scholarly journals COAL PERMEABILITY ANISOTRTOPY ESTIMATION BY FILTRATION EXPERIMENTS AND FRACTURE ANALYSIS RESULTS

2020 ◽  
Vol 2 ◽  
pp. 226-233
Author(s):  
Tatyana V. Shilova ◽  
Leonid A. Rybalkin ◽  
Alexander V. Yablokov
Keyword(s):  
Bituminous Coal ◽  
Experimental Studies ◽  
Fracture Analysis ◽  
Absolute Permeability ◽  
Uniform Compression ◽  
Direction Parallel ◽  
Coal Permeability ◽  
Depth Data ◽  
Bedding Planes ◽  
Horizontal Permeability

Experimental studies of the structure of medium-volatile bituminous coal taken from the Leninsk region of Kuzbass are performed. The main properties of endogenous cleavage fractures are determined. The dependence of coal absolute permeability on uniform compression of samples is experimentally explored. Laboratory permeability tests were conducted in the direction parallel to master cleavage fractures and bedding planes. The obtained values are typical for intensely fractured coals. Using the known models, the dependence of coal permeability on stress conditions is obtained for the directions parallel to master and side cleavage. The anisotropy of coal horizontal permeability is determined taking into account the properties of endogenous cleavage fractures. Change in coal permeability with seam depth is estimated in conditions of the Leninsk region of Kuzbass. The permeability-depth data were obtained for the conditions of uniaxial strain perpendicular to layered structure and endogenous cleavage planes.

scholarly journals The response of Opalinus Clay when exposed to cyclic relative humidity variations

2016 ◽  
Author(s):  
Katrin M. Wild ◽  
Patric Walter ◽  
Florian Amann
Keyword(s):  
Tensile Strength ◽  
Relative Humidity ◽  
Environmental Changes ◽  
Opalinus Clay ◽  
Brazilian Tensile Strength ◽  
Internal Damage ◽  
Direction Parallel ◽  
Clay Shale ◽  
Retention Characteristic ◽  
Bedding Planes

Abstract. Clay shale specimens were exposed to cyclic relative humidity variations to investigate the response of the material to natural environmental changes. Opalinus Clay, a clay shale chosen as host rock for nuclear waste disposal in Switzerland, was utilized. The specimens were exposed to stepwise relative humidity cycles where they were alternately allowed to equilibrate at 66 and 93 % relative humidity. Principal strains were monitored throughout the experiments using strain gauges. After each relative humidity cycle, Brazilian tensile strength tests were performed to identify possible changes in tensile strength due to environmental degradation. Results showed that Opalinus Clay follows a cyclic swelling-shrinkage behaviour with irreversible expansion limited to the direction normal to bedding, suggesting that internal damage is restricted along the bedding planes. The Brazilian tensile strength in direction parallel and normal to bedding as well as the water retention characteristic remained unaffected by the RH variations.

scholarly journals Analysis of filtration and electrical properties anisotropy of terrigenous reservoir rocks (for DDB axial zone reservoirs)

2019 ◽  
Keyword(s):  
Electrical Resistivity ◽  
Gas Permeability ◽  
Vertical Direction ◽  
Absolute Permeability ◽  
Electrical Anisotropy ◽  
Reservoir Rocks ◽  
Vertical Permeability ◽  
Irreducible Water Saturation ◽  
Horizontal Permeability ◽  
Filtration Properties

The paper focuses on the filtration and electrical anisotropy coefficients and relationship between vertical and horizontal permeability in sandstone reservoir rocks. Field case study of DDB reservoir rocks. Petrophysical properties and parameters are estimated from core and log data from a Moscovian and Serpukhovian stages of Dnipro-Donetsk Basin (West-Shebelynka area well 701-Bis and South-Kolomak area well 31). Routine core analysis included estimation of absolute permeability, open porosity, irreducible water saturation and electrical resistivity (on dry and saturated by mineralized solution) of 40 core samples along two orthogonal directions. Shale fraction is estimated using well logging data in wells which are analyzed. The authors report that reservoir rocks are represented by compacted poor-porous (φ <10 %), low permeable (k<1mD) laminated sandstone with different ratios of clay minerals (Vsh from 0,03 to 0,7) and high volume of micaceous minerals (in some cases 20-30 %). Research theory. One of the main objectives of the work is to develop empirical correlation between vertical permeability and other capacitive and filtration properties for compacted sandstone reservoirs. A modified Kozeny-Carman equation and the concept of hydraulic average radius form the basis for the technique. Results. Coefficients of the anisotropy of gas permeability (IA) and electrical resistivity (λ) are defined based on the results of petrophysical studies. The experiments proved that IA lies in a range from 0,49 to 5 and λ from 0,77 to 1,06. Permeability and electrical resistivity anisotropy in most cases have horizontal distribution. It has been shown that in West-Shebelynka area sample №1 (depth 4933 m) there is probably no fluids flow in vertical direction and in samples №№3 and 15 fractures have the vertical orientation. We have also found that the values of electrical and filtration anisotropy for all samples of South-Kolomak area are similar, this characterized the unidirectionality in their filtration properties, as well as the fact that the motion of the fluid flow mainly in the horizontal direction. In the studied rocks the degree of anisotropy has been concluded to depend on the volume of clay and micaceous minerals, their stratification, fractures, density, and their orientation. New correlation between vertical permeability, horizontal permeability and effective porosity are developed for Late Carboniferous DDB intervals that are analyzed.

Experimental Studies of Thermo-Induced Mechanical Effects in the Main-Chain Liquid Crystal Elastomers

2014 ◽  
Vol 896 ◽  
pp. 322-326 ◽  
Author(s):  
Supardi ◽  
Harsojo ◽  
Yusril Yusuf
Keyword(s):  
Liquid Crystal ◽  
Critical Temperature ◽  
Main Chain ◽  
Experimental Studies ◽  
Artificial Muscles ◽  
Direction Parallel ◽  
Mechanical Effects ◽  
Liquid Crystal Elastomers ◽  
Heating Up ◽  
Contraction And Expansion

Liquid crystal elastomers (LCEs), either side-chain LCEs (SCLCEs) or main-chain LCEs (MCLCEs), possess a combination of LC and elastic properties, and are expected to be used as artificial muscles. We experimentally investigated the thermo-induced mechanical effects showed by MCLCEs with four different crosslinker concentrations, i.e., 8%, 12%, 14% and 16%. The samples were heated up to the critical temperature and the images were recorded. The samples made the contraction in direction parallel to the director and the expansion in direction perpendicular to the director. Drastic changes occured when approaching the critical temperature, the greater the crosslinkers concentration the bigger the maximum contraction and expansion. The shape anisotropy expression showed that heating up to the critical temperature caused the system no longer in anisotropic state.

Bioengineering Studies of Periodic External Compression as Prophylaxis Against Deep Vein Thrombosis—Part II: Experimental Studies on a Simulated Leg

1982 ◽  
Vol 104 (2) ◽  
pp. 96-104 ◽  
Author(s):  
D. A. Olson ◽  
R. D. Kamm ◽  
A. H. Shapiro
Keyword(s):  
Deep Vein Thrombosis ◽  
Fluid Velocity ◽  
Experimental Studies ◽  
Companion Paper ◽  
Uniform Compression ◽  
External Compression ◽  
Vein Thrombosis ◽  
Sequential Mode ◽  
Deep Vein

In this companion paper to “Part I: Numerical Simulations,” we report in vitro experimental studies performed on a simple model leg consisting of a “vein” of thin-walled latex tubing surrounded by “tissue” of open-pore foam rubber. Three modes of periodic external compression were investigated: i) uniform compression; (ii) graded compression, decreasing from ankle to knee; and (iii) sequential compression, progressing from ankle to knee. The modes are compared on the basis of three hemodynamic criteria: degree of vessel collapse, level of fluid velocity, and level of shear stress. In uniform compression these measures of merit are distributed very nonuniformly along the length of the leg: they are high near the proximal end of the cuff but low elsewhere, a result due to the formation proximally of a partially occlusive throat. The latter does not form in either graded or sequential compression, with the consequence that favorable values of the three measures of merit occur more uniformly along the length of the pressurized region. It is concluded that either the graded or sequential mode of compression, or perhaps a combination of the two, would be more effective than uniform compression as a prophylaxis against deep vein thrombosis.

Research on Post-Tensioned Unbonded Prestressed Concrete Hollowed Floor

2011 ◽  
Vol 94-96 ◽  
pp. 1456-1462
Author(s):  
Xiao Hua Yang ◽  
Chao Yang Zhou ◽  
Xue Jun He ◽  
Teng Chen
Keyword(s):  
Prestressed Concrete ◽  
Experimental Studies ◽  
Load Carrying Capacity ◽  
Structure Model ◽  
Test Results ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Direction Parallel ◽  
Load Carrying ◽  
Post Tensioned

In order to study the mechanical behaviors of post-tensioned unbonded prestressed concrete hollowed floors, a 1/4 scale post-tensioned unbonded prestressed reinforced concrete hollow slab-column structure model is used to act uniform distributed load on the floor. The test results showed that the load carrying capacity is enough. The points of maximum displacement are at the centers of slabs. By means of the experimental studies and elastic finite element analysis methods, the results showed that post-tensioned unbonded prestressed concrete hollowed floor presents anisotropy with layout of circular-tubes in one way. In direction parallel to layout of hollowed tubes, the continuity of floor is destruction and bending stiffness of slab is weakened. For studying the deformations of slab, it can still be considered continuous cross-slab in two directions.

scholarly journals Characteristics of Bituminous Coal Permeability Response to the Pore Pressure and Effective Shear Stress in the Huaibei Coalfield in China

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Lei Zhang ◽  
Zhiwei Ye ◽  
Mengqian Huang ◽  
Cun Zhang
Keyword(s):  
Shear Stress ◽  
Pore Pressure ◽  
Coal Mine ◽  
Gas Flow ◽  
Bituminous Coal ◽  
Stress Conditions ◽  
Coal Permeability ◽  
Gas Seepage ◽  
Shear Slip ◽  
Huaibei Coalfield

The coal permeability is known to be influenced by the pore pressure and effective stress in coal mines. In this study, the characteristics of the bituminous coal permeability response to the pore pressure and effective shear stress in the Xutuan coal mine in Huaibei Coalfield in China were investigated under different stress conditions. For this purpose, gas seepage tests with various stress levels were conducted via the original gas flow and displacement testing apparatus using bituminous coal samples from the Xutuan coal mine. The pore pressure effect on the permeability under different stress conditions was assessed by varying the pore pressure in coal samples and simulating different in situ stresses. The axial and radial pressures were controlled to study the response of coal permeability to the effective shear stress. The experimental results revealed that with an increase in pore pressure, the permeability of coal in different stress environments firstly drops and then rises. The permeability increased gradually with the effective shear stress, which trend became more pronounced when the effective shear stress exceeded zero. In case of the axial pressure exceeding the radial one, the cross shear slip was observed, for which the permeability of coal samples increased with the effective shear stress. In the opposite case, the separated shear slip was observed, with the reverse trend.

Experimental studies on the changing characteristics of the gas flow capacity on bituminous coal in CO2-ECBM and N2-ECBM

Fuel ◽  
2021 ◽  
Vol 291 ◽  
pp. 120115
Author(s):  
Lei Zhang ◽  
Jinghua Li ◽  
Junhua Xue ◽  
Cun Zhang ◽  
Xinqiu Fang
Keyword(s):  
Gas Flow ◽  
Bituminous Coal ◽  
Experimental Studies ◽  
Flow Capacity
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