Abstract
Elastic waves cause energy loss during the transmission of coal measures. These losses include propagation loss, dielectric absorption loss, scattering loss, and frequency migration loss. The absorption loss is mainly caused by the inelastic absorption. The scattering loss is caused by the uneven heat absorption in the formation. The frequency shift loss is caused by the piezoelectric effect of coal-bearing formations and the intermodulation of different frequency signals. After considering the influence factors of the coal seam structure, this paper presents a model of low-frequency elastic waves loss coefficient. The paper proposed the loss coefficient of the elastic wave in the coal measure strata by considering two main attenuation mechanisms: intrinsic absorption and scattering. This paper theoretically studied the effects of the model parameters such as density, porosity, particle size, and wave frequency on the loss of wave energy using COMSOL simulation. Besides, the comparison of MATLAB simulation results shows that the simulation results produced by the model proposed in this paper are similar to the models embedded in COMSOL. This work can be applied to coal, oil, and gas exploration and is also helpful to study the mechanisms of wave attention on the low-frequency band.
Highlights
A portion of the energy of an elastic wave will be lost when the elastic wave propagates in a coal medium because of the nonperfect flexible and inhomogeneous characteristics of the medium. e sources of loss include absorption, scattering loss, and frequency migration loss
The wave attenuation in composite laminates is investigated by incorporating energy transfer onto a layer-wise medium. e overall attenuation coefficient for the laminate is obtained [6]. e ray-tracing method is another method that is often used to simulate the characteristics of elastic wave propagation attenuation and plane elastic waves propagation
Because it is challenging to simulate various forms of coal seams, the elastic wave energy loss formula model proposed to this paper is only an approximate value
Summary
A portion of the energy of an elastic wave will be lost when the elastic wave propagates in a coal medium because of the nonperfect flexible and inhomogeneous characteristics of the medium. e sources of loss include absorption, scattering loss, and frequency migration loss. Chirdon et al propose an elastic wave energy attenuation model to describe these losses in 2006 [1]. Song et al perform ray tracing based on an accurate near-surface velocity model to extract the signal from shot data and calculate macro-Q value based on the centroid frequency shift method. E final formula accurately simulated the absorption, but scattering loss was not considered. Many methods reveal part of the elastic wave propagation rules of different research perspectives and provide different respective formula models. We propose another loss coefficient model of a lowfrequency elastic wave of coal measure strata to solve the theoretical problems associated with estimating the propagation loss
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