Porosity and grain size controls on compaction band formation in Jurassic Navajo Sandstone

2010 ◽  
Vol 37 (22) ◽  
pp. n/a-n/a ◽  
Author(s):  
Richard A. Schultz ◽  
Chris H. Okubo ◽  
Haakon Fossen
Keyword(s):  
Grain Size ◽  
Band Formation ◽  
Navajo Sandstone ◽  
Compaction Band

Conditions and implications for compaction band formation in the Navajo Sandstone, Utah

2011 ◽  
Vol 33 (10) ◽  
pp. 1477-1490 ◽  
Author(s):  
Haakon Fossen ◽  
Richard A. Schultz ◽  
Anita Torabi
Keyword(s):  
Band Formation ◽  
Navajo Sandstone ◽  
Compaction Band

The effect of grain size and porosity on compaction localisation in high-porosity sandstones

2021 ◽  
Author(s):  
Elliot Rice-Birchall ◽  
Daniel Faulkner ◽  
John Bedford
Keyword(s):  
Grain Size ◽  
Axial Strain ◽  
Size Reduction ◽  
High Porosity ◽  
Pore Collapse ◽  
Band Formation ◽  
Compaction Bands ◽  
Grain Crushing ◽  
Porosity Reduction ◽  
Compaction Band

<p>As sandstone reservoirs are depleted, the pore pressure reduction can sometimes result in pore collapse and the formation of compaction bands. These are localised features which can significantly reduce the bulk permeability of the reservoir and are therefore problematic in the oil, water, geothermal, and CO<sub>2</sub> sequestration industries. However, the influence that grain size, grain shape and sorting have on compaction band formation in sandstone is still poorly understood, due to the fact that finding natural sandstones with specific properties is challenging. Consequently, a method of forming synthetic sandstones has been developed, in order to produce a suite of sandstone specimens with controlled grain size and porosity characteristics. During production of the synthetic sandstones, amorphous quartz cement and sodium chloride are precipitated between sand grains as a product of the reaction between sodium silicate and hydrochloric acid. The salt can then be dissolved, resulting in synthetic sandstones that have very comparable physical properties to their natural counterparts. In this study, triaxial experiments were performed on synthetic sandstone cores with four different grain size ranges of 250-300, 425-500, 600-710 and 850-1000 microns, at three different starting porosities of 27%, 32% and 37%. The samples were each axially loaded from a point along their hydrostat corresponding to 85% of their hydrostatic yield point, P*, values. These conditions mean that failure will occur within the shear-enhanced compaction regime so as to try and produce localised compaction structures. All samples were taken to 5% axial strain. The microstructural results indicate that localisation of deformation within the samples did occur and was favoured in the low starting porosity, small grain size samples. Localisation of deformation was most easily recognised by grain size reduction through grain crushing. This was weakly correlated to a change in porosity but recognition of the localisation of deformation was difficult to make using variations in porosity alone. Porosity reduction was not necessarily associated with a reduction in grain size. With increasing grain size and starting porosity, the deformation becomes more distributed in the samples with the highest starting porosity samples (37%) exhibiting more widely distributed grain crushing which was less intense overall. The results indicate a significant grain size and starting porosity influence on localisation, but also that compaction can occur by two mechanisms; one involving mostly grain rearrangement and the other primarily by grain fracturing. Consequently, the localisation of deformation is most evident in grain size reduction and is only weakly shown by porosity reduction.</p>

scholarly journals Influence of the Initial Grain Size on the Rolling and Recrystallization Textures in the Alloy Al-1.8% Cu

1995 ◽  
Vol 23 (2) ◽  
pp. 61-86 ◽  
Author(s):  
O. Engler
Keyword(s):  
Grain Size ◽  
Shear Bands ◽  
Spatial Density ◽  
Shear Band Formation ◽  
Band Formation ◽  
X Ray ◽  
Local Texture ◽  
Nucleation Sites ◽  
Large Particles ◽  
Deformation Models

The influence of the initial grain size prior to deformation on the rolling and recrystallization textures is investigated in the alloy Al-l.8wt%Cu by X-ray macrotexture analysis. Two different particle stages are examined: (i) Small shearable precipitates give rise to shear band formation and, during annealing, to nucleation of recrystallization at shear bands. (ii) Large particles cause particle stimulated nucleation of recrystallization (PSN). The microstructural evolution, particularly during recrystallization nucleation, is elucidated by metallographical investigations supported by EBSD local texture analysis.Both the initial grain size and the precipitation state strongly influence the evolution of the rolling textures. The results are interpreted with the help of Taylor-type deformation models. The recrystallization textures of Al-alloys emerge from a superposition of the orientations stemming from the various nucleation sites, i.e. Cube-bands, shear bands and particles. An increase of the initial grain size prior to deformation substantially shifts the recrystallization texture from the Cube-orientation towards the orientations being attributed to the other nucleation sites (shear bands, particles) which is interpreted by the spatial density of the various nucleation sites.

Cyclic Deformation Behaviour of Cu Multilayered Films on Si Substrates

2015 ◽  
Vol 825-826 ◽  
pp. 983-991
Author(s):  
Thomas Walter ◽  
Golta Khatibi ◽  
Michael Nelhiebel ◽  
Walther Heinz ◽  
Werner Robl
Keyword(s):  
Grain Size ◽  
Slip Band ◽  
Fatigue Damage ◽  
Surface Deformation ◽  
Fatigue Testing ◽  
Deformation Behaviour ◽  
Film Surface ◽  
Fatigue Behaviour ◽  
Band Formation ◽  
Cu Films

In the present study the high cycle fatigue behaviour of multilayered Cu films with different thicknesses and microstructure on silicon substrate was investigated. An ultrasonic resonance fatigue testing systems was used to study the isothermal mechanical fatigue behaviour of the Cu multilayers at room temperature and 150°C. Investigations of fatigue damage on the surface of the samples showed distinct slip band formation on preferentially oriented grains of the Cu metallization. The degree of fatigue damage, which could be related to the thickness, grain size and orientation of the Cu films, was evaluated by determination of the slip band density as a function of loading cycles. It was found that with increasing film thickness and grain size the density of deformed area strongly increases, with the majority of surface deformation occurring in the grains with ⟨111⟩ orientation with respect to the film surface. Furthermore increasing the testing temperature resulted in a significant degradation ofthe multilayered film stack due to a considerable increase in the degree of plastic deformation of theCu metallization layer.

scholarly journals Heat-Treatable Aluminum Alloys: Three-Point Bending

2019 ◽  
Author(s):  
Ida Westermann ◽  
Gaute Gruben
Keyword(s):  
Grain Size ◽  
Chemical Composition ◽  
Aluminum Alloys ◽  
Shear Band ◽  
Crack Propagation ◽  
Surface Topography ◽  
Shear Band Formation ◽  
Band Formation ◽  
Three Point Bending ◽  
Size And Morphology

In many applications within the automotive industry, the formability of sheets or extruded material is of great importance. The formability is strongly influenced by the chemical composition and the thermomechanical treatment prior to deformation. Grain size and morphology as well as texture and the presence of constituent particles make the material heavily anisotropic and the properties direction dependent. In all cases, shear band formation leads to surface topography during bending, and fracture initiates from the grooves. The crack propagation after initiation is, however, dependent on the grain size and the number and distribution of particles.

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