understanding unstable density-driven flow and solute transport in porous media with structured heterogeneity.

Chemical EOR in Low Permeability Sandstone Reservoirs: Impact of Clay Content on the Transport of Polymer and Surfactant

2021 ◽  
Author(s):  
Imane Guetni ◽  
Claire Marlière ◽  
David Rousseau
Keyword(s):  
Porous Media ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Clay Content ◽  
Low Permeability ◽  
Depth Propagation ◽  
The Impact ◽  
Polymer Retention ◽  
Injection Strategies

Abstract Application of chemical enhanced oil recovery (C-EOR) processes to low-permeability sandstone reservoirs (in the 10-100 mD range) can be very challenging as strong retention and difficult in-depth propagation of polymer and surfactant can occur. Transport properties of C-EOR chemicals are particularly related to porous media mineralogy (clay content). The present experimental study aimed at identifying base mechanisms and providing general recommendations to design economically viable C-EOR injection strategies in low permeability clayey reservoirs. Polymer and surfactant injection corefloods were conducted using granular packs (quartz and clay mixtures) with similar petrophysical characteristics (permeability 70-130 mD) but having various mineralogical compositions (pure quartz sand, sand with 8 wt-% kaolinite and sand with 8 wt-% smectite). The granular packs were carefully characterized in terms of structure (SEM) and specific surface area (BET). The main observables from the coreflood tests were the resistance and residual resistance factors generated during the chemical injections, the irreversible polymer retention and the surfactant retention in various injection scenarios (polymer alone, surfactant alone, polymer and surfactant). A first, the impact of the clay contents on the retention of polymer and surfactant considered independently was examined. Coreflood results have shown that retention per unit mass of rock strongly increased in presence of both kaolinite and smectite, but not in the same way for both chemicals. For polymer, retention was about twice higher with kaolinite than with smectite, despite the fact that the measured specific surface area of the kaolinite was about 5 times less than that of the smectite. Conversely, for surfactant, retention was much higher with smectite than with kaolinite. Secondly, the impact of the presence of surfactant on the polymer in-depth propagation and retention was investigated in pure quartz and kaolinite-bearing porous media. In both mineralogies, the resistance factor quickly stabilized when polymer was injected alone whereas injection of larger solution volumes was required to reach stabilization when surfactant was present. In pure quartz, polymer retention was shown, surprisingly, to be one order of magnitude higher in presence of surfactant whereas with kaolinite, surfactant did not impact polymer retention. The results can be interpreted by considering adsorption-governed retention. The mechanistic pictures being that (a) large polymer macromolecules are not able to penetrate the porosity of smectite aggregates, whereas surfactant molecules can, and (b) that surfactant and polymer mixed adsorbed layers can be formed on surfaces with limited affinity for polymer. Overall, this study shows that C-EOR can be applied in low permeability reservoirs but that successful injection strategies will strongly depend on mineralogy.

Modeling of filtration processes in periodic porous media

2021 ◽  
pp. 90-93
Author(s):  
Gennadiy Sandrakov ◽  
Andrii Hulianytskyi ◽  
Vladimir Semenov
Keyword(s):  
Porous Media ◽  
Parabolic Equations ◽  
Initial Boundary ◽  
Dynamic Processes ◽  
Low Permeability ◽  
Initial Boundary Value Problems ◽  
High Permeability ◽  
Guaranteed Accuracy ◽  
The Media ◽  
Initial Boundary Value

Modeling of dynamic processes of diffusion and filtration of liquids in porous media are discussed. The media are formed by a large number of blocks with low permeability, and separated by a connected system of faults with high permeability. The modeling is based on solving initial boundary value problems for parabolic equations of diffusion and filtration in porous media. The structure of the media leads to the dependence of the equations on a small parameter. Assertions on the solvability and regularity of such problems and the corresponding homogenized convolution problems are considered. The statements are actual for the numerical solution of this problem with guaranteed accuracy that is necessary to model the considered processes.

scholarly journals Development of PM<sub>2.5</sub> source impact spatial fields using a hybrid source apportionment air quality model

2015 ◽  
Vol 8 (7) ◽  
pp. 2153-2165 ◽  
Author(s):  
C. E. Ivey ◽  
H. A. Holmes ◽  
Y. T. Hu ◽  
J. A. Mulholland ◽  
A. G. Russell
Keyword(s):  
Air Quality ◽  
Source Apportionment ◽  
Large Scale ◽  
Major Ions ◽  
Current Knowledge ◽  
Direct Method ◽  
Hybrid Approach ◽  
Sensitivity Analyses ◽  
Adjustment Factors ◽  
The Impact

Abstract. An integral part of air quality management is knowledge of the impact of pollutant sources on ambient concentrations of particulate matter (PM). There is also a growing desire to directly use source impact estimates in health studies; however, source impacts cannot be directly measured. Several limitations are inherent in most source apportionment methods motivating the development of a novel hybrid approach that is used to estimate source impacts by combining the capabilities of receptor models (RMs) and chemical transport models (CTMs). The hybrid CTM–RM method calculates adjustment factors to refine the CTM-estimated impact of sources at monitoring sites using pollutant species observations and the results of CTM sensitivity analyses, though it does not directly generate spatial source impact fields. The CTM used here is the Community Multiscale Air Quality (CMAQ) model, and the RM approach is based on the chemical mass balance (CMB) model. This work presents a method that utilizes kriging to spatially interpolate source-specific impact adjustment factors to generate revised CTM source impact fields from the CTM–RM method results, and is applied for January 2004 over the continental United States. The kriging step is evaluated using data withholding and by comparing results to data from alternative networks. Data withholding also provides an estimate of method uncertainty. Directly applied (hybrid, HYB) and spatially interpolated (spatial hybrid, SH) hybrid adjustment factors at withheld observation sites had a correlation coefficient of 0.89, a linear regression slope of 0.83 ± 0.02, and an intercept of 0.14 ± 0.02. Refined source contributions reflect current knowledge of PM emissions (e.g., significant differences in biomass burning impact fields). Concentrations of 19 species and total PM2.5 mass were reconstructed for withheld observation sites using HYB and SH adjustment factors. The mean concentrations of total PM2.5 at withheld observation sites were 11.7 (± 8.3), 16.3 (± 11), 8.59 (± 4.7), and 9.2 (± 5.7) μg m−3 for the observations, CTM, HYB, and SH predictions, respectively. Correlations improved for concentrations of major ions, including nitrate (CMAQ–DDM (decoupled direct method): 0.404, SH: 0.449), ammonium (CMAQ–DDM: 0.454, SH: 0.492), and sulfate (CMAQ–DDM: 0.706, SH: 0.730). Errors in simulated concentrations of metals were reduced considerably: 295 % (CMAQ–DDM) to 139 % (SH) for vanadium; and 1340 % (CMAQ–DDM) to 326 % (SH) for manganese. Errors in simulated concentrations of some metals are expected to remain given the uncertainties in source profiles. Species concentrations were reconstructed using SH results, and the error relative to observed concentrations was greatly reduced as compared to CTM-simulated concentrations. Results demonstrate that the hybrid method along with a spatial extension can be used for large-scale, spatially resolved source apportionment studies where observational data are spatially and temporally limited.

Simulation Experimental Study on Aeolotropism Affects the Recovery of Low Permeable Sub Layer Reservoir

2015 ◽  
Vol 733 ◽  
pp. 174-177
Author(s):  
Xin Yuan Zhao ◽  
Yi Kun Liu ◽  
Feng Jiao Wang ◽  
Ru Ya Chen ◽  
Jin Ming Wang
Keyword(s):  
Recovery Rate ◽  
Water Flooding ◽  
Displacement Rate ◽  
Low Permeability ◽  
High Permeability ◽  
Water Displacement ◽  
Sand Body ◽  
Rock Cores ◽  
Layer Analysis ◽  
The Impact

In order to reveal the impact of reservoir heterogeneity on its recovery and by taking the interlayer heterogeneous and inner layer sand superimposition model (two forms of complexity situation) into account, water flooding experiments have been conducted on parallel connected rock cores, which are selected and artificially casted cores with different permeability, at different injection rates. Experimental results suggested that water displacement recovery is kept decreasing with the increasing of interlayer heterogeneity. when the interlayer permeability ratio (ratio of high permeability versus low permeability) is at about 6.5 and water displacement rate is set at 0.5ml/min, 1ml/min, 1.5ml/min, 2ml/min, respectively, the water flooding experiments indicated that the low permeability recovery increased significantly and low permeability layer became main producer with the increasing of water displacement rate, on the opposite, the high permeability recovery showed no little big change. Laboratory experiments on the model of layer sand body superimposition revealed that the recovery rate of FTRLPTPL model is about 5%~10% higher than that of FTPLPTRL model.(FTRLPTPL is briefed from that flooding from the thick and rich in oil layer and produced from the thin and poor in oil layer. FTPLPTRL is briefed from that flooding from the thin and poor in oil layer and produced from the thick and rich in oil layer.) Analysis on the experiments in different reservoir inner situation told us that recovery enhancement of low permeability layer can play a significant role in increasing the overall recovery rate.

Numerical analysis of magneto-natural convection and thermal radiation of SWCNT nanofluid inside T-inverted shaped corrugated cavity containing porous medium

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohamed Dhia Massoudi ◽  
Mohamed Bechir Ben Hamida ◽  
Mohammed A. Almeshaal ◽  
Yahya Ali Rothan ◽  
Khalil Hajlaoui
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Heat Source ◽  
Free Convection ◽  
Thermal Radiation ◽  
Convection And Heat Transfer ◽  
Content Type ◽  
Uniform Heat ◽  
Source Sink ◽  
The Impact

Purpose The purpose of this paper is to examine numerically the magnetohydrodynamic (MHD) free convection and thermal radiation heat transfer of single walled carbon nanotubes-water nanofluid within T-inverted shaped corrugated cavity comprising porous media including uniform heat source/sink for solar energy power plants applications. Design/methodology/approach The two-dimensional numerical simulation is performed by drawing on Comsol Multiphysics program, based on the finite element process. Findings The important results obtained show that increasing numbers of Rayleigh and Darcy and the parameter of radiation enhance the flow of convection heat. Furthermore, by increasing the corrugation height, the convection flow increases, but it decreases with the multiplication of the corrugation height. The use of a flat cavity provides better output than a corrugated cavity. Originality/value The role of surface corrugation parameters on the efficiency of free convection and heat transfer of thermal radiation within the porous media containing the T-inverted corrugated cavity including uniform heat source/sink under the impact of Lorentz forces has never been explored. A contrast is also established between a flat cavity and a corrugated one.

scholarly journals Techno-economic analysis for manufacturing cross-laminated timber

BioResources ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. 7790-7804
Author(s):  
Kristin Brandt ◽  
Alex Wilson ◽  
Donald Bender ◽  
James D. Dolan ◽  
Michael P. Wolcott
Keyword(s):  
United States ◽  
Large Scale ◽  
Low Cost ◽  
Embodied Energy ◽  
Sensitivity Analyses ◽  
Selling Price ◽  
Energy Prices ◽  
Cross Laminated Timber ◽  
The Cost ◽  
The Impact

Cross-laminated timber (CLT) is a bio-based building material that enables rapid construction and buildings with low embodied energy. Despite its comparative maturity in European markets, relatively little information regarding process design and economics for the manufacture of cross-laminated timber is available in the literature. Two techno-economic analyses were conducted to quantify the mill-gate cost of cross-laminated timber. The cross-laminated timber manufacturing process was described, and costs were analyzed for two facility scales. Cross-laminated timber produced at the large-scale facility using lumber priced at an average value for the northwest United States has a minimum selling price of $536/m3. Sensitivity analyses were used to define the impact of plant size, asset utilization, lumber price, plant capital cost, material waste, and other variables on minimum selling price. The cost of cross laminated timber rises quickly when a facility is not fully utilized. The second-ranking cost controlling variable is lumber price, while energy prices have minimal influence. The price of cross laminated timber can be optimized by locating a facility near low-cost lumber. The lowest-price region analyzed was the southeast United States using Southern Pine, which reduced the cost of cross laminated timber to $518/m3.

High Temperature Ageing of Fe-based Nanocrystalline Ribbons

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000260-000265 ◽  
Author(s):  
Christian Martin ◽  
Rémi Robutel ◽  
Cyril Buttay ◽  
Fabien Sixdenier ◽  
Pascal Bevilacqua ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Stress ◽  
Complex Permeability ◽  
Magnetic Flux Density ◽  
Low Permeability ◽  
High Permeability ◽  
Design Considerations ◽  
Temperature Ageing ◽  
The Impact

The impact of long-term high-temperature stress on nanocrystalline Finemet materials is measured by keeping samples at 200 °C for 1300 hours. The standard industrialized, high permeability Finemet materials as well as the recently available low permeability Finemet materials are investigated. Characterizations are performed at different frequencies, temperatures and magnetic field excitations on both aged and non-aged samples. Their complex permeability is also measured during the ageing test. Irreversible changes are pointed out on permeability, coercive field and magnetic flux density at saturation. Regarding the design considerations for high temperature power electronics, the suitability of these materials is demonstrated but an ageing effect has to be considered nonetheless. The presented data can be extrapolated to several thousand hours at 200 °C using the presented empiric ageing law.

Influence of pore geometry on motility and trapping of metal reducing bacteria

2020 ◽  
Author(s):  
Lazaro J. Perez ◽  
Nicole L. Sund ◽  
Rishi Parashar ◽  
Andrew E. Plymale ◽  
Dehong Hu ◽  
...  
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Large Scale ◽  
Ad Hoc ◽  
Pore Space ◽  
Practical Applications ◽  
Bacterial Migration ◽  
Reducing Bacteria ◽  
The Impact ◽  
Metal Reducing Bacteria

&lt;p&gt;Diverse processes such as bioremediation, biofertilization, and microbial drug delivery&lt;br&gt;rely on bacterial migration in porous media. However, how pore-scale confinement alters&lt;br&gt;bacterial motility is unknown due to the inherent heterogeneity in porous media. As a&lt;br&gt;result, models of migration are limited and often employ ad hoc assumptions.&lt;br&gt;We aim to determine the impact of pore confinement in the spreading dynamics of two&lt;br&gt;populations of motile metal reducing bacteria by directly visualizing individual &lt;em&gt;Acidovorax&lt;/em&gt;&lt;br&gt;and &lt;em&gt;Pelosinus&lt;/em&gt; in an unconfined liquid medium and in a microfluidic chip containing regular&lt;br&gt;placed pillars. We observe that the length of runs of the two species differs from the&lt;br&gt;unconfined and confined medium. Results show that bacteria in the confined medium&lt;br&gt;display a systematic shorter jumps due to grain obstacles when compared to the open&lt;br&gt;porous medium. Close inspection of the trajectories reveals that cells are intermittently&lt;br&gt;and transiently trapped, which produces superdiffusive motion at early and subdiffusion&lt;br&gt;behavior at late times, as they navigate through the confined pore space. While in the open&lt;br&gt;medium, we observe a linearly increasing variance with respect to time for &lt;em&gt;Acidovorax&lt;/em&gt;, and&lt;br&gt;for &lt;em&gt;Pelosinus&lt;/em&gt; the variance increases at a much faster rate showing super diffusive behavior&lt;br&gt;at early times. At late times, the rate of growth in spreading increases for &lt;em&gt;Acidovorax&lt;/em&gt; while&lt;br&gt;it reduces for &lt;em&gt;Pelosinus&lt;/em&gt;. We finally discuss that the paradigm of run-and-tumble motility&lt;br&gt;is dramatically altered in the confined porous medium and its practical applications of&lt;br&gt;these effects on large-scale transport.&lt;/p&gt;

Evaporative Cleanup of Water Blocks in Gas Wells

SPE Journal ◽  
2007 ◽  
Vol 12 (02) ◽  
pp. 209-216 ◽  
Author(s):  
Jagannathan Mahadevan ◽  
Mukul Mani Sharma ◽  
Yannis C. Yortsos
Keyword(s):  
Capillary Pressure ◽  
Damage Zone ◽  
Low Permeability ◽  
Tight Gas ◽  
High Permeability ◽  
Water Displacement ◽  
Gas Wells ◽  
Well Productivity ◽  
Gas Expansion ◽  
The Impact

Summary The flow of a gas toward the wellbore of a production well will result in the evaporative cleanup of water blocks, if the latter exist. This occurs primarily due to gas expansion. This paper presents for the first time a model to calculate the rate at which such water blocks are removed, for either fractured or unfractured gas wells. The model allows us to compute the impact of evaporative cleaning on well productivity. The removal of water first occurs by gas displacement. Evaporative cleanup is caused by gas expansion. The resulting saturation profile is qualitatively different for low- or high-permeability rocks. As a consequence, the increase in gas relative permeability, or the well productivity, with time can vary depending on the rock permeability and the well drawdown. High-permeability (e.g. fractured) rocks clean up significantly faster. By contrast, low-permeability unfractured wells may require a very long time to clean up. Large pressure drawdowns, as well as the use of more volatile fluids, such as alcohols, also result in faster cleanup. A distinctive feature of the work presented is that the model equations are formulated and solved completely without the assumption of skin factors for the damage zone. Thus, the prediction of cleanup rates can be made more accurately. Introduction Water blocks in low-permeability rocks clean up much more slowly than those of higher permeability because of the smaller pore sizes and the consequent higher capillary entry pressures (Mahadevan et al. 2003). In particular, water blocks in tight gas sands are not easily cleaned up, especially in cases where the reservoir pressures are too low to initiate flow. Past studies (Tannich 1975; Holditch 1979, Parekh and Sharma 2004) have reported the effect of water displacement by gas in the cleanup of water blocks in gas wells. They showed that when the drawdown in the gas well is significantly larger than the capillary pressure, cleanup is faster. However, in cases where the drawdown becomes comparable to the capillary pressure, as is the case in depleted tight gas reservoirs, displacement alone is not sufficient to remove water from the near-wellbore region. Subsequent water removal occurs by evaporation. The flow of a fully saturated compressible gas through a water-saturated porous rock induces evaporation. Roughly, this is because the volume of the gas, and hence its capacity for water content, increases as pressure declines. In past studies, the impact of evaporation caused by the flow of gas has been neglected. The focus of this paper is precisely on this regime in gas wells, in which the drawdown is comparable in magnitude to the capillary entry pressure, and cleanup of water blocks is by evaporation.

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