Attenuation and dispersion characteristics of P-waves based on the three-dimensional pore network model

When propagating in a porous medium containing fluid, the wave field will undergo dispersion and attenuation. Such phenomena are related to the petrophysical properties of the porous medium, including porosity, permeability, fluid properties and so forth. In previous work, based on the three-dimensional fracture/soft pore network model, the variation of the aspect ratio of the ellipse section is used to simulate a variety of conditions from flat fractures to soft pores to hard pores, but does not consider the global network space containing both pores and fractures. To better describe the fracture-pore space, we propose three-dimensional fracturepore network and the method to calculate the permeability. Through volume averaging, we derive the wave equations of these two three-dimensional pore network models. Then, the expressions of dispersion/attenuation curves of P-waves are obtained by plane wave analysis. And by using numerical simulation, many influence factors are analyzed for the attenuation and dispersion of P waves, such as total porosity, fracture porosity, fracture aspect ratio, fracture density and pore fluid viscosity. Results show that based on the 3D fracture-pore network model, the effects of total porosity and fracture parameters on the dispersion/attenuation of fast P-waves and the dispersion/attenuation trend of slow P -waves are similar to those of the 3D fracture/soft pore network model. Specifically, the attenuation and dispersion of fast P-waves occur in highfrequency bands. The change of porosity mainly affects the peak value of inverse quality factor curve. The fracture density mainly controls the range of significant change in velocity. And the fracture aspect ratio has a significant effect on the P -wave velocity and characteristic frequency.