Nonlinear Young’s Modulus of New Red Sandstone: Experimental Studies

Abstract

Young’s modulus of New Red Sandstone was investigated experimentally to gain insight into its nonlinear nature. A large experimental programme was carried out by applying a controllable quasi-static and dynamic uniaxial loading to 286 dry sandstone samples of four different sizes. The static and dynamic tests, similar to those aiming at determining the uniaxial compressive strength, were conducted using the state-of-the-art experimental facilities at the University of Aberdeen including a custom-built small experimental rig for inducing a dynamic uniaxial compressive load via a piezoelectric transducer. The obtained results have confirmed a complex nature of Young’s modulus of sandstone. Specifically, under a harmonic dynamic loading, it shows strongly nonlinear behaviour, which is hardening and softening with respect to frequency and amplitude of the dynamic loading, respectively.

Cyclic confining pressure and rock permeability: Mechanical compaction or fines migration

“…With each subsequent cycle it does not recover to the initial values and this phenomenon is also known as a permeability hysteresis [ [1] , [2] , [3] , [4] , [5] , [6] ]. According to the classical poromechanics theory, the apparent permeability degradation and hysteresis occur as a result of mechanical compaction by plastic deformations, and microcracks closure [ [7] , [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] ] which agrees well with rock mechanics [ [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] ]. In addition, during compaction, crushing of mineral grains can occur within the rocks as a result of which a certain amount of detrital material can form [ 56 ] with a size from a few microns (colloids) to tens of microns (fines) which is especially typical for higher loads.…”

The Effect of Ultrasonic Alternating Loads on Restoration of Permeability of Sedimentary Rocks during Crude Paraffinic Oil Flow

“…Improvements are shown in Figure 5. The principle of operation of the Langevin emitter is based on the ability of the material (crystals) of a piezoceramic element to change its dimensions in an electric field (also known as the inverse piezoelectric effect and similarly used as in the experiments by [38]). The actuator is characterized by one dominant frequency, at which it produces the maximum amplitude of reciprocating motion (enters into a resonance state).…”

On Frequency-Dependent Rock Experiments: A Comparative Review

“…Ma [131] studied V P of water-and glycerine-saturated specimens. Riabokon et al [132] studied the non-linearity of 286 dry specimens at different strain amplitudes where Eddy Current Probe (ECP) and Laser Vibrometer (LV) measured axial and radial strains. Lu [133] measured axial and shear strains of artificial specimens (3D printed and otherwise) at different stress and loading conditions from 0.01 to 20 Hz using a pair of Laser Displacement Sensors (LDS).…”