Artykuły w czasopismach: „Rocks Permeability”

1

Scott, Samuel W., i Thomas Driesner. "Permeability Changes Resulting from Quartz Precipitation and Dissolution around Upper Crustal Intrusions". Geofluids 2018 (31.07.2018): 1–19. http://dx.doi.org/10.1155/2018/6957306.

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It has long been recognized that quartz precipitation from circulating hydrothermal fluids may reduce porosity and permeability near intrusions. However, the magnitude of permeability changes and potential feedbacks between flow, heat transfer, and quartz precipitation/dissolution remain largely unquantified. Here, we present numerical simulations of fluid convection around upper crustal intrusions which explicitly incorporate the feedback between quartz solubility and rock permeability. As groundwater is heated to ~350°C, silica dissolves from the host rock, increasing porosity and permeability. Further heating to supercritical conditions leads to intensive quartz precipitation and consequent permeability reduction. The initial host rock permeability and porosity are found to be main controls on the magnitude and timescales of permeability changes. While the permeability changes induced by quartz precipitation are moderate in host rocks with a primary porosity ≥ 0.05, quartz precipitation may reduce rock permeability by more than an order of magnitude in host rocks with a primary porosity of 0.025. Zones of quartz precipitation transiently change locations as the intrusion cools, thereby limiting the clogging effect, except for host rocks with low initial porosity. This permeability reduction occurs in timescales of hundreds of years in host rocks with initial high permeability and thousands of years in host rocks with intermediate permeability.

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Liu, Kouqi, i Mehdi Ostadhassan. "Estimation of the Permeability of Rock Samples Obtained from the Mercury Intrusion Method Using the New Fractal Method". Fractal and Fractional 6, nr 9 (24.08.2022): 463. http://dx.doi.org/10.3390/fractalfract6090463.

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Rock permeability, defined as the ability of fluid to flow through the rocks, is one of the most important properties of rock. Many researchers have developed models to predict the permeability of rock from the porosity and pore size based on the mercury intrusion. However, these existing models still have some limitations. In this study, based on data regarding the fractal nature of the mercury intrusion of the rocks, we built a new model to predict the permeability of the rocks. In order to verify the new model, we extracted data regarding different kinds of samples from the literature and estimated the permeability using the new model. The results showed that the model could predict various types of rocks, such as tight sandstone, carbonates, and shale. The comparison of the calculated permeability using the new model is closer to the measured value than the value estimated from the existing models, indicating that the new model is better in predicting the permeability of rock samples.

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Madiutomo, Nendaryono, Willy Hermawan, Weningsulistri i Madya Pamungkas. "The effect of rock permeability value on groundwater influx in underground coal gasification reactor". IOP Conference Series: Earth and Environmental Science 882, nr 1 (1.11.2021): 012054. http://dx.doi.org/10.1088/1755-1315/882/1/012054.

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Abstract Rock permeability value is one of the most significant rock’s physical properties that affect groundwater influx processes in underground coal gasification (UCG). This value of rock permeability (K), namely the vertical permeability of flanking rocks (Kv) and horizontal permeability of coal (Kh). The purpose of this study was to determine the extent of the influence of the value of rock permeability on the potential of groundwater influx. The effect of rock permeability on groundwater influx into the UCG gasification reactor cavity in the presence of thermal loads and mineral composition content is large and significant to consider. Based on the resistance to heat loads, the type of sandstone lithology is relatively more resistant compared to siltstone and claystone lithology.

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Cooke, Andy P., Quentin J. Fisher, Emma A. H. Michie i Graham Yielding. "Permeability of carbonate fault rocks: a case study from Malta". Petroleum Geoscience 26, nr 3 (12.08.2019): 418–33. http://dx.doi.org/10.1144/petgeo2019-055.

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The inherent heterogeneity of carbonate rocks suggests that carbonate-hosted fault zones are also likely to be heterogeneous. Coupled with a lack of host–fault petrophysical relationships, this makes the hydraulic behaviour of carbonate-hosted fault zones difficult to predict. Here we investigate the link between host rock and fault rock porosity, permeability and texture, by presenting data from series of host rock, damage zone and fault rock samples from normally faulted, shallowly buried limestones from Malta. Core plug X-ray tomography indicates that texturally heterogeneous host rocks lead to greater variability in the porosity and permeability of fault rocks. Fault rocks derived from moderate- to high-porosity (>20%) formations experience permeability reductions of up to six orders of magnitude relative to the host; >30% of these fault rocks could act as baffles or barriers to fluid flow over production timescales. Fault rocks derived from lower-porosity (<20%) algal packstones have permeabilities that are lower than their hosts by up to three orders of magnitude, which is unlikely to impact fluid flow on production timescales. The variability of fault rock permeability is controlled by a number of factors, including the initial host rock texture and porosity, the magnitude of strain localization, and the extent of post-deformation diagenetic alteration. Fault displacement has no obvious control over fault rock permeability. The results enable better predictions of fault rock permeability in similar lithotypes and tectonic regimes. This may enable predictions of across-fault fluid flow potential when combined with data on fault zone architecture.

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Widarsono, Bambang. "IMBIBITION WATER-OIL RELATIVE PERMEABILITY: INTRODUCTION OF WETTABILITY STRENGTH FOR ENHANCING MODEL ROBUSTNESS". Scientific Contributions Oil and Gas 42, nr 1 (8.04.2019): 1–8. http://dx.doi.org/10.29017/scog.42.1.395.

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Water-oil relative permeabilty information of hydrocarbon reservoir rocks plays important roles in various modeling activities related to reservoir modeling and production forecast. The imbibition relative permeability scheme - the process of concern in this study affects many dynamic processes in reservoir. Water flooding and water encroachment form aquifer to oil zone in the reservoir are two two examples which representation in reservoir model requires the data. This study uses the standard Corey relative permeability model as a tool to study and model imbibition relative permeability behaviour of some reservoir rocks in Indonesia. Laboratory data from as many as 340 rock samples - sandstones and limestones - of various permeability and wettability from various oil fi elds in Indonesia is used. Activities in the modeling has pointed out the need to introduce two new empirical factors that relate to rock wettability and non- wetting fl ow hindrance to the model. The two factors appear to have signifi cantly improved the ability of the model to agree and match to the measured data. The modeling also produces suggested values of the factors for rock groups based on rock wettability type and strength, as well as on permeability categories. Comparison between modeling results before and after modifi cation has shown signifi cant improvement in validity of output.

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Winhausen, Lisa, Mohammadreza Jalali i 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 (10.11.2021): 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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Lyu, XianZhou, Zenghui Zhao, Xiaojie Wang i Weiming Wang. "Study on the Permeability of Weakly Cemented Sandstones". Geofluids 2019 (15.01.2019): 1–14. http://dx.doi.org/10.1155/2019/8310128.

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Fractured rocks are a type of complex media that widely exist in various projects including energy, hydraulic, and underground space engineering, whose permeability properties are a hotspot in current rock mechanics domain. Aiming at investigating the seepage characteristics of the fracture surfaces in different rock strata, uniaxial compressive test and permeability test were performed on single-fracture homogenous and heterogeneous rocks. Specifically, rock’s physical and mechanical parameters were measured in uniaxial tests while the initial width of the single fracture was determined through CT scanning. In combination with test results and the calculation model of the displacement of single-fracture heterogeneous rock under triaxial stress condition, the calculation formula of the permeability coefficient of single-fracture heterogeneous rock was derived. Results show that hydraulic pressure in the fracture can affect the permeability coefficient of the fractured rock. Hydraulic fracturing effect occurred with the increase of hydraulic pressure in the fracture, which then generates slight normal deformations of the rock masses on both two sides of the fracture surface, decreases the contact area in the fracture, and leads to the increases of both fracture width and permeability coefficient. For single-fracture rock, the lithological properties of the rock masses on both two sides of the fracture surface impose significant effects on the permeability coefficient. Under same hydraulic pressure and confining pressure, the permeability coefficient of single-fracture coarse sandstone is greatest, followed by that of single-fracture heterogeneous rock, and finally by single-fracture fine sandstone. Theoretical calculation results agree well with the test results, suggesting that the derived theoretical formula can adequately describe the variation tendencies of permeability coefficient with confining pressure and hydraulic pressure in the fracture.

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Xu, Tao, i Chun An Tang. "Modeling of Stress-Induced Permeability Evolution and Damage of Rock". Advanced Materials Research 33-37 (marzec 2008): 609–16. http://dx.doi.org/10.4028/www.scientific.net/amr.33-37.609.

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Rock permeability is important in civil and geo-hydraulic engineering, the mining and petroleum industries, and in environmental and engineering geology. In this paper, considering the mutual hydro-mechanical response between stress-induced permeability and damage, a coupled mathematical model for solid deformation and gas flow in the coal or rock was established and an attempt is made to investigate the rock permeability evolution, fracture patterns, and flow vectors in rock samples at the scale of usual laboratory samples as well as the relation between permeability and stress induced damage in connection with the complete strain-stress process of loaded rocks. Numerical simulations show that the permeability of rock was not constant, closely related to the state of stress, but varied with the stress and strain states in the rocks. Microcracking, resulting from the concentration of stress on relatively weak rock elements, triggers successive crack initiation and propagation that in turn leads to permeability enhancement. Prior to the peak strength, the permeability decreases with increasing load. A dramatic increase in permeability occurs in the post-peak stress-strain region due to the catastrophic collapse of microstructure in rock. Moreover, the permeability of rock in post-peak stress-strain region is much higher that that of in pre-peak region. Such intensive studies of gas flow in stressed heterogeneous rocks are useful as initial approaches to many engineering problems in mining and petroleum industries.

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LV, WEIFENG, GUOLIANG YAN, YONGDONG LIU, XUEFENG LIU, DONGXING DU i RONG WANG. "EFFECT OF FRACTAL FRACTURES ON PERMEABILITY IN THREE-DIMENSIONAL DIGITAL ROCKS". Fractals 27, nr 01 (luty 2019): 1940015. http://dx.doi.org/10.1142/s0218348x19400152.

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The fracture has great impact on the flow behavior in fractured reservoirs. Fracture traces are usually self-similar and scale-independent, which makes the fractal theory become a powerful tool to characterize fracture. To obtain three-dimensional (3D) digital rocks reflecting the properties of fractured reservoirs, we first generate discrete fracture networks by stochastic modeling based on the fractal theory. These fracture networks are then added to the existing digital rocks of rock matrixes. We combine two low-permeable cores as rock matrixes with a group of discrete fracture networks with fractal characteristics. Various types of fractured digital rocks are obtained by adjusting different fracture parameters. Pore network models are extracted from the 3D fractured digital rock. Then the permeability is predicted by Darcy law to investigate the impacts of fracture properties to the absolute permeability. The permeability of fractured rock is subject to exponential increases with fracture aperture. The relationship between the permeability and the fractal dimension of fracture centers is exponential, as well as the relationship between permeability and the fractal dimension of fracture lengths.

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10

Clauser, C. "Permeability of crystalline rocks". Eos, Transactions American Geophysical Union 73, nr 21 (1992): 233. http://dx.doi.org/10.1029/91eo00190.

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Shestopalov, V. M., i L. I. Petrenko. "FRACTURING AND PERMEABILITY OF CRYSTAL ROCKS AND THEIR FRACTURE ZONES, HYDROGEOLOGICAL ASPECT". Geological Journal, nr 2 (30.06.2022): 46–70. http://dx.doi.org/10.30836/igs.1025-6814.2022.2.254153.

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Fractured rock aquifers are regarded as of particular scientific and practical interest because of their importance for underground water supply, energy storage and safety radioactive waste disposal. The study of fissure waters of crystalline rocks in the context of global warming to address issues of drinking water supply is highly relevant today. It has potential practical importance for the future.The sustainable use of groundwater in fractured rock aquifers requires a detailed knowledge of their hydraulic properties. The complexity of hydrogeological conditions in massive fractured rocks results from uncertainties about the configuration of the fractures, while the potential for groundwater movement in such rocks is primarily determined by their permeability and, consequently, hydraulic conductivity. Fractures (fracture networks) have different permeability properties, which is one of the key parameters required for understanding and predicting fluid and water flow. This paper reviews and analyses the results of global studies of fracturing and permeability of crystalline rock massifs and the fault zones occurring in them. Since the study of permeability of crystalline rocks concerns many disciplines — including structural geology, tectonophysics, petrophysics, hydrogeology, and hydrology — this review highlights information about the distribution of groundwater in fractured crystalline rocks in the context of their potential exploitation. This study consists of two parts: generalization of research results concerning fracturing and permeability of crystalline rocks, and particularities of structure of fracture zones in crystalline rocks and of the presence of groundwater in them. Based on this review of the structure and development of fracture zones (including their evolution under the influence of weathering and other secondary processes), recommendations are given for using tectonophysical reconstructions to improve hydrogeological field works and mathematical modeling.

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Al-shajalee, Faaiz, Colin Wood, Quan Xie i Ali Saeedi. "Effective Mechanisms to Relate Initial Rock Permeability to Outcome of Relative Permeability Modification". Energies 12, nr 24 (9.12.2019): 4688. http://dx.doi.org/10.3390/en12244688.

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Excessive water production is becoming common in many gas reservoirs. Polymers have been used as relative permeability modifiers (RPM) to selectively reduce water production with minimum effect on the hydrocarbon phase. This manuscript reports the results of an experimental study where we examined the effect of initial rock permeability on the outcome of an RPM treatment for a gas/water system. The results show that in high-permeability rocks, the treatment may have no significant effect on either the water and gas relative permeabilities. In a moderate-permeability case, the treatment was found to reduce water relative permeability significantly but improve gas relative permeability, while in low-permeability rocks, it resulted in greater reduction in gas relative permeability than that of water. This research reveals that, in an RPM treatment, more important than thickness of the adsorbed polymer layer ( e ) is the ratio of this thickness on rock pore radius ( e r ).

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Shynkarenko, A. "MODERN APPROACHES TO DETERMINE THE PERMEABILITY OF RESERVOIR ROCKS BASED ON THE RESULTS OF GEOPHYSICAL INVESTIGATIONS". Visnyk of Taras Shevchenko National University of Kyiv. Geology, nr 3 (82) (2018): 45–54. http://dx.doi.org/10.17721/1728-2713.82.06.

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Permeability of rock is its physical property that describes its ability to conduct fluids under the pressure gradient. This paper presents short description and analysis of methods for determination of permeability of oil and gas reservoirs. Permeability is a function of different parameters that leads to difficulties during its estimation. Investigations of the void space structure of rocks, their anisotropy etc.were carried out in order to take into account all factors that have an influence on the permeability. Reservoir conditions could also be modeled for that purpose. Methods for determination of permeability of rocks can be divided into three groups: methods based on the laboratory studies of rocks; methods based on the well logging data; and methods based on the correlations between different parameters of rocks. The first two groups include methods for steady and unsteady fluid flow. Methods for the unsteady flow are usually more precise and rapid, thus prospects of extension of methods for permeability determination are mostly connected with them. Each of the presented methods to determine permeability is characterized by some pros and cons. The most appropriate method for the specific experiment is always chosen according to conditions and requirements and expected results. Further author's investigations will be related to the creation of petrophysical models of permeability of oil and gas reservoir rocks, including reservoirs of complex structure.

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Arkin, Eldan, Takumi Mori, Ren Himeno, Atsushi Sainoki i Akira Sato. "Analysis of the Permeability Change Resulting from Active Mineral Precipitation in Pores of Rocks by 3D-DEM". IOP Conference Series: Earth and Environmental Science 1124, nr 1 (1.01.2023): 012067. http://dx.doi.org/10.1088/1755-1315/1124/1/012067.

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Abstract Carbon dioxide capture and storage (CCS) is a promising technique for reducing the concentration of CO2 in the atmosphere, and several million tons of CO2 are sequestered every year. The most important problem in CCS is ensuring aquifer safety. However, there is still room for improvement in the flow characteristics of aquifers to prevent CO2 leakage. To decrease the permeability of porous rocks, in this study, a method called ‘active mineral deposition’ was developed. In this method, some minerals are actively precipitated in aquifers, and the pores in the rock mass are closed by precipitated minerals. Because the pores are closed and stacked by minerals, the permeability of the rock mass is expected to decrease. For the precipitated minerals, CaCO3 is a promising mineral, and CaCO3 is precipitated in the pores of rocks. From microscopic observation, the approximate size of the precipitated mineral was estimated to be 10 μm in the rock pores. To verify the effect of the method, the permeability of the porous rocks was simulated using the three-dimensional discrete-element method (3D-DEM). Here, the rock minerals and pores were simulated using DEM elements, and the initial permeability of the models was estimated. Then, the small minerals, which represent precipitated minerals, were generated in the pore space, and changes in the intrinsic permeability, flow path, and pressure distributions in the rocks were estimated. The value of intrinsic permeability decreased to one tenth of the initial condition when 1% of the pore spaces were occupied by the precipitated minerals. A small amount of precipitation could change the permeability of the porous materials.

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Shi, Di, Liping Li, Jianjun Liu, Mingyang Wu, Yishan Pan i Jupeng Tang. "Effect of discrete fractures with or without roughness on seepage characteristics of fractured rocks". Physics of Fluids 34, nr 7 (lipiec 2022): 073611. http://dx.doi.org/10.1063/5.0097025.

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This study proposes a new fractal permeability model for fractured rocks that comprehensively accounts for the geometric fracture characteristics and the fluid transport mechanism. Then, the permeability changes of fractured rocks are analyzed using discrete fracture networks (DFNs) with or without roughness and different geometry parameters in the DFN modeling and finite element simulation. The results show that the proposed permeability model well agrees with the experimental data, and the established DFN numerical model more realistically reflects the fracture network in fractured rocks. Fluctuation of tortuous fracture lines (rough fractures) increases the fracture intersection probability, consequently increasing the fracture intersection area or connecting adjacent fractures. Moreover, permeability increases with the fractal dimension Df, porosity ϕ, maximum fracture length lmax, and proportionality coefficient β, and it decreases with increasing fractal dimension DTf of fracture tortuosity. When the fracture proportionality coefficient is 0.001 ≤ β ≤ 0.01, different DFNs yield similar simulation results for permeability. However, with increasing fracture network complexity, the predictive model created using conventional DFN (C-DFN) increasingly overestimates the fractured rock permeability. Thus, building a permeability model for a fractured rock using rough DFN (R-DFN) is more effective than that using C-DFN. Our findings are helpful for real permeability predictions via DFN and analytical modeling.

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Vlahou, I., i M. G. Worster. "Freeze fracturing of elastic porous media: a mathematical model". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, nr 2175 (marzec 2015): 20140741. http://dx.doi.org/10.1098/rspa.2014.0741.

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We present a mathematical model of the fracturing of water-saturated rocks and other porous materials in cold climates. Ice growing inside porous rocks causes large pressures to develop that can significantly damage the rock. We study the growth of ice inside a penny-shaped cavity in a water-saturated porous rock and the consequent fracturing of the medium. Premelting of the ice against the rock, which results in thin films of unfrozen water forming between the ice and the rock, is one of the dominant processes of rock fracturing. We find that the fracture toughness of the rock, the size of pre-existing faults and the undercooling of the environment are the main parameters determining the susceptibility of a medium to fracturing. We also explore the dependence of the growth rates on the permeability and elasticity of the medium. Thin and fast-fracturing cracks are found for many types of rocks. We consider how the growth rate can be limited by the existence of pore ice, which decreases the permeability of a medium, and propose an expression for the effective ‘frozen’ permeability.

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Hou, Bingchang, Feng Sun, Shifeng Xue i Xudong Zhang. "Experimental study on mechanical properties and porosity and permeability of rock in high temperature environment". Journal of Physics: Conference Series 2368, nr 1 (1.11.2022): 012031. http://dx.doi.org/10.1088/1742-6596/2368/1/012031.

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In order to explore the mechanical characteristics and porosity and permeability parameter of three kinds of rock (sandstone, granite and limestone) in high temperature environment, conventional triaxial compression experiments and porosity and permeability tests were conducted on three kinds of rocks under 25°C, 300°C and 500°C. The experimental results show that the high temperature environment increases the development degree of microcracks and pore structures in sandstone and limestone. As the temperature rises, the interpenetration length of triaxial compression shear crack of sandstone decreases gradually, and the angle between shear crack and horizontal direction increases gradually. Change of damage mode from single shear damage to tension shear damage (shear-dominated) in granite and limestone. The three rocks’ permeability and porosity increase as ambient temperature rises, and the permeability exhibits clear pressure-constricting sensitivity in a range of temperature settings. The results provide a reference for understanding and predicting the mechanical properties and porosity and permeability characteristics of rocks in high temperature environment.

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Duppa M.T, Ir Hakim. "SURFACE FLOW REDUCTION AT APUDDLE AREA BY POROUS RECHARGE". INTERNATIONAL JOURNAL OF MANAGEMENT & INFORMATION TECHNOLOGY 11, nr 3 (30.08.2016): 2910–15. http://dx.doi.org/10.24297/ijmit.v11i3.5119.

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WaterloggingÂ occursÂ whenÂ rainÂ isÂ rainÂ waterÂ thatÂ gathered Â accumulation Â exceededÂ the rainageÂ capacityÂ ofÂ theÂ riverÂ and it is Â causedndue to the absenceÂ of absorption infiltration into the soil this the study aimed to assess the basic characteristics of the land area of inundation, (material volcanic rocks, and chunk) and infiltration capacity this research method is the study of soil mechanics laboratory experiments using soil samples from 2 nundation areas, areas not graceful and the samples of porous material and chunks of mountain rock (sand, cement, bricks) the result showed that the characteristics of waterlogged soil including silt soils kelempungan category and has a value of permeability 0.0002099 cm/sec, permeability volcanic rocks 0.04505 cm/s, permeability blocks (sand, cement, bricks) 0.02955 cm/sec. This suggests that the volcanic rocks have large permeability values that can be just passed substantial drainage. From the analysis carried out shows the reduction of surface water to echarge the mountain rock so big that can reduce surface runoff and can also recharge ground waterreserves.

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Kozhevnikov, Evgenii, Evgenii Riabokon i Mikhail Turbakov. "A Model of Reservoir Permeability Evolution during Oil Production". Energies 14, nr 9 (8.05.2021): 2695. http://dx.doi.org/10.3390/en14092695.

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In this paper, we present a mathematical model to predict the evolution of rock permeability depending on effective pressure during oil production. The model is based on the use of the results of well testing data from wells operating in the oil fields of the Perm–Solikamsk region in the north of the Volgo Ural oil and gas province. Dependences of the change in flow characteristics in the reservoir on the effective pressure were established. We performed a comparative assessment using permeability and effective pressure data that were normalized to dimensionless forms of k/ko and P/Po. The factors and their influence on the nature of the change in permeability from the reservoir pressure were determined. Depending on the type of rock, its composition, initial permeability, and bedding conditions, we determined the limits of variation of the constants in empirical equations describing the change in the permeability of rocks from the effective pressure. The mathematical model we developed enables the prediction of the change in permeability of rocks during oil production from reservoirs on the basis of reservoir properties such as initial permeability, initial reservoir pressure, average bedding depth, net-to-gross ratio, and initial effective rock pressure.

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Cardona, Alejandro, i J. Carlos Santamarina. "Carbonate rocks: Matrix permeability estimation". AAPG Bulletin 103, nr 1 (styczeń 2020): 131–44. http://dx.doi.org/10.1306/05021917345.

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Chen, Zhiwen, Honglin Liu, Chengyu Zhu, Shuqi Ma, Yinjian Hang i Wenjie Luo. "Seepage Characteristics and Influencing Factors of Weakly Consolidated Rocks in Triaxial Compression Test under Mining-Induced Stress Path". Minerals 12, nr 12 (29.11.2022): 1536. http://dx.doi.org/10.3390/min12121536.

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The rock of weakly consolidated coal measure strata has the characteristics of low mechanical strength and strong water sensitivity. Under the stress and seepage disturbance caused by coal seam mining, the surrounding rock structure is prone to instability, which leads to mine safety accidents and water resources loss. In order to master the mechanical response and permeability evolution law of weakly consolidated rock under the disturbance of coal seam mining, the specimens of Jurassic mudstone, sandy mudstone, and sandstone in the Ili mining area of China were collected, and a triaxial compression seepage test was carried out. A comprehensive analysis was carried out on the mineral composition and microstructure characteristics of the rock. The results show the following: (1) Compared to the constant confining pressure condition, mining-induced stress promotes the fracture development rate of weakly consolidated rocks. The ratios of strain at the yield point of mudstone, sandy mudstone, and sandstone under mining-induced stress and constant confining pressure are 0.33, 0.43, and 0.79, respectively, and the ratios of strain at the failure point were 0.48, 0.52, and 0.72, respectively. (2) Under the condition of mining-induced stress, the permeability change range and the permeability recovery rate of the three types of rocks were different, which decreased in the order of mudstone, sandy mudstone, and sandstone. (3) In the process of the triaxial compression test, there was a strong hysteresis in the permeability change of the mudstone, and the permeability and hysteresis of the three types of rocks decreased with the increase in the clay mineral content. (4) Combined with the analysis of the rock mineral composition and microstructure characteristics, it is believed that the clay minerals in the rock after water mud and swelling are the main reasons for the hysteresis of the permeability change of weakly consolidated rock, and the content of clay minerals is the main factor affecting the permeability characteristics of the weakly consolidated rock.

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Mohamed, I. M. M., i H. A. A. Nasr-El-Din. "Fluid/Rock Interactions During CO2 Sequestration in Deep Saline Carbonate Aquifers: Laboratory and Modeling Studies". SPE Journal 18, nr 03 (22.04.2013): 468–85. http://dx.doi.org/10.2118/151142-pa.

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Summary Carbon dioxide (CO2) injection in carbonate formations causes a reduction in the well injectivity caused by precipitation of the reaction products between CO2, rock, and brine. The precipitated material includes sulfate and carbonate scales. The homogeneity of the carbonate rock, in terms of mineralogy and rock structure, is an important factor that affects the behavior of permeability changes during CO2 injection. Limestone rocks that were tested in this study included homogeneous Pink Desert limestone and Austin chalk, which were mainly calcite; heterogeneous Silurian dolomite (composed of 98 wt% carbonate minerals and 2 wt% silicate minerals); and heterogeneous Indiana limestone, which was mainly calcite and had vugs. Experiments were conducted to compare the permeability loss between these rocks during corefloods. CO2 was injected with the water-alternating-gas (WAG) technique. Different brines were examined, including sulfate-bearing seawater and no-sulfate seawater. The experiments were run at a backpressure of 1,300 psi, a temperature of 200°F, and an injection rate of 5 cm3/min. A compositional-simulator tool (CMG-GEM) was used to predict the Carman-Kozeny and power-law exponents on the basis of the experimental results. More damage was observed for heterogeneous rocks compared with the homogeneous cores—the source of damage to permeability for high-permeability cores is the precipitation of reaction products—but for low-permeability cores, capillary forces between CO2 and brine increase the severity of formation damage. The form of the precipitated material changes depending on the core mineralogy and permeability. The simulation study showed that for the cores tested in this study, power-law exponent and Carman–Kozeny exponent between 5 and 6 can be used for the homogeneous carbonate rock to estimate the change in permeability depending on change in porosity, whereas a larger exponent is needed for heterogeneous cores.

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Jahanbakhsh, Amir, Hamidreza Shahverdi i Mehran Sohrabi. "Gas/Oil Relative Permeability Normalization: Effects of Permeability, Wettability, and Interfacial Tension". SPE Reservoir Evaluation & Engineering 19, nr 04 (22.03.2016): 673–82. http://dx.doi.org/10.2118/170796-pa.

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Summary Relative permeabilities (kr) are crucial flow functions governing the fluid distribution within and production from petroleum reservoirs under various oil-recovery methods. To obtain these important reservoir parameters, conventionally, it is required to take rock samples from the reservoir and perform appropriate laboratory measurements. Although kr is expressed as a function of fluid saturation, it is now well-known that kr values are affected by pore structure and distribution, absolute permeability, wettability, interfacial tension (IFT), and saturation history. These rock/fluid properties often change from one region of the reservoir to another, but it would be impossible to perform kr measurements for all regions of a reservoir. Generally, performing experiments on a core with higher permeability is faster and easier than a low-permeability rock. Therefore, assuming all other parameters such as wettability, IFT, and displacement direction are the same for two rocks with different permeabilities, the question becomes how do we estimate the kr of a rock with lower permeability from available (measured) kr of a higher-permeability rock? How do we account for wettability and IFT differences? A normalization technique has been proposed to remove the effect of irreducible water and trapped saturations, which would be different under different conditions. The relative permeabilities can then be denormalized and assigned to different regions (rock types) of the reservoir on the basis of their own irreducible water and trapped saturations. The objective of this study is to introduce a methodology to predict the gas/oil kr for new rock/fluid conditions (such as permeability, wettability, and IFT) by use of existing gas/oil kr data measured at different conditions. By use of measured data from coreflood experiments, we show that by applying an appropriate normalization technique one can adequately predict kr of rocks with different permeability and wettability conditions in two-phase gas/oil flow. However, the results show that the effect of IFT change cannot be captured by normalization techniques. To improve the methodology, a new hypothesis is introduced and proposed here on the basis of dynamic trap saturation. Finally, by use of our experimental data, we evaluate the validity of the Coats (1980) IFT scaling method. We demonstrate the shortcomings of the method and offer an improvement to its prediction.

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Krykovskyi, Oleksandr, Viktoriia Krykovska i Serhii Skipochka. "Interaction of rock-bolt supports while weak rock reinforcing by means of injection rock bolts". Mining of Mineral Deposits 15, nr 4 (grudzień 2021): 8–14. http://dx.doi.org/10.33271/mining15.04.008.

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Purpose is to analyze changes in shape and dimensions of a rock mass area, fortified with the help of a polymer, depending upon the density of injection rock bolts as well as the value of initial permeability of enclosing rocks to substantiate optimum process solutions to support roofs within the unstable rocks and protect mine workings against water inflow and gas emission. Methods. Numerical modeling method for coupled processes of rock mass strain and filtration of liquid components of a polymer has been applied. The model is based upon fundamental ideas of mechanics of solids and filtration theory. The problem has been solved using a finite element method. Its solution took into consideration both the initial permeability and the permeability stipulated by mine working driving, injection time of reagents and their polymerization, and effect of po-lymer foaming in the process of mixing of its components. Changes in physicomechanical and filtration characteristics of rock mass during polymer hardening were simulated. It has been taken into consideration that a metal delivery pipe starts operating as a reinforcing support element only after the polymer hardening. Findings. If three and five injection rock bolts are installed within a mine working section then stresses, permeability coefficients, pressure of liquid polymeric composition, and geometry of the fortified area of rock mass have been calculated. It has been shown that rock bolt location is quite important to form a rock-bolt arch. It has been demonstrated for the assumed conditions that if five injection rock bolts are installed within the mine working roof then close interaction between rock-bolt supports takes place; moreover, the integral arch is formed within the mine working roof. Originality. Dependence of change in the polymer reinforced area upon a value of initial permeability of enclosing rocks has been derived. It has been shown that in terms of low values of initial permeability, geometry of rock-bolt supports as well as its size is identified only by means of a value of the unloaded zone around the mine working. In this context, initial permeabi-lity increase results in the enlarged diameter of the reinforced rock mass area in the neighbourhood of the injection rock bolt. Practical implications. The findings are recommended to be applied while improving a method to support the mine working roof and decrease water inflow as well as gas emission from the rocks, being undermined, into the working.

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Li, Hao, Zuliang Zhong, Kenneth Imo-Imo Eshiet, Yong Sheng, Xinrong Liu i Dongmin Yang. "Experimental Investigation of the Permeability and Mechanical Behaviours of Chemically Corroded Limestone Under Different Unloading Conditions". Rock Mechanics and Rock Engineering 53, nr 4 (4.11.2019): 1587–603. http://dx.doi.org/10.1007/s00603-019-01961-y.

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Abstract This paper investigates the mechanical properties and permeability of chemically corroded rock during deep underground tunneling. Nuclear magnetic resonance tests are carried out to quantify the chemical damage of limestone samples at the microscopic scale. Coupled hydrostatic pressure-unloading tests at different unloading rates are also conducted on these chemically corroded limestone samples to investigate permeability changes and chemical effects on mechanical behaviours. Magnetic resonance imaging, T2 spectrum distribution and porosity of the samples are obtained, and the chemical micro damage is visualized and quantified. The relationship between permeability and mechanical behaviors of the rock under hydrochemical–mechanical coupled effects is investigated. The results show that the permeability development process of the chemical corroded samples can be divided into three stages: at the first stage, the permeability initially decreases, and the second stage starts at the inflection point of the permeability curve, from where the permeability begins to increase slightly. At the third stage, the permeability of the limestone increases dramatically until the sample is ruptured. Chemical corrosion and unloading rates have a combined and significant influence on the development of micro cracks in rocks, which is the root cause of the permeability changes. A stress-permeability model is proposed to describe the permeability and stresses in chemical-corroded limestone; this can be adopted for other sedimentary rocks.

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Al Hinai, Adnan, Reza Rezaee, Ali Saeedi i Roland Lenormand. "Permeability prediction from mercury injection capillary pressure: an example from the Perth Basin, Western Australia". APPEA Journal 53, nr 1 (2013): 31. http://dx.doi.org/10.1071/aj12003.

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For shale gas reservoirs, permeability is one of the most important and difficult parameters to determine. Typical shale matrix permeabilities are in the range of 10 microdarcy–100 nanodarcy, and are heavily dependent on the presence of natural fractures for gas transmissibility. Permeability is a parameter used to measure the ability of a rock to convey fluid. It is directly related to porosity and depends on the pore geometry features, such as tortuosity, pore shape and pore connectivity. Consequently, rocks with similar porosity can exhibit different permeability. Generally, permeability is measured in laboratories using core plugs. In some cases, however, it is difficult to obtain suitable core plugs. In these instances, other approaches can be used to predict permeability, which are chiefly based on mathematical and theoretical models. The approach followed in this peer-reviewed paper is to correlate permeability with capillary pressure data from mercury injection measurements. The theoretical and empirical equations, introduced in the literature for various conventional and unconventional reservoir rocks, have been used to predict permeability. Estimated gas shale permeabilities are then compared with results from transient and steady state methods on small pieces of rocks embedded in a resin disk. The study also attempts to establish a suitable equation that is applicable to gas shale formations and to investigating the relationship between permeability and porosity.

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Leger, Marie, i Linda Luquot. "Importance of Microstructure in Carbonate Rocks: Laboratory and 3D-Imaging Petrophysical Characterization". Applied Sciences 11, nr 9 (22.04.2021): 3784. http://dx.doi.org/10.3390/app11093784.

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Carbonate rocks are considered to be essential reservoirs for human development, but are known to be highly heterogeneous and difficult to fully characterize. To better understand carbonate systems, studying pore-scale is needed. For this purpose, three blocks of carbonate rocks (chalk, enthrocal limestone, and dolomite) were cored into 30 samples with diameters of 18 mm and lengths of 25 mm. They were characterized from pore to core scale with laboratory tools. These techniques, coupled with X-ray micro-tomography, enable us to quantify hydrodynamic properties (porosity, permeability), elastic and structural properties (by acoustic and electrical measurements), pore distribution (by centrifugation and calculations). The three rocks have similar properties to typical homogeneous carbonate rocks but have specific characteristics depending on the rock type. In the same rock family, sample properties are different and similarities were established between certain measured properties. For example, samples with the same hydrodynamic (porosity, permeability) and structural (formation factor, electrical tortuosity) characteristics may have different elastic properties, due to their cohesion, which itself depends on pore size distributions. Microstructure is understood as one of the essential properties of a rock and thus must be taken into account to better understand the initial characteristics of rocks.

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Vyzhva, S., V. Onyshchuk, I. Onyshchuk, M. Reva i O. Shabatura. "RESERVOIR FEATURES OF THE UPPER CARBON SEDIMENTS (RUNOVSHCHYNSKA AREA OF THE DNIEPER-DONETS BASIN)". Visnyk of Taras Shevchenko National University of Kyiv. Geology, nr 4 (83) (2018): 30–37. http://dx.doi.org/10.17721/1728-2713.83.04.

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The main objective of this article is to highlight the results of investigations of filtration capacity features of sandstones and argillites of the Upper Carbon rocks in Runovshchynska area of The Dnieper-Donets basin. The purpose of the research was to assess the promising rocks as possible hydrocarbon reservoirs. The following reservoir features of rock samples such as the open porosity factor, permeability coefficients and residual water saturation factor have been investigated. The correlation of rock density with their porosity was also studied. The porosity study was carried out in atmospheric and reservoir conditions by gas volumetric method and fluid saturation. The bulk density of dry rock samples varies from 2,122 kg/m3 to 2,615 kg/m3 (average 2318 kg/m3), saturated rocks – from 2265 to 2680 kg/m3 (average 2449 kg/m3), and the specific matrix density – from 2562 to 2786 kg/m3 (average 2650 kg/m3). The open porosity coefficient of the studied rocks, in case they were saturated with the synthetic brine, varies from 0.058 to 0.190 (mean 0.126), but if they were saturated with N2 it varies from 0.066 to 0.203 (mean 0.145). Detailed analysis of reservoir conditions modeling revealed that porosity coefficient varies from 0.038 to 0.175 (mean 0.110). Due to the closure of microcracks under rock loading reduced to reservoir conditions the porosity decreases in comparison with atmospheric conditions, which causes a relative decrease in the porosity coefficient from 4.5% to 13.8% (mean 9.0%) from atmospheric conditions to reservoir conditions. The permeability coefficient of rocks varies from 0.03 fm2 to 240.57 fm2 (mean 11.87 fm2). The residual water saturation factor of rocks varies from 0.02 to 0.89 (mean 0.36). The classification of the reservoir characteristics of the investigated samples by the permeability coefficients and residual water saturation factors has been fulfilled. The correlation analysis has allowed establishing a series of empirical relationships between the reservoir parameters of the studied rocks (density, porosity coefficient, permeability coefficient and residual water saturation factor). The results of complex petrophysical researches indicated that the promising oil-bearing intervals of the horizons G-6, G-7v, G-7n have, in general increased values of reservoir parameters.

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Zhang, Jihua, Yun Dong, Yadong Chen, Yang Jiang, Huasheng Sun, Yuqing Fan i Chun Wang. "Comparative Analysis of Roadway Reinforcement Effects Based on Fluid-Solid Coupling in the Fractured Zone of Water-Rich Fault". Advances in Civil Engineering 2018 (6.09.2018): 1–14. http://dx.doi.org/10.1155/2018/6238910.

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Water inrush is a common geological disaster during the roadway excavation process in the broken zone of water-rich faults. In this paper, the 15107 mining roadway built by Yuxing coal mine in such a fault zone was used as a case study to determine the water content of the surrounding rocks and a fault zone using the transient electromagnetic method (TEM). Also, the mechanics characteristics of such rocks in both saturated and unsaturated states were analyzed, a computational model for fluid-solid coupling in the water-rich fault fracture zone was established, and the permeability coefficient of the rocks under both shield support and bolt-grouting support was compared, along with analyzing the changes in pore pressure, fissure water velocity, and characteristics of deformation in the surrounding rocks. The numerical simulation results show that the fault range has an influence of about 20 m, which causes the forms of permeability coefficient to change like a hump. The permeability coefficient in the fractured zone is the largest, and the mutation rate at the fault plane is faster. Bolting not only reduces the permeability coefficient of the surrounding rock that is 1/10 of the beam support but also prevents the roof fissure water inrushing the roadway and the surrounding rock of the floor, while also causing the pore-water pressure to decrease, even reduce to zero, in front of the working face and floor. The flow velocity of the fissure water can be decreased by bolting, which can effectively control the deformation of the surrounding rock by 38.7%∼65% compared with the shield support. The practice results show that this method can effectively recover the cracks surrounding the mining roadway and stop gushing water. Concurrently, it successfully controls deformation of the surrounding rocks in the fault zone, thus ensuring stability of the roadway and facilitating safer mining production.

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Zhao, Ranlei, Xiao Xu, Wentao Ma, Cunlei Li, Qiushi Zhang i Qingyou Yue. "Reservoir Characteristics and Controlling Factors of Sedimentary Pyroclastic Rocks in Deep-Buried Basins: A Case Study of Yingtai Fault Depression, Southern Songliao Basin". Energies 15, nr 18 (9.09.2022): 6594. http://dx.doi.org/10.3390/en15186594.

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In this article, based on core description, thin section, scanning electron microscope (SEM), well logging and reservoir physical properties, the reservoir controlling factors of sedimentary pyroclastic rocks in deep-buried basins are assessed via the relation between reservoirs and defining factors, including lithological characteristics, sedimentary microfacies and diagenesis. In addition, the contributing factors of anomalously high-porosity and high-permeability zone are analyzed. The lithological characteristics and diagenesis of the sedimentary pyroclastic rocks are closely related to reservoirs. The reservoir porosity–permeability of sedimentary pyroclastic rocks with large volcanic clastic particles is better than in those with small volcanic clastic particles. Sedimentary pyroclastic rocks with high content of unstable clastic particles, such as feldspar and rock debris, are easier to form the high-quality reservoirs than those with high content of quartz. The dissolution is the most important and direct reason to form the anomalously high-porosity and high-permeability zones of the sedimentary pyroclastic rocks in deep-buried basins. It is concluded that the size and composition of the clastic particles in the sedimentary pyroclastic rocks are the internal-controlling factors of the effective reservoirs, while the diagenetic fluid and the burial process are the external-controlling factors which form the effective reservoirs.

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Chen, Shikuo, Chenhui Wei, Tianhong Yang, Wancheng Zhu, Honglei Liu i Pathegama Ranjith. "Three-Dimensional Numerical Investigation of Coupled Flow-Stress-Damage Failure Process in Heterogeneous Poroelastic Rocks". Energies 11, nr 8 (24.07.2018): 1923. http://dx.doi.org/10.3390/en11081923.

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The failure mechanism of heterogeneous rocks (geological materials), especially under hydraulic conditions, is important in geological engineering. The coupled mechanism of flow-stress-damage should be determined for the stability of rock mass engineering under triaxial stress states. Based on poroelasticity and damage theory, a three-dimensional coupled model of the flow-stress-damage failure process is studied, focusing mainly on the coupled characteristics of permeability evolution and damage in nonhomogeneous rocks. The influences of numerous mesoscale mechanical and hydraulic properties, including homogeneity, residual strength coefficient, loading rates, and strength criteria, on the macro mechanical response are analyzed. Results reveal that the stress sensitive factor and damage coefficient are key variables for controlling the progress of permeability evolution, and these can reflect the hydraulic properties under pre-peak and post-peak separately. Moreover, several experiments are conducted to evaluate the method in terms of permeability evolution and failure process and to verify the proposed two-stage permeability evolution model. This model can be used to illustrate the failure mechanics under hydraulic conditions and match different rock types. The relation of permeability with strain can also help confirm appropriate rock mass hydraulic parameters, thereby enhancing our understanding of the coupled failure mechanism in rock mass engineering.

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Lv, Zhaoxing, Qianqian Ji i Weijie Ren. "Experimental Study and Percolation Analysis on Seepage Characteristics of Fractured Coal and Sandstone Based on Real-Time Micro-CT". Geofluids 2020 (5.11.2020): 1–9. http://dx.doi.org/10.1155/2020/8832946.

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Sandstone and coal are the two most common types of reservoirs in nature. The permeability of sandstone in oil-bearing formations controls its oil and gas production; the permeability of the coal seam containing gas has a crucial influence on the gas drainage efficiency. One of the main factors affecting rock permeability is the spatial distribution and connectivity of pores and fissures in the rock. In this paper, a small-sized sample with a diameter of 5 mm and a height of 10 mm was used for the test. The rock samples under different stress states were scanned in real-time during the seepage testing. Based on 2D images, a 3D digital sample was reconstructed. We extracted the pores and fissures from the 3D digital sample, studied the size and distribution of the largest cluster in the sample, and revealed the influence of confining pressure and seepage pressure on the percolation probability and permeability of the sample. The research results show that brittle sandstone and plastic coal, two types of rocks with completely different properties of mechanics, have obvious differences in the spatial distribution of the largest clusters. Under the same stress state, in brittle sandstone-like rocks, the connectivity of the fissures is the primary factor affecting permeability, and the pores are the auxiliary factor; for plastic rocks such as coal, the situation is just the opposite, pores are the primary factor affecting permeability, and fissures are the auxiliary factor. The research results answer the question: Hydraulic fracturing technology can increase the oil and gas production of sandstone reservoirs but cannot increase the drainage efficiency of coalbed methane.

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Rasolofosaon, Patrick N. J., i Bernard E. Zinszner. "Comparison between permeability anisotropy and elasticity anisotropy of reservoir rocks". GEOPHYSICS 67, nr 1 (styczeń 2002): 230–40. http://dx.doi.org/10.1190/1.1451647.

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We developed new experimental and theoretical tools for the measurement and the characterization of arbitrary elasticity tensors and permeability tensors in rocks. They include an experimental technique for the 3‐D visualization of hydraulic invasion fronts in rock samples by monitoring the injection of salt solutions by X‐ray tomography, and a technique for inverting the complete set of the six coefficients of the permeability tensor from invasion front images. In addition, a technique for measuring the complete set of the 21 elastic coefficients, a technique allowing the identification and the orientation in the 3‐D space of the symmetry elements (planes, axes), and a technique for approximating the considered elastic tensor by a tensor of simpler symmetry with the quantification of the error induced by such an approximation have been developed. We apply these tools to various types of reservoir rocks and observed quite contrasted behaviors. In some rocks, the elastic anisotropy and the hydraulic anisotropy are closely correlated, for instance in terms of the symmetry directions. This is the case when elastic anisotropy and hydraulic anisotropy share the same cause (e.g., layering, fractures). In contrast, in some other rocks, hydraulic properties and elastic properties are clearly uncorrelated. These results highlight the challenge we have to face in order to estimate the rock permeability and to monitor the fluid flow from seismic measurements in the field.

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Sun, Zhong Chun, Zhong Hong Chen, Yu Hua Kong, Wen Liu i Men Yun Yang. "The Physical Properties and their Prediction of Volcanic Reservoirs in Luxi Area of Junggar Basin, China". Advanced Materials Research 616-618 (grudzień 2012): 228–33. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.228.

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The physical properties of reservoirs determine the ability on accumulating hydrocarbon. As one of the unconventional hydrocarbon reservoirs, the volcanics own the different characteristics from the clastic rocks on physical properties. The study on the relationship between physical and electrical properties of deep volcanic reservoirs was conducted, using the Luxi area of Junggar basin as an example. By our study, some conclusions have been made: The heterogeneity of physical properties is strong in volcanic rocks whose porosity and permeability vary in different lithology and lithofacies; different rocks in a same well have various values of porosity and permeability, and a certain type of volcanic rock has different values of porosity and permeability in diverse wells. According to measured data, the value of porosity an permeability in erupting and effusive facies area are high, while in volcanic channel and extrusive facies as well as volcanic sedimentation facies are low. Unlike the clastic rocks, in volcanic rocks there is little relationship between porosity and permeability and all of them do not have close relationship to the buried depth. Different electrical responses have different relationship with the porosity of one certain lithology, while one certain electrical property has different responses for the porosities of different lithologies; comparatively speaking, the porosities of tuffites, breccia correlate intensively with GR, SP and AC, so these electrical parameters can be utilized to predict the physical properties. This study illustrated that the relativities between porosity and GR, AC, and SP are Por=-0.6189×GR+52.691 (R2=0.9311), Por =-0.3771×AC + 34.5 (R2=0.8876) and Por = 2.1458×SP + 79.404 (R2=0.8236).

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Zhou, Hui, Jian Fu Shao, Xia Ting Feng i Da Wei Hu. "Coupling Analysis between Stress Induced Anisotropic Damage and Permeability Variation in Brittle Rocks". Key Engineering Materials 340-341 (czerwiec 2007): 1133–38. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.1133.

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In this paper, a coupling constitutive model is proposed for anisotropic damage and permeability variation in brittle rocks before cracks fully coalesce. In this coupling model, an anisotropic damage model is employed to perform the mechanical analysis, and a statistical penetration model is set up to describe the effective porosity and permeability evolution in brittle rocks. For the coupling analysis, anisotropic damage model offers statistical penetration model the crack length in various directions, and statistical penetration model inversely provides anisotropic damage model with permeability of rock for coupling hydro-mechanical analysis. The proposed coupling model is applied to Lac du Bonnet granite, and generally a good agreement is obtained between numerical simulations and experimental data.

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Krogulec, Ewa, Katarzyna Sawicka, Sebastian Zabłocki i Ewa Falkowska. "Mineralogy and Permeability of Gas and Oil Dolomite Reservoirs of the Zechstein Main Dolomite Basin in the Lubiatów Deposit (Poland)". Energies 13, nr 23 (5.12.2020): 6436. http://dx.doi.org/10.3390/en13236436.

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Permeability characterizes the ability of rocks to store and transport natural gas, crude oil and reservoir fluids. Permeability heterogeneity of reservoir rocks, including dolomites, results from overlapping geological and physicochemical processes. The permeability study of gas-bearing dolomites was carried out on the Lubiatów hydrocarbon deposit (Poland), located at the Ca2 carbonate platform toe-of-slope, which is a prospective area for hydrocarbon exploration in Europe. Due to the complicated rock textures and overlapping alteration processes, including secondary crystallization or dissolution of minerals, the permeability of the deposit is variable. Studies of dolomites from a depth of 3242–3380 m show high mineralogical diversity; the percentage of dolomite ranges from 79% to 95% with a variable content of other minerals: anhydrite, gypsum, quartz, fluorite, plagioclase and clay minerals. The porosity variability ranges from 4.69% to 31.21%, depending on the measurement method used. The mean permeability value is 35.27 mD, with a variation range of 0.9 to 135.6 mD. There is neither change in permeability with depth and mineral composition, nor a direct relationship between porosity and permeability.

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Kurovets, S. S., i І. V. Artym. "Evaluation of the geological factors impact on capacity and filtration properties of terrigenuous reservoirs of the Pre-Carpathian foredeep". Scientific Bulletin of Ivano-Frankivsk National Technical University of Oil and Gas, nr 1(44) (5.05.2018): 25–37. http://dx.doi.org/10.31471/1993-9965-2018-1(44)-25-37.

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The following main geological factors that determine the reservoir properties of the terrigenous rocks of the Pre-Carpathian foredeep were identified, namely: mineral composition, structural and texture features, and thermobaric factors. The mineral composition of the rock-forming minerals, the shape, the size of the fragmented grains and pores, their mutual placement, the type of fluid and the thermodynamic state determine the reservoir properties of terrigenous rocks. The best reservoirs are sandstones, compiled with larger and sorted grains. The increase of clay and carbonate material sharply worsens the reservoir properties of rocks. Sealing and secondary processes (sieving, calcifying, pyrolysis) negatively affect the reservoir properties of rocks, reduce their porosity and permeability. Some dependencies were identified. These dependencies make it possible to predict the maximum porosity of sandstones, depending on their immersion in depth. The given porosity data of sandy-clayey rocks shows, that sorted quartz sandstones with insignificant contents of clayey and carbonate materials have greater intergranular porosity and permeability at great depths.

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Zeynaly-Andabily, E. M., i S. S. Rahman. "Measurement of permeability of tight rocks". Measurement Science and Technology 6, nr 10 (1.10.1995): 1519–27. http://dx.doi.org/10.1088/0957-0233/6/10/012.

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Banks, David, Noelle E. Odling, Helge Skarphagen i Erik Rohr-Torp. "Permeability and stress in crystalline rocks". Terra Nova 8, nr 3 (maj 1996): 223–35. http://dx.doi.org/10.1111/j.1365-3121.1996.tb00751.x.

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Chi, Lu, i Zoya Heidari. "Directional-Permeability Assessment in Formations With Complex Pore Geometry With a New Nuclear-Magnetic-Resonance-Based Permeability Model". SPE Journal 21, nr 04 (15.08.2016): 1436–49. http://dx.doi.org/10.2118/179734-pa.

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Summary This paper proposes a new method for directional-permeability assessment with nuclear-magnetic-resonance (NMR) measurements. Conventional techniques for permeability assessment from NMR measurements include empirical correlations such as SDR (Schlumberger-Doll-Research) and Coates models. However, carbonate rocks are known for lack of good correlations between pore-body-size and pore-throat-size, which makes it challenging and often unreliable to estimate permeability from NMR T2 (spin-spin relaxation time) distribution in carbonate formations with complex pore structure. It also was proposed that conventional permeability models can be improved by incorporating an estimated pore-connectivity factor. However, none of the previously introduced techniques reflects the anisotropic characteristics of rock permeability. The new NMR-based directional-permeability model, introduced in this paper, incorporates a directional pore-connectivity factor into a conventional NMR-based permeability model. We introduce two approaches to quantify the directional pore-network connectivity of rock samples with pore-scale images. The first approach calculates directional pore connectivity in 3D pore-scale images with a topological technique. The second approach combines image analysis and electrical formation factor. The new NMR-based permeability model enables assessment of rock permeability in any desired direction. We successfully calibrated and tested the introduced NMR-based permeability model on carbonate, sandstone, and sandpack samples with complex pore geometry or anisotropic permeability. The anisotropic permeability used for calibration and test purposes was obtained by the lattice Boltzmann method (LBM) simulations on microcomputed tomography (CT) images of rock samples. The comparison between the permeability estimates with our new NMR model and conventional NMR models (e.g., SDR and Coates models) demonstrated that the NMR-based directional-permeability model significantly improves assessment of rock permeability, by reflecting rock's anisotropic characteristics and minimizing calibration efforts. The outcomes of this research can significantly improve permeability assessment in complex carbonate reservoirs and anisotropic sandstone reservoirs, and can be extended further to organic-rich mudrock formations.

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Nababan, Benyamin Elilaski, Eliza Veronica Zanetta, Nahdah Novia i Handoyo Handoyo. "ESTIMASI NILAI POROSITAS DAN PERMEABILITAS DENGAN PENDEKATAN DIGITAL ROCK PHYSICS (DRP) PADA SAMPEL BATUPASIR FORMASI NGRAYONG, CEKUNGAN JAWA TIMUR BAGIAN UTARA". Jurnal Geofisika Eksplorasi 5, nr 3 (17.01.2020): 34–44. http://dx.doi.org/10.23960/jge.v5i3.34.

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Reservoir rock permeability and porosity are physical properties of rocks that control reservoir quality. Conventionally, rock porosity and permeability values are obtained from measurements in the laboratory or through well logs. At present, calculation of porosity and permeability can be calculated using digital image processing / Digital Rock Physics (DRP). Core data samples are processed by X-ray diffraction using CT-micro-tomography scan. The result is an image model of the core sample, 2D and 3D images. The combination of theoretical processing and digital images can be obtained from the value of porosity and permeability of rock samples. In this study, we calculated porosity and permeability values using the Digital Rock Physics (DRP) approach in sandstone samples from the Ngrayong Formation, North East Java Basin. The results of the digital image simulation and processing on the Ngrayong Formation sandstone samples ranged in value from 33.50% and permeability around 1267.02 mDarcy.

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Li, Bo, Lulu Zhang, Jianping Wei i Yongjie Ren. "Pore Damage Properties and Permeability Change of Coal Caused by Freeze-Thaw Action of Liquid Nitrogen". Advances in Civil Engineering 2018 (2.10.2018): 1–9. http://dx.doi.org/10.1155/2018/5076391.

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A laboratory test was conducted to investigate the effect of the freeze-thaw action of liquid nitrogen on the pore structure and permeability of coal rock. First, coal rock samples with similar sound velocities and permeabilities were selected. These samples were prepared in different water saturation levels and subjected to nuclear magnetic resonance (NMR) test before and after the freeze-thaw action. Furthermore, the freeze-thaw cycle of liquid nitrogen, freezing time, and water saturation of coal rocks were controlled in permeability test. Results showed that the pore diameter, porosity, and permeability of the coal rocks increase after the freeze-thaw action of liquid nitrogen. These characteristics increase further with the increase of water saturation. The fracturing mechanisms of the freeze-thaw action of liquid nitrogen were summarized in two aspects, phase change of pore water and cold shock, and cold shock was mainly discussed. The results indicate that the effect of cold shock is still crucial at low water saturation, but it is limited by the degree of temperature drop. In general, freeze-thaw action of liquid nitrogen can cause damage to pore structure, promote the formation of fracture networks, and consequently improve the permeability of coal rock.

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Popov, Nikita A., Ivan S. Putilov, Anastasiia A. Guliaeva, Ekaterina E. Vinokurova i Iuliia V. Fairuzova. "THE INFLUENCE OF ROCK LITHOGENESIS TYPES ON POROSITY AND PERMEABILITY (THE CASE OF PERMOCARBONIFEROUS DEPOSIT OF THE USINSKOYE FIELD)". Вестник Пермского национального исследовательского политехнического университета. Геология. Нефтегазовое и горное дело 20, nr 2 (czerwiec 2020): 104–14. http://dx.doi.org/10.15593/2224-9923/2020.2.1.

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The paper analyzes a methodology aimed at differentiation of porosity, permeability and petrographic properties depending on facies attributes. Based on the Dunham classification, we offer in-depth studies of the influence of rock fabric, including full-size core samples, on changes in porosity and permeability. The work deals with the Permo-Carboniferous deposit of the Usinskoye field. Reservoir properties of the considered strata are highly heterogeneous. Along with highly porous and cavernous rocks, there are low porous and fractured varieties in the section, which refer to rocks of various lithological compositions. The porosity and permeability properties were analysed for more than 9,000 standard core samples and approximately 1,000 full-size core samples, taking into account the scale factor and including microfractures, large caverns and rock matrix, commensurable with the sample sizes.The analysis of the maximum variation range is of particular importance for structurally complex carbonate reservoirs. Furthermore, based on the conducted lithologic, petrographic and petrophysical studies, the authors identified four types of reservoirs and eight different types of lithogenesis, as well as estimated geological and physical parameters for each of them. Based on the cumulative correlation plots, four zones of heterogeneity were identified. They are subject to the influence of properties of the core samples of different lithogenesis types. This is the first time that the influence of various petrotypes/lithotypes on changes in the reservoir porosity and permeability has been studied for the Usinskoye field based on the petrographic and petrophysical research findings. All the conducted experiments show that the rocks of the Permo-Carboniferous deposit of the Usinskoye field are extremely heterogeneous in their permeability properties that vary much. Thus, it is necessary to differentiate the core-to-core petrophysical correlations depending on a void space fabric and lithology of rocks.

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Khimulia, V. V., i S. O. Barkov. "Analysis of changes in the internal structure of low-permeability reservoir rocks by means of computed tomography after implementation of the directional unloading method". Actual Problems of Oil and Gas, nr 39 (29.12.2022): 27–42. http://dx.doi.org/10.29222/ipng.2078-5712.2022-39.art3.

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The article presents the results of comprehensive studies of changes in the internal structure and evolution of filtration properties of low-permeability rocks of the Astrakhan gas-condensate field when implementing the method of increasing well productivity – the directional unloading method. Physical modeling of the deformation and filtration processes on the unique Triaxial Independent Load Test System of the Institute for Problems in Mechanics of the Russian Academy of Sciences was carried out. A 3D scan of rocks after testing was performed using a ProCon CT-MINI high-resolution X-ray tomograph in order to analyze changes in the internal structure. A digital model of the rock was obtained, and numerical simulation of filtration flow in GeoDict software based on the results of microtomography scanning was performed. Velocity fields and permeability values for different computational models and computation optimization methods are calculated. The results obtained in different filtration models are compared with the laboratory measured value of permeability. The main differences in approaches to numerical estimation of rock permeability are described, and conclusions about the applicability of the modeling techniques used are made. The research results allow us to conclude that the directional unloading method can be successfully applied to the conditions of the Astrakhan gas-condensate field, allowing to significantly improve filtration properties of rocks in the vicinity of the well.

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Chen, Tao. "Equivalent Permeability Distribution for Fractured Porous Rocks: Correlating Fracture Aperture and Length". Geofluids 2020 (10.10.2020): 1–12. http://dx.doi.org/10.1155/2020/8834666.

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Estimating equivalent permeability at grid block scale of numerical models is a critical issue for large-scale fractured porous rocks. However, it is difficult to constrain the permeability distributions for equivalent fracture models as these are strongly influenced by complex fracture properties. This study quantitatively investigated equivalent permeability distributions for fractured porous rocks, considering the impact of the correlated fracture aperture and length model. Two-dimensional discrete fracture models are generated with varied correlation exponent ranges from 0.5 to 1, which indicates different geomechanical properties of fractured porous rock. The equivalent fracture models are built by the multiple boundary upscaling method. Results indicate that the spatial distribution of equivalent permeability varied with the correlation exponent. When the minimum fracture length and the number of fractures increase, the process that the diagonal equivalent permeability tensor components change from a power law like to a lognormal like and to a normal-like distribution slows down as the correlation exponent increases. The average dimensionless equivalent permeability for the equivalent fracture models is well described by an exponential relationship with the correlation exponent. A power law model is built between the equivalent permeability of equivalent fracture models and fracture density of discrete fracture models for the correlated aperture-length models. The results demonstrate that both the fracture density and length-aperture model influence the equivalent permeability of equivalent fracture models interactively.

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Ni, Lin, Xue Zhang, Liangchao Zou i Jinsong Huang. "Phase-field modeling of hydraulic fracture network propagation in poroelastic rocks". Computational Geosciences 24, nr 5 (19.04.2020): 1767–82. http://dx.doi.org/10.1007/s10596-020-09955-4.

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Abstract Modeling of hydraulic fracturing processes is of great importance in computational geosciences. In this paper, a phase-field model is developed and applied for investigating the hydraulic fracturing propagation in saturated poroelastic rocks with pre-existing fractures. The phase-field model replaces discrete, discontinuous fractures by continuous diffused damage field, and thus is capable of simulating complex cracking phenomena such as crack branching and coalescence. Specifically, hydraulic fracturing propagation in a rock sample of a single pre-existing natural fracture or natural fracture networks is simulated using the proposed model. It is shown that distance between fractures plays a significant role in the determination of propagation direction of hydraulic fracture. While the rock permeability has a limited influence on the final crack topology induced by hydraulic fracturing, it considerably impacts the distribution of the fluid pressure in rocks. The propagation of hydraulic fractures driven by the injected fluid increases the connectivity of the natural fracture networks, which consequently enhances the effective permeability of the rocks.

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Pescov, Aleksander V. "Features of measuring absolute permeability of rocks". Vestnik of Samara State Technical University. Technical Sciences Series 28, nr 2 (27.07.2020): 73–83. http://dx.doi.org/10.14498/tech.2020.2.5.

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Aspects of gas permeability measurement on samples of terrigenic and carbonate rocks of oil and gas collectors, as well as artificial samples on the domestic Darsimeter plant are considered. The following types of reservoir rocks were used for the study: pore, fractured, cavernous. The scope of application of the Darcy Law for pore-type rocks was clarified, which is limited to small pore pressures. Permeability coefficients were determined taking into account the gas slip-law effect of Klinkenberg on regression equations. Apparent permeability at low pressure drops was determined. For a number of samples with low permeability, the pore size was calculated to relate to the apparent permeability value. The calculation was carried out on the basis of the obtained values of structural coefficients of rocks by the method of electrical resistivity and on the basis of porosity values determined using the Preobrazhenskiy method.For a number of crack and capillary samples, the relationship between the pressure gradient and the filtration rate became nonlinear, and types of filtration laws were determined. Establishing the applicability of Darcy 's law or nonlinear law was controlled by constructing indicator curves and calculating the Reynolds number. For terrigenic rocks of high permeability, errors of measurement of gas permeability coefficients at different pressure drop intervals were determined: dispersion and coefficient of variation showing low values were calculated.

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Zhang, Cheng-Han, Shuang You, Hong-Guang Ji, Fei Li i Hong-Tao Wang. "Hydraulic properties and energy dissipation of deep hard rock under H-M coupling and cycling loads". Thermal Science 23, Suppl. 3 (2019): 935–42. http://dx.doi.org/10.2298/tsci180702181z.

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The permeability of deep rock is closely related to the stability and safety of underground engineering. The rocks in deep stratum are mostly with high stress and high osmotic pressure. Therefore, it is necessary to consider the coupling effect between porewater pressure and in situ stress on rock mass. A series of triaxial cyclic loading and unloading experiments under hydraulic-mechanics coupling conditions are carried out to studied the mechanical and hydraulic properties of granite in the depth of 1300 m to 1500 m. Especially, the effect of the disturbance on the permeability of fractured rocks are investigated by unloaded the confining pressure. Tests results presented that the stress-strain curves of deep granite showed typical brittle characteristics. The principal stress of granite exhibited a linear relationship under the high confining pressure of 34-40 MPa and high osmotic pressure of 13-15 MPa. Dissipated energy of the rock decreased to a relatively low level after 2-3 loading cycles and then slowly increased. Permeability showed a decreasing trend as the loading and unloading cycles increase. Finally, acoustic emission technology was used to monitor the fracture evolution in rocks, the acoustic emission signal released as the fractures develop and energy dissipated. The results would provide basic data for the exploitation and excavation in the deep galleries.

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Li, Shi Ji, Ze Hua Wang, Yu Xue Sun i Jian Bo Xie. "Stress Sensitivity of Low-Permeability Sandstone Reservoir". Advanced Materials Research 753-755 (sierpień 2013): 686–89. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.686.

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In the time of low-permeability sandstone reservoir explored, effective stress rise gradually, stress sensitivity has happened, which cause permeability decline. Allowing to initial geostress, the study on Jilin oilfield Fuxin326 oil layer and made the rock core experiment are presented. The experimental results show that the stress sensitivity of this oil layer is small the regularity of permeability changes is in accordance with exponential function. The stress sensitivity of high permeability core is larger than low permeability. Moreover, experiments and theoretical analysis shows that low permeability core has a smaller permeability loss than high permeability core in load and unload process. Loading and unloading process leads to elastic plastic deformation of rocks, and it is the major reason which permeability can not return completely.

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Wang, Qizhi, Xuebin Su, Bangbiao Wu, Wei Wang i Wei Yuan. "A Coupled Damage-Permeability Constitutive Model for Brittle Rocks Subjected to Explosive Loading". Advances in Civil Engineering 2018 (22.07.2018): 1–9. http://dx.doi.org/10.1155/2018/6816974.

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A dynamic constitutive model considering coupled damage-permeability effect is developed for rocks under explosion. The main purpose of this model is to provide reference to in situ leaching mining (include uranium ore, gold ore, etc.) to improve the permeability of rocks using blasting. The damage is induced and described by the summation of all principal tensile strains. This method does not need to determine (distinguish) the stress state of the material and thus does not need to consider the damage induced by differential stresses. A corresponding relation between the damage status and rock permeability is established through a logarithm function. Based on the theoretical foundation, this model is embedded in a three-dimensional code of ABAQUS, and its applicability is verified through simulating the experiments under the condition of explosive load, the results from numerical simulation are consistent with the experimental results. Moreover, the obvious advantage of the numerical constitutive model is that it can clearly distinguish permeability variation that cannot be done in laboratory test.

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