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1
Zhang, Xiaolong, Jianjun Liu, and Jiecheng Song. "Optimization Algorithm of Effective Stress Coefficient for Permeability." Energies 14, no. 24 (December 10, 2021): 8345. http://dx.doi.org/10.3390/en14248345.
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The effective stress coefficient for permeability is a significant index for characterizing the variation in permeability with effective stress. The realization of its accuracy is essential for studying the stress sensitivity of oil and gas reservoirs. The determination of the effective stress coefficient for permeability can be mainly evaluated using the cross-plotting or response surface method. Both methods preprocess experimental data and preset a specific function relation, resulting in deviation in the calculation results. To improve the calculation accuracy of the effective stress coefficient for permeability, a 3D surface fitting calculation method was proposed according to the linear effective stress law and continuity hypothesis. The statistical parameters of the aforementioned three methods were compared, and the results showed that the three-dimensional (3D) surface fitting method had the advantages of a high correlation coefficient, low root mean square error, and low residual error. The principal of using the 3D surface fitting method to calculate the effective stress coefficient of permeability was to evaluate the influence of two independent variables on a dependent variable by means of a 3D nonlinear regression. Therefore, the method could be applied to studying the relationship between other physical properties and effective stress.
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Zhiming, Wang, Yang Gang, and Zhang Jian. "A New Coal Permeability Prediction Method Based on Experiment and Dimension Analysis." SPE Journal 19, no. 03 (January 21, 2013): 356–60. http://dx.doi.org/10.2118/162940-pa.
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Summary This paper aims to investigate the effect of temperature and effective stress on coal permeability. Through the experiment, we find a reversal phenomenon in which the coal permeability presents different change trends as temperature increases at two sides of the reverse point. The term “critical effective stress” refers to the effective stress at the reverse point. When effective stress is lower than the critical effective stress, the outward expansion effect of the coal block caused by grain and gas swell is greater than compaction effect as temperature increases under low effective stress condition. Therefore, the coal expands primarily outward, which results in fissure opening and permeability increase. When effective stress is higher than the critical effective stress, high effective stress limits the coal's outward expansion. The coal expands inward with increasing temperature, thus causing fissure closure and permeability decrease. On the basis of dimension analysis and regression analysis, combined with experimental data, this paper develops a high-precision semitheoretical coal permeability model of Qinshui basin in China. Simultaneously, what this paper presents is a permeability prediction method: measuring coal core permeability and performing dimension analysis and regression analysis. With this work done, we can establish a similar permeability model suitable for other target zones. Thus, the analytical method presented in this paper provides a basis for coal permeability prediction.
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Wei, Xi. "The Research of Production Split Using Well Logging and Well Testing Method." Advanced Materials Research 915-916 (April 2014): 1438–42. http://dx.doi.org/10.4028/www.scientific.net/amr.915-916.1438.
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The most popular method to split the production is mainly based on permeability and effective thickness of reservoir. In this general method, the permeability comes from the well logging interpretation. But this permeability can not reflect the flow characteristics of real fluid in the reservoir. In this paper, a new production split method is proposed considering the well logging method, the well test method and relative permeability curve. It is proved to be reliable and effective after cases study. It is worth to promote in oilfields.
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Wang, Ke Liang, Jin Yu Li, Lei Lei Zhang, Xue Li, Guo Qiang Fu, and Wei Liang Li. "Injection Method of SJT-B Collosol in the Low Permeability Reservoir." Applied Mechanics and Materials 694 (November 2014): 340–45. http://dx.doi.org/10.4028/www.scientific.net/amm.694.340.
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Profile control and flooding technique is an effective way to enhance the oil recovery of low permeability reservoir.Analyzing the relation between oil and water interface and determining injection volume under different concentration is the key to success in profile controlling and flooding in low permeability reservoir .The research is about SJT-B collosol of physicochemical property under normal pressure and temperature.We also carry on the study on measuring SJT-B collosol interfacial tension for a long time under different concentration.Besides, we conduct the plugging degree experiment by injecting SJT-B collosol with the concentration of 0.8% in different permeability core.The lower the core permeability, the higher the plugging degree. By optimizing the injection pattern we conduct the three-tube parallel profile control and flooding experiment in the low permeability heterogeneous core.It indicates that SJT-B collosol mainly access to high permeability layer and have an effective plugging effect .The absorbed liquid rate of medium permeability layer is increased apparently ,while low permeability layer is increased slightly.The SJT-B collosol of injection method has efficient effect on enhancing the oil recovery of low permeability reservoir in late water flooding.
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Cramer, David D., and Mark A. Songer. "Batch-Mix Fracturing: An Effective Method of Stimulating Moderate-Permeability Reservoirs." SPE Production Engineering 5, no. 04 (November 1, 1990): 461–68. http://dx.doi.org/10.2118/17500-pa.
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McCarthy, J. F. "Effective permeability of sandstone-shale reservoirs by a random walk method." Journal of Physics A: Mathematical and General 23, no. 9 (May 7, 1990): L445—L451. http://dx.doi.org/10.1088/0305-4470/23/9/008.
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Teimoori, Ahmad, Zhixi Chen, Sheik S. Rahman, and Thanh Tran. "Effective Permeability Calculation Using Boundary Element Method in Naturally Fractured Reservoirs." Petroleum Science and Technology 23, no. 5-6 (May 2005): 693–709. http://dx.doi.org/10.1081/lft-200033029.
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Nœtinger, Benoît. "Computing the effective permeability of log-normal permeability fields using renormalization methods." Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science 331, no. 5 (September 2000): 353–57. http://dx.doi.org/10.1016/s1251-8050(00)01412-9.
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Selvadurai, A. P. S., and P. A. Selvadurai. "Surface permeability tests: experiments and modelling for estimating effective permeability." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 466, no. 2122 (May 14, 2010): 2819–46. http://dx.doi.org/10.1098/rspa.2009.0475.
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This paper presents a technique for determining the near surface permeability of geomaterials and involves the application of a uniform flow rate to an open central region of a sealed annular patch on an otherwise unsealed flat surface. Darcy’s flow is established during attainment of a steady pressure at a constant flow rate. This paper describes the experimental configuration and its theoretical analysis via mathematical and computational techniques. The methods are applied to investigate the surface permeability characteristics of a cuboidal block of Indiana limestone measuring 508 mm. An inverse analysis procedure is used to estimate the permeability characteristics at the interior of the Indiana limestone block. The resulting spatial distribution of permeability is used to estimate the effective permeability of the tested block.
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Pang, Y., M. Y. Soliman, H. Deng, and Hossein Emadi. "Analysis of Effective Porosity and Effective Permeability in Shale-Gas Reservoirs With Consideration of Gas Adsorption and Stress Effects." SPE Journal 22, no. 06 (July 14, 2017): 1739–59. http://dx.doi.org/10.2118/180260-pa.
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Summary Nanoscale porosity and permeability play important roles in the characterization of shale-gas reservoirs and predicting shale-gas-production behavior. The gas adsorption and stress effects are two crucial parameters that should be considered in shale rocks. Although stress-dependent porosity and permeability models have been introduced and applied to calculate effective porosity and permeability, the adsorption effect specified as pore volume (PV) occupied by adsorbate is not properly accounted. Generally, gas adsorption results in significant reduction of nanoscale porosity and permeability in shale-gas reservoirs because the PV is occupied by layers of adsorbed-gas molecules. In this paper, correlations of effective porosity and permeability with the consideration of combining effects of gas adsorption and stress are developed for shale. For the adsorption effect, methane-adsorption capacity of shale rocks is measured on five shale-core samples in the laboratory by use of the gravimetric method. Methane-adsorption capacity is evaluated through performing regression analysis on Gibbs adsorption data from experimental measurements by use of the modified Dubinin-Astakhov (D-A) equation (Sakurovs et al. 2007) under the supercritical condition, from which the density of adsorbate is found. In addition, the Gibbs adsorption data are converted to absolute adsorption data to determine the volume of adsorbate. Furthermore, the stress-dependent porosity and permeability are calculated by use of McKee correlations (McKee et al. 1988) with the experimentally measured constant pore compressibility by use of the nonadsorptive-gas-expansion method. The developed correlations illustrating the changes in porosity and permeability with pore pressure in shale are similar to those produced by the Shi and Durucan model (2005), which represents the decline of porosity and permeability with the increase of pore pressure in the coalbed. The tendency of porosity and permeability change is the inverse of the common stress-dependent regulation that porosity and permeability increase with the increase of pore pressure. Here, the gas-adsorption effect has a larger influence on PV than stress effect does, which is because more gas is attempting to adsorb on the surface of the matrix as pore pressure increases. Furthermore, the developed correlations are added into a numerical-simulation model at field scale, which successfully matches production data from a horizontal well with multistage hydraulic fractures in the Barnett Shale reservoir. The simulation results note that without considering the effect of PV occupied by adsorbed gas, characterization of reservoir properties and prediction of gas production by history matching cannot be performed reliably. The purpose of this study is to introduce a model to calculate the volume of the adsorbed phase through the adsorption isotherm and propose correlations of effective porosity and permeability in shale rocks, including the consideration of the effects of both gas adsorption and stress. In addition, practical application of the developed correlations to reservoir-simulation work might achieve an appropriate evaluation of effective porosity and permeability and provide an accurate estimation of gas production in shale-gas reservoirs.
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Cong, Lin, Shi Zhong Ma, Wen Long Li, and Yan Cong. "Study on Physical Property Lower Limit of Effective Reservoir of Deep Layer in Qingshui-Yuanyang Area." Advanced Materials Research 616-618 (December 2012): 104–8. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.104.
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Synthetically using the empirical statistic method, porosity—permeability intersection method minimum flow pore throat radius method and oil test method. We can seek for the physical property lower limit of different depth of deep reservoirs of Yuan Yang Gou. According to liner regression, we achieved the functional equation which shows functional relationship between physical property lower limit and depth. At the same time, we also talk about the characteristics of different methods and the control factors of physical property lower limit The results show that although the methods have advantages and disadvantages, we should use these methods in a synthetically way. However, the porosity lower limit of the study area mainly is controlled by reservoirs which is based on primary pore and mainly affected by the depth, it also presents a good liner relationship with the logarithm of depth of burial .Permeability lower limit is mainly affected by reservoirs that is based on secondary pore Permeability lower limit shows a exponential relationship with depth of burial too, but its relative relevance is bad.
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Lv, Qiang, Ming Xiang Chen, Hui Cao, and Zhi Yin Gan. "An Effective Method for Bonding Carbon Nanotubes onto Metal Electrodes." Advanced Materials Research 403-408 (November 2011): 1099–102. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.1099.
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An effective method was used to bond carbon nanotubes onto metal electrodes by induction heating process. A good contact between carbon nanotubes and metal electrodes was formed. The contact resistance can be reduced to approximate 95% after induction heating process. Because the induction heating process will selective occur on the structures with high relative permeability and low electrical resistivity, this method could be utilized to realize large scale localized bonding.
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Matsuzaki, Ryosuke, Tomohiro Ishikawa, Tomonaga Okabe, Yutaka Oya, and Shigeki Yashiro. "Stiffness and permeability multi-objective optimization of carbon-fiber-reinforced plastic mesostructures using homogenization method." Journal of Composite Materials 53, no. 13 (November 12, 2018): 1865–80. http://dx.doi.org/10.1177/0021998318812160.
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This paper presents a stiffness and permeability multi-objective optimization method for carbon-fiber-reinforced plastic mesostructures based on a homogenization method. To reduce the computational cost of dealing with multiple design variables for complicated fiber mesostructures, we generate and extract effective design variables from optimization results derived from a smaller number of design variables. We applied the proposed method to optimization of the in-plane and out-of-plane stiffness and permeability of non-crimp fabrics. The optimization results showed that the application of effective design variables enabled attainment of an improved elastic modulus and permeability. From investigations of the obtained optimized design, we clarified the trade-off relationship between the elastic modulus and permeability, and elucidated the effects of dimensions of non-crimp fabric mesostructures on the elastic modulus and permeability.
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Zhang, Zhenying, Yingfeng Wang, Hui Xu, Yuehua Fang, and Dazhi Wu. "Influence of effective stress and dry density on the permeability of municipal solid waste." Waste Management & Research: The Journal for a Sustainable Circular Economy 36, no. 5 (March 29, 2018): 471–80. http://dx.doi.org/10.1177/0734242x18763520.
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A landfill is one of the main sites for disposal of municipal solid waste and the current landfill disposal system faces several problems. For instance, excessive leachate water is an important factor leading to landfill instability. Understanding the permeability characteristics of municipal solid waste is a relevant topic in the field of environmental geotechnical engineering. In this paper, the current research progress on permeability characteristics of municipal solid waste is discussed. A review of recent studies indicates that the research in this field is divided into two categories based on the experimental method employed: field tests and laboratory tests. This paper summarizes test methods, landfill locations, waste ages, dry densities and permeability coefficients across different studies that focus on permeability characteristics. Additionally, an experimental study on compressibility and permeability characteristics of fresh municipal solid waste under different effective stresses and compression times was carried out. Moreover, the relationships between the permeability coefficient and effective stress as well as dry density were obtained and a permeability prediction model was established. Finally, the experimental results from the existing literature and this paper were compared and the effects of effective stress and dry density on the permeability characteristics of municipal solid waste were summarized. This study provides the basis for analysis of leachate production in a landfill.
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Pang, Mingkun, Tianjun Zhang, Lu Gao, and Binfeng Qin. "Investigating the effects of effective stress on pore-dependent permeability measurements of crushed coal." PLOS ONE 16, no. 12 (December 23, 2021): e0261678. http://dx.doi.org/10.1371/journal.pone.0261678.
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The accurate determination of permeability is one of the parameters essential for the study of fluid flow and transport state. However, a large number of fractured coal bodies are faced during the production of coal mines. The study of permeability of these special media composed of grains of a certain size, whose structure is different from that of raw coal, has been in the exploratory stage. In this paper, inspired by the calculation method of median particle size and the calculation principle of KC’s equation, we calculate the permeability parameters of broken coal particles. It is considered that its permeability is closely related to the compaction and re-crushing process of skeletal grains. The lateral limit compression test of the crushed coal body was designed, and the pore-dominated permeability calculation method was given to reveal the mechanism of the action of the effective stress. The dependence relationship between the effective stress and the pore-correlation permeability is obtained by data analysis, and the force and deformation process of the crushed coal grain media is described. In contrast to the conventional Darcy series of permeability discussions, our approach excludes the influence of fluid factors on the permeability of porous media. The permeability of porous media is considered to be determined only by its own pore structure.
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Yan, Liang Dong, Zhi Juan Gao, and Feng Gang Dai. "Effective use Model of Low Permeability Oil Reservoir." Advanced Materials Research 753-755 (August 2013): 53–57. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.53.
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The throat of low permeability oil reservoir is narrow and small, the reservoir fluid flow resistance is big, and with the start-up pressure gradient, compare with medium and high permeability reservoir fluid flow, the characteristics are obviously different in performance for non-darcy flow at low speed. This kind of oil field reservoir started in the process of mining scope is small, the degree of use and the development effect is low. To solve these problems, this paper established considering start-up pressure gradient of the new unstable seepage flow mathematical model of non-darcy radial flow which the analytical solution and the productivity equation is deduced, established the effective radius of the use of low permeability reservoirs, and systemicly researched the calculation method of area well pattern of different types of non-darcy seepage.
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Zhang, Hairong, Bin Zhao, Shiqi Dong, Xixin Wang, and Pengfei Jing. "A Method for the Inversion of Reservoir Effective Permeability Based on Time-Lapse Resistivity Logging Data and Its Application." Geofluids 2022 (April 22, 2022): 1–13. http://dx.doi.org/10.1155/2022/8704344.
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Effective permeability is a key parameter for evaluating reservoirs and their productivity. With the wide application of resistivity logging tools in drilling, the advantages of resistivity logging in response to the dynamic invasion process of drilling fluids have become increasingly prominent. We analyzed the variation law of the measured resistivity data for different permeability formations at different times. In this study, we proposed an effective permeability modeling method based on the time-lapse resistivity logging data. First, based on the resistivity measurement data at different times, the dynamic resistivity profile of the reservoir was obtained through joint inversion; we then obtained the invasion depth and invasion zone resistivity of the drilling fluid at different times, along with the original formation resistivity. Subsequently, combined with parameters such as the soaking time, fluid viscosity, and saturation change of the drilling fluid, we obtained the phase permeability curve of the reservoir and dynamic effective permeability of the fluid near the wellbore. This study provides basic parameters for subsequent formation analyses and productivity prediction and substantially improves the reservoir evaluation technology from static to dynamic.
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Yuliani, Ayu, Ordas Dewanto, Karyanto Karyanto, and Ade Yogi. "PREDIKSI PERMEABILITAS MENGGUNAKAN METODE LOG DAN PORE GEOMETRY STRUCTURE (PGS) PADA DAERAH CEKUNGAN JAWA BARAT UTARA." Jurnal Geofisika Eksplorasi 6, no. 1 (March 18, 2020): 3–17. http://dx.doi.org/10.23960/jge.v6i1.57.
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Determination of reservoir rock properties is very important to be able to understand the reservoir better. One of these rock properties is permeability. Permeability is the ability of a rock to pass fluid. In this study, the calculation of permeability was carried out using log and PGS (Pore Geometry Structure) methods based on core data, logs, and CT scans. In the log method, the calculation of permeability is done by petrophysical analysis which aims to evaluate the target zone formation in the form of calculation of the distribution of shale content (effective volume), effective porosity, water saturation, and permeability. Next, the determination of porosity values from CT Scan. Performed on 2 data cores of 20 tubes, each tube was plotted as many as 15 points. The output of this stage is the CT Porosity value that will be used for the distribution of predictions of PGS permeability values. In the PGS method, rock typing is based on geological descriptions, then calculation of permeability predictions. Using these two methods, permeability can be calculated in the study area. The results of log and PGS permeability calculations that show good correlation are the results of calculation of PGS permeability. It can be seen from the data from the calculation of PGS permeability approaching a gradient of one value with R2 of 0.906, it will increasingly approach the core rock permeability value. Whereas the log permeability calculation for core rock permeability is 0.845.
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Ge, Yong, Jie Fan, Jie Yuan, Wen Cui Yang, Bao Sheng Zhang, and Ji Shou Yu. "Relation of Permeability by High Hydraulic Method and Chloride Ion Diffusion Coefficient of Concrete." Key Engineering Materials 405-406 (January 2009): 303–8. http://dx.doi.org/10.4028/www.scientific.net/kem.405-406.303.
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Permeation length, permeation coefficient of water permeated into concrete and chloride ion diffusion coefficient of C30, C45 and C60 concrete were studied by high hydraulic method (0.5MPa~25MPa) and quick method of testing chloride ion diffusion respectively, and relationship of concrete permeability tested by two methods was analyzed too. High hydraulic method can distinguish permeability of concrete with different strength or air content and it is a quick and effective method to fast test and evaluating permeability of concrete. The results showed that high hydraulic method is applicable for evaluating permeability of concrete, with advantages of short testing period, easy operating and simple pretreatment of concrete specimens. Permeation coefficient or permeation length of water permeated into concrete exhibited linear relationship with chloride ion diffusion coefficient of concrete. It is applicable for evaluating permeability of concrete using quick method of testing chloride ion diffusion.
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Wang, Yi, Hao Wang, Shangyi Qi, Shimin Liu, Yixin Zhao, and Wenting Yue. "Investigation of Shale Permeability Evolution considering Bivalued Effective Stress Coefficients for CO2 Injection." Geofluids 2021 (October 1, 2021): 1–11. http://dx.doi.org/10.1155/2021/1132440.
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Because of the existence of multiscale pores from nano- to macroscale, a multimechanistic shale gas flow process involving the Darcy and Knudsen flows occurs during gas shale well depletion. The respective contribution of the Darcy and Knudsen flows to the permeability is constantly changing with pressure evolution. In this study, laboratory measurements of shale permeability with CO2 injections were carried out under hydrostatic conditions, using the transient pulse-decay method. The “U”-shape permeability curve resulted in both positive and negative effective stress coefficients (Biot’s coefficient) χ . A permeability turning point was thus created to partition permeability curves into the Darcy and Knudsen sections. The Knudsen effect was proven to be significant at low pressure/late time in the laboratory. Effective stress and sorption-induced deformation have been found to govern the Darcy permeability evolution under the tested experimental conditions. Thus, negative effective stress coefficients, together with the positive ones, should be applied to a nonmonotonic pressure-permeability evolution to explain the concurrent effect of the Darcy flow and Knudsen flow at different pore pressures.
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Csurgai, Péter, and Miklós Kuczmann. "Sensitivity calculation of LF RFID transponder coil by the mutual effective permeability method." Pollack Periodica 6, no. 2 (August 2011): 3–12. http://dx.doi.org/10.1556/pollack.6.2011.2.1.
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Sekiguchi, Takaho, Hiromu Odanaka, Yoshinobu Okano, and Satoshi Ogino. "Effective Loading Method of High- permeability Magnetic Sheet for NFC/WPT Hybrid Antenna." IEEJ Transactions on Electronics, Information and Systems 137, no. 6 (2017): 826–33. http://dx.doi.org/10.1541/ieejeiss.137.826.
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Tawfeeq, Yahya. "DIGITAL ROCK ANALYSIS: AN ALTERNATIVE METHOD TO PREDICT PETROPHYSICAL PROPERTIES, CASE STUDY FROM MISHRIF FORMATION." Iraqi Geological Journal 53, no. 2C (September 30, 2020): 34–55. http://dx.doi.org/10.46717/igj.53.2c.4rs-2020-09-04.
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The digital core analysis of petrophysical properties replace the use of conventional core analysis by reducing the required time for investigation. Also, the ability to capture pore geometries and fluid behavior at the pore-scale improves the understanding of complex reservoir structures. In this work, 53 samples of 2D thin section petrographic images were used for analyses from the core plugs taken from the Buzurgan oil field. Each sample was impregnated with blue-dyed epoxy, thin sectioned and then was stained for discrimination of carbonate minerals. Each thin section has been described in detail and illustrated by photomicrographs. The studied samples include a variety of rock types. Packstone is the most common rock type observed followed by grainstone and packstone – wackestone. Floatstone and dolostone are noted rarely in the studied interval. However, the samples of thin section images are processed and digitized, utilizing MATLAB programming and image analysis software. The entire workflow of digital core analysis from image segmentation to petrophysical rock properties determination was performed. A focused has been made on determining effective and total porosity, absolute permeability, and irreducible water saturation. Absolute permeability is estimated with the Kozeny-Carman permeability correlation model and Timur-Coates permeability correlation model. Irreducible water saturation simply is derived from total and effective porosity. Also, some pore void characteristics, such as area and perimeter, were calculated. The results of Digital 2D image analysis have been compared to laboratory core measurements to investigate the reliability and restrictions of the digital image interpretation techniques.
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Wu, Xiao Feng, Guang Fan Li, and Wan Cheng He. "The Principle of Effective Stress Theory Research Based on Channel Rate." Applied Mechanics and Materials 275-277 (January 2013): 336–42. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.336.
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Based on the debate of effective stress principle applicability on cohesive soil in recent years and the predecessor's research achievements, this paper puts forward the idea that the effective stress surface including hydrated film surrounding soil particles. And we obtained the extended soil effective stress equation by establishment of the model of channel rate.Combined with the physical significance of permeability coefficient and substantial experimental data, it can establish the fitting equation between permeability coefficient and new proposed physical parameter channel rate. A new calculation method to unify the separate calculation and combined calculation of water and earth pressures is proposed to carry out the transition between results of the two conventional calculation methods and provide a new idea for solving the jump problem between the two results.
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Martyushev, Dmitriy A., Inna N. Ponomareva, and Vladislav I. Galkin. "Conditions for Effective Application of the Decline Curve Analysis Method." Energies 14, no. 20 (October 9, 2021): 6461. http://dx.doi.org/10.3390/en14206461.
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Determining the reliable values of the filtration parameters of productive reservoirs is the most important task in monitoring the processes of reserve production. Hydrodynamic studies of wells by the pressure build-up method, as well as a modern method based on production curve analysis (Decline Curve Analysis (DCA)), are some of the effective methods for solving this problem. This paper is devoted to assessing the reliability of these two methods in determining the filtration parameters of terrigenous and carbonaceous productive deposits of oil fields in the Perm Krai. The materials of 150 conditioned and highly informative (obtained using high-precision depth instruments) studies of wells were used to solve this problem, including 100 studies conducted in terrigenous reservoirs (C1v) and 50 carried out in carbonate reservoirs (C2b). To solve the problem, an effective tool was used—multivariate regression analysis. This approach is new and has not been previously used to assess the reliability of determining the filtration parameters of reservoir systems by different research methods. With its use, a series of statistical models with varying degrees of detail was built. A series of multivariate mathematical models of well flow rates using the filtration parameters determined for each of the methods is constructed. The inclusion or non-inclusion of these filtration parameters in the resulting flow rate models allows us to give a reasonable assessment of the possibility of using the pressure build-up method and the DCA method. All the constructed models are characterized by high statistical estimates: in all cases, a high value of the determination coefficient was obtained, and the probability of an error in all cases was significantly less than 5%. As applied to the fields under consideration, it was found that both methods demonstrate stable results in terrigenous reservoirs. The permeability determined by the DCA method and the pressure build-up curve does not control the flow of the fluid in carbonate reservoirs, which proves the complexity of the filtration processes occurring in them. The DCA method is recommended for use to determine the permeability and skin factor in the conditions of terrigenous reservoirs.
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Li, Jun, and Donald Brown. "Upscaled Lattice Boltzmann Method for Simulations of Flows in Heterogeneous Porous Media." Geofluids 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/1740693.
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An upscaled Lattice Boltzmann Method (LBM) for flow simulations in heterogeneous porous media at the Darcy scale is proposed in this paper. In the Darcy-scale simulations, the Shan-Chen force model is used to simplify the algorithm. The proposed upscaled LBM uses coarser grids to represent the average effects of the fine-grid simulations. In the upscaled LBM, each coarse grid represents a subdomain of the fine-grid discretization and the effective permeability with the reduced-order models is proposed as we coarsen the grid. The effective permeability is computed using solutions of local problems (e.g., by performing local LBM simulations on the fine grids using the original permeability distribution) and used on the coarse grids in the upscaled simulations. The upscaled LBM that can reduce the computational cost of existing LBM and transfer the information between different scales is implemented. The results of coarse-grid, reduced-order, simulations agree very well with averaged results obtained using a fine grid.
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Yan, Xinlu, Songhang Zhang, Shuheng Tang, Zhongcheng Li, Yongxiang Yi, Qian Zhang, Qiuping Hu, and Yuxin Liu. "A Comprehensive Coal Reservoir Classification Method Base on Permeability Dynamic Change and Its Application." Energies 13, no. 3 (February 3, 2020): 644. http://dx.doi.org/10.3390/en13030644.
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Due to the unique adsorption and desorption characteristics of coal, coal reservoir permeability changes dynamically during coalbed methane (CBM) development. Coal reservoirs can be classified using a permeability dynamic characterization in different production stages. In the single-phase water flow stage, four demarcating pressures are defined based on the damage from the effective stress on reservoir permeability. Coal reservoirs are classified into vulnerable, alleviative, and invulnerable reservoirs. In the gas desorption stage, two demarcating pressures are used to quantitatively characterize the recovery properties of permeability based on the recovery effect of the matrix shrinkage on permeability, namely the rebound pressure (the pressure corresponding to the lowest permeability) and recovery pressure (the pressure when permeability returns to initial permeability). Coal reservoirs are further classified into recoverable and unrecoverable reservoirs. The physical properties and influencing factors of these demarcating pressures are analyzed. Twenty-six wells from the Shizhuangnan Block in the southern Qinshui Basin of China were examined as a case study, showing that there is a significant correspondence between coal reservoir types and CBM well gas production. This study is helpful for identifying geological conditions of coal reservoirs as well as the productivity potential of CBM wells.
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Glover, P. W., and E. Walker. "Grain-size to effective pore-size transformation derived from electrokinetic theory." GEOPHYSICS 74, no. 1 (January 2009): E17—E29. http://dx.doi.org/10.1190/1.3033217.
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Most permeability models use effective grain size or effective pore size as an input parameter. Until now, an efficacious way of converting between the two has not been available. We propose a simple conversion method for effective grain diameter and effective pore radius using a relationship derived by comparing two independent equations for permeability, based on the electrokinetic properties of porous media. The relationship, which we call the theta function, is not dependent upon a particular geometry and implicitly allows for the widely varying style of microstructures exhibited by porous media by using porosity, cementation exponent, formation factor, and a packing constant. The method is validated using 22 glass bead packs, for which the effective grain diameter is known accurately, and a set of 188 samples from a sand-shale sequence in the North Sea. This validation uses measurements of effective grain size from image analysis, pore size from mercury injection capillary pressure (MICP) measurements, and effective pore radius calculated from permeability experiments, all of which are independent. Validation tests agree that the technique accurately converts an effective grain diameter into an effective pore radius. Furthermore, for the clastic data set, there exists a power law relationship in porosity between effective grain size and effective pore size. The theta function also can be used to predict the fluid permeability of a sample, based on effective pore radius. The result is extremely good predictions over seven orders of magnitude.
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Wang, Gang, Ke Wang, Yujing Jiang, and Shugang Wang. "Reservoir Permeability Evolution during the Process of CO2-Enhanced Coalbed Methane Recovery." Energies 11, no. 11 (November 1, 2018): 2996. http://dx.doi.org/10.3390/en11112996.
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In this study, we have built a dual porosity/permeability model through accurately expressing the volumetric strain of matrix and fracture from a three-dimensional method which aims to reveal the reservoir permeability evolution during the process of CO2-enhanced coalbed methane (CO2-ECBM) recovery. This model has accommodated the key competing processes of mechanical deformation and adsorption/desorption induced swelling/shrinkage, and it also considered the effect of fracture aperture and effective stress difference between each medium (fracture and matrix). We then numerically solve the permeability model using a group of multi-field coupling equations with the finite element method (FEM) to understand how permeability evolves temporally and spatially. We further conduct multifaceted analyses to reveal that permeability evolution near the wells is the most dramatic. This study shows that the farther away from the well, the gentler the evolution of permeability. The evolution of reservoir permeability near the injection well (IW) and the production well (PW) are very different, due to the combined effects of effective stress changes and gas adsorption and desorption. Furthermore, adsorption is the main controlling factor for the change of permeability for regions near the IW, while the change in effective stress is the main cause for the change in permeability near the PW. Increasing the injection pressure of CO2 will cause the reservoir permeability to evolve more quickly and dynamically.
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Zhou, Sui Hua, Zhi Yi Chen, and Shi Min Feng. "Improvement Methods of Apparent Permeability of Ferromagnetic Core." Advanced Materials Research 712-715 (June 2013): 1876–80. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.1876.
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The performance of induction coil magnetic sensors , which usually have large dimensions and heavy weights, is mainly decided by apparent permeability of the core. But flux concentrator is a effective equipment to improve apparent permeability of the core, which will hardly increase dimensions and weights of magnetic sensors. Firstly, mathematical equations of apparent permeability are explained and influencing factors are analysed. Then influencing degrees of different parameters of the flux concentrator are simulated by Maxwell 2D/3D. The results are shown as follows. (a) The larger diameter and thickness of the flux concentrator, the better is the effect of magnetic concentration. (b) The less the gap between core and concentrator, the better is the effect of magnetic concentration. (c) The larger relative permeability of the flux concentrator, the effect of magnetic concentration is unconspicuous for the material whose relative permeabilityis larger than ten thousands.
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CAI, JIANCHAO, LIJUN YOU, XIANGYUN HU, JING WANG, and RONGHUA PENG. "PREDICTION OF EFFECTIVE PERMEABILITY IN POROUS MEDIA BASED ON SPONTANEOUS IMBIBITION EFFECT." International Journal of Modern Physics C 23, no. 07 (July 2012): 1250054. http://dx.doi.org/10.1142/s0129183112500544.
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Permeability is an important parameter for characterizing the transport properties (e.g. heat and mass transfer) of porous media. It is one of the crucial issues that the permeability of porous media is exactly and quickly decided in many fields such as reservoir engineering, groundwater engineering and composite material modeling. Spontaneous imbibition is a fundamental and ubiquitous natural phenomenon extensively existing in a variety of processes. In this paper, the relationships between the height and weight of imbibition versus the time are derived based on Darcy's law, and a simple method for predicting effective permeability of porous media using spontaneous imbibition effect is proposed, including expressions for permeabilities of artificial and natural porous media. The validity of the proposed models is analysed and tested by experimental data.
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Sun, W. C., J. E. Andrade, and J. W. Rudnicki. "Multiscale method for characterization of porous microstructures and their impact on macroscopic effective permeability." International Journal for Numerical Methods in Engineering 88, no. 12 (May 9, 2011): 1260–79. http://dx.doi.org/10.1002/nme.3220.
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Banerjee, Ananya. "Investigation Of Effective Permeability And Dielectric Aspect Of Dilute Magnetic Dielectrics By Optical Method." Advanced Materials Letters 12, no. 1 (January 1, 2021): 21011592. http://dx.doi.org/10.5185/amlett.2021.011592.
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Zhao, Peiqiang, Jianchao Cai, Zhenhua Huang, Mehdi Ostadhassan, and Fuqiang Ran. "Estimating permeability of shale-gas reservoirs from porosity and rock compositions." GEOPHYSICS 83, no. 5 (September 1, 2018): MR283—MR294. http://dx.doi.org/10.1190/geo2018-0048.1.
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Effectively estimating the permeability of shale-gas reservoirs by traditional models is challenging; however, study in this area is lacking and deficient. We have developed a method for predicting the permeability of shale-gas reservoirs from porosity and rock compositions including mineralogy and organic matter content, which is applicable to laboratory data and downhole measurements. First, two sets including 38 samples from the Longmaxi Formations were tested for porosity, permeability, grain density, total-organic-carbon (TOC) content, mineralogical composition, and low-temperature nitrogen adsorption (LTNA). We used Kozeny’s equation to calculate the specific surface area, which was viewed as the effective specific surface in shale formations through comparing with the specific surface from LTNA. Furthermore, the effective specific surface was found to be positively correlated with clays, pyrite, and TOC contents, whereas it was negatively correlated with quartz, feldspar, and carbonates. Then, an empirical equation between the effective specific surface area and rock compositions was established via a partial least-squares method, which can process the serious multicollinearity of various mineral contents. Combined with Kozeny’s equation, this equation enabled a prediction of permeability from porosity and rock composition. The results indicated that the predicted and measured permeability have a reasonable match. Compared with other models, this method avoids the correlations between porosity and minerals, providing better insight to the influence of minerals and organic matter on permeability. The influences of rock composition on permeability are different, and are caused by the different types and sizes of pores developed within the minerals and organic matter. In addition, the new method was successfully applied to the well-log data from a shale-gas well for permeability predictions.
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Ma, Shi-Jia, Yuan-Jian Lin, Jiang-Feng Liu, Tao Chen, Pei-Lin Wang, and Fan Zhang. "A simple method to calibrate the temperature effect for the calculation of gas permeability." Thermal Science 25, no. 6 Part B (2021): 4605–10. http://dx.doi.org/10.2298/tsci2106605m.
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Temperature plays an important role in the gas permeability test. A small temperature variation still exists in the experimental process since the temperature control device cannot strictly maintain a constant temperature. This can further affect the accuracy of the gas permeability. To solve this problem, a simple method based on the ideal gas equation of state is introduced to calibrate the gas pressure variation because of the temperature effect. We verified the calibration results through sever?al examples, and the results proved the feasibility and effectiveness of the method. In particular, this method is particularly effective for low permeability materials in long-term gas permeation tests.
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Lubkov, M. V. "Application of the finite element-differences method for modeling of anisotropic filtration processes." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 3 (2021): 63–66. http://dx.doi.org/10.17721/1812-5409.2021/3.10.
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We consider modeling and geophysical interpretation of the obtained results in the oil and gas production problems in anisotropic reservoirs. For solving these practical problems, we use combined finite element-differences method of resolving anisotropic piezoconductivity problem with calculation of heterogeneous filtration parameters distribution of oil and gas productive reservoirs and oil-gas penetration conditions in the borders of investigating areas. We have defined that the anisotropy of oil and gas permeability in the far zone of the well has a greater effect on the filtration processes around the well and, accordingly, on the producing of the raw materials than the anisotropy of permeability in the near zone of the well. We have shown that the intensity of filtration processes in anisotropic reservoirs near the acting well depends significantly on the shear permeability and to a lesser extent on the axial permeability of the corresponding phase. Therefore, for the effective using of anisotropic reservoirs, it is necessary to place production wells in local areas with relatively low anisotropy of permeability of the reservoir, especially to avoid places with shear anisotropy.
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Aladadi, Yosef T., and Majeed A. S. Alkanhal. "Anisotropy Characterization of Metallic Lens Structures." Micromachines 12, no. 9 (September 16, 2021): 1114. http://dx.doi.org/10.3390/mi12091114.
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This paper presents a full electromagnetic (EM) characterization of metallic lenses. The method is based on the utilization of free-space transmission and reflection coefficients to accurately obtain lenses’ tensorial EM parameters. The applied method reveals a clear anisotropic behavior with a full tensorial directional permittivity and permeability and noticeably dispersive permeability and wave impedance. This method yields accurate values for the effective refractive index, wave impedance, permittivity, and permeability, unlike those obtained by simple methods such as the eigenmode method. These correct cell parameters affect their lens performance, as manifested in a clear level of anisotropy, impedance matching, and losses. The effect of anisotropy caused by oblique incidence on the performance and operation of lens designs is illustrated in a lens design case.
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Yu, Qiang, Xinjie Wang, Yifei Wang, and Xingjiao Zhang. "Study on Evaluation Method of Water Injection Efficiency in Low-Permeability Reservoir." Geofluids 2021 (May 25, 2021): 1–6. http://dx.doi.org/10.1155/2021/6616569.
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Low-permeability reservoirs, especially ultralow-permeability reservoirs, usually show a problem of ineffective water injection which leads to low pressure with high injection-production ratio. It is urgent to determine the direction and proportion of ineffective water injection, so as to guide the adjustment of water injection development. Based on the theory of percolation mechanics and combined with the modern well test analysis method, the determination method of effective water injection ratio was established. This method can not only judge the direction of injected water but also determine the proportion of invalid injected water. This method was applied on typical oil reservoirs; the evaluation results showed that extremely low permeability and ultralow permeability usually exist the situation of water holding around the injected well which is almost 20% of the injected water. Some areas existed the water channeling; the evaluation results showed that the water channeling was closely related with sedimentary microfacies rather than microfractures, and the invalid injection accounts are about 45% of the injected water. The method is simple and feasible, which can provide technical reference for the development strategy adjustment of water drive development in low-permeability reservoir.
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Li, Yanyan, Shuoliang Wang, Zhihong Kang, Qinghong Yuan, Xiaoqiang Xue, Chunlei Yu, and Xiaodong Zhang. "Research on the Correction Method of the Capillary End Effect of the Relative Permeability Curve of the Steady State." Energies 14, no. 15 (July 27, 2021): 4528. http://dx.doi.org/10.3390/en14154528.
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Relative permeability curve is a key factor in describing the characteristics of multiphase flow in porous media. The steady-state method is an effective method to measure the relative permeability curve of oil and water. The capillary discontinuity at the end of the samples will cause the capillary end effect. The capillary end effect (CEE) affects the flow and retention of the fluid. If the experimental design and data interpretation fail to eliminate the impact of capillary end effects, the relative permeability curve may be wrong. This paper proposes a new stability factor method, which can quickly and accurately correct the relative permeability measured by the steady-state method. This method requires two steady-state experiments at the same proportion of injected liquid (wetting phase and non-wetting phase), and two groups of flow rates and pressure drop data are obtained. The pressure drop is corrected according to the new relationship between the pressure drop and the core length. This new relationship is summarized as a stability factor. Then the true relative permeability curve that is not affected by the capillary end effect can be obtained. The validity of the proposed method is verified against a wide range of experimental results. The results emphasize that the proposed method is effective, reliable, and accurate. The operation steps of the proposed method are simple and easy to apply.
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Anand, V., R. Freedman, S. Crary, C. C. C. Minh, and R. L. L. Terry. "Predicting Effective Permeability to Oil in Sandstone and Carbonate Reservoirs From Well-Logging Data." SPE Reservoir Evaluation & Engineering 14, no. 06 (December 28, 2011): 750–62. http://dx.doi.org/10.2118/134011-pa.
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Summary This paper discusses a new method for predicting continuous logs of effective permeability to oil in sandstone and carbonate formations from well-logging data. This important problem in formation evaluation has remained previously unsolved because the conventional approach used to predict reservoir properties from well-log data relies on simple empirical equations and idealized models of reservoir rocks. The use of such equations and models to predict a complex reservoir property (e.g., effective permeability) can result in an inaccurate representation of the formation. This paper shows that accurate values of effective permeability to oil can be predicted using model-independent mapping functions constructed from Gaussian radial basis functions (RBFs), which can be derived from a laboratory database of measurements on partially saturated core samples. The mapping functions replace the empirical equations used in the conventional approach and are model-independent representations of the database measurements. Once the mapping functions are constructed from the database, there are no adjustable parameters. In this study, mapping functions for sandstones and carbonates were derived from a worldwide database of laboratory measurements made on 79 sandstone and 25 carbonate core samples. The laboratory measurements available on each sample included irreducible water saturation, effective permeability to oil, porosity, and nuclear-magnetic-resonance (NMR) T2 distributions. The mapping functions can be used to predict effective permeability to oil of reservoirs at irreducible water saturation from input measurements of porosity, T2 distribution, irreducible water saturation, and knowledge of rock lithology (e.g., sandstone or carbonate). The methodology for deriving the mapping functions is explained in detail. The mapping functions are applied to the database itself to show the accuracy of the effective-permeability predictions on core samples. The method is also applied to log data from both sandstone and carbonate formations in three wells from different parts of the world. The predicted effective permeabilities to oil are shown to be consistent with oil mobilities measured in the formations by fluid-sampling tools.
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Zemel, Désirée, Raymond T. Krediet, Gerardus C. M. Koomen, Dirk G. Struijk, and Lambertus Arisz. "Day-To-Day Variability of Protein Transport Used as a Method for Analyzing Peritoneal Permeability in CAPD." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 11, no. 3 (July 1991): 217–23. http://dx.doi.org/10.1177/089686089101100306.
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The transperitoneal transport of macromolecules is dependent on both effective peritoneal surface area and intrinsic permeability of the peritoneum. For passage of small solutes, the effective surface area is the main determinant. We hypothesized that day-to-day variations in peritoneal clearances are caused by changes in the effective surface area and not in the intrinsic permeability. Four CAPD {continuous ambulatory peritoneal dialysis) patients without peritonitis were investigated on 28 consecutive days. Concentrations of beta-2-microglobulin, albumin, IgG, and alpha-2-macroglobulin were determined daily in dialysate {night bags) and weekly in serum. Clearances and their coefficients of variation were calculated. Mean coefficients of the intraindividual variation of protein clearances increased, the higher the molecular weight: they ranged from 12% for beta-2microglobulin clearance to 22% for alpha-2-macroglobulin clearance. Correlations were present between the clearances of albumin, IgG, and alpha-2-macroglobulin, but not between any of these and beta-2-microglobulin clearance. In all patients, protein clearance {C) was a power function of the free diffusion coefficient in water {D) according to the equation: C=a. Db in which b represents the restriction coefficient of the peritoneum, and thus intrinsic permeability. The coefficient of variation of the restriction coefficient was low (range 4–6%). This supports our assumption that the intrinsic permeability is fairly constant on the short term. Day-to-day variations in protein clearances are thus mainly caused by alterations in the effective peritoneal surface area. Longterm follow-up of the restriction coefficient in individual patients might identify those at risk for the development of structural changes in the peritoneal membrane.
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Al Ayesh, A. H., R. Salazar, R. Farajzadeh, S. Vincent-Bonnieu, and W. R. Rossen. "Foam Diversion in Heterogeneous Reservoirs: Effect of Permeability and Injection Method." SPE Journal 22, no. 05 (April 10, 2017): 1402–15. http://dx.doi.org/10.2118/179650-pa.
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Summary Foam can divert flow from higher- to lower-permeability layers and thereby improve the injection profile in gas-injection enhanced oil recovery (EOR). This paper compares two methods of foam injection, surfactant-alternating-gas (SAG) and coinjection of gas and surfactant solution, in their abilities to improve injection profiles in heterogeneous reservoirs. We examine the effects of these two injection methods on diversion by use of fractional-flow modeling. The foam-model parameters for four sandstone formations ranging in permeability from 6 to 1,900 md presented by Kapetas et al. (2015) are used to represent a hypothetical reservoir containing four noncommunicating layers. Permeability affects both the mobility reduction of wet foam in the low-quality-foam regime and the limiting capillary pressure at which foam collapses. The effectiveness of diversion varies greatly with the injection method. In a SAG process, diversion of the first slug of gas depends on foam behavior at very-high foam quality. Mobility in the foam bank during gas injection depends on the nature of a shock front that bypasses most foam qualities usually studied in the laboratory. The foam with the lowest mobility at fixed foam quality does not necessarily give the lowest mobility in a SAG process. In particular, diversion in SAG depends on how and whether foam collapses at low water saturation; this property varies greatly among the foams reported by Kapetas et al. (2015). Moreover, diversion depends on the size of the surfactant slug received by each layer before gas injection. This favors diversion away from high-permeability layers that receive a large surfactant slug. However, there is an optimum surfactant-slug size: Too little surfactant and diversion from high-permeability layers is not effective, whereas with too much, mobility is reduced in low-permeability layers. For a SAG process, injectivity and diversion depend critically on whether foam collapses completely at irreducible water saturation. In addition, we show the diversion expected in a foam-injection process as a function of foam quality. The faster propagation of surfactant and foam in the higher-permeability layers aids in diversion, as expected. This depends on foam quality and non-Newtonian foam mobility and varies with injection time. Injectivity is extremely poor with foam injection for these extremely strong foams, but for some SAG foam processes with effective diversion it is better than injectivity in a waterflood.
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Liu, Zhen Yu, Tian Tian Cai, Hu Zhen Wang, and Cheng Yu Zhang. "Numerical Simulation of Stimulated Volume in Low-Permeability Reservoir." Advanced Materials Research 734-737 (August 2013): 1415–19. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.1415.
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There is an increasing focus on the effective methods to develop low-permeability reservoirs, especially for ultra-low permeability reservoirs. It is hard to achieve the expected stimulation effect only on the traditional single fracturing, because of the poor supply ability from the matrix to fracture in low-permeability reservoirs. Volume stimulating to reservoir, achieving short distance from matrix to fracture because of producing fracture network. So the volume fracturing technology proposed for increasing oil or gas production, this technology is suitable for low porosity and low permeability reservoir. The conventional simulation method can't describe the complex fracture network accurately,but this paper established hydraulic fracturing complex fracture model based on the finite element numerical simulation method , making the simulated complex fracture more close to the real description,it can accurately describe the flow state in the reservoir and cracks.It has an important reference value to the low permeability reservoirs.
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Yang, Jun Feng, Han Qiao Jiang, Han Dong Rui, and Xiao Qing Xie. "Advance Water-Flooding to Reduce the Stress Sensitivity Affect on Low Permeability Reservoir Development." Advanced Materials Research 361-363 (October 2011): 520–25. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.520.
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Physical simulation experiments were made to research on the stress sensitivity on physical property of low permeability reservoir rocks. The experimental results shown that effective pressure had good exponential relationship with reservoir permeability. Combining with materaial balance method, reservoir engineering and rational deducation was made to reserach on water-flooding timing of low permeability reservoir development. Several production targets were obtained by these method, such as formation pressure, water and oil production, water cut and so on. The results shown that advanced water-flooding was very important in low permeability reservoir development to reduce the bad impact of stress sensitivity on formation permeability and maintain formation pressure.
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Rabinovich, A. "Analytical Corrections to Core Relative Permeability for Low-Flow-Rate Simulation." SPE Journal 23, no. 05 (May 30, 2018): 1851–65. http://dx.doi.org/10.2118/191127-pa.
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Summary Relative permeability is one of the fundamental parameters controlling multiphase flow in reservoirs. Core samples recovered from subsurface formations are characterized in laboratory experiments to determine the core relative permeability curves. These curves represent the entire core sample and thus can be considered an effective property. Typically, coreflooding experiments are conducted at high injection rates so that the resulting flow is viscous-dominated. However, at lower rates, it has been shown that the effective curves may change as capillary heterogeneity effects become significant. Using relative permeability determined by conventional coreflooding in simulations with low-flow rates [e.g., to model gravity drainage or carbon dioxide (CO2) storage] may incur significant error. A new method for calculating low-flow-rate relative permeability curves is presented. The method is based on approximate analytical solutions for effective relative permeability under steady-state and capillary-limit conditions. Derivation is performed using power-law averaging, assuming log normally distributed core permeability. We validate the analytical solution by comparing it with numerical solutions for a wide range of cases. An additional correction for the nonwetting-phase curves is shown to be necessary and derived by matching analytical and numerical results. Given a core that has been characterized by conventional high-rate coreflooding experiments, the current method gives a fast and efficient correction for low-flow-rate applications. It circumvents the need for additional experiments or computationally expensive coreflooding simulations.
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FEDOROV, Pavel A. "COMPARATIVE ANALYSIS OF METHODS FOR DETERMINING THE EFFECTIVE CO2 DIFFUSION COEFFICIENT IN FINE-GRAINED CONCRETE OF DIFFERENT DENSITIES." Urban construction and architecture 10, no. 1 (March 15, 2020): 63–70. http://dx.doi.org/10.17673/vestnik.2020.01.9.
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Direct and indirect methods for determining the effective diffusion coefficient of CO2 in concrete are considered. The features of the diffusion process in a capillary-porous body are described. Based on the test results of samples of fine-grained concrete with different densities, a comparative analysis of the coefficients obtained by the main methods was carried out. The criteria for comparison were the dependence of the water-cement ratio on diffusion, as well as the rate of carbonization on time. The presence of significant deviations in the low permeability concretes of the coefficients obtained by the membrane methods of 72 % and the electrical conductivity of concrete saturated with electrolyte 85 % in the low permeability concrete from the values obtained by the carbonization method was established.
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Buckman, James, and Sean Higgins. "A Simple Effective Method for Three-Dimensional Modelling of Cementation, Fracturing and Dissolution of Carbonate Rocks: Illustrated through Oolitic Limestone." Geosciences 9, no. 6 (June 1, 2019): 246. http://dx.doi.org/10.3390/geosciences9060246.
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Sandstones and many carbonates (e.g., oolitic limestone and other grainstones), comprise solid particulates (grains) and pores, which have a given pore network architecture relationship, and associated porosity—permeability values. Over time, through the process of diagenesis, the pore network architecture may be extensively altered. Changes can include compaction, particle deformation, cementation, dissolution and fracturing, with the pathway followed after deposition depending on factors such as the energy level, rate of burial, degree of biological activity, local heat flow, sediment composition, Eh, pH and the presence or absence of organic materials. Any method that provides a means of modelling changes is therefore highly desirable, in particular, allowing a prediction of changes in porosity and permeability with time. The current work illustrates a simple method that uses freely available open source image analysis software to model the development of cement phases within an oolitic limestone in three-dimensions. As well as cementation, it demonstrates the modelling of fracture development and dissolution processes, and records how porosity and permeability change during such processes.
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Jin, Qing, Xinzhuang Cui, Junwei Su, Tu Lu, Jieru Wang, and Ruonan Han. "Laboratory Measurement and Analysis of the Deteriorated Layer Permeability Coefficient of Soil-Cement Deteriorated in a Saline Environment." Materials 12, no. 14 (July 12, 2019): 2245. http://dx.doi.org/10.3390/ma12142245.
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The deterioration of soil-cement in a saline environment leads to a reduction in strength and an increase in permeability. Effective methods of determining the deteriorated layer permeability coefficient of soil-cement are currently lacking. A laboratory test method for measuring the permeability coefficient of the deteriorated layer was proposed using the modified permeability coefficient testing apparatus. According to the proposed method, the permeability coefficient of the deteriorated layer could be obtained after testing the permeability coefficient of the soil-cement specimen in acuring room and testing the equivalent permeability coefficient and deterioration depth of the soil-cement specimen in a deteriorated environment. Using the marine dredger fill from Jiaozhou Bay as a case study, the deteriorated layer permeability coefficients of soil-cements with different cement contents were tested. It turned out that the permeability of the deteriorated layer increases with age. At the beginning of the curing age, higher cement content led to a smaller permeability coefficient of the deteriorated layer of soil-cement. As the curing age increased, the deteriorated layer permeability coefficient of the soil-cement with higher cement content increased. The evolution of the permeability coefficient of a deteriorated layer with age can be formulated as the Logistic function. This study provides support for anti-permeability designs of soil-cement structures in saline environments.
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Winhausen, Lisa, Mohammadreza Jalali, and Florian Amann. "The pore pressure oscillation method as a proven tool for determining the hydraulic properties of low-permeability rocks." Safety of Nuclear Waste Disposal 1 (November 10, 2021): 301. http://dx.doi.org/10.5194/sand-1-301-2021.
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Abstract. In the context of selecting and designing a future repository site for nuclear waste, a proper understanding of the host rock's physical behavior is required. One of the fundamental characteristics is the hydraulic diffusivity of the host rock, i.e., the ratio between permeability and storativity. For low-permeability rocks, however, determination of these properties is technically challenging and often time consuming. Among various steady-state and transient methods, the pore pressure oscillation technique has been proven to be an advantageous method for the simultaneous measurement of permeability and storativity for potential host rocks on a laboratory scale. In this contribution, we will introduce the methodological approach and highlight the advantages and disadvantages compared to other methods. Furthermore, we will demonstrate the applicability of this method for clay-rich rocks by presenting our experimental results. Carefully chosen boundary conditions allow us to constrain dependencies of the properties on, e.g., effective stress or bedding orientation with respect to the fluid flow direction. Additionally, this method is practical for measuring the damage-induced changes of permeability and storativity due to differential loading.
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Raza, Syed Shabbar, Victor Rudolph, Tom Rufford, and Zhongwei Chen. "A Stochastic Method to Estimate the Anisotropic Stress-Dependent Coal Permeability by Pore-Volume Distribution and Stress-Strain Measurements." SPE Journal 25, no. 05 (July 30, 2020): 2582–600. http://dx.doi.org/10.2118/198260-pa.
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Summary A novel, simple, economical, and time-effective method to estimate the anisotropic permeability of coal is presented in this paper. This method estimates the coal’s anisotropic permeability by avoiding the tedious experimentation using triaxial permeameter or history-matching exercises. This method calculates the absolute magnitude of the permeability of the sample. In this regard, it is unlike other analytical permeability models, such as given by Palmer and Mansoori (1998) and Shi and Durucan (2014), that only calculate the permeability ratio (k/k0). The motivation is to find a method by which the permeability of the coal may be determined with reasonable accuracy by using only two easy measurements: mercury intrusion porosimetry (MIP) and anisotropic stress-strain (σ-ɛ) measurement. The main blocks of the method are based on cleat size that is obtained from MIP and randomly allocated to form flow channels/cleats through the coal; these cleats form parallel paths in the orthogonal face and butt cleat directions that provide the permeability; and the cleat width (b) is stress dependent. This method is further validated by comparing with the experimentally measured stress-dependent permeability of Surat Basin (Australia) coal and German coal in face cleat and butt cleat directions.