An enhanced broad-frequency-band apparatus for dynamic measurement of elastic moduli and Poisson’s ratio of rock samples

Abstract

We built a broad-frequency-band measurement system for rock elastic parameters based on the stress-strain method following Batzle et al., Geophysics 71, N1-N9 (2006). The system gives strain amplitude anomalies at some measurement frequencies. These anomalies put limitations on the range of the measurement frequency and jeopardize the credibility of the measurement results over a broad frequency band. To overcome these limitations, we investigated the cause of these anomalous strains by numerical model simulations with a finite element method based on the experimental apparatus. Through the systematic analysis of the modeling results, we conclude that the resonances caused by non-axial perturbations lead to such anomalous measurement results. Based on the analysis, we give a solution to reduce the effect of the resonances and shift the first resonance frequency beyond the frequency band of 1-2000 Hz. The enhanced measurement system can provide robust and reliable measurements on the elastic parameters of rocks between 1 and 2000 Hz, which is crucial for a quantitative study of the frequency-dependent phenomenon related to fluid effects. This in turn will provide a powerful tool for the experimental characterization of elastic properties of oil/gas reservoir rocks, thus laying a solid foundation for low-frequency rock physics analysis and quantitative seismic interpretation.

An apparatus to measure elastic dispersion and attenuation using hydrostatic- and axial-stress oscillations under undrained conditions

“…scitation.org/journal/rsi (2011), Tisato and Madonna (2012), Szewczyk et al (2016), and Sun et al (2018)]. The apparatus developed by Jackson and Paterson (1993) is able to measure the shear modulus and Young's modulus up to 1 Hz, through torsional and flexural oscillations, respectively (Jackson et al, 2011).…”

Dispersion and Attenuation of Elastic Wave Velocities: Impact of Microstructure Heterogeneity and Local Measurements

“…Here, we briefly present some information of the apparatus used in our experiments. More details can be found in the papers of Yin et al (2017) and Sun et al (2018). An oscillating stress is applied axially at a given frequency to the column consisting of the rock sample and two end-caps (i.e., reference aluminum, Figure 1).…”

A Laboratory Forced-Oscillation Apparatus for Measurements of Elastic and Anelastic Properties of Rocks at Seismic Frequencies

“…The FO laboratory apparatuses, which are capable of measuring the complete set of elastic moduli, such as Young's, bulk and shear moduli, and also satisfy the strain-amplitude and boundary conditions, were designed by Spencer et al (1994); Batzle et al (2006), Mikhaltsevitch et al (2014); Pimienta et al (2015), Szewczyk et al (2016); Sun et al (2018), and Borgomano et al (2020).…”

“…In the devices proposed by Spencer et al (1994); Batzle et al (2006) and Sun et al (2018) the hydrostatic confining pressure is exerted by pressurized nitrogen gas. An axial periodical dynamic force is applied to the sample by an electromechanical shaker at a frequency of 0.2-155 Hz (Spencer et al, 1994), 5 Hz-2 kHz (Batzle et al, 2006), or 1 Hz-2 kHz (Sun et al, 2018).…”

“…In the devices proposed by Spencer et al (1994); Batzle et al (2006) and Sun et al (2018) the hydrostatic confining pressure is exerted by pressurized nitrogen gas. An axial periodical dynamic force is applied to the sample by an electromechanical shaker at a frequency of 0.2-155 Hz (Spencer et al, 1994), 5 Hz-2 kHz (Batzle et al, 2006), or 1 Hz-2 kHz (Sun et al, 2018). Since the shaker is unable to operate under high load, the entire device, including the jacketed rock sample with two strain gauges (Batzle et al, 2006) or capacitive displacement transducers (Spencer et al, 1994) to measure axial and radial strains, is mounted inside a gas pressure vessel.…”