Can we use seismic reflection data to infer the interconnectivity of fracture networks?

While variations of seismic reflection amplitudes with incidence angle (AVA) and azimuth have been widely used to provide information on geometric characteristics of fractures, this attribute has, as of yet, not been linked to fracture interconnectivity, which tends to govern the hydraulic property of the affected formation. This is due to limitations of the forward models considered to represent the corresponding seismic responses. Based on a poroelastic upscaling procedure and a subsequent plane-wave analysis, we show for the first time that seismic reflection coefficients are highly sensitive to fracture interconnectivity. Moreover, our results suggest that crossplots of commonly used AVA coefficients can be used to delineate regions of fractured formations with higher or lower fracture interconnectivity. This sensitivity is due to changes of the stiffening effect of the fluid contained within interconnected fractures in response to wave-induced fluid-pressure diffusion, a physical process that has not been previously accounted for in seismic reflection analyses.