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Numerical Simulation for a Low-frequency Measurement Technique - Differential Acoustical Resonance Spectroscopy
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 77th EAGE Conference and Exhibition 2015, Jun 2015, Volume 2015, p.1 - 5
Abstract
Summary
Differential Acoustical Resonance Spectroscopy (DARS) has been developed to estimate the elastic properties of rock samples at kilohertz frequency range. The laboratory technique, which is based on a perturbation theory, measures the resonance frequencies of the resonator cavity with and without a test sample, and utilizes the resonant frequency shift to estimate the acoustic properties of the loaded sample. In order to better understand the operation mechanism of DARS, it is important to develop an accurate and efficient numerical simulation. This study presents a new multi-physics model for simulating the acoustic pressure field and identifying resonance frequencies of the DARS system through a standard finite element approach. The multi-physics numerical model is validated by using extensive experiment data for the empty cavity at three different resonance modes. It shows that the acoustic pressure fields and resonance frequencies are in fairly good agreement with the experiment data. Using simulated resonance frequencies with the newly developed numerical model, the DARS-estimated compressibility and density of the synthetic samples are very close to their true values. The numerical model is conducive to understanding the process of DARS, and can be used in the future for optimizing the low-frequency measurement technique.
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