The influence of mean grain size on unconfined compressive strength of weakly consolidated reservoir sandstones

Atapour, Hashem; Mortazavi, Ali

doi:10.1016/j.petrol.2018.07.029

Cited by 47 publications

(16 citation statements)

References 20 publications

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“…The small particles of sandstone are weakly cemented due to the existing of various voids and cracks, while the sandy mudstone shown in Figure 8f is composed of mud crystals and powder particles, filled with the mixture of flaky kaolinite and flocculent ionic mixture around the small cracks. It has been well established that the mechanical behavior of porous rock material is closely relevant to its particle size, porosity, and cementation [18][19][20][21][22][23]. From the cementation aspect, the cementation of sandstone presented in this research is much worse than that of mudstone and sandy mudstone, resulting in its worse mechanical behavior as presented earlier.…”

Section: Transfer Confining Pressure (σ T )mentioning

confidence: 61%

Behavior of Weakly Cemented Rock with Different Moisture Contents under Various Tri-Axial Loading States

et al. 2019

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To better understand the physical and mechanical behavior of weakly cemented rock with different moisture contents for the success of water-preserved mining, this paper presents the systematic tri-axial compression tests on three typical rock samples (i.e., mudstone, sandstone, and sandy mudstone) sampled from Ili mining area, where the environmental requirements for water conservation are significantly strict. Both the influences of moisture content and confining pressure on the failure mode and the stress-strain behavior of weakly cemented rock have been discussed and compared with each other. Test results showed that: (1) compared to sandstone and sandy mudstone, both the peak stress and residual stress of the weakly cemented mudstone are much more sensitive to confining pressure and moisture content. In detail, the peak stress is very relevant to moisture content, whereas, the residual stress is more sensitive to the confining pressure, (2) with the increase of moisture content, both the yield and ductility of weakly cemented mudstone have been significantly enhanced. However, a similar experimental observation has been found for sandstone and sandy mudstone, and (3) the microstructure and the mineral component are believed to be the two main factors leading to the scatter in terms of the stress-strain behavior for different weakly cemented rocks. Experimental results and discussions presented in this paper can provide the guideline for further research on the application of water-preserved mining in other coal mines with a similar geological condition.

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Section: Transfer Confining Pressure (σ T )mentioning

confidence: 61%

Behavior of Weakly Cemented Rock with Different Moisture Contents under Various Tri-Axial Loading States

et al. 2019

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“…Grain size in artificial pure sandstones (quartz arenite) without chemical compaction correlates well with UCS (Atapour and Mortazavi 2018). Chemical compaction is driven by (i) the amount of overburden, temperature, and fluid pressure i.e.…”

Section: Impact Of Chemical Compactionmentioning

confidence: 85%

“…6b1) and density ( Fig. 6b2) due to lower strength and densities (Atapour and Mortazavi 2018;Baud et al 2014;Hsieh et al 2008;Weng et al 2005). Thus, the reduction of porosity and the increase of the effective contact ratio (ECR) during diagenesis need to be constrained to assess rock strength in context of diagenetic alterations.…”

Section: Impact Of Porositymentioning

confidence: 99%

Coupling of diagenetic alterations and mechanical properties of Lower Permian siliciclastic sandstones: a pilot study

Monsees

Biebricher²,

Busch

et al. 2021

Environ Earth Sci

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Initial detrital composition and authigenic alterations during diagenesis of three sandstone types are related to their mechanical properties. Sandstones were prepared for geotechnical standard tests [density, uniaxial compressive strength (UCS), Young’s modulus (E), strain at failure (ε)] and thin sections for petrographic analyses (point counting). UCS ranges from 3 to 62 MPa and positively correlates with density (1.75–2.35 g/cm3) and E (0.3–12.7 GPa). Optical porosity is controlling these mechanical parameters and was linked to diagenetic alterations. Diagenetic alterations affecting porosity reduction are the abundance of clay minerals, and the intensity of mechanical and chemical compaction. The latter is controlled by clay mineral coatings on contacts between detrital grains, and the occurrence of authigenic quartz and dolomite. Horizontal contact lengths of grains normalized to their respective particle diameter (effective contact ratio, ECR) and porosity are identified as a control on the mechanical properties UCS and E, reflected by the rock strength index SR. The results of this pilot study suggest that SR is able to predict UCS and E based on petrographic information obtained from the studied samples. These results enhance the understanding of the coupling between mineralogy and geomechanics and highlight the impact of diagenesis on geomechanical behavior.

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“…size, shape, orientation of mineral grains, porosity) on the mechanical behaviour of rock materials have been recognized and studied from several years in different rock types. In particular, the effect of mean grain-size was described in different rock types: limestone (Handin et al, 1957;Fredrich et al, 1990), sandstone (Singh, 1988;Klein et al, 2001;Cheung et al, 2012;Atapour and Mortazavi, 2018), marbles (Olsson, 1974;Wong et al, 1996), anhydrite (Skinner, 1959), dolomite Palchik, 1997, 1998), and igneous rocks (Eberhardt et al, 1999). Generally, it has been observed that larger grains and longer grain boundaries result in longer weakness surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…Some studies recognized also the influence of other geometrical parameters related to grains organization: shape and azimuth angle (Howarth and Rowlands, 1986) and orientation angle (Přikryl et al, 2007). In highly porous rocks, the role of grain-size is less crucial, because it is hidden by other more influential parameters, such as cementation or porosity (Ulusay et al, 1994;Palchik, 1999;Baud et al, 2017;Atapour and Mortazavi, 2018).…”

Section: Introductionmentioning

confidence: 99%

Dependence of macro mechanical behaviour of gypsum on micro-scale grain-size distribution

Caselle

Bonetto

Vagnon

et al. 2019

Géotechnique Letters

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The exploitation of gypsum by both open pit and underground quarries requires attentive evaluations of mechanical features and variability. However, gypsum rock testing often neglects the natural heterogeneity. The result is an inaccurate mechanical characterization that averages the strength values of different materials leading to an underestimation or the overestimation of the stability conditions, without offering a real representation of the mechanical behaviour of the rock. Grain-size, grain-sorting, mineral composition and porosity significantly influence gypsum mechanical behaviour. The individuation of textural and compositional features that primarily influence the variation in mechanical parameters may offer an interpretation key of the phenomenon. In this study, the relation between features at the microscale and macro-mechanical behaviour of gypsum rock was analysed with a multiscale approach. Relationships between Uniaxial Compression Strength (UCS), grain-size distribution and porosity were analysed and discussed. Microscopic observations on thin sections were performed, developing an image analysis procedure for correlating textural and structural parameters with UCS.

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The influence of mean grain size on unconfined compressive strength of weakly consolidated reservoir sandstones

Cited by 47 publications

References 20 publications

Behavior of Weakly Cemented Rock with Different Moisture Contents under Various Tri-Axial Loading States

Behavior of Weakly Cemented Rock with Different Moisture Contents under Various Tri-Axial Loading States

Coupling of diagenetic alterations and mechanical properties of Lower Permian siliciclastic sandstones: a pilot study

Dependence of macro mechanical behaviour of gypsum on micro-scale grain-size distribution

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