Abstract Wellbore instability problems cause nonproductive time, especially during drilling operations in the shale formations. These include stuck pipe, caving, lost circulation, and tight hole, requiring more time to treat therefore additional costs. The extensive hole collapse problem is considered one of main challenges experienced when Zubair formation. In turn, it caused by increasing wel...

Sometimes it is difficult to choose the most appropriate failure criterion for problem analyzed. For brittle materials, attention must be paid availability of experimental data and calibration representative parameters, within chosen criterion. The work herein presented, starting with an overview on machromechanical criteria, analysed in Haigh-Westergaard Stress Space, investigates suitability ...

Abstract Borehole breakout initiation, progression, and stabilization are modeled using a semi-analytical method based on Melentiev’s graphical conformal mapping procedure, Kolosov–Muskhelishvili complex stress potentials. The only input data required the elastic moduli of rock, Coulomb strength parameters (cohesion angle internal friction), far-field stresses. stresses around borehole wall com...

geometrical profile (roughness) of joint surfaces influences the behaviour of rock joints under shear loading. with regard to the dilation, there are two models of direct shear test that may simulate the original loading condition existing in the location from where the specimens have been sampled. the first model in which the normal load is constant (cnl) and the discontinuity is free to dilat...

‎in this study‎, ‎properties of spectral characteristic are investigated for‎ ‎singular sturm-liouville operators in the case where an eigen‎ ‎parameter not only appears in the differential equation but is‎ ‎also linearly contained in the jump conditions‎. ‎also weyl function‎ ‎for considering operator has been defined and the theorems which‎ ‎related to uniqueness of solution of inverse proble...

The stratification of entropy and the stratification of angular momentum are closely analogous. The analogy has been developed for a number of different problems in the fluid literature, but its consequences for the behavior of turbulent accretion disks are less appreciated. Of particular interest is the behavior of disks in which angular momentum transport is controlled by convection, and heat...

Based on a previous experimental study that we conducted granite joint replicas including thirty direct shear tests, this article proposes to integrate the roughness in Mohr-Coulomb behaviour model (MC). The integrates into constitutive stress-displacement relationships describing mechanical of rock joint. strength is assessed by MC criterion takes account apparent cohesion. This integrating co...

A rock failure criterion is very important for prediction of the ultimate strength in rock mechanics and geotechnics; it is determined for rock mechanics studies in mining, civil, and oil wellborn drilling operations. Also shales are among the most difficult to treat formations. Therefore, in this research work, using the artificial neural network (ANN), a model was built to predict the ultimat...

We develop a minimal theory for the recently observed metal-insulator transition (MIT) in two-dimensional (2D) moir\'e multilayer metal dichalcogenides (mTMD) using Coulomb disorder environment as underlying mechanism. In particular, carrier scattering by random charged impurities leads to an effective 2D MIT approximately controlled Ioffe-Regel criterion, which is qualitatively consistent with...