A theoretical study on Krauklis wave characteristics

Abstract The Krauklis wave is a special seismic phenomenon in fluid saturated fracture medium. The wave can prompt a unique resonance effect and enhance the amplitude at special frequencies. These frequencies have a quantitative relationship with the fracture geometry parameters and can be used for quantitative interpretation of geometry parameters. Such frequency information can be transmitted to body waves by the transformation between the Krauklis wave and the body wave. Both P- and S-waves become frequency dependent. In this study, an original numerical method is brought out to solve the equation of the Krauklis wave dispersion relation. The method has fine computational performance, and the frequency band for numerical solution is extended to the megahertz level. The dispersion, resonance, and attenuation of the Krauklis wave can be analyzed within the entire frequency range for Krauklis wave existence. What is more, the formation mechanism, existence, and observability are illuminated. The analysis shows that there are upper limits of frequency and fracture aperture for Krauklis wave existence, but within the frequency band for artificial seismic and micro-seismic exploration, the Krauklis wave exists widely. For experimental research, the frequency and fracture aperture should be well designed to ensure the generation of the Krauklis wave. The attenuation of the Krauklis wave can suppress the resonance effect. The influence of the attenuation should be taken into account, when the wave is used for seismic characterization of fracture reservoirs or micro-seismic monitoring of hydraulic fracturing.