scholarly journals Dynamical effects during compaction band formation affecting their spatial periodicity

2014 ◽  
Vol 119 (10) ◽  
pp. 7487-7502 ◽  
Author(s):  
Francesco Cecinato ◽  
Alessandro Gajo
Keyword(s):  
Band Formation ◽  
Spatial Periodicity ◽  
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

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

scholarly journals Time-dependent compaction band formation in sandstone

2015 ◽  
Vol 120 (7) ◽  
pp. 4808-4830 ◽  
Author(s):  
Michael J. Heap ◽  
Nicolas Brantut ◽  
Patrick Baud ◽  
Philip G. Meredith
Keyword(s):  
Time Dependent ◽  
Band Formation ◽  
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 Dzyaloshinskii–Moriya interaction in noncentrosymmetric superlattices

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Woo Seung Ham ◽  
Abdul-Muizz Pradipto ◽  
Kay Yakushiji ◽  
Kwangsu Kim ◽  
Sonny H. Rhim ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Degrees Of Freedom ◽  
Orbit Coupling ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Band Formation ◽  
Research Activities ◽  
Moriya Interaction

AbstractDzyaloshinskii–Moriya interaction (DMI) is considered as one of the most important energies for specific chiral textures such as magnetic skyrmions. The keys of generating DMI are the absence of structural inversion symmetry and exchange energy with spin–orbit coupling. Therefore, a vast majority of research activities about DMI are mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report an asymmetric band formation in a superlattices (SL) which arises from inversion symmetry breaking in stacking order of atomic layers, implying the role of bulk-like contribution. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin–orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Our work provides more degrees of freedom to design chiral magnets for spintronics applications.

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