Numerical simulation of seismic wave attenuation effects altered by hydraulic fracturing

We have used 2D numerical modelling on the synthetic digital rock to investigate the relationship between the seismic wave attenuation effects and the complexity of the fracture network induced by hydraulic fracturing (HF) at phases with different scales (levels) of fractures. The HF-induced fracture network at each phase is characterized by three geometry parameters, i.e. fracture inclination, area ratio and fractal dimension, from which the fracture complexity Fc is derived. The frequency-dependent quality factor Q and phase velocity dispersion spectra of both P and S waves are then obtained by 2D numerical modelling on the synthetic digital rocks. The normalized effective factor QV is derived from the modelling results for quantifying the attenuation effects of the fractured rock. The results show that QV increases with increasing Fc, i.e. attenuation effects are positively correlated to the fracture complexity. The arithmetic mean of QV and Fc provides a useful tool for quantifying the efficiency of the HF operation, which indicates all levels of fractures are of equal importance.